class Opal::Nodes::StringNode

def compile
  string_value = value
  sanitized_value = string_value.inspect.gsub(/\\u\{([0-9a-f]+)\}/) do
    code_point = Regexp.last_match(1).to_i(16)
    to_utf16(code_point)
  end
  push translate_escape_chars(sanitized_value)
  if RUBY_ENGINE != 'opal'
    encoding = string_value.encoding
    unless encoding == Encoding::UTF_8
      helper :enc
      wrap "$enc(", ", \"#{encoding.name}\")"
    end
  end
  unless value.valid_encoding?
    helper :binary
    wrap "$binary(", ")"
  end
end

def to_utf16(code_point)
  ten_bits = 0b1111111111
  u = ->(code_unit) { '\\u' + code_unit.to_s(16).upcase }
  return u.call(code_point) if code_point <= 0xFFFF
  code_point -= 0x10000
  # Shift right to get to most significant 10 bits
  lead_surrogate = 0xD800 + (code_point >> 10)
  # Mask to get least significant 10 bits
  tail_surrogate = 0xDC00 + (code_point & ten_bits)
  u.call(lead_surrogate) + u.call(tail_surrogate)
end

def translate_escape_chars(inspect_string)
  inspect_string.gsub(ESCAPE_REGEX) do |original|
    if Regexp.last_match(1).length.even?
      original
    else
      Regexp.last_match(1).chop + ESCAPE_CHARS[Regexp.last_match(2)]
    end
  end
end