module Aubio
  class Onsets

    def initialize(aubio_source, params)
      # TODO: cleanup param dups
      @sample_rate = params[:sample_rate] || 44100
      @window_size = params[:window_size] || 1024
      @hop_size    = params[:hop_size]    || 512

      @source = aubio_source
      @onset = Api.new_aubio_onset('default', @window_size, @hop_size, @sample_rate)
      Api.aubio_onset_set_minioi_ms(@onset, 12.0)
      Api.aubio_onset_set_threshold(@onset, 0.3)

      # create output for source
      @sample_buffer = Api.new_fvec(@hop_size)
      # create output for pitch and beat
      @out_fvec = Api.new_fvec(1)
    end

    def each
      return enum_for(:each) unless block_given?

      total_frames_counter = 0
      read_buffer = FFI::MemoryPointer.new(:int)

      loop do
        # Perform onset calculation
        Api.aubio_source_do(@source, @sample_buffer, read_buffer)
        Api.aubio_onset_do(@onset, @sample_buffer, @out_fvec)

        # Retrieve result
        onset_new_peak = Api.fvec_get_sample(@out_fvec, 0)
        no_of_bytes_read = read_buffer.read_int
        total_frames_counter += no_of_bytes_read

        if onset_new_peak > 0.0
          onset_seconds = Api.aubio_onset_get_last_s(@onset)
          onset_silence = Api.aubio_onset_get_silence(@onset)
          onset_delay = Api.aubio_onset_get_delay_s(@onset)
          output = {
            :s => onset_seconds,
            :silence => onset_silence,
            :peak => onset_new_peak,
            :delay => onset_delay,
            :start => (onset_seconds == 0.0 ? 1 : 0),
            :end => 0
          }
          yield output
        end

        if no_of_bytes_read != @hop_size
          # there's no more audio to look at

          # Let's output one last onset to mark the end of the file
          total_time = total_frames_counter.to_f / @sample_rate.to_f
          output = {
            :s => total_time,
            :start => 0,
            :end  => 1
          }
          yield output

          # clean up
          Api.del_aubio_onset(@onset)
          Api.del_fvec(@sample_buffer)
          Api.del_fvec(@out_fvec)

          break
        end
      end
    end

  end
end
