text: #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  #
  
  import copy
  import itertools
  import json
  import logging
  import math
  import socket
  import traceback
  from collections import defaultdict
  from datetime import datetime, timedelta
  from json import JSONDecodeError
  from typing import Dict, List, Optional, Tuple
  from urllib.parse import unquote
  
  import lazy_object_proxy
  import nvd3
  import sqlalchemy as sqla
  from flask import (
      Markup, Response, current_app, escape, flash, jsonify, make_response, redirect, render_template, request,
      session as flask_session, url_for,
  )
  from flask_appbuilder import BaseView, ModelView, expose, has_access, permission_name
  from flask_appbuilder.actions import action
  from flask_appbuilder.models.sqla.filters import BaseFilter
  from flask_babel import lazy_gettext
  from jinja2.utils import htmlsafe_json_dumps, pformat  # type: ignore
  from pygments import highlight, lexers
  from pygments.formatters import HtmlFormatter
  from sqlalchemy import and_, desc, func, or_, union_all
  from sqlalchemy.orm import joinedload
  from wtforms import SelectField, validators
  
  import airflow
  from airflow import models, settings
  from airflow.api.common.experimental.mark_tasks import (
      set_dag_run_state_to_failed, set_dag_run_state_to_success,
  )
  from airflow.configuration import AIRFLOW_CONFIG, conf
  from airflow.exceptions import AirflowException
  from airflow.executors.executor_loader import ExecutorLoader
  from airflow.jobs.base_job import BaseJob
  from airflow.jobs.scheduler_job import SchedulerJob
  from airflow.models import Connection, DagModel, DagTag, Log, SlaMiss, TaskFail, XCom, errors
  from airflow.models.dagcode import DagCode
  from airflow.models.dagrun import DagRun, DagRunType
  from airflow.ti_deps.dep_context import DepContext
  from airflow.ti_deps.dependencies_deps import RUNNING_DEPS, SCHEDULER_QUEUED_DEPS
  from airflow.utils import timezone
  from airflow.utils.dates import infer_time_unit, scale_time_units
  from airflow.utils.helpers import alchemy_to_dict
  from airflow.utils.log.log_reader import TaskLogReader
  from airflow.utils.platform import get_airflow_git_version
  from airflow.utils.session import create_session, provide_session
  from airflow.utils.state import State
  from airflow.www import utils as wwwutils
  from airflow.www.decorators import action_logging, gzipped, has_dag_access
  from airflow.www.forms import (
      ConnectionForm, DagRunForm, DateTimeForm, DateTimeWithNumRunsForm, DateTimeWithNumRunsWithDagRunsForm,
  )
  from airflow.www.widgets import AirflowModelListWidget
  
  PAGE_SIZE = conf.getint('webserver', 'page_size')
  FILTER_TAGS_COOKIE = 'tags_filter'
  FILTER_STATUS_COOKIE = 'dag_status_filter'
  
  
  def get_date_time_num_runs_dag_runs_form_data(request, session, dag):
      """Get Execution Data, Base Date & Number of runs from a Request """
      dttm = request.args.get('execution_date')
      if dttm:
          dttm = timezone.parse(dttm)
      else:
          dttm = dag.get_latest_execution_date(session=session) or timezone.utcnow()
  
      base_date = request.args.get('base_date')
      if base_date:
          base_date = timezone.parse(base_date)
      else:
          # The DateTimeField widget truncates milliseconds and would loose
          # the first dag run. Round to next second.
          base_date = (dttm + timedelta(seconds=1)).replace(microsecond=0)
  
      default_dag_run = conf.getint('webserver', 'default_dag_run_display_number')
      num_runs = request.args.get('num_runs')
      num_runs = int(num_runs) if num_runs else default_dag_run
  
      DR = models.DagRun
      drs = (
          session.query(DR)
          .filter(
              DR.dag_id == dag.dag_id,
              DR.execution_date <= base_date)
          .order_by(desc(DR.execution_date))
          .limit(num_runs)
          .all()
      )
      dr_choices = []
      dr_state = None
      for dr in drs:
          dr_choices.append((dr.execution_date.isoformat(), dr.run_id))
          if dttm == dr.execution_date:
              dr_state = dr.state
  
      # Happens if base_date was changed and the selected dag run is not in result
      if not dr_state and drs:
          dr = drs[0]
          dttm = dr.execution_date
          dr_state = dr.state
  
      return {
          'dttm': dttm,
          'base_date': base_date,
          'num_runs': num_runs,
          'execution_date': dttm.isoformat(),
          'dr_choices': dr_choices,
          'dr_state': dr_state,
      }
  
  
  ######################################################################################
  #                                    Error handlers
  ######################################################################################
  
  def circles(error):
      """Show Circles on screen for any error in the Webserver"""
      return render_template(
          'airflow/circles.html', hostname=socket.getfqdn() if conf.getboolean(
              'webserver',
              'EXPOSE_HOSTNAME',
              fallback=True) else 'redact'), 404
  
  
  def show_traceback(error):
      """Show Traceback for a given error"""
      from airflow.utils import asciiart as ascii_
      return render_template(
          'airflow/traceback.html',
          hostname=socket.getfqdn() if conf.getboolean(
              'webserver',
              'EXPOSE_HOSTNAME',
              fallback=True) else 'redact',
          nukular=ascii_.nukular,
          info=traceback.format_exc() if conf.getboolean(
              'webserver',
              'EXPOSE_STACKTRACE',
              fallback=True) else 'Error! Please contact server admin'), 500
  
  ######################################################################################
  #                                    BaseViews
  ######################################################################################
  
  
  class AirflowBaseView(BaseView):  # noqa: D101
      """Base View to set Airflow related properties"""
      from airflow import macros
      route_base = ''
  
      # Make our macros available to our UI templates too.
      extra_args = {
          'macros': macros,
      }
  
      def render_template(self, *args, **kwargs):
          return super().render_template(
              *args,
              # Cache this at most once per request, not for the lifetime of the view instance
              scheduler_job=lazy_object_proxy.Proxy(SchedulerJob.most_recent_job),
              **kwargs
          )
  
  
  class Airflow(AirflowBaseView):  # noqa: D101
      @expose('/health')
      def health(self):
          """
          An endpoint helping check the health status of the Airflow instance,
          including metadatabase and scheduler.
          """
  
          payload = {
              'metadatabase': {'status': 'unhealthy'}
          }
  
          latest_scheduler_heartbeat = None
          scheduler_status = 'unhealthy'
          payload['metadatabase'] = {'status': 'healthy'}
          try:
              scheduler_job = SchedulerJob.most_recent_job()
  
              if scheduler_job:
                  latest_scheduler_heartbeat = scheduler_job.latest_heartbeat.isoformat()
                  if scheduler_job.is_alive():
                      scheduler_status = 'healthy'
          except Exception:
              payload['metadatabase']['status'] = 'unhealthy'
  
          payload['scheduler'] = {'status': scheduler_status,
                                  'latest_scheduler_heartbeat': latest_scheduler_heartbeat}
  
          return wwwutils.json_response(payload)
  
      @expose('/home')
      @has_access
      def index(self):
          hide_paused_dags_by_default = conf.getboolean('webserver',
                                                        'hide_paused_dags_by_default')
  
          default_dag_run = conf.getint('webserver', 'default_dag_run_display_number')
          num_runs = request.args.get('num_runs')
          num_runs = int(num_runs) if num_runs else default_dag_run
  
          def get_int_arg(value, default=0):
              try:
                  return int(value)
              except ValueError:
                  return default
  
          arg_current_page = request.args.get('page', '0')
          arg_search_query = request.args.get('search', None)
          arg_tags_filter = request.args.getlist('tags', None)
          arg_status_filter = request.args.get('status', None)
  
          if request.args.get('reset_tags') is not None:
              flask_session[FILTER_TAGS_COOKIE] = None
              arg_tags_filter = None
          else:
              cookie_val = flask_session.get(FILTER_TAGS_COOKIE)
              if arg_tags_filter:
                  flask_session[FILTER_TAGS_COOKIE] = ','.join(arg_tags_filter)
              elif cookie_val:
                  arg_tags_filter = cookie_val.split(',')
  
          if arg_status_filter is None:
              cookie_val = flask_session.get(FILTER_STATUS_COOKIE)
              if cookie_val:
                  arg_status_filter = cookie_val
              else:
                  arg_status_filter = 'active' if hide_paused_dags_by_default else 'all'
                  flask_session[FILTER_STATUS_COOKIE] = arg_status_filter
          else:
              status = arg_status_filter.strip().lower()
              flask_session[FILTER_STATUS_COOKIE] = status
              arg_status_filter = status
  
          dags_per_page = PAGE_SIZE
          current_page = get_int_arg(arg_current_page, default=0)
  
          start = current_page * dags_per_page
          end = start + dags_per_page
  
          # Get all the dag id the user could access
          filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
  
          with create_session() as session:
              # read orm_dags from the db
              dags_query = session.query(DagModel).filter(
                  ~DagModel.is_subdag, DagModel.is_active
              )
  
              if arg_search_query:
                  dags_query = dags_query.filter(
                      DagModel.dag_id.ilike('%' + arg_search_query + '%') |
                      DagModel.owners.ilike('%' + arg_search_query + '%')
                  )
  
              if arg_tags_filter:
                  dags_query = dags_query.filter(DagModel.tags.any(DagTag.name.in_(arg_tags_filter)))
  
              if 'all_dags' not in filter_dag_ids:
                  dags_query = dags_query.filter(DagModel.dag_id.in_(filter_dag_ids))
  
              all_dags = dags_query
              active_dags = dags_query.filter(~DagModel.is_paused)
              paused_dags = dags_query.filter(DagModel.is_paused)
  
              is_paused_count = dict(
                  all_dags.with_entities(DagModel.is_paused, func.count(DagModel.dag_id))
                  .group_by(DagModel.is_paused).all()
              )
              status_count_active = is_paused_count.get(False, 0)
              status_count_paused = is_paused_count.get(True, 0)
              all_dags_count = status_count_active + status_count_paused
              if arg_status_filter == 'active':
                  current_dags = active_dags
                  num_of_all_dags = status_count_active
              elif arg_status_filter == 'paused':
                  current_dags = paused_dags
                  num_of_all_dags = status_count_paused
              else:
                  current_dags = all_dags
                  num_of_all_dags = all_dags_count
  
              dags = current_dags.order_by(DagModel.dag_id).options(
                  joinedload(DagModel.tags)).offset(start).limit(dags_per_page).all()
  
              dagtags = session.query(DagTag.name).distinct(DagTag.name).all()
              tags = [
                  {"name": name, "selected": bool(arg_tags_filter and name in arg_tags_filter)}
                  for name, in dagtags
              ]
  
              import_errors = session.query(errors.ImportError).all()
  
          for ie in import_errors:
              flash(
                  "Broken DAG: [{ie.filename}] {ie.stacktrace}".format(ie=ie),
                  "dag_import_error")
  
          from airflow.plugins_manager import import_errors as plugin_import_errors
          for filename, stacktrace in plugin_import_errors.items():
              flash(
                  "Broken plugin: [{filename}] {stacktrace}".format(
                      stacktrace=stacktrace,
                      filename=filename),
                  "error")
  
          num_of_pages = int(math.ceil(num_of_all_dags / float(dags_per_page)))
  
          state_color_mapping = State.state_color.copy()
          state_color_mapping["null"] = state_color_mapping.pop(None)
  
          return self.render_template(
              'airflow/dags.html',
              dags=dags,
              current_page=current_page,
              search_query=arg_search_query if arg_search_query else '',
              page_size=dags_per_page,
              num_of_pages=num_of_pages,
              num_dag_from=min(start + 1, num_of_all_dags),
              num_dag_to=min(end, num_of_all_dags),
              num_of_all_dags=num_of_all_dags,
              paging=wwwutils.generate_pages(current_page,
                                             num_of_pages,
                                             search=escape(arg_search_query) if arg_search_query else None,
                                             status=arg_status_filter if arg_status_filter else None),
              num_runs=num_runs,
              tags=tags,
              state_color=state_color_mapping,
              status_filter=arg_status_filter,
              status_count_all=all_dags_count,
              status_count_active=status_count_active,
              status_count_paused=status_count_paused)
  
