text: # -*- coding: utf-8 -*-
  # Copyright 2014 - 2016 OpenMarket Ltd
  # Copyright 2018 New Vector Ltd
  #
  # Licensed 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 imp
  import logging
  import os
  import re
  from collections import Counter
  from typing import Generator, Iterable, List, Optional, TextIO, Tuple
  
  import attr
  from typing_extensions import Counter as CounterType
  
  from synapse.config.homeserver import HomeServerConfig
  from synapse.storage.database import LoggingDatabaseConnection
  from synapse.storage.engines import BaseDatabaseEngine
  from synapse.storage.engines.postgres import PostgresEngine
  from synapse.storage.types import Cursor
  from synapse.types import Collection
  
  logger = logging.getLogger(__name__)
  
  
  # Remember to update this number every time a change is made to database
  # schema files, so the users will be informed on server restarts.
  SCHEMA_VERSION = 59
  
  dir_path = os.path.abspath(os.path.dirname(__file__))
  
  
  class PrepareDatabaseException(Exception):
      pass
  
  
  class UpgradeDatabaseException(PrepareDatabaseException):
      pass
  
  
  OUTDATED_SCHEMA_ON_WORKER_ERROR = (
      "Expected database schema version %i but got %i: run the main synapse process to "
      "upgrade the database schema before starting worker processes."
  )
  
  EMPTY_DATABASE_ON_WORKER_ERROR = (
      "Uninitialised database: run the main synapse process to prepare the database "
      "schema before starting worker processes."
  )
  
  UNAPPLIED_DELTA_ON_WORKER_ERROR = (
      "Database schema delta %s has not been applied: run the main synapse process to "
      "upgrade the database schema before starting worker processes."
  )
  
  
  def prepare_database(
      db_conn: LoggingDatabaseConnection,
      database_engine: BaseDatabaseEngine,
      config: Optional[HomeServerConfig],
      databases: Collection[str] = ("main", "state"),
  ):
      """Prepares a physical database for usage. Will either create all necessary tables
      or upgrade from an older schema version.
  
      If `config` is None then prepare_database will assert that no upgrade is
      necessary, *or* will create a fresh database if the database is empty.
  
      Args:
          db_conn:
          database_engine:
          config :
              application config, or None if we are connecting to an existing
              database which we expect to be configured already
          databases: The name of the databases that will be used
              with this physical database. Defaults to all databases.
      """
  
      try:
          cur = db_conn.cursor(txn_name="prepare_database")
  
          # sqlite does not automatically start transactions for DDL / SELECT statements,
          # so we start one before running anything. This ensures that any upgrades
          # are either applied completely, or not at all.
          #
          # (psycopg2 automatically starts a transaction as soon as we run any statements
          # at all, so this is redundant but harmless there.)
          cur.execute("BEGIN TRANSACTION")
  
          logger.info("%r: Checking existing schema version", databases)
          version_info = _get_or_create_schema_state(cur, database_engine)
  
          if version_info:
              user_version, delta_files, upgraded = version_info
              logger.info(
                  "%r: Existing schema is %i (+%i deltas)",
                  databases,
                  user_version,
                  len(delta_files),
              )
  
              # config should only be None when we are preparing an in-memory SQLite db,
              # which should be empty.
              if config is None:
                  raise ValueError(
                      "config==None in prepare_database, but databse is not empty"
                  )
  
              # if it's a worker app, refuse to upgrade the database, to avoid multiple
              # workers doing it at once.
              if config.worker_app is not None and user_version != SCHEMA_VERSION:
                  raise UpgradeDatabaseException(
                      OUTDATED_SCHEMA_ON_WORKER_ERROR % (SCHEMA_VERSION, user_version)
                  )
  
              _upgrade_existing_database(
                  cur,
                  user_version,
                  delta_files,
                  upgraded,
                  database_engine,
                  config,
                  databases=databases,
              )
          else:
              logger.info("%r: Initialising new database", databases)
  
