discourse/plugins/chat/app/jobs/regular/chat_channel_delete.rb

# frozen_string_literal: true

module Jobs
  class ChatChannelDelete < ::Jobs::Base
    def execute(args = {})
      chat_channel = ::ChatChannel.with_deleted.find_by(id: args[:chat_channel_id])

      # this should not really happen, but better to do this than throw an error
      if chat_channel.blank?
        Rails.logger.warn(
          "Chat channel #{args[:chat_channel_id]} could not be found, aborting delete job.",
        )
        return
      end

      DistributedMutex.synchronize("delete_chat_channel_#{chat_channel.id}") do
        Rails.logger.debug("Deleting webhooks and events for channel #{chat_channel.id}")
        ChatMessage.transaction do
          webhooks = IncomingChatWebhook.where(chat_channel: chat_channel)
          ChatWebhookEvent.where(incoming_chat_webhook_id: webhooks.select(:id)).delete_all
          webhooks.delete_all
        end

        Rails.logger.debug("Deleting drafts and memberships for channel #{chat_channel.id}")
        ChatDraft.where(chat_channel: chat_channel).delete_all
        UserChatChannelMembership.where(chat_channel: chat_channel).delete_all

        Rails.logger.debug(
          "Deleting chat messages, mentions, revisions, and uploads for channel #{chat_channel.id}",
        )
        chat_messages = ChatMessage.where(chat_channel: chat_channel)
        delete_messages_and_related_records(chat_channel, chat_messages) if chat_messages.any?
      end
    end

    def delete_messages_and_related_records(chat_channel, chat_messages)
      message_ids = chat_messages.pluck(:id)

      ChatMessage.transaction do
        ChatMention.where(chat_message_id: message_ids).delete_all
        ChatMessageRevision.where(chat_message_id: message_ids).delete_all
        ChatMessageReaction.where(chat_message_id: message_ids).delete_all

        # if the uploads are not used anywhere else they will be deleted
        # by the CleanUpUploads job in core
        DB.exec("DELETE FROM chat_uploads WHERE chat_message_id IN (#{message_ids.join(",")})")
        UploadReference.where(target_id: message_ids, target_type: "ChatMessage").delete_all

        # only the messages and the channel are Trashable, everything else gets
        # permanently destroyed
        chat_messages.update_all(
          deleted_by_id: chat_channel.deleted_by_id,
          deleted_at: Time.zone.now,
        )
      end
    end
  end
end