class HTTParty::TextEncoder

def call
  if can_encode?
    encoded_text
  else
    text
  end
end

def can_encode?
  ''.respond_to?(:encoding) && charset
end

def charset
  return nil if content_type.nil?
  if (matchdata = content_type.match(/;\s*charset\s*=\s*([^=,;"\s]+)/i))
    return matchdata.captures.first
  end
  if (matchdata = content_type.match(/;\s*charset\s*=\s*"((\\.|[^\\"])+)"/i))
    return matchdata.captures.first.gsub(/\\(.)/, '\1')
  end
end

def encode_utf_16
  if text.bytesize >= 2
    if text.getbyte(0) == 0xFF && text.getbyte(1) == 0xFE
      return text.force_encoding('UTF-16LE')
    elsif text.getbyte(0) == 0xFE && text.getbyte(1) == 0xFF
      return text.force_encoding('UTF-16BE')
    end
  end
  if assume_utf16_is_big_endian # option
    text.force_encoding('UTF-16BE')
  else
    text.force_encoding('UTF-16LE')
  end
end

def encode_with_ruby_encoding
  # NOTE: This will raise an argument error if the
  # charset does not exist
  encoding = Encoding.find(charset)
  text.force_encoding(encoding.to_s)
rescue ArgumentError
  text
end

def encoded_text
  if 'utf-16'.casecmp(charset) == 0
    encode_utf_16
  else
    encode_with_ruby_encoding
  end
end

def initialize(text, assume_utf16_is_big_endian: true, content_type: nil)
  @text = +text
  @content_type = content_type
  @assume_utf16_is_big_endian = assume_utf16_is_big_endian
end