action.py

#!/usr/bin/env python3

import argparse
from github import Github
import os
import sys

NOTE = "\n\n*Note: This comment is automatically posted by the " \
       "Documentation Publish GitHub Action.*"
PREFIX = "You can find the documentation preview for this PR at this " \
         "<a href='{}'>link</a>." \


def main():
    parser = argparse.ArgumentParser(
        description="GH action to comment on a PR with the documentation preview URL",
        formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument('-u', '--urlroot', action='store', required=True,
                        help='Root of the URL were documentation preview is '
                             'located.')
    parser.add_argument('-p', '--pr-prefix', action='store', required=False,
                        help='Prefix added to the contents of "--pr-file" '
                             'when generating the URL link.')
    parser.add_argument('-f', '--pr-file', action='store', required=True,
                        help='File generated by the workflow containing the '
                             'number of the PR for which documentation '
                             'preview is being generated.')

    token = os.environ.get('GITHUB_TOKEN', None)
    if not token:
        sys.exit('Github token not set in environment, please set the '
                 'GITHUB_TOKEN environment variable and retry.')

    args = parser.parse_args()

    urlroot = args.urlroot
    pr_prefix = args.pr_prefix
    pr_file = args.pr_file

    action = os.environ.get('GITHUB_ACTION', None)
    workflow = os.environ.get('GITHUB_WORKFLOW', None)
    org_repo = os.environ.get('GITHUB_REPOSITORY', None)

    print(f'Running action {action} from workflow {workflow} in {org_repo}')

    try:
        f = open(pr_file)
    except FileNotFoundError:
        print(f'Skipping comment because {pr_file} does not exist')
        sys.exit(0)

    pull_request = f.read()

    gh = Github(token)

    tk_usr = gh.get_user()
    gh_repo = gh.get_repo(org_repo)
    gh_pr = gh_repo.get_pull(int(pull_request))

    if not urlroot.endswith('/'):
        urlroot += '/'
    if pr_prefix is None:
        pr_prefix = ''
    url = urlroot + pr_prefix + pull_request + '/'
    message = PREFIX.format(url) + NOTE

    comment = None
    for c in gh_pr.get_issue_comments():
        if c.user.login == tk_usr.login and NOTE in c.body:
            comment = c
            break

    if comment is None:
        print('Creating comment')
        gh_pr.create_issue_comment(message)
    else:
        print('Comment already exists, skipping')

    sys.exit(0)


if __name__ == '__main__':
    main()