      @expose('/dag_stats', methods=['POST'])
      @has_access
      @provide_session
      def dag_stats(self, session=None):
          dr = models.DagRun
  
          allowed_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
          if 'all_dags' in allowed_dag_ids:
              allowed_dag_ids = [dag_id for dag_id, in session.query(models.DagModel.dag_id)]
  
          dag_state_stats = session.query(dr.dag_id, dr.state, sqla.func.count(dr.state))\
              .group_by(dr.dag_id, dr.state)
  
          # Filter by post parameters
          selected_dag_ids = {
              unquote(dag_id) for dag_id in request.form.getlist('dag_ids') if dag_id
          }
  
          if selected_dag_ids:
              filter_dag_ids = selected_dag_ids.intersection(allowed_dag_ids)
          else:
              filter_dag_ids = allowed_dag_ids
  
          if not filter_dag_ids:
              return wwwutils.json_response({})
  
          payload = {}
          dag_state_stats = dag_state_stats.filter(dr.dag_id.in_(filter_dag_ids))
          data = {}
  
          for dag_id, state, count in dag_state_stats:
              if dag_id not in data:
                  data[dag_id] = {}
              data[dag_id][state] = count
  
          for dag_id in filter_dag_ids:
              payload[dag_id] = []
              for state in State.dag_states:
                  count = data.get(dag_id, {}).get(state, 0)
                  payload[dag_id].append({
                      'state': state,
                      'count': count
                  })
  
          return wwwutils.json_response(payload)
  
      @expose('/task_stats', methods=['POST'])
      @has_access
      @provide_session
      def task_stats(self, session=None):
          TI = models.TaskInstance
          DagRun = models.DagRun
          Dag = models.DagModel
  
          allowed_dag_ids = set(current_app.appbuilder.sm.get_accessible_dag_ids())
  
          if not allowed_dag_ids:
              return wwwutils.json_response({})
  
          if 'all_dags' in allowed_dag_ids:
              allowed_dag_ids = {dag_id for dag_id, in session.query(models.DagModel.dag_id)}
  
          # Filter by post parameters
          selected_dag_ids = {
              unquote(dag_id) for dag_id in request.form.getlist('dag_ids') if dag_id
          }
  
          if selected_dag_ids:
              filter_dag_ids = selected_dag_ids.intersection(allowed_dag_ids)
          else:
              filter_dag_ids = allowed_dag_ids
  
          RunningDagRun = (
              session.query(DagRun.dag_id, DagRun.execution_date)
                     .join(Dag, Dag.dag_id == DagRun.dag_id)
                     .filter(DagRun.state == State.RUNNING, Dag.is_active)
          )
  
          if selected_dag_ids:
              RunningDagRun = RunningDagRun.filter(DagRun.dag_id.in_(filter_dag_ids))
          RunningDagRun = RunningDagRun.subquery('running_dag_run')
  
          # Select all task_instances from active dag_runs.
          RunningTI = (
              session.query(TI.dag_id.label('dag_id'), TI.state.label('state'))
                     .join(RunningDagRun,
                           and_(RunningDagRun.c.dag_id == TI.dag_id,
                                RunningDagRun.c.execution_date == TI.execution_date))
          )
          if selected_dag_ids:
              RunningTI = RunningTI.filter(TI.dag_id.in_(filter_dag_ids))
  
          if conf.getboolean('webserver', 'SHOW_RECENT_STATS_FOR_COMPLETED_RUNS', fallback=True):
              LastDagRun = (
                  session.query(
                      DagRun.dag_id,
                      sqla.func.max(DagRun.execution_date).label('execution_date')
                  )
                  .join(Dag, Dag.dag_id == DagRun.dag_id)
                  .filter(DagRun.state != State.RUNNING, Dag.is_active)
                  .group_by(DagRun.dag_id)
              )
  
              if selected_dag_ids:
                  LastDagRun = LastDagRun.filter(DagRun.dag_id.in_(filter_dag_ids))
              LastDagRun = LastDagRun.subquery('last_dag_run')
  
              # Select all task_instances from active dag_runs.
              # If no dag_run is active, return task instances from most recent dag_run.
              LastTI = (
                  session.query(TI.dag_id.label('dag_id'), TI.state.label('state'))
                         .join(LastDagRun,
                               and_(LastDagRun.c.dag_id == TI.dag_id,
                                    LastDagRun.c.execution_date == TI.execution_date))
              )
              if selected_dag_ids:
                  LastTI = LastTI.filter(TI.dag_id.in_(filter_dag_ids))
  
              FinalTI = union_all(LastTI, RunningTI).alias('final_ti')
          else:
              FinalTI = RunningTI.subquery('final_ti')
  
          qry = (
              session.query(FinalTI.c.dag_id, FinalTI.c.state, sqla.func.count())
                     .group_by(FinalTI.c.dag_id, FinalTI.c.state)
          )
  
          data = {}
          for dag_id, state, count in qry:
              if dag_id not in data:
                  data[dag_id] = {}
              data[dag_id][state] = count
  
          payload = {}
          for dag_id in filter_dag_ids:
              payload[dag_id] = []
              for state in State.task_states:
                  count = data.get(dag_id, {}).get(state, 0)
                  payload[dag_id].append({
                      'state': state,
                      'count': count
                  })
          return wwwutils.json_response(payload)
  
      @expose('/last_dagruns', methods=['POST'])
      @has_access
      @provide_session
      def last_dagruns(self, session=None):
          DagRun = models.DagRun
  
          allowed_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
  
          if 'all_dags' in allowed_dag_ids:
              allowed_dag_ids = [dag_id for dag_id, in session.query(models.DagModel.dag_id)]
  
          # Filter by post parameters
          selected_dag_ids = {
              unquote(dag_id) for dag_id in request.form.getlist('dag_ids') if dag_id
          }
  
          if selected_dag_ids:
              filter_dag_ids = selected_dag_ids.intersection(allowed_dag_ids)
          else:
              filter_dag_ids = allowed_dag_ids
  
          if not filter_dag_ids:
              return wwwutils.json_response({})
  
          query = session.query(
              DagRun.dag_id, sqla.func.max(DagRun.execution_date).label('last_run')
          ).group_by(DagRun.dag_id)
  
          # Filter to only ask for accessible and selected dags
          query = query.filter(DagRun.dag_id.in_(filter_dag_ids))
  
          resp = {
              r.dag_id.replace('.', '__dot__'): {
                  'dag_id': r.dag_id,
                  'last_run': r.last_run.isoformat(),
              } for r in query
          }
          return wwwutils.json_response(resp)
  
      @expose('/code')
      @has_dag_access(can_dag_read=True)
      @has_access
      @provide_session
      def code(self, session=None):
          all_errors = ""
  
          try:
              dag_id = request.args.get('dag_id')
              dag_orm = DagModel.get_dagmodel(dag_id, session=session)
              code = DagCode.get_code_by_fileloc(dag_orm.fileloc)
              html_code = Markup(highlight(
                  code, lexers.PythonLexer(), HtmlFormatter(linenos=True)))
  
          except Exception as e:
              all_errors += (
                  "Exception encountered during " +
                  "dag_id retrieval/dag retrieval fallback/code highlighting:\n\n{}\n".format(e)
              )
              html_code = Markup('<p>Failed to load file.</p><p>Details: {}</p>').format(
                  escape(all_errors))
  
          return self.render_template(
              'airflow/dag_code.html', html_code=html_code, dag=dag_orm, title=dag_id,
              root=request.args.get('root'),
              demo_mode=conf.getboolean('webserver', 'demo_mode'),
              wrapped=conf.getboolean('webserver', 'default_wrap'))
  
      @expose('/dag_details')
      @has_dag_access(can_dag_read=True)
      @has_access
      @provide_session
      def dag_details(self, session=None):
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
          title = "DAG details"
          root = request.args.get('root', '')
  
          TI = models.TaskInstance
          states = (
              session.query(TI.state, sqla.func.count(TI.dag_id))
                     .filter(TI.dag_id == dag_id)
                     .group_by(TI.state)
                     .all()
          )
  
          active_runs = models.DagRun.find(
              dag_id=dag_id,
              state=State.RUNNING,
              external_trigger=False
          )
  
          return self.render_template(
              'airflow/dag_details.html',
              dag=dag, title=title, root=root, states=states, State=State, active_runs=active_runs)
  
      @expose('/rendered')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      def rendered(self):
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          execution_date = request.args.get('execution_date')
          dttm = timezone.parse(execution_date)
          form = DateTimeForm(data={'execution_date': dttm})
          root = request.args.get('root', '')
  
          logging.info("Retrieving rendered templates.")
          dag = current_app.dag_bag.get_dag(dag_id)
  
          task = copy.copy(dag.get_task(task_id))
          ti = models.TaskInstance(task=task, execution_date=dttm)
          try:
              ti.get_rendered_template_fields()
          except AirflowException as e:
              msg = "Error rendering template: " + escape(e)
              if e.__cause__:
                  msg += Markup("<br/><br/>OriginalError: ") + escape(e.__cause__)
              flash(msg, "error")
          except Exception as e:
              flash("Error rendering template: " + str(e), "error")
          title = "Rendered Template"
          html_dict = {}
          for template_field in task.template_fields:
              content = getattr(task, template_field)
              if template_field in wwwutils.get_attr_renderer():
                  html_dict[template_field] = wwwutils.get_attr_renderer()[template_field](content)
              else:
                  html_dict[template_field] = Markup("<pre><code>{}</pre></code>").format(pformat(content))
  
          return self.render_template(
              'airflow/ti_code.html',
              html_dict=html_dict,
              dag=dag,
              task_id=task_id,
              execution_date=execution_date,
              form=form,
              root=root,
              title=title)
  
      @expose('/get_logs_with_metadata')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def get_logs_with_metadata(self, session=None):
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          execution_date = request.args.get('execution_date')
          if request.args.get('try_number') is not None:
              try_number = int(request.args.get('try_number'))
          else:
              try_number = None
          metadata = request.args.get('metadata')
          metadata = json.loads(metadata)
          response_format = request.args.get('format', 'json')
  