              # if it's a worker app, refuse to upgrade the database, to avoid multiple
              # workers doing it at once.
              if config and config.worker_app is not None:
                  raise UpgradeDatabaseException(EMPTY_DATABASE_ON_WORKER_ERROR)
  
              _setup_new_database(cur, database_engine, databases=databases)
  
          # check if any of our configured dynamic modules want a database
          if config is not None:
              _apply_module_schemas(cur, database_engine, config)
  
          cur.close()
          db_conn.commit()
      except Exception:
          db_conn.rollback()
          raise
  
  
  def _setup_new_database(
      cur: Cursor, database_engine: BaseDatabaseEngine, databases: Collection[str]
  ) -> None:
      """Sets up the physical database by finding a base set of "full schemas" and
      then applying any necessary deltas, including schemas from the given data
      stores.
  
      The "full_schemas" directory has subdirectories named after versions. This
      function searches for the highest version less than or equal to
      `SCHEMA_VERSION` and executes all .sql files in that directory.
  
      The function will then apply all deltas for all versions after the base
      version.
  
      Example directory structure:
  
          schema/
              delta/
                  ...
              full_schemas/
                  3/
                      test.sql
                      ...
                  11/
                      foo.sql
                      bar.sql
                  ...
  
      In the example foo.sql and bar.sql would be run, and then any delta files
      for versions strictly greater than 11.
  
      Note: we apply the full schemas and deltas from the top level `schema/`
      folder as well those in the data stores specified.
  
      Args:
          cur: a database cursor
          database_engine
          databases: The names of the databases to instantiate on the given physical database.
      """
  
      # We're about to set up a brand new database so we check that its
      # configured to our liking.
      database_engine.check_new_database(cur)
  
      current_dir = os.path.join(dir_path, "schema", "full_schemas")
  
      # First we find the highest full schema version we have
      valid_versions = []
  
      for filename in os.listdir(current_dir):
          try:
              ver = int(filename)
          except ValueError:
              continue
  
          if ver <= SCHEMA_VERSION:
              valid_versions.append(ver)
  
      if not valid_versions:
          raise PrepareDatabaseException(
              "Could not find a suitable base set of full schemas"
          )
  
      max_current_ver = max(valid_versions)
  
      logger.debug("Initialising schema v%d", max_current_ver)
  
      # Now lets find all the full schema files, both in the global schema and
      # in data store schemas.
      directories = [os.path.join(current_dir, str(max_current_ver))]
      directories.extend(
          os.path.join(
              dir_path,
              "databases",
              database,
              "schema",
              "full_schemas",
              str(max_current_ver),
          )
          for database in databases
      )
  
      directory_entries = []  # type: List[_DirectoryListing]
      for directory in directories:
          directory_entries.extend(
              _DirectoryListing(file_name, os.path.join(directory, file_name))
              for file_name in os.listdir(directory)
          )
  
      if isinstance(database_engine, PostgresEngine):
          specific = "postgres"
      else:
          specific = "sqlite"
  
      directory_entries.sort()
      for entry in directory_entries:
          if entry.file_name.endswith(".sql") or entry.file_name.endswith(
              ".sql." + specific
          ):
              logger.debug("Applying schema %s", entry.absolute_path)
              executescript(cur, entry.absolute_path)
  
      cur.execute(
          "INSERT INTO schema_version (version, upgraded) VALUES (?,?)",
          (max_current_ver, False),
      )
  
      _upgrade_existing_database(
          cur,
          current_version=max_current_ver,
          applied_delta_files=[],
          upgraded=False,
          database_engine=database_engine,
          config=None,
          databases=databases,
          is_empty=True,
      )
  
  
  def _upgrade_existing_database(
      cur: Cursor,
      current_version: int,
      applied_delta_files: List[str],
      upgraded: bool,
      database_engine: BaseDatabaseEngine,
      config: Optional[HomeServerConfig],
      databases: Collection[str],
      is_empty: bool = False,
  ) -> None:
      """Upgrades an existing physical database.
  
