require "mp3tag"
require "fileutils"
require "mp3info"
require "shellwords"

class Folder

  attr_reader :dirname,:tocname,:parentname

  def initialize(givenpath)
    Dir.chdir givenpath
    @dirname = File.basename(Dir.pwd)
    @parentname = File.dirname(Dir.pwd)
    @tocname = find_tocname
  end

  def find_tocname
    expr = %r{(.*)\.0}
    m1 = expr.match(dirname)
    if m1
      toc = m1[1] + ".toc"
    else
      toc = dirname + ".toc"
    end
    toc
  end

  def parse_toc_v1
    expr1 = %r{^DTITLE=(.*) / ([^\r]*)}
    expr2 = %r{^TTITLE(\d+)=([^\r]*)}
    title = []
    artist = ""
    album = ""
    # reading lines... into line
    tocfile = File.new(tocname)
    tocfile.each_line {|line|
     m1 = expr1.match(line)
      if m1
        artist = m1[1].chomp
        album = m1[2].chomp
      end
      m2 = expr2.match(line)
      if m2
        # We store Track Number minus one
        n = m2[1].to_i
        title[n] = m2[2].chomp
        #puts "title[#{n}] = {#{title[n]}}"
      end
    }
    title != [] && artist != "" && album != "" &&
      {:artist => artist,:album => album,:title => title}
  end

  def valid_toc_v1
    File.exist?(tocname) && parse_toc_v1
  end

  def classify
    {:toc_exists => File.exist?(tocname),
      :toc_version => (if valid_toc_v1 then 1 else 0 end)}
  end

  def debug
    puts "directory: #{dirname}"
    puts "parentname: #{parentname}"
    puts "tocname: #{tocname}"
    classify.each_pair {|k,v| puts "#{k.to_s}: #{v.to_s}"}
    puts " "
  end

  def songs
    expr = %r{\.mp3$}
    Dir.entries(".").delete_if{|file|
      !(expr =~ file) ||
      !FileTest.file?(file) || !FileTest.readable?(file) || FileTest.zero?(file)
    }.sort
  end
end

class Song

  attr_reader :filename,:dirname

  attr_writer :filename
 
  def initialize(dirname,filename)
    @dirname = dirname
    @filename = filename
  end

  # An id3 tag is not "valid" unless the four tags below are not null.
  def has_valid_id3v1
    has_id3v1 = Mp3Tag.hastag?(filename)
    if !has_id3v1 then false
    else
      tags = Mp3Tag.new(filename)
      tags.artist.length > 0 &&
        tags.album.length > 0 &&
        tags.tracknum.class != nil &&
        tags.songname.length > 0
    end
  end

  def has_id3v2
    Mp3Info.hastag2?(filename)
  end


  # This is false: nirvana-nevermind-album/01_-_smells_like_teen_spirit_192_lame_cbr.mp3
  # This is true: gorillaz-first-album/gorillaz-first-album.01.mp3
  def filename_is_album
    expr1 = %r{^(.*)\.\d\d\.mp3}
    m1 = expr1.match(filename)
    (m1 &&  dirname == m1[1]) || false
  end

  def title_puts(title)
    title.each_index{ |i| puts "track #{i.to_s} is: #{title[i]}"}
  end

  def classify
    {:has_valid_id3v1 => has_valid_id3v1,
      :has_id3v2 => has_id3v2,
      :filename_is_album => filename_is_album}
  end

  def debug
    puts "filename: #{filename}"
    classify.each_pair {|k,v| puts "#{k.to_s}: #{v.to_s}"}
    puts " "

  end

end

def make_songs(folder)
  folder.songs.collect{|filename| Song.new(folder.dirname,filename)}
end

class Automaton

  attr_reader :action_table, :folder, :song, :songhash

  def initialize(folder,song)
    @action_table =
      [{:conditions => {:has_valid_id3v1 => false,:has_id3v2 => false,:toc_exists => true,:toc_version => 1, :filename_is_album => true},
         :actions => [:convert_toc1_to_metadata]},
       {:conditions => {:has_valid_id3v1 => false,:has_id3v2 => false,:toc_exists => true,:toc_version => 1, :filename_is_album => false},
         :actions => [:rename_file, :convert_toc1_to_metadata]},
       {:conditions => {:has_valid_id3v1 => false,:has_id3v2 => true},
         :actions => [:move_v2_to_v1,:delete_v2,:restart_script]},
       {:conditions => {:has_valid_id3v1 => true,:has_id3v2 => true,:filename_is_album => true},
         :actions => [:delete_v2]},
       {:conditions => {:has_valid_id3v1 => true,:has_id3v2 => true,:filename_is_album => false},
         :actions => [:delete_v2,:rename_file]},
       {:conditions => {:toc_exists => false,:filename_is_album => false,:has_valid_id3v1 => false,:has_id3v2 => false},
         :actions => [:partial_info]},
       {:conditions => {:has_valid_id3v1 => true,:has_id3v2 => false,:filename_is_album => true},
         :actions => [:everything_is_ok]},
       {:conditions => {:has_valid_id3v1 => true,:has_id3v2 => false,:filename_is_album => false},
         :actions => [:rename_file]},
       {:conditions => {:has_valid_id3v1 => false,:has_id3v2 => false,:toc_exists => true,:toc_version => 0},
         :actions => [:unknown_toc_format]},
       {:conditions => {:has_valid_id3v1 => false, :has_id3v2 => false, :filename_is_album => true, :toc_exists => false},
         :actions => [:youre_screwed]}]
    @folder = folder
    @song = song
    @songhash = merge_hashes(folder.classify,song.classify)
  end

