git-sync.py

#!/usr/bin/env python3

import os
import os.path
import re
import signal
import sys
import time

from datetime import datetime as dt
from datetime import timedelta as td
from pathlib import Path

import git
import pywikibot as pwb
import yaml


class SignalHandler:

    def __init__(self):
        self._is_sleeping = False
        self._exit_requested = False
        signal.signal(signal.SIGINT, self._request_exit)
        signal.signal(signal.SIGTERM, self._request_exit)

    def _request_exit(self, signal, frame):
        if self._is_sleeping:
            self._exit_now()
        else:
            self._exit_requested = True

    def _exit_now(self):
        print('SIGINT or SIGTERM received, exiting...')
        sys.exit(0)

    def sleep(self, seconds):
        if self._exit_requested:
            self._exit_now()
        else:
            self._is_sleeping = True
            time.sleep(seconds)
            self._is_sleeping = False


class GitSync:

    def __init__(self):
        self._base_path = Path(__file__).parent
        self._config_file = self._base_path / 'config.yml'
        self.config = {}
        self.repos = []
        self.usermap_email_list = []

    def init_repos(self):
        for repo in self.config['repos']:
            file_regex = re.compile(
                    repo['file_regex'],
                    re.I if repo['regex_nocase'] else 0)
            repo_path = os.path.join(self.config['repositories_root'], repo['name'])
            git_repo = git.Repo(repo_path)
            site = pwb.Site(
                    code=repo['project']['code'],
                    fam=repo['project']['family'],
                    user=self.config['mediawiki_username'])
            self.repos.append(GitRepo(repo['name'], git_repo, site,
                              repo['namespace'], file_regex, repo['force_extension'],
                              repo['ignore_list'] + self.config['global_ignore_list'],
                              self.config['usermap'], self.usermap_email_list))

    def read_config(self):
        self.config = yaml.load(self._config_file.read_text(), Loader=yaml.FullLoader)
        if not self.config:
            print('Error: Configuration file not found or empty.', file=sys.stderr)
            sys.exit(1)
        else:
            self.usermap_email_list = [_['email'] for _ in self.config['usermap'].values()]


class GitRepo:

    def __init__(self, name, repo, site, namespace, title_regex, force_ext, ignores, usermap, usermap_email_list):
        self.name = name
        self.repo = repo
        self.site = site
        self.namespace = namespace
        self.title_regex = title_regex
        self.force_ext = force_ext
        if force_ext:
            self.re_force_ext = re.compile(r'\.' + force_ext + '$')
        self.ignores = ignores
        self._need_resync = False
        self._pending_commits = {}
        self._usermap = usermap
        self._usermap_email_list = usermap_email_list

    def _create_summary(self, author_name, author_email, repo_name, commit_sha, message):
        base_url = 'https://github.com/wikimedia-bg'
        message = message.replace('\n', ' ')
        # Try finding the commit author email in the usermap dictionary. For this we have two lists:
        #   * the top-level keys, i.e. the Wikimedia usernames (list(self._usermap.keys()));
        #   * the email subkeys in the _same_ order (created in GitSync.read_config()).
        # Because the two lists have the same order, the username in index N in the first list corresponds to the email
        # in index N in the second list. Thus, if we find the commit author email in the second list at index N, we know
        # that the corresponding Wikimedia username will be at index N in the first list.
        try:
            wiki_user = list(self._usermap.keys())[self._usermap_email_list.index(author_email)]
        # If there's no match, just mention the commit author's name in the edit summary, but don't create a user page
        # link.
        except ValueError:
            wiki_user_mention = author_name
        # If there is a match, create a user page link, since this must be a valid Wikimedia user.
        else:
            wiki_user_mention = '[[User:{user}|{user}]]'.format(user=wiki_user)
        return '{user_mention} | {base_url}/{repo}/commit/{sha} | {message}'.format(
                user_mention=wiki_user_mention,
                base_url=base_url,
                repo=repo_name,
                sha=commit_sha,
                message=message[:400] + (message[400:] and '..'))