          # metadata may be null
          if not metadata:
              metadata = {}
  
          # Convert string datetime into actual datetime
          try:
              execution_date = timezone.parse(execution_date)
          except ValueError:
              error_message = (
                  'Given execution date, {}, could not be identified '
                  'as a date. Example date format: 2015-11-16T14:34:15+00:00'.format(
                      execution_date))
              response = jsonify({'error': error_message})
              response.status_code = 400
  
              return response
  
          task_log_reader = TaskLogReader()
          if not task_log_reader.supports_read:
              return jsonify(
                  message="Task log handler does not support read logs.",
                  error=True,
                  metadata={
                      "end_of_log": True
                  }
              )
  
          ti = session.query(models.TaskInstance).filter(
              models.TaskInstance.dag_id == dag_id,
              models.TaskInstance.task_id == task_id,
              models.TaskInstance.execution_date == execution_date).first()
  
          if ti is None:
              return jsonify(
                  message="*** Task instance did not exist in the DB\n",
                  error=True,
                  metadata={
                      "end_of_log": True
                  }
              )
  
          try:
              dag = current_app.dag_bag.get_dag(dag_id)
              if dag:
                  ti.task = dag.get_task(ti.task_id)
  
              if response_format == 'json':
                  logs, metadata = task_log_reader.read_log_chunks(ti, try_number, metadata)
                  message = logs[0] if try_number is not None else logs
                  return jsonify(message=message, metadata=metadata)
  
              metadata['download_logs'] = True
              attachment_filename = task_log_reader.render_log_filename(ti, try_number)
              log_stream = task_log_reader.read_log_stream(ti, try_number, metadata)
              return Response(
                  response=log_stream,
                  mimetype="text/plain",
                  headers={
                      "Content-Disposition": f"attachment; filename={attachment_filename}"
                  })
          except AttributeError as e:
              error_message = [
                  f"Task log handler does not support read logs.\n{str(e)}\n"
              ]
              metadata['end_of_log'] = True
              return jsonify(message=error_message, error=True, metadata=metadata)
  
      @expose('/log')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def log(self, session=None):
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          execution_date = request.args.get('execution_date')
          dttm = timezone.parse(execution_date)
          form = DateTimeForm(data={'execution_date': dttm})
          dag_model = DagModel.get_dagmodel(dag_id)
  
          ti = session.query(models.TaskInstance).filter(
              models.TaskInstance.dag_id == dag_id,
              models.TaskInstance.task_id == task_id,
              models.TaskInstance.execution_date == dttm).first()
  
          num_logs = 0
          if ti is not None:
              num_logs = ti.next_try_number - 1
              if ti.state == State.UP_FOR_RESCHEDULE:
                  # Tasks in reschedule state decremented the try number
                  num_logs += 1
          logs = [''] * num_logs
          root = request.args.get('root', '')
          return self.render_template(
              'airflow/ti_log.html',
              logs=logs, dag=dag_model, title="Log by attempts",
              dag_id=dag_id, task_id=task_id,
              execution_date=execution_date, form=form,
              root=root, wrapped=conf.getboolean('webserver', 'default_wrap'))
  
      @expose('/redirect_to_external_log')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def redirect_to_external_log(self, session=None):
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          execution_date = request.args.get('execution_date')
          dttm = timezone.parse(execution_date)
          try_number = request.args.get('try_number', 1)
  
          ti = session.query(models.TaskInstance).filter(
              models.TaskInstance.dag_id == dag_id,
              models.TaskInstance.task_id == task_id,
              models.TaskInstance.execution_date == dttm).first()
  
          if not ti:
              flash(f"Task [{dag_id}.{task_id}] does not exist", "error")
              return redirect(url_for('Airflow.index'))
  
          task_log_reader = TaskLogReader()
          if not task_log_reader.supports_external_link:
              flash("Task log handler does not support external links", "error")
              return redirect(url_for('Airflow.index'))
  
          handler = task_log_reader.log_handler
          url = handler.get_external_log_url(ti, try_number)
          return redirect(url)
  
      @expose('/task')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      def task(self):
          TI = models.TaskInstance
  
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          # Carrying execution_date through, even though it's irrelevant for
          # this context
          execution_date = request.args.get('execution_date')
          dttm = timezone.parse(execution_date)
          form = DateTimeForm(data={'execution_date': dttm})
          root = request.args.get('root', '')
          dag = current_app.dag_bag.get_dag(dag_id)
  
          if not dag or task_id not in dag.task_ids:
              flash(
                  "Task [{}.{}] doesn't seem to exist"
                  " at the moment".format(dag_id, task_id),
                  "error")
              return redirect(url_for('Airflow.index'))
          task = copy.copy(dag.get_task(task_id))
          task.resolve_template_files()
          ti = TI(task=task, execution_date=dttm)
          ti.refresh_from_db()
  
          ti_attrs = []
          for attr_name in dir(ti):
              if not attr_name.startswith('_'):
                  attr = getattr(ti, attr_name)
                  if type(attr) != type(self.task):  # noqa
                      ti_attrs.append((attr_name, str(attr)))
  
          task_attrs = []
          for attr_name in dir(task):
              if not attr_name.startswith('_'):
                  attr = getattr(task, attr_name)
                  if type(attr) != type(self.task) and \
                          attr_name not in wwwutils.get_attr_renderer():  # noqa
                      task_attrs.append((attr_name, str(attr)))
  
          # Color coding the special attributes that are code
          special_attrs_rendered = {}
          for attr_name in wwwutils.get_attr_renderer():
              if hasattr(task, attr_name):
                  source = getattr(task, attr_name)
                  special_attrs_rendered[attr_name] = \
                      wwwutils.get_attr_renderer()[attr_name](source)
  
          no_failed_deps_result = [(
              "Unknown",
              "All dependencies are met but the task instance is not running. In most "
              "cases this just means that the task will probably be scheduled soon "
              "unless:<br/>\n- The scheduler is down or under heavy load<br/>\n{}\n"
              "<br/>\nIf this task instance does not start soon please contact your "
              "Airflow administrator for assistance.".format(
                  "- This task instance already ran and had it's state changed manually "
                  "(e.g. cleared in the UI)<br/>" if ti.state == State.NONE else ""))]
  
          # Use the scheduler's context to figure out which dependencies are not met
          dep_context = DepContext(SCHEDULER_QUEUED_DEPS)
          failed_dep_reasons = [(dep.dep_name, dep.reason) for dep in
                                ti.get_failed_dep_statuses(
                                    dep_context=dep_context)]
  
          title = "Task Instance Details"
          return self.render_template(
              'airflow/task.html',
              task_attrs=task_attrs,
              ti_attrs=ti_attrs,
              failed_dep_reasons=failed_dep_reasons or no_failed_deps_result,
              task_id=task_id,
              execution_date=execution_date,
              special_attrs_rendered=special_attrs_rendered,
              form=form,
              root=root,
              dag=dag, title=title)
  
      @expose('/xcom')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def xcom(self, session=None):
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          # Carrying execution_date through, even though it's irrelevant for
          # this context
          execution_date = request.args.get('execution_date')
          dttm = timezone.parse(execution_date)
          form = DateTimeForm(data={'execution_date': dttm})
          root = request.args.get('root', '')
          dm_db = models.DagModel
          ti_db = models.TaskInstance
          dag = session.query(dm_db).filter(dm_db.dag_id == dag_id).first()
          ti = session.query(ti_db).filter(ti_db.dag_id == dag_id and ti_db.task_id == task_id).first()
  
          if not ti:
              flash(
                  "Task [{}.{}] doesn't seem to exist"
                  " at the moment".format(dag_id, task_id),
                  "error")
              return redirect(url_for('Airflow.index'))
  
          xcomlist = session.query(XCom).filter(
              XCom.dag_id == dag_id, XCom.task_id == task_id,
              XCom.execution_date == dttm).all()
  
          attributes = []
          for xcom in xcomlist:
              if not xcom.key.startswith('_'):
                  attributes.append((xcom.key, xcom.value))
  
          title = "XCom"
          return self.render_template(
              'airflow/xcom.html',
              attributes=attributes,
              task_id=task_id,
              execution_date=execution_date,
              form=form,
              root=root,
              dag=dag, title=title)
  
      @expose('/run', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def run(self):
          dag_id = request.form.get('dag_id')
          task_id = request.form.get('task_id')
          origin = request.form.get('origin')
          dag = current_app.dag_bag.get_dag(dag_id)
          task = dag.get_task(task_id)
  
          execution_date = request.form.get('execution_date')
          execution_date = timezone.parse(execution_date)
          ignore_all_deps = request.form.get('ignore_all_deps') == "true"
          ignore_task_deps = request.form.get('ignore_task_deps') == "true"
          ignore_ti_state = request.form.get('ignore_ti_state') == "true"
  
          executor = ExecutorLoader.get_default_executor()
          valid_celery_config = False
          valid_kubernetes_config = False
  
          try:
              from airflow.executors.celery_executor import CeleryExecutor
              valid_celery_config = isinstance(executor, CeleryExecutor)
          except ImportError:
              pass
  
          try:
              from airflow.executors.kubernetes_executor import KubernetesExecutor
              valid_kubernetes_config = isinstance(executor, KubernetesExecutor)
          except ImportError:
              pass
  
          if not valid_celery_config and not valid_kubernetes_config:
              flash("Only works with the Celery or Kubernetes executors, sorry", "error")
              return redirect(origin)
  
          ti = models.TaskInstance(task=task, execution_date=execution_date)
          ti.refresh_from_db()
  
          # Make sure the task instance can be run
          dep_context = DepContext(
              deps=RUNNING_DEPS,
              ignore_all_deps=ignore_all_deps,
              ignore_task_deps=ignore_task_deps,
              ignore_ti_state=ignore_ti_state)
          failed_deps = list(ti.get_failed_dep_statuses(dep_context=dep_context))
          if failed_deps:
              failed_deps_str = ", ".join(
                  ["{}: {}".format(dep.dep_name, dep.reason) for dep in failed_deps])
              flash("Could not queue task instance for execution, dependencies not met: "
                    "{}".format(failed_deps_str),
                    "error")
              return redirect(origin)
  
          executor.start()
          executor.queue_task_instance(
              ti,
              ignore_all_deps=ignore_all_deps,
              ignore_task_deps=ignore_task_deps,
              ignore_ti_state=ignore_ti_state)
          executor.heartbeat()
          flash(
              "Sent {} to the message queue, "
              "it should start any moment now.".format(ti))
          return redirect(origin)
  
      @expose('/delete', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def delete(self):
          from airflow.api.common.experimental import delete_dag
          from airflow.exceptions import DagNotFound, DagFileExists
  
          dag_id = request.values.get('dag_id')
          origin = request.values.get('origin') or url_for('Airflow.index')
  
          try:
              delete_dag.delete_dag(dag_id)
          except DagNotFound:
              flash("DAG with id {} not found. Cannot delete".format(dag_id), 'error')
              return redirect(request.referrer)
          except DagFileExists:
              flash("Dag id {} is still in DagBag. "
                    "Remove the DAG file first.".format(dag_id),
                    'error')
              return redirect(request.referrer)
  
          flash("Deleting DAG with id {}. May take a couple minutes to fully"
                " disappear.".format(dag_id))
  