  def rename_file
    expr1 = %r{^(\d\d)[\. _-](.*)\.mp3}
    m1 = expr1.match(song.filename)
    expr2 = %r{(.*)_-_(\d\d)_\.(.*)\.mp3}
    m2 = expr2.match(song.filename)
    if m1
      File.rename("#{song.filename}","#{song.dirname}.#{m1[1]}.mp3")
      song.filename = "#{song.dirname}.#{m1[1]}.mp3"
      puts "renaming file to #{song.filename}"
    else
      if m2
        File.rename("#{song.filename}","#{song.dirname}.#{m2[2]}.mp3")
        song.filename = "#{song.dirname}.#{m2[2]}.mp3"
        puts "renaming file to #{song.filename}"
      else
        puts "#{song.filename}: filename parse error"
      end
    end
  end

  def convert_toc1_to_metadata
    toc = folder.parse_toc_v1
    tags = Mp3Tag.new(song.filename)
    expr = %r{^(.*)\.(\d\d)\.mp3}
    m1 = expr.match(song.filename)
    if m1
      puts "#{song.filename}: Writing Mp3 Tag."
    tags.artist = toc[:artist]
    tags.album = toc[:album]
    tags.tracknum = m1[2].to_i
    tags.songname = toc[:title][m1[2].to_i - 1]
    tags.commit
    #puts "Artist: #{tags.artist}","Album: #{tags.album}","Track Number: #{tags.tracknum}","Title: #{tags.songname}"
    else
      puts "#{song.filename}: filename parse error"
    end
  end

  def move_v2_to_v1
    system("eyeD3 --to-v1.1 #{song.filename.shellescape}")
  end

  def delete_v2
    system("eyeD3 --remove-v2 #{song.filename.shellescape}")
  end

  def restart_script
    make_songs(folder).each{|song| Automaton.new(folder,song).dispatch}
  end

  def partial_info
    # expr1 = %r{^(\d\d)(?:_| )?-(?:_| )?(.*?)(?:_192_lame_cbr)?.mp3}
    # m1 = expr1.match(song.filename)
    # if m1
    #   tracknum = m1[1].to_i
    #   songname = m1[2].gsub("_"," ")
    # else
    #   puts "#{song.filename}: filename parse error"
    # end
    # tags = Mp3Tag.new(song.filename)
    # tags.artist = artist
    # tags.album = album
    # tags.tracknum = tracknum
    # tags.songname = songname
    # tags.commit
    #puts "Artist: #{tags.artist}","Album: #{tags.album}","Track Number: #{tags.tracknum}","Title: #{tags.songname}"
    puts "#{folder.dirname}/#{song.filename}: partial information"
  end

  def everything_is_ok
    puts "#{song.filename} is okay"
  end

  def unknown_toc_format
    puts "#{folder.dirname}: Unknown toc format"
  end

  def youre_screwed
    puts "#{song.filename}: insufficient data for tags."
  end

  def error_message
    puts "#{song.filename}: unrecognized conditions."
  end

  def merge_hashes(hash1,hash2)
    combined = {}
    hash1.each_pair{|k,v| combined[k] = v}
    hash2.each_pair{|k,v| combined[k] = v}
    combined
  end

  def myall(hash)
    bool = true
    hash.each_pair{|k,v| bool = bool && yield(k,v)}
    bool
  end

  def left_join(hash1,hash2)
    myall(hash2) {|k,v| v == hash1[k]}
  end

  def dispatch
    actions = [:error_message]
    action_table.each{|entry|
      if left_join(songhash,entry[:conditions])
#        puts "#{song.filename}: #{entry[:conditions]} ==> #{entry[:actions]}"
        actions = entry[:actions]
      end}
    actions.each{|v| method(v).call}
  end

end

def hashdraw(title,hash)
  puts title
  hash.each_pair{|k,v| puts "#{k}: #{v}"}
  puts ""
end
folder = Folder.new(ARGV[0])
#folder.debug

make_songs(folder).each{|song| Automaton.new(folder,song).dispatch}
#hashdraw("lets see if this works",folder.parse_toc_v1)