#!/usr/bin/env python

#
# 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.
#

# Utility for creating well-formed pull request merges and pushing them to Apache.
#   usage: ./merge-submarine-pr.py    (see config env vars below)
#
# This utility assumes you already have local a Submarine git folder and that you
# have added remotes corresponding to both (i) the github apache Submarine
# mirror and (ii) the apache git repo.

import json
import os
import re
import subprocess
import sys
import urllib
from typing import List

try:
    import jira.client

    JIRA_IMPORTED = True
except ImportError:
    JIRA_IMPORTED = False

# Location of your Submarine git development area
SUBMARINE_HOME = os.environ.get("SUBMARINE_HOME", os.getcwd())
# Remote name which points to the Github site
PR_REMOTE_NAME = os.environ.get("PR_REMOTE_NAME", "apache-github")
# Remote name which points to Apache git
PUSH_REMOTE_NAME = os.environ.get("PUSH_REMOTE_NAME", "apache")
# ASF JIRA username
JIRA_USERNAME = os.environ.get("JIRA_USERNAME", "you-jira-user-name")
# ASF JIRA password
JIRA_PASSWORD = os.environ.get("JIRA_PASSWORD", "you-jira-password")

GITHUB_BASE = "https://github.com/apache/submarine/pull"
GITHUB_API_BASE = "https://api.github.com/repos/apache/submarine"
JIRA_BASE = "https://issues.apache.org/jira/browse"
JIRA_API_BASE = "https://issues.apache.org/jira"
# Prefix added to temporary branches
BRANCH_PREFIX = "PR_TOOL"

os.chdir(SUBMARINE_HOME)


def get_json(url):
    try:
        return json.load(urllib.request.urlopen(url))
    except urllib.error.HTTPError:
        print("Unable to fetch URL, exiting: %s" % url)
        sys.exit(-1)


def fail(msg):
    print(msg)
    clean_up()
    sys.exit(-1)


def run_cmd(cmd):
    print(cmd)
    if isinstance(cmd, list):
        return subprocess.check_output(cmd).decode()
    else:
        return subprocess.check_output(cmd.split(" ")).decode()


def continue_maybe(prompt):
    result = input("\n%s (y/n): " % prompt)
    if result.lower() != "y":
        fail("Okay, exiting")


original_head = run_cmd("git rev-parse HEAD")[:8]


def clean_up():
    print("Restoring head pointer to %s" % original_head)
    run_cmd("git checkout %s" % original_head)

    branches = run_cmd("git branch").replace(" ", "").split("\n")

    for branch in list(filter(lambda x: x.startswith(BRANCH_PREFIX), branches)):
        print("Deleting local branch %s" % branch)
        run_cmd("git branch -D %s" % branch)


# merge the requested PR and return the merge hash
def merge_pr(pr_num, target_ref):
    pr_branch_name = "{}_MERGE_PR_{}".format(BRANCH_PREFIX, pr_num)
    target_branch_name = "{}_MERGE_PR_{}_{}".format(BRANCH_PREFIX, pr_num, target_ref.upper())
    run_cmd("git fetch {} pull/{}/head:{}".format(PR_REMOTE_NAME, pr_num, pr_branch_name))
    run_cmd("git fetch {} {}:{}".format(PUSH_REMOTE_NAME, target_ref, target_branch_name))
    run_cmd("git checkout %s" % target_branch_name)

    had_conflicts = False
    try:
        run_cmd(["git", "merge", pr_branch_name, "--squash"])
    except Exception as e:
        msg = "Error merging: %s\nWould you like to manually fix-up this merge?" % e
        continue_maybe(msg)
        msg = "Okay, please fix any conflicts and 'git add' conflicting files... Finished?"
        continue_maybe(msg)
        had_conflicts = True
    commit_authors = run_cmd(["git", "log", "HEAD..%s" % pr_branch_name, "--pretty=format:%an <%ae>"]).split(
        "\n"
    )
    commit_date = run_cmd(["git", "log", "%s" % pr_branch_name, "-1", "--pretty=format:%ad"])
    distinct_authors = sorted(set(commit_authors), key=lambda x: commit_authors.count(x), reverse=True)
    primary_author = distinct_authors[0]
    commits = run_cmd(["git", "log", "HEAD..%s" % pr_branch_name, "--pretty=format:%h [%an] %s"]).split(
        "\n\n"
    )

    merge_message_flags = []

    merge_message_flags += ["-m", title]
    if body is not None:
        # We remove @ symbols from the body to avoid triggering e-mails
        # to people every time someone creates a public fork of Submarine.
        merge_message_flags += ["-m", body.replace("@", "")]

    authors = "\n".join(["Author: %s" % a for a in distinct_authors])

    merge_message_flags += ["-m", authors]

    committer_name = run_cmd("git config --get user.name").strip()
    committer_email = run_cmd("git config --get user.email").strip()
    merge_message_flags += [
        "-m",
        "\n" + "Signed-off-by: {} <{}>".format(committer_name, committer_email),
    ]

    if had_conflicts:
        message = "This patch had conflicts when merged, resolved by\nCommitter: {} <{}>".format(
            committer_name,
            committer_email,
        )
        merge_message_flags += ["-m", message]