          # Upon success return to origin.
          return redirect(origin)
  
      @expose('/trigger', methods=['POST', 'GET'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      @provide_session
      def trigger(self, session=None):
  
          dag_id = request.values.get('dag_id')
          origin = request.values.get('origin') or url_for('Airflow.index')
  
          if request.method == 'GET':
              return self.render_template(
                  'airflow/trigger.html',
                  dag_id=dag_id,
                  origin=origin,
                  conf=''
              )
  
          dag_orm = session.query(models.DagModel).filter(models.DagModel.dag_id == dag_id).first()
          if not dag_orm:
              flash("Cannot find dag {}".format(dag_id))
              return redirect(origin)
  
          execution_date = timezone.utcnow()
  
          dr = DagRun.find(dag_id=dag_id, execution_date=execution_date, run_type=DagRunType.MANUAL)
          if dr:
              flash(f"This run_id {dr.run_id} already exists")
              return redirect(origin)
  
          run_conf = {}
          conf = request.values.get('conf')
          if conf:
              try:
                  run_conf = json.loads(conf)
              except json.decoder.JSONDecodeError:
                  flash("Invalid JSON configuration", "error")
                  return self.render_template(
                      'airflow/trigger.html',
                      dag_id=dag_id,
                      origin=origin,
                      conf=conf
                  )
  
          dag = current_app.dag_bag.get_dag(dag_id)
          dag.create_dagrun(
              run_type=DagRunType.MANUAL,
              execution_date=execution_date,
              state=State.RUNNING,
              conf=run_conf,
              external_trigger=True,
          )
  
          flash(
              "Triggered {}, "
              "it should start any moment now.".format(dag_id))
          return redirect(origin)
  
      def _clear_dag_tis(self, dag, start_date, end_date, origin,
                         recursive=False, confirmed=False, only_failed=False):
          if confirmed:
              count = dag.clear(
                  start_date=start_date,
                  end_date=end_date,
                  include_subdags=recursive,
                  include_parentdag=recursive,
                  only_failed=only_failed,
              )
  
              flash("{0} task instances have been cleared".format(count))
              return redirect(origin)
  
          try:
              tis = dag.clear(
                  start_date=start_date,
                  end_date=end_date,
                  include_subdags=recursive,
                  include_parentdag=recursive,
                  only_failed=only_failed,
                  dry_run=True,
              )
          except AirflowException as ex:
              flash(str(ex), 'error')
              return redirect(origin)
  
          if not tis:
              flash("No task instances to clear", 'error')
              response = redirect(origin)
          else:
              details = "\n".join([str(t) for t in tis])
  
              response = self.render_template(
                  'airflow/confirm.html',
                  message=("Here's the list of task instances you are about "
                           "to clear:"),
                  details=details)
  
          return response
  
      @expose('/clear', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def clear(self):
          dag_id = request.form.get('dag_id')
          task_id = request.form.get('task_id')
          origin = request.form.get('origin')
          dag = current_app.dag_bag.get_dag(dag_id)
  
          execution_date = request.form.get('execution_date')
          execution_date = timezone.parse(execution_date)
          confirmed = request.form.get('confirmed') == "true"
          upstream = request.form.get('upstream') == "true"
          downstream = request.form.get('downstream') == "true"
          future = request.form.get('future') == "true"
          past = request.form.get('past') == "true"
          recursive = request.form.get('recursive') == "true"
          only_failed = request.form.get('only_failed') == "true"
  
          dag = dag.sub_dag(
              task_regex=r"^{0}$".format(task_id),
              include_downstream=downstream,
              include_upstream=upstream)
  
          end_date = execution_date if not future else None
          start_date = execution_date if not past else None
  
          return self._clear_dag_tis(dag, start_date, end_date, origin,
                                     recursive=recursive, confirmed=confirmed, only_failed=only_failed)
  
      @expose('/dagrun_clear', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def dagrun_clear(self):
          dag_id = request.form.get('dag_id')
          origin = request.form.get('origin')
          execution_date = request.form.get('execution_date')
          confirmed = request.form.get('confirmed') == "true"
  
          dag = current_app.dag_bag.get_dag(dag_id)
          execution_date = timezone.parse(execution_date)
          start_date = execution_date
          end_date = execution_date
  
          return self._clear_dag_tis(dag, start_date, end_date, origin,
                                     recursive=True, confirmed=confirmed)
  
      @expose('/blocked', methods=['POST'])
      @has_access
      @provide_session
      def blocked(self, session=None):
          allowed_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
  
          if 'all_dags' in allowed_dag_ids:
              allowed_dag_ids = [dag_id for dag_id, in session.query(models.DagModel.dag_id)]
  
          # Filter by post parameters
          selected_dag_ids = {
              unquote(dag_id) for dag_id in request.form.getlist('dag_ids') if dag_id
          }
  
          if selected_dag_ids:
              filter_dag_ids = selected_dag_ids.intersection(allowed_dag_ids)
          else:
              filter_dag_ids = allowed_dag_ids
  
          if not filter_dag_ids:
              return wwwutils.json_response([])
  
          DR = models.DagRun
  
          dags = (
              session.query(DR.dag_id, sqla.func.count(DR.id))
                     .filter(DR.state == State.RUNNING)
                     .filter(DR.dag_id.in_(filter_dag_ids))
                     .group_by(DR.dag_id)
          )
  
          payload = []
          for dag_id, active_dag_runs in dags:
              max_active_runs = 0
              dag = current_app.dag_bag.get_dag(dag_id)
              if dag:
                  # TODO: Make max_active_runs a column so we can query for it directly
                  max_active_runs = dag.max_active_runs
              payload.append({
                  'dag_id': dag_id,
                  'active_dag_run': active_dag_runs,
                  'max_active_runs': max_active_runs,
              })
          return wwwutils.json_response(payload)
  
      def _mark_dagrun_state_as_failed(self, dag_id, execution_date, confirmed, origin):
          if not execution_date:
              flash('Invalid execution date', 'error')
              return redirect(origin)
  
          execution_date = timezone.parse(execution_date)
          dag = current_app.dag_bag.get_dag(dag_id)
  
          if not dag:
              flash('Cannot find DAG: {}'.format(dag_id), 'error')
              return redirect(origin)
  
          new_dag_state = set_dag_run_state_to_failed(dag, execution_date, commit=confirmed)
  
          if confirmed:
              flash('Marked failed on {} task instances'.format(len(new_dag_state)))
              return redirect(origin)
  
          else:
              details = '\n'.join([str(t) for t in new_dag_state])
  
              response = self.render_template(
                  'airflow/confirm.html',
                  message="Here's the list of task instances you are about to mark as failed",
                  details=details)
  
              return response
  
      def _mark_dagrun_state_as_success(self, dag_id, execution_date, confirmed, origin):
          if not execution_date:
              flash('Invalid execution date', 'error')
              return redirect(origin)
  
          execution_date = timezone.parse(execution_date)
          dag = current_app.dag_bag.get_dag(dag_id)
  
          if not dag:
              flash('Cannot find DAG: {}'.format(dag_id), 'error')
              return redirect(origin)
  
          new_dag_state = set_dag_run_state_to_success(dag, execution_date,
                                                       commit=confirmed)
  
          if confirmed:
              flash('Marked success on {} task instances'.format(len(new_dag_state)))
              return redirect(origin)
  
          else:
              details = '\n'.join([str(t) for t in new_dag_state])
  
              response = self.render_template(
                  'airflow/confirm.html',
                  message="Here's the list of task instances you are about to mark as success",
                  details=details)
  
              return response
  
      @expose('/dagrun_failed', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def dagrun_failed(self):
          dag_id = request.form.get('dag_id')
          execution_date = request.form.get('execution_date')
          confirmed = request.form.get('confirmed') == 'true'
          origin = request.form.get('origin')
          return self._mark_dagrun_state_as_failed(dag_id, execution_date,
                                                   confirmed, origin)
  
      @expose('/dagrun_success', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def dagrun_success(self):
          dag_id = request.form.get('dag_id')
          execution_date = request.form.get('execution_date')
          confirmed = request.form.get('confirmed') == 'true'
          origin = request.form.get('origin')
          return self._mark_dagrun_state_as_success(dag_id, execution_date,
                                                    confirmed, origin)
  
      def _mark_task_instance_state(self, dag_id, task_id, origin, execution_date,
                                    confirmed, upstream, downstream,
                                    future, past, state):
          dag = current_app.dag_bag.get_dag(dag_id)
          task = dag.get_task(task_id)
          task.dag = dag
  
          latest_execution_date = dag.get_latest_execution_date()
          if not latest_execution_date:
              flash(f"Cannot make {state}, seem that dag {dag_id} has never run", "error")
              return redirect(origin)
  
          execution_date = timezone.parse(execution_date)
  
          from airflow.api.common.experimental.mark_tasks import set_state
  
          if confirmed:
              altered = set_state(tasks=[task], execution_date=execution_date,
                                  upstream=upstream, downstream=downstream,
                                  future=future, past=past, state=state,
                                  commit=True)
  
              flash("Marked {} on {} task instances".format(state, len(altered)))
              return redirect(origin)
  
          to_be_altered = set_state(tasks=[task], execution_date=execution_date,
                                    upstream=upstream, downstream=downstream,
                                    future=future, past=past, state=state,
                                    commit=False)
  
          details = "\n".join([str(t) for t in to_be_altered])
  
          response = self.render_template(
              "airflow/confirm.html",
              message=("Here's the list of task instances you are about to mark as {}:".format(state)),
              details=details)
  
          return response
  
      @expose('/failed', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def failed(self):
          dag_id = request.form.get('dag_id')
          task_id = request.form.get('task_id')
          origin = request.form.get('origin')
          execution_date = request.form.get('execution_date')
  
          confirmed = request.form.get('confirmed') == "true"
          upstream = request.form.get('failed_upstream') == "true"
          downstream = request.form.get('failed_downstream') == "true"
          future = request.form.get('failed_future') == "true"
          past = request.form.get('failed_past') == "true"
  
          return self._mark_task_instance_state(dag_id, task_id, origin, execution_date,
                                                confirmed, upstream, downstream,
                                                future, past, State.FAILED)
  
      @expose('/success', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def success(self):
          dag_id = request.form.get('dag_id')
          task_id = request.form.get('task_id')
          origin = request.form.get('origin')
          execution_date = request.form.get('execution_date')
  
          confirmed = request.form.get('confirmed') == "true"
          upstream = request.form.get('success_upstream') == "true"
          downstream = request.form.get('success_downstream') == "true"
          future = request.form.get('success_future') == "true"
          past = request.form.get('success_past') == "true"
  
          return self._mark_task_instance_state(dag_id, task_id, origin, execution_date,
                                                confirmed, upstream, downstream,
                                                future, past, State.SUCCESS)
  
      @expose('/tree')
      @has_dag_access(can_dag_read=True)
      @has_access
      @gzipped
      @action_logging
      def tree(self):
          dag_id = request.args.get('dag_id')
          blur = conf.getboolean('webserver', 'demo_mode')
          dag = current_app.dag_bag.get_dag(dag_id)
          if not dag:
              flash('DAG "{0}" seems to be missing from DagBag.'.format(dag_id), "error")
              return redirect(url_for('Airflow.index'))
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_downstream=False,
                  include_upstream=True)
  
          base_date = request.args.get('base_date')
          num_runs = request.args.get('num_runs')
          if num_runs:
              num_runs = int(num_runs)
          else:
              num_runs = conf.getint('webserver', 'default_dag_run_display_number')
  
          if base_date:
              base_date = timezone.parse(base_date)
          else:
              base_date = dag.get_latest_execution_date() or timezone.utcnow()
  
          with create_session() as session:
              dag_runs = (
                  session.query(DagRun)
                  .filter(
                      DagRun.dag_id == dag.dag_id,
                      DagRun.execution_date <= base_date)
                  .order_by(DagRun.execution_date.desc())
                  .limit(num_runs)
                  .all()
              )
          dag_runs = {
              dr.execution_date: alchemy_to_dict(dr) for dr in dag_runs
          }
  
          dates = sorted(list(dag_runs.keys()))
          max_date = max(dates) if dates else None
          min_date = min(dates) if dates else None
  
          tis = dag.get_task_instances(start_date=min_date, end_date=base_date)
          task_instances: Dict[Tuple[str, datetime], models.TaskInstance] = {}
          for ti in tis:
              task_instances[(ti.task_id, ti.execution_date)] = ti
  
          expanded = set()
          # The default recursion traces every path so that tree view has full
          # expand/collapse functionality. After 5,000 nodes we stop and fall
          # back on a quick DFS search for performance. See PR #320.
          node_count = 0
          node_limit = 5000 / max(1, len(dag.leaves))
  
          def encode_ti(ti: Optional[models.TaskInstance]) -> Optional[List]:
              if not ti:
                  return None
  
