#!/usr/bin/env ruby
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/. -}

# frozen_string_literal: true

require 'pathname'
require 'open3'
require 'optparse'
require 'zip'

# Renames music files in a directory according to the file's tags.
# Expects two arguments:
# - Path to the zip file with music files.
# - Music directory to extract songs into.

class Song
  attr_reader :track, :extension
  attr_accessor :title, :album

  def initialize(extension)
    @extension = extension
  end

  def track=(track)
    @track = track.strip.split('/').first.rjust(2, '0')
  end

  def to_s
    @track + ' - ' + @title + @extension
  end
end

def find_unnamed_directory(parent_path)
  parent_path.children.filter { |child| child.basename.to_s.start_with? '_' }.first
end

def extract_and_rename_archive(album_archive, music_directory)
  music_directory.mkpath
  artist_name, album_name = album_archive.basename('.zip').to_s.split(' - ')

  Zip::File.open album_archive.to_path do |zip_file|
    zip_file.each do |entry|
      puts "Inflating #{entry.name}"
      extract_target = music_directory + File.basename(entry.name)

      entry.extract extract_target
    end
  end

  music_directory
end

def probe_song(song_path)
  song = Song.new song_path.extname

  Open3.popen3 'ffprobe', song_path.to_s do |_stdin, _stdout, stderr, _wait_pid|
    while (line = stderr.gets)
      key, value = line.split ':', 2
      next if value.nil?

      case key.strip.downcase
      when 'title'
        song.title = value.strip if song.title.nil?
      when 'track'
        song.track = value if song.track.nil?
      when 'album'
        song.album = value.strip if song.album.nil?
      end
    end
  end
  song
end

unless ARGV.length == 2
  $stderr.puts 'Usage: 7digital.rb MUSIC_ARCHIVE.zip DIRECTORY'
  exit 1
end

album_archive = Pathname.new ARGV[0]
music_directory = Pathname.new ARGV[1]
metadata = {}

extract_and_rename_archive album_archive, music_directory

Dir.each_child music_directory do |filename|
  song_path = music_directory + filename

  metadata[song_path] = probe_song(song_path)
end

metadata.each_pair do |from, to|
  album_path = music_directory + to.album

  album_path.mkpath
  File.rename(from, album_path + to.to_s)
end