"use strict";
const punycode = require("punycode");

const tr46 = require("tr46");

/*jshint unused: false */

const specialSchemas = {
  "ftp": "21",
  "file": null,
  "gopher": "70",
  "http": "80",
  "https": "443",
  "ws": "80",
  "wss": "443"
};

const localSchemas = [
  "about",
  "blob",
  "data",
  "filesystem"
];

const bufferReplacement = {
  "%2e": ".",
  ".%2e": "..",
  "%2e.": "..",
  "%2e%2e": ".."
};

const STATES = {
  SCHEME_START: 1,
  SCHEME: 2,
  NO_SCHEME: 3,
  RELATIVE: 4,
  SPECIAL_RELATIVE_OR_AUTHORITY: 5,
  SPECIAL_AUTHORITY_SLASHES: 6,
  NON_RELATIVE_PATH: 7,
  QUERY: 8,
  FRAGMENT: 9,
  SPECIAL_AUTHORITY_IGNORE_SLASHES: 10,
  RELATIVE_SLASH: 11,
  PATH: 12,
  FILE_HOST: 13,
  AUTHORITY: 14,
  HOST: 15,
  PATH_START: 16,
  HOST_NAME: 17,
  PORT: 18,
  PATH_OR_AUTHORITY: 19
};

function countSymbols(str) {
  return punycode.ucs2.decode(str).length;
}

function at(input, idx) {
  const c = input[idx];
  return isNaN(c) ? undefined : String.fromCodePoint(c);
}

function isASCIIDigit(c) {
  return c >= 0x30 && c <= 0x39;
}

function isASCIIAlpha(c) {
  return (c >= 0x41 && c <= 0x5A) || (c >= 0x61 && c <= 0x7A);
}

function isASCIIHex(c) {
  return isASCIIDigit(c) || (c >= 0x41 && c <= 0x46) || (c >= 0x61 && c <= 0x66);
}

function percentEncode(c) {
  let hex = c.toString(16).toUpperCase();
  if (hex.length === 1) {
    hex = "0" + hex;
  }

  return "%" + hex;
}

const invalidCodePoint = String.fromCodePoint(65533);
function utf8PercentEncode(c) {
  const buf = new Buffer(c);
  if (buf.toString() === invalidCodePoint) {
    return "";
  }

  let str = "";

  for (let i = 0; i < buf.length; ++i) {
    str += percentEncode(buf[i]);
  }

  return str;
}

function simpleEncode(c) {
  const c_str = String.fromCodePoint(c);

  if (c < 0x20 || c > 0x7E) {
    return utf8PercentEncode(c_str);
  } else {
    return c_str;
  }
}

function defaultEncode(c) {
  const c_str = String.fromCodePoint(c);
  if (c <= 0x20 || c >= 0x7E || c_str === "\"" || c_str === "#" ||
    c_str === "<" || c_str === ">" || c_str === "?" || c_str === "`" ||
    c_str === "{" || c_str === "}") {
    return utf8PercentEncode(c_str);
  } else {
    return c_str;
  }
}

function passwordEncode(c) {
  const c_str = String.fromCodePoint(c);
  if (c <= 0x20 || c >= 0x7E || c_str === "\"" || c_str === "#" ||
    c_str === "<" || c_str === ">" || c_str === "?" || c_str === "`" ||
    c_str === "{" || c_str === "}" ||
    c_str === "/" || c_str === "@" || c_str === "\\") {
    return utf8PercentEncode(c_str);
  } else {
    return c_str;
  }
}

function usernameEncode(c) {
  const c_str = String.fromCodePoint(c);
  if (c <= 0x20 || c >= 0x7E || c_str === "\"" || c_str === "#" ||
    c_str === "<" || c_str === ">" || c_str === "?" || c_str === "`" ||
    c_str === "{" || c_str === "}" ||
    c_str === "/" || c_str === "@" || c_str === "\\" || c_str === ":") {
    return utf8PercentEncode(c_str);
  } else {
    return c_str;
  }
}

function parseIPv4Number(input) {
  let R = 10;