      Delta files can either be SQL stored in *.sql files, or python modules
      in *.py.
  
      There can be multiple delta files per version. Synapse will keep track of
      which delta files have been applied, and will apply any that haven't been
      even if there has been no version bump. This is useful for development
      where orthogonal schema changes may happen on separate branches.
  
      Different delta files for the same version *must* be orthogonal and give
      the same result when applied in any order. No guarantees are made on the
      order of execution of these scripts.
  
      This is a no-op of current_version == SCHEMA_VERSION.
  
      Example directory structure:
  
          schema/
              delta/
                  11/
                      foo.sql
                      ...
                  12/
                      foo.sql
                      bar.py
                  ...
              full_schemas/
                  ...
  
      In the example, if current_version is 11, then foo.sql will be run if and
      only if `upgraded` is True. Then `foo.sql` and `bar.py` would be run in
      some arbitrary order.
  
      Note: we apply the delta files from the specified data stores as well as
      those in the top-level schema. We apply all delta files across data stores
      for a version before applying those in the next version.
  
      Args:
          cur
          current_version: The current version of the schema.
          applied_delta_files: A list of deltas that have already been applied.
          upgraded: Whether the current version was generated by having
              applied deltas or from full schema file. If `True` the function
              will never apply delta files for the given `current_version`, since
              the current_version wasn't generated by applying those delta files.
          database_engine
          config:
              None if we are initialising a blank database, otherwise the application
              config
          databases: The names of the databases to instantiate
              on the given physical database.
          is_empty: Is this a blank database? I.e. do we need to run the
              upgrade portions of the delta scripts.
      """
      if is_empty:
          assert not applied_delta_files
      else:
          assert config
  
      is_worker = config and config.worker_app is not None
  
      if current_version > SCHEMA_VERSION:
          raise ValueError(
              "Cannot use this database as it is too "
              + "new for the server to understand"
          )
  
      # some of the deltas assume that config.server_name is set correctly, so now
      # is a good time to run the sanity check.
      if not is_empty and "main" in databases:
          from synapse.storage.databases.main import check_database_before_upgrade
  
          assert config is not None
          check_database_before_upgrade(cur, database_engine, config)
  
      start_ver = current_version
      if not upgraded:
          start_ver += 1
  
      logger.debug("applied_delta_files: %s", applied_delta_files)
  
      if isinstance(database_engine, PostgresEngine):
          specific_engine_extension = ".postgres"
      else:
          specific_engine_extension = ".sqlite"
  
      specific_engine_extensions = (".sqlite", ".postgres")
  
      for v in range(start_ver, SCHEMA_VERSION + 1):
          if not is_worker:
              logger.info("Applying schema deltas for v%d", v)
  
              cur.execute("DELETE FROM schema_version")
              cur.execute(
                  "INSERT INTO schema_version (version, upgraded) VALUES (?,?)",
                  (v, True),
              )
          else:
              logger.info("Checking schema deltas for v%d", v)
  
          # We need to search both the global and per data store schema
          # directories for schema updates.
  
          # First we find the directories to search in
          delta_dir = os.path.join(dir_path, "schema", "delta", str(v))
          directories = [delta_dir]
          for database in databases:
              directories.append(
                  os.path.join(dir_path, "databases", database, "schema", "delta", str(v))
              )
  
