discourse/plugins/chat/lib/chat/user_notifications_extension.rb

# frozen_string_literal: true

module Chat
  module UserNotificationsExtension
    def chat_summary(user, opts)
      guardian = Guardian.new(user)
      return unless guardian.can_chat?

      @messages =
        Chat::Message
          .joins(:user, :chat_channel)
          .where.not(user: user)
          .where("chat_messages.created_at > ?", 1.week.ago)
          .joins(
            "LEFT OUTER JOIN chat_mentions cm ON cm.chat_message_id = chat_messages.id AND cm.notification_id IS NOT NULL",
          )
          .joins(
            "INNER JOIN user_chat_channel_memberships uccm ON uccm.chat_channel_id = chat_channels.id",
          )
          .where(<<~SQL, user_id: user.id)
          uccm.user_id = :user_id AND
          (uccm.last_read_message_id IS NULL OR chat_messages.id > uccm.last_read_message_id) AND
          (uccm.last_unread_mention_when_emailed_id IS NULL OR chat_messages.id > uccm.last_unread_mention_when_emailed_id) AND
          (
            (cm.user_id = :user_id AND uccm.following IS true AND chat_channels.chatable_type = 'Category') OR
            (chat_channels.chatable_type = 'DirectMessage')
          )
        SQL
          .to_a

      return if @messages.empty?
      @grouped_messages = @messages.group_by { |message| message.chat_channel }
      @grouped_messages =
        @grouped_messages.select { |channel, _| guardian.can_join_chat_channel?(channel) }
      return if @grouped_messages.empty?

      @grouped_messages.each do |chat_channel, messages|
        @grouped_messages[chat_channel] = messages.sort_by(&:created_at)
      end
      @user = user
      @user_tz = UserOption.user_tzinfo(user.id)
      @display_usernames = SiteSetting.prioritize_username_in_ux || !SiteSetting.enable_names

      build_summary_for(user)
      @preferences_path = "#{Discourse.base_url}/my/preferences/chat"

      # TODO(roman): Remove after the 2.9 release
      add_unsubscribe_link = UnsubscribeKey.respond_to?(:get_unsubscribe_strategy_for)

      if add_unsubscribe_link
        unsubscribe_key = UnsubscribeKey.create_key_for(@user, "chat_summary")
        @unsubscribe_link = "#{Discourse.base_url}/email/unsubscribe/#{unsubscribe_key}"
        opts[:unsubscribe_url] = @unsubscribe_link
      end

      opts = {
        from_alias: I18n.t("user_notifications.chat_summary.from", site_name: Email.site_title),
        subject: summary_subject(user, @grouped_messages),
        add_unsubscribe_link: add_unsubscribe_link,
      }

      build_email(user.email, opts)
    end

    def summary_subject(user, grouped_messages)
      all_channels = grouped_messages.keys
      grouped_channels = all_channels.partition { |c| !c.direct_message_channel? }
      channels = grouped_channels.first

      dm_messages = grouped_channels.last.flat_map { |c| grouped_messages[c] }
      dm_users = dm_messages.sort_by(&:created_at).uniq { |m| m.user_id }.map(&:user)

      # Prioritize messages from regular channels over direct messages
      if channels.any?
        channel_notification_text(
          channels.sort_by { |channel| [channel.last_message_sent_at, channel.created_at] },
          dm_users,
        )
      else
        direct_message_notification_text(dm_users)
      end
    end

    private

    def channel_notification_text(channels, dm_users)
      total_count = channels.size + dm_users.size

      if total_count > 2
        I18n.t(
          "user_notifications.chat_summary.subject.chat_channel_more",
          email_prefix: @email_prefix,
          channel: channels.first.title,
          count: total_count - 1,
        )
      elsif channels.size == 1 && dm_users.size == 0
        I18n.t(
          "user_notifications.chat_summary.subject.chat_channel_1",
          email_prefix: @email_prefix,
          channel: channels.first.title,
        )
      elsif channels.size == 1 && dm_users.size == 1
        I18n.t(
          "user_notifications.chat_summary.subject.chat_channel_and_direct_message",
          email_prefix: @email_prefix,
          channel: channels.first.title,
          username: dm_users.first.username,
        )
      elsif channels.size == 2
        I18n.t(
          "user_notifications.chat_summary.subject.chat_channel_2",
          email_prefix: @email_prefix,
          channel1: channels.first.title,
          channel2: channels.second.title,
        )
      end
    end

    def direct_message_notification_text(dm_users)
      case dm_users.size
      when 1
        I18n.t(
          "user_notifications.chat_summary.subject.direct_message_from_1",
          email_prefix: @email_prefix,
          username: dm_users.first.username,
        )
      when 2
        I18n.t(
          "user_notifications.chat_summary.subject.direct_message_from_2",
          email_prefix: @email_prefix,
          username1: dm_users.first.username,
          username2: dm_users.second.username,
        )
      else
        I18n.t(
          "user_notifications.chat_summary.subject.direct_message_from_more",
          email_prefix: @email_prefix,
          username: dm_users.first.username,
          count: dm_users.size - 1,
        )
      end
    end
  end
end