  if (input.length >= 2 && input.charAt(0) === "0" && input.charAt(1).toLowerCase() === "x") {
    input = input.substring(2);
    R = 16;
  } else if (input.length >= 2 && input.charAt(0) === "0") {
    input = input.substring(1);
    R = 8;
  }

  if (input === "") {
    return 0;
  }

  const regex = R === 10 ? /[^0-9]/ : (R === 16 ? /[^0-9A-Fa-f]/ : /[^0-7]/);
  if (regex.test(input)) {
    return null;
  }

  return parseInt(input, R);
}

function parseIPv4(input) {
  let parts = input.split(".");
  if (parts[parts.length - 1] === "") {
    parts.pop();
  }

  if (parts.length > 4) {
    return input;
  }

  let numbers = [];
  for (const part of parts) {
    const n = parseIPv4Number(part);
    if (n === null) {
      return input;
    }

    numbers.push(n);
  }

  for (let i = 0; i < numbers.length - 1; ++i) {
    if (numbers[i] > 255) {
      throw new TypeError("Invalid Host");
    }
  }
  if (numbers[numbers.length - 1] >= Math.pow(256, 5 - numbers.length)) {
    throw new TypeError("Invalid Host");
  }

  let ipv4 = numbers.pop();
  let counter = 0;

  for (const n of numbers) {
    ipv4 += n * Math.pow(256, 3 - counter);
    ++counter;
  }

  return ipv4;
}

function serializeIPv4(address) {
  let output = "";
  let n = address;

  for (let i = 0; i < 4; ++i) {
    output = String(n % 256) + output;
    if (i !== 3) {
      output = "." + output;
    }
    n = Math.floor(n / 256);
  }

  return output;
}

function parseIPv6(input) {
  const ip = [0, 0, 0, 0, 0, 0, 0, 0];
  let piecePtr = 0;
  let compressPtr = null;
  let pointer = 0;

  input = punycode.ucs2.decode(input);

  if (at(input, pointer) === ":") {
    if (at(input, pointer + 1) !== ":") {
      throw new TypeError("Invalid Host");
    }

    pointer += 2;
    ++piecePtr;
    compressPtr = piecePtr;
  }

  let ipv4 = false;
  Main:
  while (pointer < input.length) {
    if (piecePtr === 8) {
      throw new TypeError("Invalid Host");
    }

    if (at(input, pointer) === ":") {
      if (compressPtr !== null) {
        throw new TypeError("Invalid Host");
      }
      ++pointer;
      ++piecePtr;
      compressPtr = piecePtr;
      continue;
    }

    let value = 0;
    let length = 0;

    while (length < 4 && isASCIIHex(input[pointer])) {
      value = value * 0x10 + parseInt(at(input, pointer), 16);
      ++pointer;
      ++length;
    }

    switch (at(input, pointer)) {
      case ".":
        if (length === 0) {
          throw new TypeError("Invalid Host");
        }
        pointer -= length;
        ipv4 = true;
        break Main;
      case ":":
        ++pointer;
        if (input[pointer] === undefined) {
          throw new TypeError("Invalid Host");
        }
        break;
      case undefined:
        break;
      default:
        throw new TypeError("Invalid Host");
    }

    ip[piecePtr] = value;
    ++piecePtr;
  }

  if (ipv4 && piecePtr > 6) {
    throw new TypeError("Invalid Host");
  } else if (input[pointer] !== undefined) {
    let dotsSeen = 0;

    while (input[pointer] !== undefined) {
      let value = null;
      if (!isASCIIDigit(input[pointer])) {
        throw new TypeError("Invalid Host");
      }

      while (isASCIIDigit(input[pointer])) {
        const number = parseInt(at(input, pointer), 10);
        if (value === null) {
          value = number;
        } else if (value === 0) {
          throw new TypeError("Invalid Host");
        } else {
          value = value * 10 + number;
        }
        ++pointer;
        if (value > 255) {
          throw new TypeError("Invalid Host");
        }
      }

      if (dotsSeen < 3 && at(input, pointer) !== ".") {
        throw new TypeError("Invalid Host");
      }
      ip[piecePtr] = ip[piecePtr] * 0x100 + value;
      if (dotsSeen === 1 || dotsSeen === 3) {
        ++piecePtr;
      }

