QutBioacoustics/baw-workers

module BawWorkers
  module Media
    # This is the class that uses the audio tools and cache tools to cut audio segments
    # and generate spectrograms, then save them to the correct path.
    class WorkHelper

      attr_reader :audio, :spectrogram,
                  :audio_original, :audio_cache, :spectrogram_cache,
                  :temp_dir

      public

      # Construct a new BawWorkers::Media::Process
      # @param [BawAudioTools::AudioBase] audio_base
      # @param [BawAudioTools::Spectrogram] spectrogram
      # @param [BawWorkers::Storage::AudioOriginal] audio_original
      # @param [BawWorkers::Storage::AudioCache] audio_cache
      # @param [BawWorkers::Storage::SpectrogramCache] spectrogram_cache
      # @param [FileInfo] file_info
      # @param [Logger] logger
      # @param [String] temp_dir
      def initialize(
          audio_base, spectrogram,
          audio_original, audio_cache, spectrogram_cache,
          file_info, logger, temp_dir)
        @audio = audio_base
        @spectrogram = spectrogram
        @audio_original = audio_original
        @audio_cache = audio_cache
        @spectrogram_cache = spectrogram_cache
        @file_info = file_info
        @logger = logger
        @temp_dir = temp_dir
      end

      def create_audio_segment(modify_parameters = {})
        cache_audio_info = @audio_cache.path_info(modify_parameters)
        target_existing = cache_audio_info[:existing]

        if target_existing.blank?
          original_audio_info = @audio_original.path_info(modify_parameters)

          check_original_paths(
              original_audio_info[:possible],
              original_audio_info[:existing],
              modify_parameters)

          # create in temp dir to prevent access while creating
          temp_target_existing = File.join(@temp_dir, cache_audio_info[:file_names].first)

          # ensure the subdirectories exist
          FileUtils.mkpath(File.dirname(temp_target_existing))

          # create the audio segment
          @audio.modify(
              original_audio_info[:existing].first,
              temp_target_existing,
              modify_parameters)

          # copy to target dirs when finished creating temp file
          @file_info.copy_to_many(temp_target_existing, cache_audio_info[:possible])

          # delete temp file
          FileUtils.rm(temp_target_existing)

          # update existing paths after cutting audio
          target_existing = check_cached_audio_paths(
              cache_audio_info[:file_names].first,
              original_audio_info[:existing],
              original_audio_info[:possible],
              modify_parameters)
        end

        target_existing
      end

      def generate_spectrogram(modify_parameters = {})
        cache_spectrogram_info = @spectrogram_cache.path_info(modify_parameters)
        target_existing = cache_spectrogram_info[:existing]

        if target_existing.blank?
          # create the cached audio segment (it must be a wav file)
          # merge does not include nested hashes, but will actually create a new hash
          # http://thingsaaronmade.com/blog/ruby-shallow-copy-surprise.html
          cached_wav_audio_parameters = {}.merge(modify_parameters)
          cached_wav_audio_parameters[:format] = 'wav'

          # create cached wav audio
          source_existing = create_audio_segment(cached_wav_audio_parameters)

          # create in temp dir to prevent access while creating
          temp_target_existing = File.join(@temp_dir, cache_spectrogram_info[:file_names].first)

          # create the spectrogram image in target
          # only needs the window, window_function, colour,
          # and sample rate (for calculating pixels per second)
          # everything else has already been done

          spectrogram_parameters = {
              window: modify_parameters[:window],
              window_function: modify_parameters[:window_function],
              colour: modify_parameters[:colour],
              sample_rate: modify_parameters[:sample_rate]
          }

          # ensure the subdirectories exist
          FileUtils.mkpath(File.dirname(temp_target_existing))

          # create the spectrogram
          @spectrogram.modify(
              source_existing.first,
              temp_target_existing,
              spectrogram_parameters)

          # copy to target dirs when finished creating temp file
          @file_info.copy_to_many(temp_target_existing, cache_spectrogram_info[:possible])

          # delete temp file
          FileUtils.rm(temp_target_existing)

          # update existing paths after generating spectrogram
          target_existing = check_cached_spectrogram_paths(
              cache_spectrogram_info[:file_names].first,
              source_existing,
              cache_spectrogram_info[:possible],
              modify_parameters)
        end

        target_existing
      end

      def check_original_paths(possible, existing, modify_parameters)
        # if the original audio file(s) cannot be found, raise an exception
        if existing.blank?
          msg = "Could not find original audio in '#{possible}' using #{modify_parameters}."
          fail BawAudioTools::Exceptions::AudioFileNotFoundError, msg
        end
      end

      def check_cached_audio_paths(file_name, source_existing, target_possible, modify_parameters)
        target_existing_paths = @audio_cache.existing_paths(modify_parameters)
        if target_existing_paths.blank?
          msg = "Could not create cached audio for #{file_name} from " +
              " #{source_existing} in #{target_possible} using #{modify_parameters}."
          fail BawAudioTools::Exceptions::AudioFileNotFoundError, msg
        end
        target_existing_paths
      end

      def check_cached_spectrogram_paths(file_name, source_existing, target_possible, modify_parameters)
        target_existing_paths = @spectrogram_cache.existing_paths(modify_parameters)
        if target_existing_paths.blank?
          msg = "Could not create cached spectrogram for #{file_name} from " +
              " #{source_existing} in #{target_possible} using #{modify_parameters}."
          fail BawAudioTools::Exceptions::SpectrogramFileNotFoundError, msg
        end
        target_existing_paths
      end

    end
  end
end