require 'alsa'
require 'sndfile'

require 'fileutils'

module AlsaBackup
  class Recorder

    def initialize(file = "record.wav")
      @file = file
      @directory = "."
    end

    attr_accessor :file, :directory

    def start(seconds_to_record = nil)
      frames_to_record = format[:sample_rate] * seconds_to_record if seconds_to_record

      # prepare sndfile
      self.sndfile

      ALSA::PCM::Capture.open("hw:0", self.format(:sample_format => :s16_le)) do |capture|
        capture.read do |buffer, frame_count|
          self.sndfile.write buffer, frame_count
          if frames_to_record
            (frames_to_record -= frame_count) > 0
          else
            true
          end
        end
      end
    rescue Exception => e
      AlsaBackup.logger.error(e)
      raise e
    ensure
      @sndfile.close if @sndfile
    end

    def file
      case @file
      when Proc
        @file.call
      else
        @file
      end
    end

    def target_file
      File.join self.directory, self.file
    end

    def format(additional_parameters = {})
      {:sample_rate => 44100, :channels => 2}.merge(additional_parameters)
    end

    def sndfile
      target_file = self.target_file
      raise "no recording file" unless target_file

      unless @sndfile and @sndfile.path == target_file
        @sndfile.close if @sndfile
        AlsaBackup.logger.info "new file #{target_file}"

        FileUtils.mkdir_p File.dirname(target_file)
        @sndfile = Sndfile::File.new(target_file, "w", self.format(:format => "wav pcm_16"))
      end
      @sndfile
    end
    
  end
end