    # The string "Closes #%s" string is required for GitHub to correctly close the PR
    merge_message_flags += [
        "-m",
        "Closes #{} from {} and squashes the following commits:".format(pr_num, pr_repo_desc),
    ]
    for c in commits:
        merge_message_flags += ["-m", c]

    run_cmd(
        ["git", "commit", '--author="%s"' % primary_author, '--date="%s"' % commit_date] + merge_message_flags
    )

    continue_maybe("Merge complete (local ref {}). Push to {}?".format(target_branch_name, PUSH_REMOTE_NAME))

    try:
        run_cmd("git push {} {}:{}".format(PUSH_REMOTE_NAME, target_branch_name, target_ref))
    except Exception as e:
        clean_up()
        fail("Exception while pushing: %s" % e)

    merge_hash = run_cmd("git rev-parse %s" % target_branch_name)[:8]
    clean_up()
    print("Pull request #%s merged!" % pr_num)
    print("Merge hash: %s" % merge_hash)
    return merge_hash


def cherry_pick(pr_num, merge_hash, default_branch):
    pick_ref = input("Enter a branch name [%s]: " % default_branch)
    if pick_ref == "":
        pick_ref = default_branch

    pick_branch_name = "{}_PICK_PR_{}_{}".format(BRANCH_PREFIX, pr_num, pick_ref.upper())

    run_cmd("git fetch {} {}:{}".format(PUSH_REMOTE_NAME, pick_ref, pick_branch_name))
    run_cmd("git checkout %s" % pick_branch_name)

    try:
        run_cmd("git cherry-pick -sx %s" % merge_hash)
    except Exception as e:
        msg = "Error cherry-picking: %s\nWould you like to manually fix-up this merge?" % e
        continue_maybe(msg)
        msg = "Okay, please fix any conflicts and finish the cherry-pick. Finished?"
        continue_maybe(msg)

    continue_maybe("Pick complete (local ref {}). Push to {}?".format(pick_branch_name, PUSH_REMOTE_NAME))

    try:
        run_cmd("git push {} {}:{}".format(PUSH_REMOTE_NAME, pick_branch_name, pick_ref))
    except Exception as e:
        clean_up()
        fail("Exception while pushing: %s" % e)

    pick_hash = run_cmd("git rev-parse %s" % pick_branch_name)[:8]
    clean_up()

    print("Pull request #{} picked into {}!".format(pr_num, pick_ref))
    print("Pick hash: %s" % pick_hash)
    return pick_ref


def fix_version_from_branch(branch, versions) -> List:
    # Note: Assumes this is a sorted (newest->oldest) list of un-released versions
    if branch == "master":
        return versions[0]
    else:
        branch_ver = branch.replace("branch-", "")
        return list(filter(lambda x: x.name.startswith(branch_ver), versions))[-1]


def resolve_jira_issue(merge_branches, comment, default_jira_id=""):
    asf_jira = jira.client.JIRA({"server": JIRA_API_BASE}, basic_auth=(JIRA_USERNAME, JIRA_PASSWORD))

    jira_id = input("Enter a JIRA id [%s]: " % default_jira_id)
    if jira_id == "":
        jira_id = default_jira_id

    try:
        issue = asf_jira.issue(jira_id)
    except Exception as e:
        fail("ASF JIRA could not find {}\n{}".format(jira_id, e))

    cur_status = issue.fields.status.name
    cur_summary = issue.fields.summary
    cur_assignee = issue.fields.assignee
    if cur_assignee is None:
        cur_assignee = "NOT ASSIGNED!!!"
    else:
        cur_assignee = cur_assignee.displayName

    if cur_status == "Resolved" or cur_status == "Closed":
        fail("JIRA issue {} already has status '{}'".format(jira_id, cur_status))
    print("=== JIRA %s ===" % jira_id)
    print(
        "summary\t\t%s\nassignee\t%s\nstatus\t\t%s\nurl\t\t%s/%s\n"
        % (cur_summary, cur_assignee, cur_status, JIRA_BASE, jira_id)
    )

    versions = asf_jira.project_versions("SUBMARINE")
    versions = sorted(versions, key=lambda x: x.name, reverse=True)
    versions = list(filter(lambda x: x.raw["released"] is False, versions))
    # Consider only x.y.z versions
    versions = list(filter(lambda x: re.match(r"\d+\.\d+\.\d+", x.name), versions))

