#!/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
# Hivemall. This script is a modified version of the ones created by the Spark project
# (https://github.com/apache/spark/blob/master/dev/merge_spark_pr.py) and Kafka project
# (https://github.com/apache/kafka/blob/trunk/kafka-merge-pr.py).
#   usage: ./merge_pr.py    (see config env vars below)
#
# This utility assumes you already have a local git folder and that you
# have added remotes corresponding to both (i) the github apache mirror
# and (ii) the apache git repo.

import json
import os
import re
import subprocess
import sys
from urllib.request import Request, urlopen
from urllib.error import HTTPError

try:
    import jira.client
    JIRA_IMPORTED = True
except ImportError:
    JIRA_IMPORTED = False

PROJECT_NAME = 'hivemall'
PROJECT_NAME_CAPITALIZED = PROJECT_NAME.upper()
INCUBATOR = True

# git remote add apache https://gitbox.apache.org/repos/asf/incubator-hivemall.git
# git remote add apache-github https://github.com/apache/incubator-hivemall.git

# Location of your project's git development area
REPO_HOME = os.environ.get('%s_HOME' % PROJECT_NAME_CAPITALIZED, os.getcwd())
# Remote name which points to the Gihub 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', '')
# ASF JIRA password
JIRA_PASSWORD = os.environ.get('JIRA_PASSWORD', '')
# OAuth key used for issuing requests against the GitHub API. If this is not defined, then requests
# will be unauthenticated. You should only need to configure this if you find yourself regularly
# exceeding your IP's unauthenticated request rate limit. You can create an OAuth key at
# https://github.com/settings/tokens. This script only requires the "public_repo" scope.
GITHUB_OAUTH_KEY = os.environ.get('GITHUB_OAUTH_KEY')

REPO_NAME = ('incubator-%s' % PROJECT_NAME) if INCUBATOR else PROJECT_NAME
GITHUB_BASE = 'https://github.com/apache/%s/pull' % REPO_NAME
GITHUB_API_BASE = 'https://api.github.com/repos/apache/%s' % REPO_NAME
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"

RELEASE_BRANCH_PREFIX = 'dev/'  # tmp


def get_json(url):
    try:
        request = Request(url)
        if GITHUB_OAUTH_KEY:
            request.add_header('Authorization', 'token %s' % GITHUB_OAUTH_KEY)
        return json.loads(urlopen(request).read().decode('utf-8'))
    except HTTPError as e:
        if 'X-RateLimit-Remaining' in e.headers and e.headers['X-RateLimit-Remaining'] == '0':
            print('Exceeded the GitHub API rate limit; see the instructions in ' +
                  'merge_pr.py to configure an OAuth token for making authenticated ' +
                  'GitHub requests.')
        else:
            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('utf-8')
    else:
        return subprocess.check_output(cmd.split(' ')).decode('utf-8')


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


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 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, title, body, pr_repo_desc):
    pr_branch_name = '%s_MERGE_PR_%s' % (BRANCH_PREFIX, pr_num)
    target_branch_name = '%s_MERGE_PR_%s_%s' % (BRANCH_PREFIX, pr_num, target_ref.upper())
    run_cmd('git fetch %s pull/%s/head:%s' % (PR_REMOTE_NAME, pr_num, pr_branch_name))
    run_cmd('git fetch %s %s:%s' % (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')
    distinct_authors = sorted(set(commit_authors),
                              key=lambda x: commit_authors.count(x), reverse=True)
    primary_author = input(
        'Enter primary author in the format of "name <email>" [%s]: ' %
        distinct_authors[0])
    if primary_author == '':
        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 the project.
        merge_message_flags += ['-m', body.replace('@', '')]

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

    merge_message_flags += ['-m', authors]

    if had_conflicts:
        committer_name = run_cmd('git config --get user.name').strip()
        committer_email = run_cmd('git config --get user.email').strip()
        message = 'This patch had conflicts when merged, resolved by\nCommitter: %s <%s>' % (
            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 #%s from %s.' % (pr_num, pr_repo_desc)]

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

    continue_maybe('Merge complete (local ref %s). Push to %s?' % (
        target_branch_name, PUSH_REMOTE_NAME))

    try:
        run_cmd('git push %s %s:%s' % (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 = '%s_PICK_PR_%s_%s' % (BRANCH_PREFIX, pr_num, pick_ref.upper())

    run_cmd('git fetch %s %s:%s' % (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 %s). Push to %s?' % (
        pick_branch_name, PUSH_REMOTE_NAME))

    try:
        run_cmd('git push %s %s:%s' % (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 #%s picked into %s!' % (pr_num, pick_ref))
    print('Pick hash: %s' % pick_hash)
    return pick_ref


def fix_version_from_branch(branch, versions):
    # 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 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 %s\n%s' % (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 %s already has status '%s'" % (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(PROJECT_NAME_CAPITALIZED)
    versions = sorted(versions, key=lambda x: x.name, reverse=True)
    versions = filter(lambda x: x.raw['released'] is False, versions)
    # Consider only x.y.z versions
    versions = filter(lambda x: re.match('\d+\.\d+\.\d+', x.name), versions)

    default_fix_versions = map(lambda x: fix_version_from_branch(x, 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 = '%s.%s.%s' % (major, int(minor) - 1, 0)
            if previous in default_fix_versions:
                default_fix_versions = 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 filter(lambda v: v.name == version_str, versions)[0].raw

