# frozen_string_literal: true

# TODO: Test & Document
module Hg
  class ApiAiClient
    class QueryError < StandardError
      def initialize
        super('There was a problem with the API.ai query.')
      end
    end

    # Name of action for unrecognized messages.
    UNKNOWN_SYSTEM_ACTION = 'input.unknown'

    def initialize(session_id)
      # TODO: access token should be set by Hg config option
      @client = ApiAiRuby::Client.new(
        client_access_token: ENV['API_AI_CLIENT_ACCESS_TOKEN'],
        api_version: '20170210',
        api_session_id: session_id
      )
    end

    # Parse a natural language message with API.ai.
    #
    # @param message [String]
    #   The natural language query to be parsed.
    # @param context_name [String]
    #   The context name to set on the Dialogflow session.
    #
    # @return [Hash] The information parsed from the message.
    def query(message, context_name: nil)
      # TODO: which logger?
      retry_counter = 0

      begin
        retry_counter += 1

        # Build a contexts object if one is passed.
        contexts = context_name ? [context_name] : nil

        api_ai_response = @client.text_request(message, contexts: contexts)
      rescue ApiAiRuby::ClientError, ApiAiRuby::RequestError => e
        Sidekiq::Logging.logger.error 'Error with API.ai query request'
        Sidekiq::Logging.logger.error e
        Sidekiq::Logging.logger.error e.backtrace.join("\n")

        # Retry the call 3 times.
        retry if retry_counter < 3

        raise QueryError.new
      else
        # If the API.ai call fails...
        if api_ai_response[:status][:code] != 200
          # ...log an error.
          Sidekiq::Logging.logger.error "Error with API.ai request: #{api_ai_response.inspect}"

          # Return the default action.
          return {
            action: Hg::InternalActions::DEFAULT,
            intent: Hg::InternalActions::DEFAULT
          }
        end

        intent_name = api_ai_response[:result][:metadata][:intentName]

        # Determine the action name
        action_from_response = api_ai_response[:result][:action]

        # Use intent name as action name if no action name is defined for this intent.
        action_name =
          if action_from_response.blank?
            intent_name
          # Set to default action if message is not recognized.
          elsif action_from_response == UNKNOWN_SYSTEM_ACTION.freeze
            Hg::InternalActions::DEFAULT
          else
            action_from_response
          end

        response = api_ai_response[:result][:fulfillment][:speech]

        return {
          intent: intent_name,
          action: action_name,
          parameters: parsed_params(api_ai_response[:result][:parameters]),
          response: response
        }
      end
    end

    private

    # Remove any params which were not matched.
    #
    # @param params [Hash]
    #   The raw parsed params.
    #
    # @return [Hash]
    #   Only those params that were matched.
    def parsed_params(params)
      params.reject{ |p| p.blank? }
    end
  end
end
