# frozen_string_literal: true

class Grumlin::RequestDispatcher
  attr_reader :requests

  SUCCESS = {
    200 => :success,
    204 => :no_content,
    206 => :partial_content
  }.freeze

  class DispatcherError < Grumlin::Error; end

  class RequestAlreadyAddedError < DispatcherError; end

  class UnknownRequestError < DispatcherError; end

  def initialize
    @requests = {}
  end

  def add_request(request)
    raise RequestAlreadyAddedError if @requests.include?(request[:requestId])

    Async::Channel.new.tap do |channel|
      @requests[request[:requestId]] = { request: request, result: [], channel: channel }
    end
  end

  # builds a response object, when it's ready sends it to the client via a channel
  # TODO: sometimes response does not include requestID, no idea how to handle it so far.
  def add_response(response) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
    request_id = response[:requestId]
    raise UnknownRequestError unless ongoing_request?(request_id)

    begin
      request = @requests[request_id]

      Grumlin::RequestErrorFactory.build(request, response).tap do |err|
        raise err unless err.nil?
      end

      case SUCCESS[response.dig(:status, :code)]
      when :success
        request[:result] << response.dig(:result, :data)
        request[:channel] << request[:result]
        close_request(request_id)
      when :partial_content then request[:result] << response.dig(:result, :data)
      when :no_content
        request[:channel] << []
        close_request(request_id)
      end
    rescue StandardError => e
      request[:channel].exception(e)
      close_request(request_id)
    end
  end

  def ongoing_request?(request_id)
    @requests.include?(request_id)
  end

  def clear
    @requests.each do |_id, request|
      request[:channel].close!
    end
    @requests.clear
  end

  private

  def close_request(request_id)
    raise UnknownRequestError unless ongoing_request?(request_id)

    request = @requests.delete(request_id)
    request[:channel].close
  end
end