# -*- coding: utf-8 -*-

# Genshi imports.
from genshi.builder import tag
from genshi.filters.transform import Transformer

# Trac imports.
from trac.core import *
from trac.resource import Resource
from trac.config import ListOption

# TracTags imports.
from tractags.api import DefaultTagProvider, TagSystem

# Local imports
from tracdiscussion.api import DiscussionApi

# Local interfaces.
from tracdiscussion.api import IForumChangeListener, ITopicChangeListener

class DiscussionTagProvider(DefaultTagProvider):
    """
      Tag provider for the discussion forums and topics.
    """
    realm = 'discussion'

    def check_permission(self, perm, operation):
        permissions = {'view': 'WIKI_VIEW', 'modify': 'WIKI_MODIFY'}

        # First check permissions in default provider then for discussion.
        return super(DiscussionTagProvider, self).check_permission(perm,
          operation) and permissions[operation] in perm

class DiscussionTags(Component):
    """
       The tags module implements plugin's ability to create tags related
       to discussion forums and topics.
    """
    implements(IForumChangeListener, ITopicChangeListener)

    # Configuration options.
    automatic_forum_tags = ListOption('discussion', 'automatic_forum_tags',
      'name,author', doc = "Tags that will be created automatically from "
      "discussion forums fields. Possible values are: name, author.")
    automatic_topic_tags = ListOption('discussion', 'automatic_topic_tags',
      'author,status', doc = "Tags that will be created automatically from "
      "discussion topics fields. Possible values are: author, status.")

    # IForumChangeListener methods.

    def forum_created(self, context, forum):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'forum/%s' % (
          forum['id']))

        # Update tags.
        new_tags = self._get_forum_tags(forum)
        self._update_tags(context.req, resource, new_tags)

    def forum_changed(self, context, forum, old_forum):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'forum/%s' % (
          forum['id']))

        # Update tags.
        new_tags = self._get_forum_tags(forum)
        self._update_tags(context.req, resource, new_tags)

    def forum_deleted(self, context, forum):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'forum/%s' % (
          forum['id']))

        # Remove tags.
        self._delete_tags(context.req, resource)

    # ITopicChangeListener methods.

    def topic_created(self, context, topic):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'topic/%s' % (
          topic['id']))

        # Update tags.
        new_tags = self._get_topic_tags(topic)
        self._update_tags(context.req, resource, new_tags)

    def topic_changed(self, context, topic, old_topic):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'topic/%s' % (
          topic['id']))

        # Update tags.
        new_tags = self._get_topic_tags(topic)
        self._update_tags(context.req, resource, new_tags)

    def topic_deleted(self, context, topic):
        # Create temporary resource.
        resource = Resource(DiscussionTagProvider.realm, 'topic/%s' % (
          topic['id']))

        # Remove tags.
        self._delete_tags(context.req, resource)

    # Internal methods.

    def _update_tags(self, req, resource, new_tags):
        # Get old tags of the resource.
        tag_system = TagSystem(self.env)
        old_tags = self._get_stored_tags(req, resource)

        self.log.debug("setting tags: %s" % (new_tags,))

        # Replace with new tags if different.
        if old_tags != new_tags:
            tag_system.set_tags(req, resource, new_tags)
            return True
        return False

    def _delete_tags(self, req, resource):
        self.log.debug("deleting tags: %s" % (new_tags,))

        # Delete tags of the resource.
        tag_system = TagSystem(self.env)
        tag_system.delete_tags(req, resource)

    def _get_stored_tags(self, req, resource):
        # Return tags associated to resource.
        tag_system = TagSystem(self.env)
        tags = tag_system.get_tags(req, resource)
        return sorted(tags)

    def _get_forum_tags(self, forum):
        tags = []
        if forum.has_key('tags'):
            tags += forum['tags']
        if 'name' in self.automatic_forum_tags and forum['name']:
            if not forum['name'] in tags:
                tags.append(forum['name'])
        if 'author' in self.automatic_forum_tags and forum['author']:
            if forum['author'] not in tags:
                tags.append(forum['author'])
        return sorted(tags)

    def _get_topic_tags(self, topic):
        tags = []
        if topic.has_key('tags'):
            tags += topic['tags']
        if 'author' in self.automatic_topic_tags and topic['author']:
            if not topic['author'] in tags:
                tags.append(topic['author'])
        if 'status' in self.automatic_topic_tags and len(topic['status']):
            for status in topic['status']:
                if not status in tags:
                    tags.append(status)
        return sorted(tags)