class Api::V1::Accounts::Conversations::ParticipantsController < Api::V1::Accounts::Conversations::BaseController
  include Events::Types

  def show
    @participants = @conversation.conversation_participants
  end

  def create
    participant_ids_to_add = participants_to_be_added_ids

    ActiveRecord::Base.transaction do
      @participants = participant_ids_to_add.map { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
    end
    notify_unread_count_change if participant_ids_to_add.any?
  end

  def update
    participant_ids_to_add = participants_to_be_added_ids
    participant_ids_to_remove = participants_to_be_removed_ids
    changed_participant_ids = participant_ids_to_add + participant_ids_to_remove

    ActiveRecord::Base.transaction do
      participant_ids_to_add.each { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
      participant_ids_to_remove.each { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
    end
    notify_unread_count_change if changed_participant_ids.any?
    @participants = @conversation.conversation_participants
    render action: 'show'
  end

  def destroy
    participant_ids_to_remove = current_participant_ids & params[:user_ids]

    ActiveRecord::Base.transaction do
      params[:user_ids].map { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
    end
    notify_unread_count_change if participant_ids_to_remove.any?
    head :ok
  end

  private

  def participants_to_be_added_ids
    params[:user_ids] - current_participant_ids
  end

  def participants_to_be_removed_ids
    current_participant_ids - params[:user_ids]
  end

  def current_participant_ids
    @current_participant_ids ||= @conversation.conversation_participants.pluck(:user_id)
  end

  def notify_unread_count_change
    return unless Current.account.feature_enabled?('conversation_unread_counts')
    return unless Current.account.feature_enabled?('unread_count_for_filters')

    Rails.configuration.dispatcher.dispatch(CONVERSATION_UNREAD_COUNT_CHANGED, Time.zone.now, conversation: @conversation)
  end
end