    def _pagelist(self):
        return [_ for _ in self.site.allpages(namespace=self.namespace)
                if self.title_regex.search(_.title(with_ns=False))]

    def _last_changed(self):
        return dt.utcfromtimestamp(self.repo.commit('master').committed_date) + td(seconds=1)

    def _pending_revs(self):
        pending_revs = []
        for page in self._pagelist():
            try:
                revs_since_last_sync = page.revisions(endtime=self._last_changed(), content=True)
                candidate_revs = [(page.title(with_ns=False), _, 'edit') for _ in revs_since_last_sync]
                if self._need_resync:
                    # Full re-sync requested, so get the latest revision of _all_ pages in the repo.
                    last_rev = page.latest_revision
                    candidate_revs.append(
                            (
                                page.title(with_ns=False),
                                {
                                    'user': 'syncbot',
                                    'comment': 'forced resync from wiki',
                                    'text': last_rev['text'],
                                    'timestamp': dt.utcnow(),
                                },
                                'resync',
                            )
                    )
            except pwb.exceptions.NoPage:
                # Apparently, the page got deleted on-wiki during our processing so scrap the candiate_revs.
                pass
            else:
                pending_revs += candidate_revs
        # If a resync has been requested, it's done.
        self._need_resync = False
        # We need to also check for deleted pages that we keep track of.
        repo_files = [_.path for _ in self.repo.tree().traverse() if _.type != 'tree']
        page_files = set(repo_files) - set(self.ignores)
        if self.force_ext:
            repo_pages = [self.re_force_ext.sub('', _.replace('.d/', '/')) for _ in page_files]
        else:
            repo_pages = [_.replace('.d/', '/') for _ in page_files]
        existing_pages = [_.title(with_ns=False) for _ in self._pagelist()]
        deleted_pages = set(repo_pages) - set(existing_pages)
        for page_name in deleted_pages:
            for event in self.site.logevents(page=self.namespace + ':' + page_name):
                if event.type() in ['delete', 'move']:
                    pending_revs.append(
                            (
                                page_name,
                                {
                                    'user': event.user(),
                                    'comment': event.comment(),
                                    'timestamp': event.timestamp(),
                                },
                                event.type(),
                            )
                    )
                    # We need only the first (chronologically last) delete or move event.
                    break
        pending_revs.sort(key=lambda rev: rev[1]['timestamp'])
        return pending_revs

    def _pull(self):
        old_master = self.repo.commit('master')
        self.repo.git.pull()
        new_master = self.repo.commit('master')
        if new_master == old_master:
            return
        pull_commits_newest_first = self.repo.iter_commits(
                old_master.hexsha + '...' + self.repo.commit('master').hexsha)
        pull_commits = reversed([_ for _ in pull_commits_newest_first])
        # This requires Python 3.7+ to keep the insertion order of the dictionary.
        for commit in pull_commits:
            self._pending_commits[commit] = self.repo.git.diff_tree(
                    '--no-commit-id', '--name-only', '-r', '-z',
                    commit.parents[0], commit
                    ).split('\0')[:-1]

    def _wiki2git(self):
        revs = self._pending_revs()
        synced_files = []
        for rev in revs:
            #
            # Summary/commit message parsing.
            #
            git_commit_message = rev[1]['comment'] or '*** празно резюме ***'

            #
            # User parsing.
            #
            wiki_user = rev[1]['user']
            # Ignore our own sync edits in the wiki.
            if wiki_user == self.site.username():
                continue
            try:
                author = self._usermap[wiki_user]['author']
                email = self._usermap[wiki_user]['email']
            except KeyError:
                author = wiki_user
                email = ''
            git_author = git.Actor(author, email)
            git_committer = git.Actor(author, email)

            #
            # Page/file parsing.
            #
            # We cannot have both a file and a directory with the same name, so where we have
            # 'Page' and 'Page/doc', the latter gets converted to 'Page.d/doc'.
            file_name = rev[0].replace('/', '.d/')
            # If we've configured a file extension for syntax highlighting, add it, but only for
            # files in the root of the namespace/repository (the rest will likely be 'Page/doc').
            if self.force_ext and '.d/' not in file_name:
                file_name = file_name + '.' + self.force_ext
            file_path = os.path.join(self.repo.working_dir, file_name)

