module Serinette
  # Has functions for kicking off initializer chain, rendering final song, and
  # constants necessary for determining song-level characteristcs
  class Song
    LOWEST_DURATION  = 60
    HIGHEST_DURATION = 180
    TRACK_NUMBER     = 2
    EFFECT_NUMBER    = 1

    CHANNELS         = 2
    RATE             = 99_600

    attr_accessor :duration, :tracks, :effects

    def self.default_effects
      { rate: RATE, channels: CHANNELS }
    end

    def initialize
      init_duration
      init_tracks
      init_effects
    end

    # Recurses render tree via render
    def render
      @tracks.map(&:render)
    end

    # Taks a sox instance and adds input, sets effects, and sets output
    #
    # @param sox [Sox::Cmd] Sox command instance
    def configure_command(sox)
      render.each do |file|
        sox.add_input(file)
      end
      sox.set_effects(generate_effects_options)
      sox.set_output(Serinette.output_path)
    end

    private

    # Uses effects instance variable to generate hash of all effects as sox
    # key/pairs
    def generate_effects_options
      effects_hash = Song.default_effects

      @effects.each do |effect|
        effects_hash.merge! effect.to_sox_key_pair
      end

      effects_hash
    end

    # Initializes duration
    def init_duration
      @duration = (LOWEST_DURATION..HIGHEST_DURATION).to_a.sample
    end

    # Initializes tracks
    def init_tracks
      @tracks = Array.new(TRACK_NUMBER) { Track.new }
    end

    # Initializes effects
    def init_effects
      @effects = Effect.sample_effects_classes(1)
    end
  end
end