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

    resolve = filter(lambda a: a['name'] == 'Resolve Issue', asf_jira.transitions(jira_id))[0]
    resolution = filter(lambda r: r.raw['name'] == 'Fixed', asf_jira.resolutions())[0]
    asf_jira.transition_issue(
        jira_id, resolve['id'], fixVersions=jira_fix_versions,
        comment=comment, resolution={'id': resolution.raw['id']})

    print('Successfully resolved %s with fixVersions=%s!' % (jira_id, fix_versions))


def resolve_jira_issues(title, merge_branches, comment):
    jira_ids = re.findall('%s-[0-9]{4,5}' % PROJECT_NAME_CAPITALIZED, 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)


def standardize_jira_ref(text):
    """
    Standardize the [PROJECT_NAME_CAPITALIZED-XXXXX] [MODULE] prefix
    Converts "[PROJECT_NAME_CAPITALIZED_XXX][module] Issue", "[Module] PROJECT_NAME_CAPITALIZED-XXX. Issue" or "PROJECT_NAME_CAPITALIZED XXX [MODULE]: Issue" to
    "[PROJECT_NAME_CAPITALIZED-XXX][MODULE] Issue"
    >>> standardize_jira_ref('[%s-0000] [MODULE] Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000][MODULE] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('[%s-0000][Module][WIP]: Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000][MODULE][WIP] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('[Module] %s  0000: Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000][MODULE] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('[%s-0000] Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('%s-0000 Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('[WIP]  [%s-0000] Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000][WIP] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref('%s-0000. Issue' % PROJECT_NAME_CAPITALIZED) == '[%s-0000] Issue' % PROJECT_NAME_CAPITALIZED
    True
    >>> standardize_jira_ref(
    ...     '[%s-0000][%s-1111][%s-2222][MODULE] Issue' % ((PROJECT_NAME_CAPITALIZED,) * 3)) == '[%s-0000][%s-1111][%s-2222][MODULE] Issue' % ((PROJECT_NAME_CAPITALIZED,) * 3)
    True
    >>> standardize_jira_ref('Issue') == 'Issue'
    True
    """
    jira_refs = []
    components = []

    # If the string is compliant, no need to process any further
    if (re.search('^\[%s-[0-9]{3,6}\](\[[A-Z0-9_\s,]+\] )+\S+' % PROJECT_NAME_CAPITALIZED, text)):
        return text

    # Extract JIRA ref(s):
    pattern = re.compile('(%s[-\s]*[0-9]{3,6})+' % PROJECT_NAME_CAPITALIZED, re.IGNORECASE)
    for ref in pattern.findall(text):
        # Add brackets, replace spaces with a dash, & convert to uppercase
        jira_refs.append('[' + re.sub(r'\s+', '-', ref.upper()) + ']')
        text = text.replace(ref, '')

    # Extract spark component(s):
    # Look for alphanumeric chars, spaces, dashes, periods, and/or commas
    pattern = re.compile(r'(\[[\w\s,-\.]+\])', re.IGNORECASE)
    for component in pattern.findall(text):
        components.append(component.upper())
        text = text.replace(component, '')

    # Cleanup any remaining symbols:
    pattern = re.compile(r'^\W+(.*)', re.IGNORECASE)
    if (pattern.search(text) is not None):
        text = pattern.search(text).groups()[0]

    # Assemble full text (JIRA ref(s), module(s), remaining text)
    clean_text = ''.join(jira_refs).strip() + ''.join(components).strip() + ' ' + text.strip()

    # Replace multiple spaces with a single space, e.g. if no jira refs and/or components were
    # included
    clean_text = re.sub(r'\s+', ' ', clean_text.strip())

    return clean_text


def get_current_ref():
    ref = run_cmd('git rev-parse --abbrev-ref HEAD').strip()
    if ref == 'HEAD':
        # The current ref is a detached HEAD, so grab its SHA.
        return run_cmd('git rev-parse HEAD').strip()
    else:
        return ref


def main():
    global original_head

    os.chdir(REPO_HOME)
    original_head = get_current_ref()

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

    pr_num = input('Which pull request would you like to merge? (e.g. 34): ')
    pr = get_json('%s/pulls/%s' % (GITHUB_API_BASE, pr_num))
    pr_events = get_json('%s/issues/%s/events' % (GITHUB_API_BASE, pr_num))

    url = pr['url']

    # Decide whether to use the modified title or not
    modified_title = standardize_jira_ref(pr['title'])
    if modified_title != pr['title']:
        print("I've re-written the title as follows to match the standard format:")
        print('Original: %s' % pr['title'])
        print("Modified: %s" % modified_title)
        result = input('Would you like to use the modified title? (y/n): ')
        if result.lower() == 'y':
            title = modified_title
            print('Using modified title:')
        else:
            title = pr['title']
            print('Using original title:')
        print(title)
    else:
        title = pr['title']

    body = pr['body']
    target_ref = pr['base']['ref']
    user_login = pr['user']['login']
    base_ref = pr['head']['ref']
    pr_repo_desc = '%s/%s' % (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('%s/commits/%s' % (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 %s:\n%s' % (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%s\nsource\t%s\ntarget\t%s\nurl\t%s' %
          (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, title, body, pr_repo_desc)

    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 %s\n[%s/%s]' % \
                           (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-python library. Run 'sudo pip install jira' to install.")
        print('Exiting without trying to close the associated JIRA.')


if __name__ == '__main__':
    import doctest
    (failure_count, test_count) = doctest.testmod()
    if failure_count:
        exit(-1)
    if sys.version_info < (3,):
        print('This script requires you to use Python 3')
        exit(-1)
    try:
        main()
    except Exception:
        clean_up()
        raise