          # Used to check if we have any duplicate file names
          file_name_counter = Counter()  # type: CounterType[str]
  
          # Now find which directories have anything of interest.
          directory_entries = []  # type: List[_DirectoryListing]
          for directory in directories:
              logger.debug("Looking for schema deltas in %s", directory)
              try:
                  file_names = os.listdir(directory)
                  directory_entries.extend(
                      _DirectoryListing(file_name, os.path.join(directory, file_name))
                      for file_name in file_names
                  )
  
                  for file_name in file_names:
                      file_name_counter[file_name] += 1
              except FileNotFoundError:
                  # Data stores can have empty entries for a given version delta.
                  pass
              except OSError:
                  raise UpgradeDatabaseException(
                      "Could not open delta dir for version %d: %s" % (v, directory)
                  )
  
          duplicates = {
              file_name for file_name, count in file_name_counter.items() if count > 1
          }
          if duplicates:
              # We don't support using the same file name in the same delta version.
              raise PrepareDatabaseException(
                  "Found multiple delta files with the same name in v%d: %s"
                  % (v, duplicates,)
              )
  
          # We sort to ensure that we apply the delta files in a consistent
          # order (to avoid bugs caused by inconsistent directory listing order)
          directory_entries.sort()
          for entry in directory_entries:
              file_name = entry.file_name
              relative_path = os.path.join(str(v), file_name)
              absolute_path = entry.absolute_path
  
              logger.debug("Found file: %s (%s)", relative_path, absolute_path)
              if relative_path in applied_delta_files:
                  continue
  
              root_name, ext = os.path.splitext(file_name)
  
              if ext == ".py":
                  # This is a python upgrade module. We need to import into some
                  # package and then execute its `run_upgrade` function.
                  if is_worker:
                      raise PrepareDatabaseException(
                          UNAPPLIED_DELTA_ON_WORKER_ERROR % relative_path
                      )
  
                  module_name = "synapse.storage.v%d_%s" % (v, root_name)
                  with open(absolute_path) as python_file:
                      module = imp.load_source(module_name, absolute_path, python_file)  # type: ignore
                  logger.info("Running script %s", relative_path)
                  module.run_create(cur, database_engine)  # type: ignore
                  if not is_empty:
                      module.run_upgrade(cur, database_engine, config=config)  # type: ignore
              elif ext == ".pyc" or file_name == "__pycache__":
                  # Sometimes .pyc files turn up anyway even though we've
                  # disabled their generation; e.g. from distribution package
                  # installers. Silently skip it
                  continue
              elif ext == ".sql":
                  # A plain old .sql file, just read and execute it
                  if is_worker:
                      raise PrepareDatabaseException(
                          UNAPPLIED_DELTA_ON_WORKER_ERROR % relative_path
                      )
                  logger.info("Applying schema %s", relative_path)
                  executescript(cur, absolute_path)
              elif ext == specific_engine_extension and root_name.endswith(".sql"):
                  # A .sql file specific to our engine; just read and execute it
                  if is_worker:
                      raise PrepareDatabaseException(
                          UNAPPLIED_DELTA_ON_WORKER_ERROR % relative_path
                      )
                  logger.info("Applying engine-specific schema %s", relative_path)
                  executescript(cur, absolute_path)
              elif ext in specific_engine_extensions and root_name.endswith(".sql"):
                  # A .sql file for a different engine; skip it.
                  continue
              else:
                  # Not a valid delta file.
                  logger.warning(
                      "Found directory entry that did not end in .py or .sql: %s",
                      relative_path,
                  )
                  continue
  
              # Mark as done.
              cur.execute(
                  "INSERT INTO applied_schema_deltas (version, file) VALUES (?,?)",
                  (v, relative_path),
              )
  
      logger.info("Schema now up to date")
  
  
  def _apply_module_schemas(
      txn: Cursor, database_engine: BaseDatabaseEngine, config: HomeServerConfig
  ) -> None:
      """Apply the module schemas for the dynamic modules, if any
  