              # NOTE: order of entry is important here because client JS relies on it for
              # tree node reconstruction. Remember to change JS code in tree.html
              # whenever order is altered.
              data = [
                  ti.state,
                  ti.try_number,
                  None,  # start_ts
                  None,  # duration
              ]
  
              if ti.start_date:
                  # round to seconds to reduce payload size
                  data[2] = int(ti.start_date.timestamp())
                  if ti.duration is not None:
                      data[3] = int(ti.duration)
  
              return data
  
          def recurse_nodes(task, visited):
              nonlocal node_count
              node_count += 1
              visited.add(task)
              task_id = task.task_id
  
              node = {
                  'name': task.task_id,
                  'instances': [
                      encode_ti(task_instances.get((task_id, d)))
                      for d in dates
                  ],
                  'num_dep': len(task.downstream_list),
                  'operator': task.task_type,
                  'retries': task.retries,
                  'owner': task.owner,
                  'ui_color': task.ui_color,
              }
  
              if task.downstream_list:
                  children = [
                      recurse_nodes(t, visited) for t in task.downstream_list
                      if node_count < node_limit or t not in visited]
  
                  # D3 tree uses children vs _children to define what is
                  # expanded or not. The following block makes it such that
                  # repeated nodes are collapsed by default.
                  if task.task_id not in expanded:
                      children_key = 'children'
                      expanded.add(task.task_id)
                  else:
                      children_key = "_children"
                  node[children_key] = children
  
              if task.depends_on_past:
                  node['depends_on_past'] = task.depends_on_past
              if task.start_date:
                  # round to seconds to reduce payload size
                  node['start_ts'] = int(task.start_date.timestamp())
                  if task.end_date:
                      # round to seconds to reduce payload size
                      node['end_ts'] = int(task.end_date.timestamp())
              if task.extra_links:
                  node['extra_links'] = task.extra_links
              return node
  
          data = {
              'name': '[DAG]',
              'children': [recurse_nodes(t, set()) for t in dag.roots],
              'instances': [
                  dag_runs.get(d) or {'execution_date': d.isoformat()}
                  for d in dates
              ],
          }
  
          form = DateTimeWithNumRunsForm(data={'base_date': max_date,
                                               'num_runs': num_runs})
  
          doc_md = wwwutils.wrapped_markdown(getattr(dag, 'doc_md', None), css_class='dag-doc')
  
          task_log_reader = TaskLogReader()
          if task_log_reader.supports_external_link:
              external_log_name = task_log_reader.log_handler.log_name
          else:
              external_log_name = None
  
          # avoid spaces to reduce payload size
          data = htmlsafe_json_dumps(data, separators=(',', ':'))
  
          return self.render_template(
              'airflow/tree.html',
              operators=sorted({op.task_type: op for op in dag.tasks}.values(), key=lambda x: x.task_type),
              root=root,
              form=form,
              dag=dag,
              doc_md=doc_md,
              data=data,
              blur=blur, num_runs=num_runs,
              show_external_log_redirect=task_log_reader.supports_external_link,
              external_log_name=external_log_name)
  
      @expose('/graph')
      @has_dag_access(can_dag_read=True)
      @has_access
      @gzipped
      @action_logging
      @provide_session
      def graph(self, session=None):
          dag_id = request.args.get('dag_id')
          blur = conf.getboolean('webserver', 'demo_mode')
          dag = current_app.dag_bag.get_dag(dag_id)
          if not dag:
              flash('DAG "{0}" seems to be missing.'.format(dag_id), "error")
              return redirect(url_for('Airflow.index'))
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_upstream=True,
                  include_downstream=False)
  
          arrange = request.args.get('arrange', dag.orientation)
  
          nodes = []
          edges = []
          for task in dag.tasks:
              nodes.append({
                  'id': task.task_id,
                  'value': {
                      'label': task.task_id,
                      'labelStyle': "fill:{0};".format(task.ui_fgcolor),
                      'style': "fill:{0};".format(task.ui_color),
                      'rx': 5,
                      'ry': 5,
                  }
              })
  
          def get_downstream(task):
              for t in task.downstream_list:
                  edge = {
                      'source_id': task.task_id,
                      'target_id': t.task_id,
                  }
                  if edge not in edges:
                      edges.append(edge)
                      get_downstream(t)
  
          for t in dag.roots:
              get_downstream(t)
  
          dt_nr_dr_data = get_date_time_num_runs_dag_runs_form_data(request, session, dag)
          dt_nr_dr_data['arrange'] = arrange
          dttm = dt_nr_dr_data['dttm']
  
          class GraphForm(DateTimeWithNumRunsWithDagRunsForm):
              arrange = SelectField("Layout", choices=(
                  ('LR', "Left->Right"),
                  ('RL', "Right->Left"),
                  ('TB', "Top->Bottom"),
                  ('BT', "Bottom->Top"),
              ))
  
          form = GraphForm(data=dt_nr_dr_data)
          form.execution_date.choices = dt_nr_dr_data['dr_choices']
  
          task_instances = {
              ti.task_id: alchemy_to_dict(ti)
              for ti in dag.get_task_instances(dttm, dttm)}
          tasks = {
              t.task_id: {
                  'dag_id': t.dag_id,
                  'task_type': t.task_type,
                  'extra_links': t.extra_links,
              }
              for t in dag.tasks}
          if not tasks:
              flash("No tasks found", "error")
          session.commit()
          doc_md = wwwutils.wrapped_markdown(getattr(dag, 'doc_md', None), css_class='dag-doc')
  
          task_log_reader = TaskLogReader()
          if task_log_reader.supports_external_link:
              external_log_name = task_log_reader.log_handler.log_name
          else:
              external_log_name = None
  
          return self.render_template(
              'airflow/graph.html',
              dag=dag,
              form=form,
              width=request.args.get('width', "100%"),
              height=request.args.get('height', "800"),
              execution_date=dttm.isoformat(),
              state_token=wwwutils.state_token(dt_nr_dr_data['dr_state']),
              doc_md=doc_md,
              arrange=arrange,
              operators=sorted({op.task_type: op for op in dag.tasks}.values(), key=lambda x: x.task_type),
              blur=blur,
              root=root or '',
              task_instances=task_instances,
              tasks=tasks,
              nodes=nodes,
              edges=edges,
              show_external_log_redirect=task_log_reader.supports_external_link,
              external_log_name=external_log_name)
  
      @expose('/duration')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def duration(self, session=None):
          default_dag_run = conf.getint('webserver', 'default_dag_run_display_number')
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
          base_date = request.args.get('base_date')
          num_runs = request.args.get('num_runs')
          num_runs = int(num_runs) if num_runs else default_dag_run
  
          if dag is None:
              flash('DAG "{0}" seems to be missing.'.format(dag_id), "error")
              return redirect(url_for('Airflow.index'))
  
          if base_date:
              base_date = timezone.parse(base_date)
          else:
              base_date = dag.get_latest_execution_date() or timezone.utcnow()
  
          dates = dag.date_range(base_date, num=-abs(num_runs))
          min_date = dates[0] if dates else timezone.utc_epoch()
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_upstream=True,
                  include_downstream=False)
  
          chart_height = wwwutils.get_chart_height(dag)
          chart = nvd3.lineChart(
              name="lineChart", x_is_date=True, height=chart_height, width="1200")
          cum_chart = nvd3.lineChart(
              name="cumLineChart", x_is_date=True, height=chart_height, width="1200")
  
          y = defaultdict(list)
          x = defaultdict(list)
          cum_y = defaultdict(list)
  
          tis = dag.get_task_instances(start_date=min_date, end_date=base_date)
          TF = TaskFail
          ti_fails = (
              session.query(TF)
              .filter(TF.dag_id == dag.dag_id,
                      TF.execution_date >= min_date,
                      TF.execution_date <= base_date,
                      TF.task_id.in_([t.task_id for t in dag.tasks]))
              .all()
          )
  
          fails_totals = defaultdict(int)
          for tf in ti_fails:
              dict_key = (tf.dag_id, tf.task_id, tf.execution_date)
              if tf.duration:
                  fails_totals[dict_key] += tf.duration
  
          for ti in tis:
              if ti.duration:
                  dttm = wwwutils.epoch(ti.execution_date)
                  x[ti.task_id].append(dttm)
                  y[ti.task_id].append(float(ti.duration))
                  fails_dict_key = (ti.dag_id, ti.task_id, ti.execution_date)
                  fails_total = fails_totals[fails_dict_key]
                  cum_y[ti.task_id].append(float(ti.duration + fails_total))
  
          # determine the most relevant time unit for the set of task instance
          # durations for the DAG
          y_unit = infer_time_unit([d for t in y.values() for d in t])
          cum_y_unit = infer_time_unit([d for t in cum_y.values() for d in t])
          # update the y Axis on both charts to have the correct time units
          chart.create_y_axis('yAxis', format='.02f', custom_format=False,
                              label='Duration ({})'.format(y_unit))
          chart.axislist['yAxis']['axisLabelDistance'] = '-15'
          cum_chart.create_y_axis('yAxis', format='.02f', custom_format=False,
                                  label='Duration ({})'.format(cum_y_unit))
          cum_chart.axislist['yAxis']['axisLabelDistance'] = '-15'
  
          for task in dag.tasks:
              if x[task.task_id]:
                  chart.add_serie(name=task.task_id, x=x[task.task_id],
                                  y=scale_time_units(y[task.task_id], y_unit))
                  cum_chart.add_serie(name=task.task_id, x=x[task.task_id],
                                      y=scale_time_units(cum_y[task.task_id],
                                                         cum_y_unit))
  
          dates = sorted(list({ti.execution_date for ti in tis}))
          max_date = max([ti.execution_date for ti in tis]) if dates else None
  
          session.commit()
  
          form = DateTimeWithNumRunsForm(data={'base_date': max_date,
                                               'num_runs': num_runs})
          chart.buildcontent()
          cum_chart.buildcontent()
          s_index = cum_chart.htmlcontent.rfind('});')
          cum_chart.htmlcontent = (cum_chart.htmlcontent[:s_index] +
                                   "$( document ).trigger('chartload')" +
                                   cum_chart.htmlcontent[s_index:])
  
          return self.render_template(
              'airflow/duration_chart.html',
              dag=dag,
              demo_mode=conf.getboolean('webserver', 'demo_mode'),
              root=root,
              form=form,
              chart=Markup(chart.htmlcontent),
              cum_chart=Markup(cum_chart.htmlcontent),
          )
  
      @expose('/tries')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def tries(self, session=None):
          default_dag_run = conf.getint('webserver', 'default_dag_run_display_number')
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
          base_date = request.args.get('base_date')
          num_runs = request.args.get('num_runs')
          num_runs = int(num_runs) if num_runs else default_dag_run
  
          if base_date:
              base_date = timezone.parse(base_date)
          else:
              base_date = dag.get_latest_execution_date() or timezone.utcnow()
  
          dates = dag.date_range(base_date, num=-abs(num_runs))
          min_date = dates[0] if dates else timezone.utc_epoch()
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_upstream=True,
                  include_downstream=False)
  
          chart_height = wwwutils.get_chart_height(dag)
          chart = nvd3.lineChart(
              name="lineChart", x_is_date=True, y_axis_format='d', height=chart_height,
              width="1200")
  
          for task in dag.tasks:
              y = []
              x = []
              for ti in task.get_task_instances(start_date=min_date, end_date=base_date):
                  dttm = wwwutils.epoch(ti.execution_date)
                  x.append(dttm)
                  # y value should reflect completed tries to have a 0 baseline.
                  y.append(ti.prev_attempted_tries)
              if x:
                  chart.add_serie(name=task.task_id, x=x, y=y)
  
          tis = dag.get_task_instances(start_date=min_date, end_date=base_date)
          tries = sorted(list({ti.try_number for ti in tis}))
          max_date = max([ti.execution_date for ti in tis]) if tries else None
  
          session.commit()
  
          form = DateTimeWithNumRunsForm(data={'base_date': max_date,
                                               'num_runs': num_runs})
  
          chart.buildcontent()
  
          return self.render_template(
              'airflow/chart.html',
              dag=dag,
              demo_mode=conf.getboolean('webserver', 'demo_mode'),
              root=root,
              form=form,
              chart=Markup(chart.htmlcontent),
              tab_title='Tries',
          )
  