      if (input[pointer] !== undefined) {
        ++pointer;
      }

      if (dotsSeen === 3 && input[pointer] !== undefined) {
        throw new TypeError("Invalid Host");
      }
      ++dotsSeen;
    }
  }

  if (compressPtr !== null) {
    let swaps = piecePtr - compressPtr;
    piecePtr = 7;
    while (piecePtr !== 0 && swaps > 0) {
      const temp = ip[compressPtr + swaps - 1]; // piece
      ip[compressPtr + swaps - 1] = ip[piecePtr];
      ip[piecePtr] = temp;
      --piecePtr;
      --swaps;
    }
  } else if (piecePtr !== 8) {
    throw new TypeError("Invalid Host");
  }

  return ip;
}

function serializeIPv6(address) {
  let output = "";
  const seqResult = findLongestZeroSequence(address);
  const compressPtr = seqResult.idx;

  for (var i = 0; i < address.length; ++i) {
    if (compressPtr === i) {
      if (i === 0) {
        output += "::";
      } else {
        output += ":";
      }

      i += seqResult.len - 1;
      continue;
    }

    output += address[i].toString(16);
    if (i !== address.length - 1) {
      output += ":";
    }
  }

  return output;
}

function parseHost(input, isUnicode) {
  if (input[0] === "[") {
    if (input[input.length - 1] !== "]") {
      throw new TypeError("Invalid Host");
    }

    return parseIPv6(input.substring(1, input.length - 1));
  }

  let domain;
  try {
    domain = decodeURIComponent(input);
  } catch (e) {
    throw new TypeError("Error while decoding host");
  }

  const asciiDomain = tr46.toASCII(domain, false, tr46.PROCESSING_OPTIONS.TRANSITIONAL, false);
  if (asciiDomain === null) {
    throw new TypeError("Invalid Host");
  }

  if (asciiDomain.search(/\u0000|\u0009|\u000A|\u000D|\u0020|#|%|\/|:|\?|@|\[|\\|\]/) !== -1) {
    throw new TypeError("Invalid Host");
  }

  let ipv4Host = parseIPv4(asciiDomain);
  if (typeof ipv4Host === "number") {
    return ipv4Host;
  }

  return isUnicode ? tr46.toUnicode(asciiDomain, false).domain : asciiDomain;
}

function findLongestZeroSequence(arr) {
  let maxIdx = null;
  let maxLen = 1; // only find elements > 1
  let currStart = null;
  let currLen = 0;

  for (var i = 0; i < arr.length; ++i) {
    if (arr[i] !== 0) {
      if (currLen > maxLen) {
        maxIdx = currStart;
        maxLen = currLen;
      }

      currStart = null;
      currLen = 0;
    } else {
      if (currStart === null) {
        currStart = i;
      }
      ++currLen;
    }
  }

  return {
    idx: maxIdx,
    len: maxLen
  };
}

function serializeHost(host) {
  if (typeof host === "number") {
    return serializeIPv4(host);
  }

  // IPv6 serializer
  if (host instanceof Array) {
    return "[" + serializeIPv6(host) + "]";
  }

  return host;
}

function trimControlChars(url) {
  return url.replace(/^[\u0000-\u001F\u0020]+|[\u0000-\u001F\u0020]+$/g, "");
}

function URLStateMachine(input, base, encoding_override, url, state_override) {
  this.pointer = 0;
  this.input = input;
  this.base = base || null;
  this.encoding_override = encoding_override || "utf-8";
  this.state_override = state_override;
  this.url = url;

  if (!this.url) {
    this.url = {
      scheme: "",
      username: "",
      password: null,
      host: null,
      port: "",
      path: [],
      query: null,
      fragment: null,

      nonRelative: false
    };

    this.input = trimControlChars(this.input);
  }

  this.state = state_override || STATES.SCHEME_START;

  this.buffer = "";
  this.at_flag = false;
  this.arr_flag = false;
  this.parse_error = false;

  this.input = punycode.ucs2.decode(this.input);

  for (; this.pointer <= this.input.length; ++this.pointer) {
    const c = this.input[this.pointer];
    const c_str = isNaN(c) ? undefined : String.fromCodePoint(c);

