#! /usr/bin/env ruby
#
# playstand - "Put and Play" CD Player
#
# Copyright (C) 2002 Satoru Takabayashi <satoru@namazu.org> 
#     All rights reserved.
#     This is free software with ABSOLUTELY NO WARRANTY.
#
# You can redistribute it and/or modify it under the terms of 
# the GNU General Public License version 2.
#
require 'termios'
require 'fcntl'
require 'getoptlong'
require 'net/http'

class LightController
  def initialize (host)
    @host = host
  end

  def on
    Net::HTTP.start(@host, 80) {|http| http.get('modify.cgi?RB2=H') }
  end

  def off
    Net::HTTP.start(@host, 80) {|http| http.get('modify.cgi?RB2=L') }
  end
end

class Message
  def initialize (start, len, status, data, bcc)
    @start = start
    @len = len
    @status = status
    @data = data
    @id  = to_hex(@data)
    @bcc = bcc
  end
  attr_reader :status
  attr_reader :data
  attr_reader :id

  private
  #
  # Generate a hexadecimal string from binary data. 
  # e.g. "82 11 c6 00 00 00 00 00"
  #
  def to_hex (data)
    data.map {|x| sprintf("%02x", x) }.join(" ")
  end

  public
  def inspect
    msg =  sprintf("message: %02x %02x %02x ", @start, @len, @status)
    msg << sprintf("%s", (if @data.empty? then "" else to_hex(data) + " " end))
    msg << sprintf("%02x", @bcc)
    msg
  end

  def id_detected?
    @status == 0x0c
  end
end

class Player
  def initialize (device = "/dev/ttyS0", 
		  mp3dir = "#{ENV['HOME']}/mp3", 
		  mp3cmd = "mpg123",
		  mp3opt = "-b4096")

    @line = open_serial(device)
    @oldtio = Termios::getattr(@line)
    init_line

    @now_playing_id = nil
    @jukebox = Hash.new
    @mp3dir = mp3dir
    @mp3cmd = mp3cmd
    @mp3opt = mp3opt
    @verbose = false
    @allowable_mishit = 3
    @start_hook = lambda {}
    @stop_hook = lambda {}
  end
  attr_accessor :verbose

  private
  def open_serial (device)
    #
    # To avoid blocking while opening the serial device, open
    # the serial device with the NONBLOCK flag and cancel
    # the NONBLOCK flag after the serial device is opened.
    # The technique is borrowed from minicom-1.82.1.orig/src/main.c.
    #
    line = open(device, File::RDWR | File::NONBLOCK)
    mode = line.fcntl(Fcntl::F_GETFL, 0);
    line.fcntl(Fcntl::F_SETFL, mode & ~File::NONBLOCK);
    return line
  end

  def init_line
    newtio = Termios::new_termios()
    newtio.c_iflag = Termios::IGNPAR
    newtio.c_oflag = 0
    newtio.c_cflag = (Termios::B9600 | Termios::CLOCAL |
		      Termios::CS8 | Termios::CREAD | Termios::HUPCL)
    newtio.c_lflag = 0
    newtio.c_cc[Termios::VMIN]  = 1
    newtio.c_cc[Termios::VTIME] = 0
    Termios::flush(@line, Termios::TCIOFLUSH)
    Termios::setattr(@line, Termios::TCSANOW, newtio)
  end

  # Redundancy Check calculation (Xor'ed bytes)
  def valid_bcc? (len, status, data, bcc)
    x = len ^ status
    data.each {|y| x = x ^ y }
    x == bcc
  end

  def read_message
    start = @line.getc
    raise "bad start byte #{start}" unless start == 1
    len  = @line.getc
    data = []
    len.times {|x| data.push(@line.getc) }
    status = data.shift
    bcc = @line.getc
    raise "bad bcc #{bcc}" unless valid_bcc?(len, status, data, bcc)
    return Message.new(start, len, status, data, bcc)
  end

