#!/usr/bin/env ruby

require "optparse"

ARTIST = "David Eisinger"

Config = Struct.new(:file, :title, :directory, :artist)

config = Config.new(artist: ARTIST)

parser = OptionParser.new do |opts|
  opts.banner = "Usage: bin/audio [options]"

  opts.on("-f", "--file FILE", "input file") do |file|
    config.file = file
  end

  opts.on("-t", "--title TITLE", "title of the track") do |title|
    config.title = title
  end

  opts.on("-d", "--directory DIRECTORY", "directory to put the output file") do |directory|
    config.directory = directory
  end

  opts.on("-a", "--artist ARTIST", "artist (default: #{ARTIST})") do |artist|
    config.artist = artist
  end
end

begin
  parser.parse!(ARGV)
  missing = config.to_h.filter_map { |k, v| k if v.nil? }
  raise OptionParser::MissingArgument.new(missing * ", ") unless missing.empty?
rescue
  puts $!.to_s
  puts parser
  exit
end

dest = [config.directory, "#{config.title}.mp3"].join("/").squeeze("/")

# `ffmpeg -i "#{config.file}" -af "pan=mono|FC=FL" -y "#{dest}"`
`ffmpeg -i "#{config.file}" -y "#{dest}"`
`id3tag --artist="#{config.artist}" --song="#{config.title}" "#{dest}"`

puts `id3info "#{dest}"`