      @expose('/landing_times')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def landing_times(self, session=None):
          default_dag_run = conf.getint('webserver', 'default_dag_run_display_number')
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
          base_date = request.args.get('base_date')
          num_runs = request.args.get('num_runs')
          num_runs = int(num_runs) if num_runs else default_dag_run
  
          if base_date:
              base_date = timezone.parse(base_date)
          else:
              base_date = dag.get_latest_execution_date() or timezone.utcnow()
  
          dates = dag.date_range(base_date, num=-abs(num_runs))
          min_date = dates[0] if dates else timezone.utc_epoch()
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_upstream=True,
                  include_downstream=False)
  
          chart_height = wwwutils.get_chart_height(dag)
          chart = nvd3.lineChart(
              name="lineChart", x_is_date=True, height=chart_height, width="1200")
          y = {}
          x = {}
          for task in dag.tasks:
              task_id = task.task_id
              y[task_id] = []
              x[task_id] = []
              for ti in task.get_task_instances(start_date=min_date, end_date=base_date):
                  ts = ti.execution_date
                  if dag.schedule_interval and dag.following_schedule(ts):
                      ts = dag.following_schedule(ts)
                  if ti.end_date:
                      dttm = wwwutils.epoch(ti.execution_date)
                      secs = (ti.end_date - ts).total_seconds()
                      x[task_id].append(dttm)
                      y[task_id].append(secs)
  
          # determine the most relevant time unit for the set of landing times
          # for the DAG
          y_unit = infer_time_unit([d for t in y.values() for d in t])
          # update the y Axis to have the correct time units
          chart.create_y_axis('yAxis', format='.02f', custom_format=False,
                              label='Landing Time ({})'.format(y_unit))
          chart.axislist['yAxis']['axisLabelDistance'] = '-15'
          for task in dag.tasks:
              if x[task.task_id]:
                  chart.add_serie(name=task.task_id, x=x[task.task_id],
                                  y=scale_time_units(y[task.task_id], y_unit))
  
          tis = dag.get_task_instances(start_date=min_date, end_date=base_date)
          dates = sorted(list({ti.execution_date for ti in tis}))
          max_date = max([ti.execution_date for ti in tis]) if dates else None
  
          session.commit()
  
          form = DateTimeWithNumRunsForm(data={'base_date': max_date,
                                               'num_runs': num_runs})
          chart.buildcontent()
          return self.render_template(
              'airflow/chart.html',
              dag=dag,
              chart=Markup(chart.htmlcontent),
              height=str(chart_height + 100) + "px",
              demo_mode=conf.getboolean('webserver', 'demo_mode'),
              root=root,
              form=form,
              tab_title='Landing times',
          )
  
      @expose('/paused', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      def paused(self):
          dag_id = request.args.get('dag_id')
          is_paused = True if request.args.get('is_paused') == 'false' else False
          models.DagModel.get_dagmodel(dag_id).set_is_paused(
              is_paused=is_paused)
          return "OK"
  
      @expose('/refresh', methods=['POST'])
      @has_dag_access(can_dag_edit=True)
      @has_access
      @action_logging
      @provide_session
      def refresh(self, session=None):
          DagModel = models.DagModel
          dag_id = request.values.get('dag_id')
          orm_dag = session.query(
              DagModel).filter(DagModel.dag_id == dag_id).first()
  
          if orm_dag:
              orm_dag.last_expired = timezone.utcnow()
              session.merge(orm_dag)
          session.commit()
  
          dag = current_app.dag_bag.get_dag(dag_id)
          # sync dag permission
          current_app.appbuilder.sm.sync_perm_for_dag(dag_id, dag.access_control)
  
          flash("DAG [{}] is now fresh as a daisy".format(dag_id))
          return redirect(request.referrer)
  
      @expose('/gantt')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      @provide_session
      def gantt(self, session=None):
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
          demo_mode = conf.getboolean('webserver', 'demo_mode')
  
          root = request.args.get('root')
          if root:
              dag = dag.sub_dag(
                  task_regex=root,
                  include_upstream=True,
                  include_downstream=False)
  
          dt_nr_dr_data = get_date_time_num_runs_dag_runs_form_data(request, session, dag)
          dttm = dt_nr_dr_data['dttm']
  
          form = DateTimeWithNumRunsWithDagRunsForm(data=dt_nr_dr_data)
          form.execution_date.choices = dt_nr_dr_data['dr_choices']
  
          tis = [
              ti for ti in dag.get_task_instances(dttm, dttm)
              if ti.start_date and ti.state]
          tis = sorted(tis, key=lambda ti: ti.start_date)
          TF = TaskFail
          ti_fails = list(itertools.chain(*[(
              session
              .query(TF)
              .filter(TF.dag_id == ti.dag_id,
                      TF.task_id == ti.task_id,
                      TF.execution_date == ti.execution_date)
              .all()
          ) for ti in tis]))
  
          # determine bars to show in the gantt chart
          gantt_bar_items = []
  
          tasks = []
          for ti in tis:
              end_date = ti.end_date or timezone.utcnow()
              # prev_attempted_tries will reflect the currently running try_number
              # or the try_number of the last complete run
              # https://issues.apache.org/jira/browse/AIRFLOW-2143
              try_count = ti.prev_attempted_tries
              gantt_bar_items.append((ti.task_id, ti.start_date, end_date, ti.state, try_count))
              d = alchemy_to_dict(ti)
              d['extraLinks'] = dag.get_task(ti.task_id).extra_links
              tasks.append(d)
  
          tf_count = 0
          try_count = 1
          prev_task_id = ""
          for tf in ti_fails:
              end_date = tf.end_date or timezone.utcnow()
              start_date = tf.start_date or end_date
              if tf_count != 0 and tf.task_id == prev_task_id:
                  try_count = try_count + 1
              else:
                  try_count = 1
              prev_task_id = tf.task_id
              gantt_bar_items.append((tf.task_id, start_date, end_date, State.FAILED, try_count))
              tf_count = tf_count + 1
              task = dag.get_task(tf.task_id)
              d = alchemy_to_dict(tf)
              d['state'] = State.FAILED
              d['operator'] = task.task_type
              d['try_number'] = try_count
              d['extraLinks'] = task.extra_links
              tasks.append(d)
  
          data = {
              'taskNames': [ti.task_id for ti in tis],
              'tasks': tasks,
              'height': len(tis) * 25 + 25,
          }
  
          session.commit()
  
          return self.render_template(
              'airflow/gantt.html',
              dag=dag,
              execution_date=dttm.isoformat(),
              form=form,
              data=data,
              base_date='',
              demo_mode=demo_mode,
              root=root,
          )
  
      @expose('/extra_links')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      def extra_links(self):
          """
          A restful endpoint that returns external links for a given Operator
  
          It queries the operator that sent the request for the links it wishes
          to provide for a given external link name.
  
          API: GET
          Args: dag_id: The id of the dag containing the task in question
                task_id: The id of the task in question
                execution_date: The date of execution of the task
                link_name: The name of the link reference to find the actual URL for
  
          Returns:
              200: {url: <url of link>, error: None} - returned when there was no problem
                  finding the URL
              404: {url: None, error: <error message>} - returned when the operator does
                  not return a URL
          """
          dag_id = request.args.get('dag_id')
          task_id = request.args.get('task_id')
          execution_date = request.args.get('execution_date')
          link_name = request.args.get('link_name')
          dttm = timezone.parse(execution_date)
          dag = current_app.dag_bag.get_dag(dag_id)
  
          if not dag or task_id not in dag.task_ids:
              response = jsonify(
                  {'url': None,
                   'error': "can't find dag {dag} or task_id {task_id}".format(
                       dag=dag,
                       task_id=task_id
                   )}
              )
              response.status_code = 404
              return response
  
          task = dag.get_task(task_id)
  
          try:
              url = task.get_extra_links(dttm, link_name)
          except ValueError as err:
              response = jsonify({'url': None, 'error': str(err)})
              response.status_code = 404
              return response
          if url:
              response = jsonify({'error': None, 'url': url})
              response.status_code = 200
              return response
          else:
              response = jsonify(
                  {'url': None, 'error': 'No URL found for {dest}'.format(dest=link_name)})
              response.status_code = 404
              return response
  
      @expose('/object/task_instances')
      @has_dag_access(can_dag_read=True)
      @has_access
      @action_logging
      def task_instances(self):
          dag_id = request.args.get('dag_id')
          dag = current_app.dag_bag.get_dag(dag_id)
  
          dttm = request.args.get('execution_date')
          if dttm:
              dttm = timezone.parse(dttm)
          else:
              return "Error: Invalid execution_date"
  
          task_instances = {
              ti.task_id: alchemy_to_dict(ti)
              for ti in dag.get_task_instances(dttm, dttm)}
  
          return json.dumps(task_instances)
  
  
  class VersionView(AirflowBaseView):
      """View to show Airflow Version and optionally Git commit SHA"""
      default_view = 'version'
  
      @expose('/version')
      @has_access
      def version(self):
          try:
              airflow_version = airflow.__version__
          except Exception as e:
              airflow_version = None
              logging.error(e)
  
          git_version = get_airflow_git_version()
          # Render information
          title = "Version Info"
          return self.render_template(
              'airflow/version.html',
              title=title,
              airflow_version=airflow_version,
              git_version=git_version)
  
  
  class ConfigurationView(AirflowBaseView):
      """View to show Airflow Configurations"""
      default_view = 'conf'
  
      @expose('/configuration')
      @has_access
      def conf(self):
          raw = request.args.get('raw') == "true"
          title = "Airflow Configuration"
          subtitle = AIRFLOW_CONFIG
          # Don't show config when expose_config variable is False in airflow config
          if conf.getboolean("webserver", "expose_config"):
              with open(AIRFLOW_CONFIG, 'r') as file:
                  config = file.read()
              table = [(section, key, value, source)
                       for section, parameters in conf.as_dict(True, True).items()
                       for key, (value, source) in parameters.items()]
          else:
              config = (
                  "# Your Airflow administrator chose not to expose the "
                  "configuration, most likely for security reasons.")
              table = None
  
          if raw:
              return Response(
                  response=config,
                  status=200,
                  mimetype="application/text")
          else:
              code_html = Markup(highlight(
                  config,
                  lexers.IniLexer(),  # Lexer call
                  HtmlFormatter(noclasses=True))
              )
              return self.render_template(
                  'airflow/config.html',
                  pre_subtitle=settings.HEADER + "  v" + airflow.__version__,
                  code_html=code_html, title=title, subtitle=subtitle,
                  table=table)
  
  
  class RedocView(AirflowBaseView):
      """Redoc Open API documentation"""
      default_view = 'redoc'
  
      @expose('/redoc')
      def redoc(self):
          openapi_spec_url = url_for("/api/v1./api/v1_openapi_yaml")
          return self.render_template('airflow/redoc.html', openapi_spec_url=openapi_spec_url)
  
