# Copyright 2016 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


module Gcloud
  module Translate
    ##
    # # Detection
    #
    # Represents a detect language query result. Returned by
    # {Gcloud::Translate::Api#detect}.
    #
    # @see https://cloud.google.com/translate/v2/using_rest#detect-language
    #   Detect Language
    #
    # @example
    #   require "gcloud"
    #
    #   gcloud = Gcloud.new
    #   translate = gcloud.translate
    #
    #   detections = translate.detect "chien", "chat"
    #
    #   detections.size #=> 2
    #   detections[0].text #=> "chien"
    #   detections[0].language #=> "fr"
    #   detections[0].confidence #=> 0.7109375
    #   detections[1].text #=> "chat"
    #   detections[1].language #=> "en"
    #   detections[1].confidence #=> 0.59922177
    #
    class Detection
      ##
      # The text upon which the language detection was performed.
      #
      # @return [String]
      attr_reader :text

      ##
      # The list of detection results for the given text. The most likely
      # language is listed first, and its attributes can be accessed through
      # {#language} and {#confidence}.
      #
      # @return [Array<Detection::Result>]
      attr_reader :results

      ##
      # @private Create a new object.
      def initialize text, results
        @text = text
        @results = results
      end

      ##
      # The confidence that the language detection result is correct. The closer
      # this value is to 1, the higher the confidence in language detection.
      #
      # @return [Float] a value between 0 and 1
      def confidence
        return nil if results.empty?
        results.first.confidence
      end

      ##
      # The most likely language that was detected. This is an [ISO
      # 639-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) language
      # code.
      #
      # @return [String] the language code
      def language
        return nil if results.empty?
        results.first.language
      end

      ##
      # @private New Detection from a ListDetectionsResponse object as
      # defined by the Google API Client object.
      def self.from_gapi gapi, text
        res = text.zip(Array(gapi.detections)).map do |txt, detections_gapi|
          results = detections_gapi.map { |g| Result.from_gapi g }
          new txt, results
        end
        return res.first if res.size == 1
        res
      end

      ##
      # # Result
      #
      # Represents an individual result in a {Gcloud::Translate::Detection}
      # result.
      #
      class Result
        ##
        # The confidence that the language detection result is correct. The
        # closer this value is to 1, the higher the confidence in language
        # detection.
        #
        # @return [Float] a value between 0 and 1
        attr_reader :confidence

        ##
        # The language detected. This is an [ISO
        # 639-1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) language
        # code.
        #
        # @return [String] the language code
        attr_reader :language

        ##
        # @private Create a new object.
        def initialize confidence, language
          @confidence = confidence
          @language = language
        end

        ##
        # @private New Detection::Result from a DetectionsResource object as
        # defined by the Google API Client object.
        def self.from_gapi gapi
          new gapi.confidence, gapi.language
        end
      end
    end
  end
end