  def start_playing (id)
    volume_max
    artist, album = @jukebox[id]
    printf "Artist: %s\n", artist
    printf "Album:  %s\n", album
    path = sprintf("%s/%s/%s", @mp3dir, artist, album)
    system "#{@mp3cmd} #{@mp3opt} #{path}/*.mp3 >/dev/null 2>&1 &"
    @now_playing_id = id
    @start_hook.call
  end

  def play (id)
    if @jukebox[id].nil?
      puts "unknown disc."
    elsif @jukebox[id] and id != @now_playing_id
      stop_playing
      start_playing(id)
    end
  end

  public
  def add_stop_hook (proc)
    @stop_hook = proc
  end

  def add_start_hook (proc)
    @start_hook = proc
  end

  def get_message
    @line.syswrite("\x01\x02\x08\x32\x38")
    read_message
  end

  def volume_max
    system("aumix -v 100")
  end

  def volume_fadeout
    point = 40
    100.step(point, -1) {|x|
      system("aumix -v #{x}")
      sleep(0.015)
    }
    point.step(0, -10) {|x|
      system("aumix -v #{x}")
      sleep(0.01)
    }
  end

  def stop_playing
    if @now_playing_id
      Thread.new { @stop_hook.call }
      volume_fadeout
      system "killall #{@mp3cmd}"
      @now_playing_id = nil
    end
  end

  def start
    mishit = 0
    while true
      message = get_message
      p message if @verbose
      if message.id_detected?
	play(message.id)
	mishit = 0
      else
	mishit += 1
	stop_playing if mishit > @allowable_mishit
      end
      sleep(0.1)
    end
  end

  def add (id, artist, album)
    @jukebox[id] = [artist, album]
  end

  def finish
    stop_playing
    Termios::setattr(@line, Termios::TCSANOW, @oldtio)
    Termios::flush(@line, Termios::TCIOFLUSH)
    @line.close
  end
end

def show_usage
  puts "usage: playstand [OPTIONS] [DEVICE] [PICNIC]"
  puts "  -v, --verbose     work noisily (diagnostic output)"
  puts "  -h, --help        display this help and exit"
end

def parse_options
  parser = GetoptLong.new
  parser.set_options(['--verbose', '-v', GetoptLong::NO_ARGUMENT],
		     ['--help',    '-h', GetoptLong::NO_ARGUMENT])
  options = Hash.new
  parser.each_option {|name, arg| options[name.sub /^--/, ""] = arg}
  (show_usage; exit(1)) if options['help']
  return options
end

def main
  options = parse_options
  raise if ARGV.empty?
  device = (ARGV.shift or "/dev/ttyS0")
  picnic = (ARGV.shift or nil)

  player = Player.new(device)
  player.verbose = true if options['verbose']

  player.add("82 11 c6 00 00 00 00 00",
	     "chick_corea_and_return_to_forever", 
	     "light_as_a_feather")
  player.add("83 11 c6 00 00 00 00 00",
	     "booker_little",
	     "bainbridge")
  player.add("77 11 c6 00 00 00 00 00",
	     "pat_metheny_group",
	     "we_live_here")
  player.add("79 11 c6 00 00 00 00 00",
	     "freddie_hubbard",
	     "hub-tones")
  player.add("81 11 c6 00 00 00 00 00",
	     "arista_all_stars",
	     "blue_montreux")
  player.add("78 11 c6 00 00 00 00 00",
	     "chet_baker",
	     "chet_baker_sings")
  player.add("84 11 c6 00 00 00 00 00",
	     "john_coltrane",
	     "my_favorite_things")
  player.add("7a 11 c6 00 00 00 00 00",
	     "squarepusher",
	     "feed_me_weird_things")

  if picnic
    controller = LightController.new(picnic)
    player.add_start_hook(lambda { controller.on })
    player.add_stop_hook( lambda { controller.off })
  end

  trap(:TERM) { player.finish }
  trap(:INT)  { player.finish }
  begin 
    player.start
  ensure
    player.finish
  end
end

main