module Subtitle2utf8

# File lib/subtitle2utf8.rb, line 5
def self.convert(subtitle, type, recursion = false)
  path = File.expand_path(subtitle)

  case type
  when :file
    if !File.exist?(path)
      abort "#{path} does not exist!"
    end

    convert_file(path)
  when :dir
    if !Dir.exist?(path)
      abort "#{path} does not exist!"
    end

    if recursion
      convert_dirs(path)
    else
      convert_dir(path)
    end
  end
end

# File lib/subtitle2utf8.rb, line 66
def convert_dir(present)
  Dir.chdir(present) do
    Dir['*.srt'].each { |name| convert_file name }
    Dir['*.ass'].each { |name| convert_file name }
  end
end

# File lib/subtitle2utf8.rb, line 73
def convert_dirs(present)
  Dir.chdir(present) do
    Dir['**/*.srt'].each { |name| convert_file name }
    Dir['**/*.ass'].each { |name| convert_file name }
  end
end

# File lib/subtitle2utf8.rb, line 30
def convert_file(origin)
  valid = ['.srt', '.ass']

  ext = File.extname(origin)
  if !valid.include?(ext)
    abort "#{origin} is not valid file!"
  end

  name = File.basename(origin, ext)
  # Ignore converted file.
  return if name =~ /^*.utf-8/

  dir = File.dirname(origin)
  new_file = "#{dir}/#{name}.utf-8#{ext}"
  encoding = CharDet.detect(File.new(origin).read(64))['encoding']
  # GB18030 is a superset of Chinese encoding GB2312.
  encoding = begin
    encoding == 'GB2312' ? 'GB18030' : encoding
  end

  begin
    file_content =
      # For UTF-16 encodings(UTF-16LE(UNIX platform) and UTF-16BE(WIndows platform))
      # the file open mode must be binary.
      if encoding == 'UTF-16LE' || encoding == 'UTF-16BE'
        IO.read(origin, mode: 'rb', encoding: encoding).dup.force_encoding(encoding).encode('utf-8')
      else
        File.read(origin, encoding: encoding).dup.force_encoding(encoding).encode('utf-8')
      end
  rescue Exception => e
    abort "#{e}: #{origin} cannot be converted to utf-8..."
  end

  File.open(new_file, 'w') { |f| f.write(file_content) }
end