import json
import re
import hmac
import hashlib
from buildbot.process.properties import Properties
from buildbot.util import bytes2unicode, unicode2bytes
from buildbot.www.hooks.base import BaseHookHandler

from twisted.internet import defer
from twisted.python import log

from dateutil.parser import parse as dateparse

_HEADER_EVENT_TYPE = 'X-Gitea-Event'
_HEADER_SIGNATURE = 'X-Gitea-Signature'


class GiteaHandler(BaseHookHandler):

    def process_push(self, payload, event_type, codebase):
        refname = payload["ref"]

        changes = []

        # We only care about regular heads or tags
        match = re.match(r"^refs/(heads|tags)/(.+)$", refname)
        if not match:
            log.msg("Ignoring refname '{}': Not a branch or tag".format(refname))
            return changes

        branch = match.group(2)

        repository = payload['repository']
        repo_url = repository['ssh_url']
        project = repository['full_name']

        commits = payload['commits']
        if isinstance(self.options, dict) and self.options.get('onlyIncludePushCommit', False):
            commits = commits[:1]

        for commit in commits:
            files = []
            for kind in ('added', 'modified', 'removed'):
                files.extend(commit.get(kind, []))
            timestamp = dateparse(commit['timestamp'])
            change = {
                'author': '{} <{}>'.format(commit['author']['name'],
                                           commit['author']['email']),
                'files': files,
                'comments': commit['message'],
                'revision': commit['id'],
                'when_timestamp': timestamp,
                'branch': branch,
                'revlink': commit['url'],
                'repository': repo_url,
                'project': project,
                'category': event_type,
                'properties': {
                    'event': event_type,
                    'repository_name': repository['name'],
                    'owner': repository["owner"]["username"]
                },
            }
            if codebase is not None:
                change['codebase'] = codebase
            changes.insert(0, change)
        return changes

    def process_pull_request(self, payload, event_type, codebase):
        action = payload['action']

        # Only handle potential new stuff, ignore close/.
        # Merge itself is handled by the regular branch push message
        if action not in ['opened', 'synchronized', 'edited', 'reopened']:
            log.msg("Gitea Pull Request event '{}' ignored".format(action))
            return []
        pull_request = payload['pull_request']
        if not pull_request['mergeable']:
            log.msg("Gitea Pull Request ignored because it is not mergeable.")
            return []
        if pull_request['merged']:
            log.msg("Gitea Pull Request ignored because it is already merged.")
            return []
        timestamp = dateparse(pull_request['updated_at'])
        base = pull_request['base']
        head = pull_request['head']
        repository = payload['repository']
        change = {
            'author': '{} <{}>'.format(pull_request['user']['full_name'],
                                       pull_request['user']['email']),
            'comments': 'PR#{}: {}\n\n{}'.format(
                pull_request['number'],
                pull_request['title'],
                pull_request['body']),
            'revision': base['sha'],
            'when_timestamp': timestamp,
            'branch': base['ref'],
            'revlink': pull_request['html_url'],
            'repository': base['repo']['ssh_url'],
            'project': repository['full_name'],
            'category': event_type,
            'properties': {
                'event': event_type,
                'base_branch': base['ref'],
                'base_sha': base['sha'],
                'base_repo_id': base['repo_id'],
                'base_repository': base['repo']['clone_url'],
                'base_git_ssh_url': base['repo']['ssh_url'],
                'head_branch': head['ref'],
                'head_sha': head['sha'],
                'head_repo_id': head['repo_id'],
                'head_repository': head['repo']['clone_url'],
                'head_git_ssh_url': head['repo']['ssh_url'],
                'head_owner': head['repo']['owner']['username'],
                'head_reponame': head['repo']['name'],
                'pr_id': pull_request['id'],
                'pr_number': pull_request['number'],
                'repository_name': repository['name'],
                'owner': repository["owner"]["username"],
            },
        }
        if codebase is not None:
            change['codebase'] = codebase
        return [change]

    @defer.inlineCallbacks
    def getChanges(self, request):
        secret = None
        if isinstance(self.options, dict):
            secret = self.options.get('secret')
        try:
            content = request.content.read()
            content_text = bytes2unicode(content)
            payload = json.loads(content_text)
        except Exception as exception:
            raise ValueError('Error loading JSON: ' + str(exception))

        if secret is not None:
            p = Properties()
            p.master = self.master
            rendered_secret = yield p.render(secret)
            signature = hmac.new(
                unicode2bytes(rendered_secret),
                unicode2bytes(content_text.strip()),
                digestmod=hashlib.sha256)
            header_signature = bytes2unicode(
                request.getHeader(_HEADER_SIGNATURE))
            if signature.hexdigest() != header_signature:
                raise ValueError('Invalid secret')

        event_type = bytes2unicode(request.getHeader(_HEADER_EVENT_TYPE))
        log.msg("Received event '{}' from gitea".format(event_type))

        codebases = request.args.get('codebase', [None])
        codebase = bytes2unicode(codebases[0])
        changes = []

        handler_function = getattr(self, 'process_{}'.format(event_type), None)
        if not handler_function:
            log.msg("Ignoring gitea event '{}'".format(event_type))
        else:
            changes = handler_function(payload, event_type, codebase)

        return (changes, 'git')


class GiteaHandlerPlugin(BaseHookHandler):
    def __init__(self, master, options):
        if not options:
            options = {}
        super().__init__(master, options)

        handler_class = options.get('class', GiteaHandler)
        if 'class' in options:
            del options['class']

        self.handler = handler_class(master, options)

    def getChanges(self, request):
        return self.handler.getChanges(request)

# Plugin name
gitea = GiteaHandlerPlugin