#!/usr/bin/env ruby

# Run to create a playlist named "today's tunes". The playlist is 
# populated with tracks selected because the first character of their
# names begins with a randomly selected letter or digit. For example, 
# my list today begins like this:
#  Galang
#  Gamma Ray
#  Gary Stomp
#  Gear

require 'osx/cocoa'
include OSX
OSX.require_framework 'ScriptingBridge'

PLAYLIST_NAME = "today's tunes"

def main
  todays_tunes = make_empty_playlist
  tracks = tracks_beginning_with(some_random_character, all_songs)
  tracks.each do | track |
    track.duplicateTo(todays_tunes)
  end
end

def make_empty_playlist
  ensure_no_playlist(PLAYLIST_NAME)
  p = ITunesPlaylist.alloc.initWithProperties({'name' => PLAYLIST_NAME})
  # TODO: why does following fail?
  # LIBRARY.userPlaylists.addObject(p)
  LIBRARY.userPlaylists.insertObject_atIndex(p,0)
  p.shuffle = true
  p
end

def tracks_beginning_with(letter, tracks)
  tracks.find_all do | track |
    name = if starts_with_qualifier?(track.name)
             phrase_tail(track.name)
           else
             track.name
           end
    /^#{letter}/i =~ name
  end
end

def ensure_no_playlist(name)
  p = LIBRARY.playlists.objectWithName(name)
  p.delete if p.exists == 1
end

def all_songs
  LIBRARY.playlists.objectWithName('Library').tracks
end

def some_random_character
  possibilities = ('a'..'z').to_a + ('0'..'9').to_a
  possibilities[rand(possibilities.length)]
end

# Works with either a NSCFString or a string.
# TODO: Change tests to indicate that?
def starts_with_qualifier?(name)
  name =~ /^the\s/i || name =~ /^an\s/i || name =~ /^a\s/i
end

def phrase_tail(name)
  name.gsub(/^\w+\s+/, '')
end

def bapp(bundle_name)
  SBApplication.applicationWithBundleIdentifier(bundle_name)
end

ITUNES = bapp('com.apple.iTunes')
LIBRARY = ITUNES.sources.objectWithName('Library')


if $0 == __FILE__
  main
end