module DiscourseChat
  module Manager

    def self.guardian
      Guardian.new(User.find_by(username: SiteSetting.chat_integration_discourse_username))
    end

    def self.trigger_notifications(post_id)
      Rails.logger.info("Triggering chat notifications for post #{post_id}")

      post = Post.find_by(id: post_id)

      # Abort if the chat_user doesn't have permission to see the post
      return if !guardian.can_see?(post) 

      # Abort if the post is blank, or is non-regular (e.g. a "topic closed" notification)
      return if post.blank? || post.post_type != Post.types[:regular]

      topic = post.topic

      # Abort if a private message (possible TODO: Add support for notifying about group PMs)
      return if topic.blank? || topic.archetype == Archetype.private_message

      # Load all the rules that apply to this topic's category
      matching_rules = DiscourseChat::Rule.all_for_category(topic.category_id)

      if topic.category # Also load the rules for the wildcard category
        matching_rules += DiscourseChat::Rule.all_for_category(nil)
      end

      # If tagging is enabled, thow away rules that don't apply to this topic
      if SiteSetting.tagging_enabled
        topic_tags = topic.tags.present? ? topic.tags.pluck(:name) : []
        matching_rules = matching_rules.select do |rule|
          next true if rule.tags.nil? or rule.tags.empty? # Filter has no tags specified
          any_tags_match = !((rule.tags & topic_tags).empty?)
          next any_tags_match # If any tags match, keep this filter, otherwise throw away
        end
      end

      # Sort by order of precedence (mute always wins; watch beats follow)
      precedence = { 'mute' => 0, 'watch' => 1, 'follow' => 2}
      sort_func = proc { |a, b| precedence[a.filter] <=> precedence[b.filter] }
      matching_rules = matching_rules.sort(&sort_func)

      # Take the first rule for each channel
      uniq_func = proc { |rule| [rule.provider, rule.channel] }
      matching_rules = matching_rules.uniq(&uniq_func)

      # If a matching rule is set to mute, we can discard it now
      matching_rules = matching_rules.select { |rule| rule.filter != "mute" }

      # If this is not the first post, discard all "follow" rules
      if not post.is_first_post?
        matching_rules = matching_rules.select { |rule| rule.filter != "follow" }
      end

      # All remaining rules now require a notification to be sent
      # If there are none left, abort
      return false if matching_rules.empty?

      # Loop through each rule, and trigger appropriate notifications
      matching_rules.each do |rule|
        Rails.logger.info("Sending notification to provider #{rule.provider}, channel #{rule.channel}")
        provider = ::DiscourseChat::Provider.get_by_name(rule.provider)
        is_enabled = ::DiscourseChat::Provider.is_enabled(provider)
        if provider and is_enabled
          provider.trigger_notification(post, rule.channel)
        elsif provider
          # Provider is disabled, don't do anything
        else
          # TODO: Handle when the provider does not exist
        end
      end

    end


  end
end