    default_fix_versions: List = list(
        map(lambda x: fix_version_from_branch(x, list(versions)).name, merge_branches)
    )
    for v in default_fix_versions:
        # Handles the case where we have forked a release branch but not yet made the release.
        # In this case, if the PR is committed to the master branch and the release branch, we
        # only consider the release branch to be the fix version. E.g. it is not valid to have
        # both 1.1.0 and 1.0.0 as fix versions.
        (major, minor, patch) = v.split(".")
        if patch == "0":
            previous = "{}.{}.{}".format(major, int(minor) - 1, 0)
            if previous in default_fix_versions:
                default_fix_versions: List = list(filter(lambda x: x != v, default_fix_versions))
    default_fix_versions = ",".join(default_fix_versions)

    fix_versions = input("Enter comma-separated fix version(s) [%s]: " % default_fix_versions)
    if fix_versions == "":
        fix_versions = default_fix_versions
    fix_versions = fix_versions.replace(" ", "").split(",")

    def get_version_json(version_str):
        return list(filter(lambda v: v.name == version_str, versions))[0].raw

    jira_fix_versions = list(map(lambda v: get_version_json(v), fix_versions))

    resolve = list(filter(lambda a: a["name"] == "Resolve Issue", asf_jira.transitions(jira_id)))[0]
    asf_jira.transition_issue(jira_id, resolve["id"], fixVersions=jira_fix_versions, comment=comment)

    print("Successfully resolved {} with fixVersions={}!".format(jira_id, fix_versions))


def resolve_jira_issues(title, merge_branches, comment):
    jira_ids = re.findall("SUBMARINE-[0-9]{3,5}", title)

    if len(jira_ids) == 0:
        resolve_jira_issue(merge_branches, comment)
    for jira_id in jira_ids:
        resolve_jira_issue(merge_branches, comment, jira_id)


# branches = get_json("%s/branches" % GITHUB_API_BASE)
# branch_names = filter(lambda x: x.startswith("branch-"), [x['name'] for x in branches])
# Assumes branch names can be sorted lexicographically
# latest_branch = sorted(branch_names, reverse=True)[0]
latest_branch = "master"

pr_num = input("Which pull request would you like to merge? (e.g. 23): ")
pr = get_json("{}/pulls/{}".format(GITHUB_API_BASE, pr_num))
pr_events = get_json("{}/issues/{}/events".format(GITHUB_API_BASE, pr_num))

url = pr["url"]
title = pr["title"]
body = pr["body"]
target_ref = pr["base"]["ref"]
user_login = pr["user"]["login"]
base_ref = pr["head"]["ref"]
pr_repo_desc = "{}/{}".format(user_login, base_ref)

# Merged pull requests don't appear as merged in the GitHub API;
# Instead, they're closed by asfgit.
merge_commits = [e for e in pr_events if e["actor"]["login"] == "asfgit" and e["event"] == "closed"]

if merge_commits:
    merge_hash = merge_commits[0]["commit_id"]
    message = get_json("{}/commits/{}".format(GITHUB_API_BASE, merge_hash))["commit"]["message"]

    print("Pull request %s has already been merged, assuming you want to backport" % pr_num)
    commit_is_downloaded = (
        run_cmd(["git", "rev-parse", "--quiet", "--verify", "%s^{commit}" % merge_hash]).strip() != ""
    )
    if not commit_is_downloaded:
        fail("Couldn't find any merge commit for #%s, you may need to update HEAD." % pr_num)

    print("Found commit {}:\n{}".format(merge_hash, message))
    cherry_pick(pr_num, merge_hash, latest_branch)
    sys.exit(0)

if not bool(pr["mergeable"]):
    msg = "Pull request %s is not mergeable in its current form.\n" % pr_num + "Continue? (experts only!)"
    continue_maybe(msg)

print("\n=== Pull Request #%s ===" % pr_num)
print("title\t{}\nsource\t{}\ntarget\t{}\nurl\t{}".format(title, pr_repo_desc, target_ref, url))
continue_maybe("Proceed with merging pull request #%s?" % pr_num)

merged_refs = [target_ref]

merge_hash = merge_pr(pr_num, target_ref)

pick_prompt = "Would you like to pick %s into another branch?" % merge_hash
while input("\n%s (y/n): " % pick_prompt).lower() == "y":
    merged_refs = merged_refs + [cherry_pick(pr_num, merge_hash, latest_branch)]

if JIRA_IMPORTED:
    if JIRA_USERNAME and JIRA_PASSWORD:
        continue_maybe("Would you like to update an associated JIRA?")
        jira_comment = "Issue resolved by pull request {}\n[{}/{}]".format(pr_num, GITHUB_BASE, pr_num)
        resolve_jira_issues(title, merged_refs, jira_comment)
    else:
        print("JIRA_USERNAME and JIRA_PASSWORD not set")
        print("Exiting without trying to close the associated JIRA.")
else:
    print("Could not find jira library. Run 'sudo pip install jira' to install.")
    print("Exiting without trying to close the associated JIRA.")