            #
            # Committing.
            #
            # To avoid conflicts as much as possible, perform git pull right before we apply the
            # change and commit it.
            self._pull()
            if rev[2] in ['edit', 'resync']:
                os.makedirs(os.path.dirname(file_path), exist_ok=True)
                if rev[2] == 'resync' and os.path.exists(file_path):
                    with open(file_path, 'r') as f:
                        if rev[1]['text'] == f.read().rstrip('\n'):
                            # The on-wiki and Git versions are the same. No need to resync.
                            continue
                with open(file_path, 'w') as f:
                    f.write(rev[1]['text'] + '\n')
                self.repo.index.add([file_path])
            elif rev[2] in ['delete', 'move']:
                self.repo.index.remove([file_path], working_tree=True)
            else:
                print('Error: Unknown revision type: "{}"'.format(rev[2]))
                continue
            print('Syncing to Git: {}'.format(file_name))
            self.repo.index.commit(
                    git_commit_message,
                    author=git_author,
                    committer=git_committer,
                    author_date=dt.isoformat(rev[1]['timestamp'], timespec='seconds'),
                    commit_date=dt.isoformat(rev[1]['timestamp'], timespec='seconds'))
            # Push after each commit. It's inefficient, but should minimize possible conflicts.
            self.repo.git.push()
            synced_files.append(file_name)
        return synced_files

    def _git2wiki(self, synced_from_wiki):
        # Iterate over a list of the keys, instead of directly on the dictionary. This allows to
        # delete the pending commits from the latter once they are processed.
        commit_list = list(self._pending_commits)
        for commit in commit_list:
            if re.search(r'\bDO\s+NOT\s+(MERGE|SYNC)\b', commit.message):
                print('Ignoring commit {} because of DO NOT MERGE/SYNC.'.format(commit.hexsha))
                del self._pending_commits[commit]
                continue
            for file_name in self._pending_commits[commit]:
                # We cannot have both a file and a directory with the same name, so where we have
                # 'Page' and 'Page/doc', the latter was converted to 'Page.d/doc'.
                page_name = self.namespace + ':' + file_name.replace('.d/', '/')
                # If we've configured a file extension for syntax highlighting, remove it, but only
                # for files in the root of the namespace/repo (the rest will likely be 'Page/doc').
                if self.force_ext and '/' not in page_name:
                    page_name = self.re_force_ext.sub('', page_name)
                page = pwb.Page(self.site, page_name)
                summary = self._create_summary(
                        commit.author.name,
                        commit.author.email,
                        self.name,
                        commit.hexsha,
                        commit.message)
                if file_name in synced_from_wiki:
                    # This page has been updated on the wiki in this sync run. To be on the safe
                    # side, we'll discard the possibly conflicting changes from the Git repo.
                    print('Ignoring possibly conflicting changes in {}'.format(file_name))
                    # Sometimes this might lead to out-of-sync situations, so schedule a resync.
                    self._need_resync = True
                    continue
                file_removed = False
                try:
                    file_git_blob = self.repo.commit(commit).tree.join(file_name)
                except KeyError as e:
                    if str(e).endswith('\'{file}\' not found"'.format(file=file_name)):
                        file_removed = True
                    else:
                        raise
                if not file_removed:
                    file_contents_at_commit = b''.join(file_git_blob.data_stream[3].readlines())
                    page.text = file_contents_at_commit.decode('utf-8').rstrip('\n')
                    print('Saving {}'.format(page.title()))
                    try:
                        page.save(summary=summary, botflag=True, quiet=True)
                    except pwb.data.api.APIError as e:
                        print('APIError exception: {}'.format(str(e)), file=sys.stderr)
                else:
                    print('Deleting {}'.format(page.title()))
                    try:
                        page.delete(reason=summary, prompt=False)
                    except pwb.data.api.APIError as e:
                        print('APIError exception: {}'.format(str(e)), file=sys.stderr)
            # When all files in a commit have been processed, remove it from the pending list.
            del self._pending_commits[commit]

    def sync(self, resync=False):
        if resync:
            self._need_resync = True
        w2g_synced_files = self._wiki2git()
        self._pull()
        if self._pending_commits:
            self._git2wiki(w2g_synced_files)


def main(argv):
    sig_handler = SignalHandler()
    git_sync = GitSync()
    git_sync.read_config()
    git_sync.init_repos()
    '''
    Disabled temporarily.

    if argv:
        if argv.pop() in ['resync', 'force']:
            for repo in repos:
                print('Resyncing repo "{}"...'.format(repo.repo.git_dir))
                repo.sync(resync=True)
    '''
    while True:
        for repo in git_sync.repos:
            print('Syncing repo "{}"...'.format(repo.repo.git_dir))
            repo.sync()
            # Sleep for a second between repos to catch requests to shutdown faster.
            sig_handler.sleep(1)
        print('Sleeping...')
        sig_handler.sleep(git_sync.config['daemon_sleep_seconds'])


if __name__ == '__main__':
    main(sys.argv[1:])