discourse/plugins/chat/app/controllers/direct_messages_controller.rb

# frozen_string_literal: true

class Chat::DirectMessagesController < Chat::ChatBaseController
  # NOTE: For V1 of chat channel archiving and deleting we are not doing
  # anything for DM channels, their behaviour will stay as is.
  def create
    guardian.ensure_can_chat!(current_user)
    users = users_from_usernames(current_user, params)

    begin
      chat_channel =
        Chat::DirectMessageChannelCreator.create!(acting_user: current_user, target_users: users)
      render_serialized(
        chat_channel,
        ChatChannelSerializer,
        root: "chat_channel",
        membership: chat_channel.membership_for(current_user),
      )
    rescue Chat::DirectMessageChannelCreator::NotAllowed => err
      render_json_error(err.message)
    end
  end

  def index
    guardian.ensure_can_chat!(current_user)
    users = users_from_usernames(current_user, params)

    direct_message = DirectMessage.for_user_ids(users.map(&:id).uniq)
    if direct_message
      chat_channel = ChatChannel.find_by(chatable: direct_message)
      render_serialized(
        chat_channel,
        ChatChannelSerializer,
        root: "chat_channel",
        membership: chat_channel.membership_for(current_user),
      )
    else
      render body: nil, status: 404
    end
  end

  private

  def users_from_usernames(current_user, params)
    params.require(:usernames)

    usernames =
      (params[:usernames].is_a?(String) ? params[:usernames].split(",") : params[:usernames])

    users = [current_user]
    other_usernames = usernames - [current_user.username]
    users.concat(User.where(username: other_usernames).to_a) if other_usernames.any?
    users
  end
end