  
  ######################################################################################
  #                                    ModelViews
  ######################################################################################
  
  class DagFilter(BaseFilter):
      """Filter using DagIDs"""
      def apply(self, query, func): # noqa
          if current_app.appbuilder.sm.has_all_dags_access():
              return query
          filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
          return query.filter(self.model.dag_id.in_(filter_dag_ids))
  
  
  class AirflowModelView(ModelView):  # noqa: D101
      list_widget = AirflowModelListWidget
      page_size = PAGE_SIZE
  
      CustomSQLAInterface = wwwutils.CustomSQLAInterface
  
  
  class SlaMissModelView(AirflowModelView):
      """View to show SlaMiss table"""
      route_base = '/slamiss'
  
      datamodel = AirflowModelView.CustomSQLAInterface(SlaMiss)
  
      base_permissions = ['can_list']
  
      list_columns = ['dag_id', 'task_id', 'execution_date', 'email_sent', 'timestamp']
      add_columns = ['dag_id', 'task_id', 'execution_date', 'email_sent', 'timestamp']
      edit_columns = ['dag_id', 'task_id', 'execution_date', 'email_sent', 'timestamp']
      search_columns = ['dag_id', 'task_id', 'email_sent', 'timestamp', 'execution_date']
      base_order = ('execution_date', 'desc')
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      formatters_columns = {
          'task_id': wwwutils.task_instance_link,
          'execution_date': wwwutils.datetime_f('execution_date'),
          'timestamp': wwwutils.datetime_f('timestamp'),
          'dag_id': wwwutils.dag_link,
      }
  
  
  class XComModelView(AirflowModelView):
      """View to show records from XCom table"""
      route_base = '/xcom'
  
      datamodel = AirflowModelView.CustomSQLAInterface(XCom)
  
      base_permissions = ['can_list', 'can_delete']
  
      search_columns = ['key', 'value', 'timestamp', 'execution_date', 'task_id', 'dag_id']
      list_columns = ['key', 'value', 'timestamp', 'execution_date', 'task_id', 'dag_id']
      base_order = ('execution_date', 'desc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      formatters_columns = {
          'task_id': wwwutils.task_instance_link,
          'execution_date': wwwutils.datetime_f('execution_date'),
          'timestamp': wwwutils.datetime_f('timestamp'),
          'dag_id': wwwutils.dag_link,
      }
  
      @action('muldelete', 'Delete', "Are you sure you want to delete selected records?",
              single=False)
      def action_muldelete(self, items):
          self.datamodel.delete_all(items)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      def pre_add(self, item):
          item.execution_date = timezone.make_aware(item.execution_date)
          item.value = XCom.serialize_value(item.value)
  
      def pre_update(self, item):
          item.execution_date = timezone.make_aware(item.execution_date)
          item.value = XCom.serialize_value(item.value)
  
  
  class ConnectionModelView(AirflowModelView):
      """View to show records from Connections table"""
      route_base = '/connection'
  
      datamodel = AirflowModelView.CustomSQLAInterface(Connection)
  
      base_permissions = ['can_add', 'can_list', 'can_edit', 'can_delete']
  
      extra_fields = ['extra__jdbc__drv_path', 'extra__jdbc__drv_clsname',
                      'extra__google_cloud_platform__project',
                      'extra__google_cloud_platform__key_path',
                      'extra__google_cloud_platform__keyfile_dict',
                      'extra__google_cloud_platform__scope',
                      'extra__google_cloud_platform__num_retries',
                      'extra__grpc__auth_type',
                      'extra__grpc__credential_pem_file',
                      'extra__grpc__scopes',
                      'extra__yandexcloud__service_account_json',
                      'extra__yandexcloud__service_account_json_path',
                      'extra__yandexcloud__oauth',
                      'extra__yandexcloud__public_ssh_key',
                      'extra__yandexcloud__folder_id',
                      'extra__kubernetes__in_cluster',
                      'extra__kubernetes__kube_config',
                      'extra__kubernetes__namespace']
      list_columns = ['conn_id', 'conn_type', 'host', 'port', 'is_encrypted',
                      'is_extra_encrypted']
      add_columns = edit_columns = ['conn_id', 'conn_type', 'host', 'schema',
                                    'login', 'password', 'port', 'extra'] + extra_fields
      add_form = edit_form = ConnectionForm
      add_template = 'airflow/conn_create.html'
      edit_template = 'airflow/conn_edit.html'
  
      base_order = ('conn_id', 'asc')
  
      @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?',
              single=False)
      @has_dag_access(can_dag_edit=True)
      def action_muldelete(self, items):
          self.datamodel.delete_all(items)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      def process_form(self, form, is_created):
          formdata = form.data
          if formdata['conn_type'] in ['jdbc', 'google_cloud_platform', 'grpc', 'yandexcloud', 'kubernetes']:
              extra = {
                  key: formdata[key]
                  for key in self.extra_fields if key in formdata}
              form.extra.data = json.dumps(extra)
  
      def prefill_form(self, form, pk):
          try:
              d = json.loads(form.data.get('extra', '{}'))
          except JSONDecodeError:
              d = {}
  
          if not hasattr(d, 'get'):
              logging.warning('extra field for {} is not iterable'.format(
                  form.data.get('conn_id', '<unknown>')))
              return
  
          for field in self.extra_fields:
              value = d.get(field, '')
              if value:
                  field = getattr(form, field)
                  field.data = value
  
  
  class PoolModelView(AirflowModelView):
      """View to show records from Pool table"""
      route_base = '/pool'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.Pool)
  
      base_permissions = ['can_add', 'can_list', 'can_edit', 'can_delete']
  
      list_columns = ['pool', 'slots', 'running_slots', 'queued_slots']
      add_columns = ['pool', 'slots', 'description']
      edit_columns = ['pool', 'slots', 'description']
  
      base_order = ('pool', 'asc')
  
      @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?',
              single=False)
      def action_muldelete(self, items):
          if any(item.pool == models.Pool.DEFAULT_POOL_NAME for item in items):
              flash("default_pool cannot be deleted", 'error')
              self.update_redirect()
              return redirect(self.get_redirect())
          self.datamodel.delete_all(items)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      def pool_link(attr):
          pool_id = attr.get('pool')
          if pool_id is not None:
              url = url_for('TaskInstanceModelView.list', _flt_3_pool=pool_id)
              return Markup("<a href='{url}'>{pool_id}</a>").format(url=url, pool_id=pool_id)
          else:
              return Markup('<span class="label label-danger">Invalid</span>')
  
      def frunning_slots(attr):
          pool_id = attr.get('pool')
          running_slots = attr.get('running_slots')
          if pool_id is not None and running_slots is not None:
              url = url_for('TaskInstanceModelView.list', _flt_3_pool=pool_id, _flt_3_state='running')
              return Markup("<a href='{url}'>{running_slots}</a>").format(url=url, running_slots=running_slots)
          else:
              return Markup('<span class="label label-danger">Invalid</span>')
  
      def fqueued_slots(attr):
          pool_id = attr.get('pool')
          queued_slots = attr.get('queued_slots')
          if pool_id is not None and queued_slots is not None:
              url = url_for('TaskInstanceModelView.list', _flt_3_pool=pool_id, _flt_3_state='queued')
              return Markup("<a href='{url}'>{queued_slots}</a>").format(url=url, queued_slots=queued_slots)
          else:
              return Markup('<span class="label label-danger">Invalid</span>')
  
      formatters_columns = {
          'pool': pool_link,
          'running_slots': frunning_slots,
          'queued_slots': fqueued_slots
      }
  
      validators_columns = {
          'pool': [validators.DataRequired()],
          'slots': [validators.NumberRange(min=-1)]
      }
  
  
  class VariableModelView(AirflowModelView):
      """View to show records from Variable table"""
      route_base = '/variable'
  
      list_template = 'airflow/variable_list.html'
      edit_template = 'airflow/variable_edit.html'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.Variable)
  
      base_permissions = ['can_add', 'can_list', 'can_edit', 'can_delete', 'can_varimport']
  
      list_columns = ['key', 'val', 'is_encrypted']
      add_columns = ['key', 'val']
      edit_columns = ['key', 'val']
      search_columns = ['key', 'val']
  
      base_order = ('key', 'asc')
  
      def hidden_field_formatter(attr):
          key = attr.get('key')
          val = attr.get('val')
          if wwwutils.should_hide_value_for_key(key):
              return Markup('*' * 8)
          if val:
              return val
          else:
              return Markup('<span class="label label-danger">Invalid</span>')
  
      formatters_columns = {
          'val': hidden_field_formatter,
      }
  
      validators_columns = {
          'key': [validators.DataRequired()]
      }
  
      def prefill_form(self, form, id):
          if wwwutils.should_hide_value_for_key(form.key.data):
              form.val.data = '*' * 8
  
      @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?',
              single=False)
      def action_muldelete(self, items):
          self.datamodel.delete_all(items)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      @action('varexport', 'Export', '', single=False)
      def action_varexport(self, items):
          var_dict = {}
          d = json.JSONDecoder()
          for var in items:
              try:
                  val = d.decode(var.val)
              except Exception:
                  val = var.val
              var_dict[var.key] = val
  
          response = make_response(json.dumps(var_dict, sort_keys=True, indent=4))
          response.headers["Content-Disposition"] = "attachment; filename=variables.json"
          response.headers["Content-Type"] = "application/json; charset=utf-8"
          return response
  
      @expose('/varimport', methods=["POST"])
      @has_access
      @action_logging
      def varimport(self):
          try:
              out = request.files['file'].read()
              if isinstance(out, bytes):
                  d = json.loads(out.decode('utf-8'))
              else:
                  d = json.loads(out)
          except Exception:
              self.update_redirect()
              flash("Missing file or syntax error.", 'error')
              return redirect(self.get_redirect())
          else:
              suc_count = fail_count = 0
              for k, v in d.items():
                  try:
                      models.Variable.set(k, v, serialize_json=not isinstance(v, str))
                  except Exception as e:
                      logging.info('Variable import failed: {}'.format(repr(e)))
                      fail_count += 1
                  else:
                      suc_count += 1
              flash("{} variable(s) successfully updated.".format(suc_count))
              if fail_count:
                  flash("{} variable(s) failed to be updated.".format(fail_count), 'error')
              self.update_redirect()
              return redirect(self.get_redirect())
  
  
  class JobModelView(AirflowModelView):
      """View to show records from Job table"""
      route_base = '/job'
  
      datamodel = AirflowModelView.CustomSQLAInterface(BaseJob)
  
      base_permissions = ['can_list']
  
      list_columns = ['id', 'dag_id', 'state', 'job_type', 'start_date',
                      'end_date', 'latest_heartbeat',
                      'executor_class', 'hostname', 'unixname']
      search_columns = ['id', 'dag_id', 'state', 'job_type', 'start_date',
                        'end_date', 'latest_heartbeat', 'executor_class',
                        'hostname', 'unixname']
  
      base_order = ('start_date', 'desc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      formatters_columns = {
          'start_date': wwwutils.datetime_f('start_date'),
          'end_date': wwwutils.datetime_f('end_date'),
          'hostname': wwwutils.nobr_f('hostname'),
          'state': wwwutils.state_f,
          'latest_heartbeat': wwwutils.datetime_f('latest_heartbeat'),
      }
  
  
  class DagRunModelView(AirflowModelView):
      """View to show records from DagRun table"""
      route_base = '/dagrun'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.DagRun)
  
      base_permissions = ['can_list', 'can_add']
  
      add_columns = ['state', 'dag_id', 'execution_date', 'run_id', 'external_trigger', 'conf']
      list_columns = ['state', 'dag_id', 'execution_date', 'run_id', 'run_type', 'external_trigger', 'conf']
      search_columns = ['state', 'dag_id', 'execution_date', 'run_id', 'run_type', 'external_trigger', 'conf']
  
      base_order = ('execution_date', 'desc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      add_form = edit_form = DagRunForm
  
      formatters_columns = {
          'execution_date': wwwutils.datetime_f('execution_date'),
          'state': wwwutils.state_f,
          'start_date': wwwutils.datetime_f('start_date'),
          'dag_id': wwwutils.dag_link,
          'run_id': wwwutils.dag_run_link,
      }
  
