require 'active_support/core_ext/hash'

module Europeana
  module API
    ##
    # Interface to Europeana API's Search method
    class Search
      autoload :Fields, 'europeana/api/search/fields'

      # Query params
      attr_accessor :params

      ##
      # @param [Hash] params Europeana API request parameters for Search query
      def initialize(params = {})
        @params = HashWithIndifferentAccess.new(params)
      end

      ##
      # Sends the Search request to the API
      #
      # @return [HashWithIndifferentAccess]
      # @raise [Europeana::Errors::ResponseError] if API response could not be
      #   parsed as JSON
      # @raise [Europeana::Errors::RequestError] if API response has
      #   `success:false`
      def execute
        request = Request.new(request_uri)
        response = request.execute
        body = JSON.parse(response.body)
        unless body['success']
          fail Errors::RequestError, (body.key?('error') ? body['error'] : response.code)
        end
        HashWithIndifferentAccess.new(body)
      rescue JSON::ParserError
        raise Errors::ResponseError
      end

      ##
      # Returns query params with API key added
      #
      # @return [Hash]
      def params_with_authentication
        return params if params.key?(:wskey) && params[:wskey].present?
        unless Europeana::API.api_key.present?
          fail Errors::MissingAPIKeyError
        end
        params.merge(wskey: Europeana::API.api_key)
      end

      ##
      # Gets the URI for this Search request with parameters
      #
      # @return [URI]
      def request_uri
        uri = URI.parse(Europeana::API.url + '/search.json')
        uri.query = request_uri_query
        uri
      end

      def request_uri_query
        uri_query = ''
        params_with_authentication.each_pair do |name, value|
          [value].flatten.each do |v|
            uri_query << '&' unless uri_query.blank?
            uri_query << CGI.escape(name.to_s) + '=' + CGI.escape(v.to_s)
          end
        end
        uri_query
      end
    end
  end
end