      Args:
          cur: database cursor
          database_engine:
          config: application config
      """
      for (mod, _config) in config.password_providers:
          if not hasattr(mod, "get_db_schema_files"):
              continue
          modname = ".".join((mod.__module__, mod.__name__))
          _apply_module_schema_files(
              txn, database_engine, modname, mod.get_db_schema_files()
          )
  
  
  def _apply_module_schema_files(
      cur: Cursor,
      database_engine: BaseDatabaseEngine,
      modname: str,
      names_and_streams: Iterable[Tuple[str, TextIO]],
  ) -> None:
      """Apply the module schemas for a single module
  
      Args:
          cur: database cursor
          database_engine: synapse database engine class
          modname: fully qualified name of the module
          names_and_streams: the names and streams of schemas to be applied
      """
      cur.execute(
          "SELECT file FROM applied_module_schemas WHERE module_name = ?", (modname,),
      )
      applied_deltas = {d for d, in cur}
      for (name, stream) in names_and_streams:
          if name in applied_deltas:
              continue
  
          root_name, ext = os.path.splitext(name)
          if ext != ".sql":
              raise PrepareDatabaseException(
                  "only .sql files are currently supported for module schemas"
              )
  
          logger.info("applying schema %s for %s", name, modname)
          execute_statements_from_stream(cur, stream)
  
          # Mark as done.
          cur.execute(
              "INSERT INTO applied_module_schemas (module_name, file) VALUES (?,?)",
              (modname, name),
          )
  
  
  def get_statements(f: Iterable[str]) -> Generator[str, None, None]:
      statement_buffer = ""
      in_comment = False  # If we're in a /* ... */ style comment
  
      for line in f:
          line = line.strip()
  
          if in_comment:
              # Check if this line contains an end to the comment
              comments = line.split("*/", 1)
              if len(comments) == 1:
                  continue
              line = comments[1]
              in_comment = False
  
          # Remove inline block comments
          line = re.sub(r"/\*.*\*/", " ", line)
  
          # Does this line start a comment?
          comments = line.split("/*", 1)
          if len(comments) > 1:
              line = comments[0]
              in_comment = True
  
          # Deal with line comments
          line = line.split("--", 1)[0]
          line = line.split("//", 1)[0]
  
          # Find *all* semicolons. We need to treat first and last entry
          # specially.
          statements = line.split(";")
  
          # We must prepend statement_buffer to the first statement
          first_statement = "%s %s" % (statement_buffer.strip(), statements[0].strip())
          statements[0] = first_statement
  
          # Every entry, except the last, is a full statement
          for statement in statements[:-1]:
              yield statement.strip()
  
          # The last entry did *not* end in a semicolon, so we store it for the
          # next semicolon we find
          statement_buffer = statements[-1].strip()
  
  
  def executescript(txn: Cursor, schema_path: str) -> None:
      with open(schema_path, "r") as f:
          execute_statements_from_stream(txn, f)
  
  
  def execute_statements_from_stream(cur: Cursor, f: TextIO) -> None:
      for statement in get_statements(f):
          cur.execute(statement)
  
  
  def _get_or_create_schema_state(
      txn: Cursor, database_engine: BaseDatabaseEngine
  ) -> Optional[Tuple[int, List[str], bool]]:
      # Bluntly try creating the schema_version tables.
      schema_path = os.path.join(dir_path, "schema", "schema_version.sql")
      executescript(txn, schema_path)
  
      txn.execute("SELECT version, upgraded FROM schema_version")
      row = txn.fetchone()
      current_version = int(row[0]) if row else None
  
      if current_version:
          txn.execute(
              "SELECT file FROM applied_schema_deltas WHERE version >= ?",
              (current_version,),
          )
          applied_deltas = [d for d, in txn]
          upgraded = bool(row[1])
          return current_version, applied_deltas, upgraded
  
      return None
  
  
  @attr.s(slots=True)
  class _DirectoryListing:
      """Helper class to store schema file name and the
      absolute path to it.
  
      These entries get sorted, so for consistency we want to ensure that
      `file_name` attr is kept first.
      """
  
      file_name = attr.ib(type=str)
      absolute_path = attr.ib(type=str)
  