      @action('muldelete', "Delete", "Are you sure you want to delete selected records?",
              single=False)
      @has_dag_access(can_dag_edit=True)
      @provide_session
      def action_muldelete(self, items, session=None):
          self.datamodel.delete_all(items)
          self.update_redirect()
          dirty_ids = []
          for item in items:
              dirty_ids.append(item.dag_id)
          return redirect(self.get_redirect())
  
      @action('set_running', "Set state to 'running'", '', single=False)
      @provide_session
      def action_set_running(self, drs, session=None):
          try:
              DR = models.DagRun
              count = 0
              dirty_ids = []
              for dr in session.query(DR).filter(
                      DR.id.in_([dagrun.id for dagrun in drs])).all():
                  dirty_ids.append(dr.dag_id)
                  count += 1
                  dr.start_date = timezone.utcnow()
                  dr.state = State.RUNNING
              session.commit()
              flash("{count} dag runs were set to running".format(count=count))
          except Exception as ex:
              flash(str(ex), 'error')
              flash('Failed to set state', 'error')
          return redirect(self.get_default_url())
  
      @action('set_failed', "Set state to 'failed'",
              "All running task instances would also be marked as failed, are you sure?",
              single=False)
      @provide_session
      def action_set_failed(self, drs, session=None):
          try:
              DR = models.DagRun
              count = 0
              dirty_ids = []
              altered_tis = []
              for dr in session.query(DR).filter(
                      DR.id.in_([dagrun.id for dagrun in drs])).all():
                  dirty_ids.append(dr.dag_id)
                  count += 1
                  altered_tis += \
                      set_dag_run_state_to_failed(current_app.dag_bag.get_dag(dr.dag_id),
                                                  dr.execution_date,
                                                  commit=True,
                                                  session=session)
              altered_ti_count = len(altered_tis)
              flash(
                  "{count} dag runs and {altered_ti_count} task instances "
                  "were set to failed".format(count=count, altered_ti_count=altered_ti_count))
          except Exception:
              flash('Failed to set state', 'error')
          return redirect(self.get_default_url())
  
      @action('set_success', "Set state to 'success'",
              "All task instances would also be marked as success, are you sure?",
              single=False)
      @provide_session
      def action_set_success(self, drs, session=None):
          try:
              DR = models.DagRun
              count = 0
              dirty_ids = []
              altered_tis = []
              for dr in session.query(DR).filter(
                      DR.id.in_([dagrun.id for dagrun in drs])).all():
                  dirty_ids.append(dr.dag_id)
                  count += 1
                  altered_tis += \
                      set_dag_run_state_to_success(current_app.dag_bag.get_dag(dr.dag_id),
                                                   dr.execution_date,
                                                   commit=True,
                                                   session=session)
              altered_ti_count = len(altered_tis)
              flash(
                  "{count} dag runs and {altered_ti_count} task instances "
                  "were set to success".format(count=count, altered_ti_count=altered_ti_count))
          except Exception:
              flash('Failed to set state', 'error')
          return redirect(self.get_default_url())
  
  
  class LogModelView(AirflowModelView):
      """View to show records from Log table"""
      route_base = '/log'
  
      datamodel = AirflowModelView.CustomSQLAInterface(Log)
  
      base_permissions = ['can_list']
  
      list_columns = ['id', 'dttm', 'dag_id', 'task_id', 'event', 'execution_date',
                      'owner', 'extra']
      search_columns = ['dag_id', 'task_id', 'event', 'execution_date', 'owner', 'extra']
  
      base_order = ('dttm', 'desc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      formatters_columns = {
          'dttm': wwwutils.datetime_f('dttm'),
          'execution_date': wwwutils.datetime_f('execution_date'),
          'dag_id': wwwutils.dag_link,
      }
  
  
  class TaskRescheduleModelView(AirflowModelView):
      """View to show records from Task Reschedule table"""
      route_base = '/taskreschedule'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.TaskReschedule)
  
      base_permissions = ['can_list']
  
      list_columns = ['id', 'dag_id', 'task_id', 'execution_date', 'try_number',
                      'start_date', 'end_date', 'duration', 'reschedule_date']
  
      search_columns = ['dag_id', 'task_id', 'execution_date', 'start_date', 'end_date',
                        'reschedule_date']
  
      base_order = ('id', 'desc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      def duration_f(attr):
          end_date = attr.get('end_date')
          duration = attr.get('duration')
          if end_date and duration:
              return timedelta(seconds=duration)
  
      formatters_columns = {
          'dag_id': wwwutils.dag_link,
          'task_id': wwwutils.task_instance_link,
          'start_date': wwwutils.datetime_f('start_date'),
          'end_date': wwwutils.datetime_f('end_date'),
          'execution_date': wwwutils.datetime_f('execution_date'),
          'reschedule_date': wwwutils.datetime_f('reschedule_date'),
          'duration': duration_f,
      }
  
  
  class TaskInstanceModelView(AirflowModelView):
      """View to show records from TaskInstance table"""
      route_base = '/taskinstance'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.TaskInstance)
  
      base_permissions = ['can_list']
  
      page_size = PAGE_SIZE
  
      list_columns = ['state', 'dag_id', 'task_id', 'execution_date', 'operator',
                      'start_date', 'end_date', 'duration', 'job_id', 'hostname',
                      'unixname', 'priority_weight', 'queue', 'queued_dttm', 'try_number',
                      'pool', 'log_url']
  
      order_columns = [item for item in list_columns if item not in ['try_number', 'log_url']]
  
      search_columns = ['state', 'dag_id', 'task_id', 'execution_date', 'hostname',
                        'queue', 'pool', 'operator', 'start_date', 'end_date']
  
      base_order = ('job_id', 'asc')
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      def log_url_formatter(attr):
          log_url = attr.get('log_url')
          return Markup(
              '<a href="{log_url}">'
              '    <span class="glyphicon glyphicon-book" aria-hidden="true">'
              '</span></a>').format(log_url=log_url)
  
      def duration_f(attr):
          end_date = attr.get('end_date')
          duration = attr.get('duration')
          if end_date and duration:
              return timedelta(seconds=duration)
  
      formatters_columns = {
          'log_url': log_url_formatter,
          'task_id': wwwutils.task_instance_link,
          'hostname': wwwutils.nobr_f('hostname'),
          'state': wwwutils.state_f,
          'execution_date': wwwutils.datetime_f('execution_date'),
          'start_date': wwwutils.datetime_f('start_date'),
          'end_date': wwwutils.datetime_f('end_date'),
          'queued_dttm': wwwutils.datetime_f('queued_dttm'),
          'dag_id': wwwutils.dag_link,
          'duration': duration_f,
      }
  
      @provide_session
      @action('clear', lazy_gettext('Clear'),
              lazy_gettext('Are you sure you want to clear the state of the selected task'
                           ' instance(s) and set their dagruns to the running state?'),
              single=False)
      def action_clear(self, tis, session=None):
          try:
              dag_to_tis = {}
  
              for ti in tis:
                  dag = current_app.dag_bag.get_dag(ti.dag_id)
                  tis = dag_to_tis.setdefault(dag, [])
                  tis.append(ti)
  
              for dag, tis in dag_to_tis.items():
                  models.clear_task_instances(tis, session, dag=dag)
  
              session.commit()
              flash("{0} task instances have been cleared".format(len(tis)))
              self.update_redirect()
              return redirect(self.get_redirect())
  
          except Exception:
              flash('Failed to clear task instances', 'error')
  
      @provide_session
      def set_task_instance_state(self, tis, target_state, session=None):
          try:
              count = len(tis)
              for ti in tis:
                  ti.set_state(target_state, session)
              session.commit()
              flash("{count} task instances were set to '{target_state}'".format(
                  count=count, target_state=target_state))
          except Exception:
              flash('Failed to set state', 'error')
  
      @action('set_running', "Set state to 'running'", '', single=False)
      @has_dag_access(can_dag_edit=True)
      def action_set_running(self, tis):
          self.set_task_instance_state(tis, State.RUNNING)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      @action('set_failed', "Set state to 'failed'", '', single=False)
      @has_dag_access(can_dag_edit=True)
      def action_set_failed(self, tis):
          self.set_task_instance_state(tis, State.FAILED)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      @action('set_success', "Set state to 'success'", '', single=False)
      @has_dag_access(can_dag_edit=True)
      def action_set_success(self, tis):
          self.set_task_instance_state(tis, State.SUCCESS)
          self.update_redirect()
          return redirect(self.get_redirect())
  
      @action('set_retry', "Set state to 'up_for_retry'", '', single=False)
      @has_dag_access(can_dag_edit=True)
      def action_set_retry(self, tis):
          self.set_task_instance_state(tis, State.UP_FOR_RETRY)
          self.update_redirect()
          return redirect(self.get_redirect())
  
  
  class DagModelView(AirflowModelView):
      """View to show records from DAG table"""
      route_base = '/dagmodel'
  
      datamodel = AirflowModelView.CustomSQLAInterface(models.DagModel)
  
      base_permissions = ['can_list', 'can_show']
  
      list_columns = ['dag_id', 'is_paused', 'last_scheduler_run',
                      'last_expired', 'scheduler_lock', 'fileloc', 'owners']
  
      formatters_columns = {
          'dag_id': wwwutils.dag_link
      }
  
      base_filters = [['dag_id', DagFilter, lambda: []]]
  
      def get_query(self):
          """
          Default filters for model
          """
          return (
              super().get_query()
              .filter(or_(models.DagModel.is_active,
                          models.DagModel.is_paused))
              .filter(~models.DagModel.is_subdag)
          )
  
      def get_count_query(self):
          """
          Default filters for model
          """
          return (
              super().get_count_query()
              .filter(models.DagModel.is_active)
              .filter(~models.DagModel.is_subdag)
          )
  
      @has_access
      @permission_name("list")
      @provide_session
      @expose('/autocomplete')
      def autocomplete(self, session=None):
          query = unquote(request.args.get('query', ''))
  
          if not query:
              wwwutils.json_response([])
  
          # Provide suggestions of dag_ids and owners
          dag_ids_query = session.query(DagModel.dag_id.label('item')).filter(
              ~DagModel.is_subdag, DagModel.is_active,
              DagModel.dag_id.ilike('%' + query + '%'))
  
          owners_query = session.query(func.distinct(DagModel.owners).label('item')).filter(
              ~DagModel.is_subdag, DagModel.is_active,
              DagModel.owners.ilike('%' + query + '%'))
  
          # Hide DAGs if not showing status: "all"
          status = flask_session.get(FILTER_STATUS_COOKIE)
          if status == 'active':
              dag_ids_query = dag_ids_query.filter(~DagModel.is_paused)
              owners_query = owners_query.filter(~DagModel.is_paused)
          elif status == 'paused':
              dag_ids_query = dag_ids_query.filter(DagModel.is_paused)
              owners_query = owners_query.filter(DagModel.is_paused)
  
          filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
          if 'all_dags' not in filter_dag_ids:
              dag_ids_query = dag_ids_query.filter(DagModel.dag_id.in_(filter_dag_ids))
              owners_query = owners_query.filter(DagModel.dag_id.in_(filter_dag_ids))
  
          payload = [row[0] for row in dag_ids_query.union(owners_query).limit(10).all()]
  
          return wwwutils.json_response(payload)
  