    // exec state machine
    if (this["parse" + this.state](c, c_str) === false) {
      break; // terminate algorithm
    }
  }
}

URLStateMachine.prototype["parse" + STATES.SCHEME_START] =
    function parseSchemeStart(c, c_str) {
  if (isASCIIAlpha(c)) {
    this.buffer += c_str.toLowerCase();
    this.state = STATES.SCHEME;
  } else if (!this.state_override) {
    this.state = STATES.NO_SCHEME;
    --this.pointer;
  } else {
    this.parse_error = true;
    return false;
  }
};

URLStateMachine.prototype["parse" + STATES.SCHEME] =
    function parseScheme(c, c_str) {
  if (isASCIIAlpha(c) || c_str === "+" || c_str === "-" || c_str === ".") {
    this.buffer += c_str.toLowerCase();
  } else if (c_str === ":") {
    if (this.state_override) {
      // TODO: XOR
      if (specialSchemas[this.url.scheme] !== undefined && !specialSchemas[this.buffer]) {
        return false;
      } else if (specialSchemas[this.url.scheme] === undefined && specialSchemas[this.buffer]) {
        return false;
      }
    }
    this.url.scheme = this.buffer;
    this.buffer = "";
    if (this.state_override) {
      return false;
    }
    if (this.url.scheme === "file") {
      this.state = STATES.RELATIVE;
    } else if (specialSchemas[this.url.scheme] !== undefined && this.base !== null &&
               this.base.scheme === this.url.scheme) {
      this.state = STATES.SPECIAL_RELATIVE_OR_AUTHORITY;
    } else if (specialSchemas[this.url.scheme] !== undefined) {
      this.state = STATES.SPECIAL_AUTHORITY_SLASHES;
    } else if (at(this.input, this.pointer + 1) === "/") {
      this.state = STATES.PATH_OR_AUTHORITY;
      ++this.pointer;
    } else {
      this.url.nonRelative = true;
      this.url.path.push("");
      this.state = STATES.NON_RELATIVE_PATH;
    }
  } else if (!this.state_override) {
    this.buffer = "";
    this.state = STATES.NO_SCHEME;
    this.pointer = -1;
  } else {
    this.parse_error = true;
    return false;
  }
};

URLStateMachine.prototype["parse" + STATES.NO_SCHEME] =
    function parseNoScheme(c, c_str) {
  //jshint unused:false
  if (this.base === null || (this.base.nonRelative && c_str !== "#")) {
    throw new TypeError("Invalid URL");
  } else if (this.base.nonRelative && c_str === "#") {
    this.url.scheme = this.base.scheme;
    this.url.path = this.base.path.slice();
    this.url.query = this.base.query;
    this.url.fragment = "";
    this.url.nonRelative = true;
    this.state = STATES.FRAGMENT;
  } else {
    this.state = STATES.RELATIVE;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.SPECIAL_RELATIVE_OR_AUTHORITY] =
    function parseSpecialRelativeOrAuthority(c, c_str) {
  if (c_str === "/" && at(this.input, this.pointer + 1) === "/") {
    this.state = STATES.SPECIAL_AUTHORITY_IGNORE_SLASHES;
    ++this.pointer;
  } else {
    this.parse_error = true;
    this.state = STATES.RELATIVE;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.PATH_OR_AUTHORITY] =
    function parsePathOrAuthority(c, c_str) {
  if (c_str === "/") {
    this.state = STATES.AUTHORITY;
  } else {
    this.state = STATES.PATH;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.RELATIVE] =
    function parseRelative(c, c_str) {
  if (this.url.scheme !== "file") {
    this.url.scheme = this.base.scheme;
  }
  if (isNaN(c)) {
    this.url.username = this.base.username;
    this.url.password = this.base.password;
    this.url.host = this.base.host;
    this.url.port = this.base.port;
    this.url.path = this.base.path.slice();
    this.url.query = this.base.query;
  } else if (c_str === "/") {
    this.state = STATES.RELATIVE_SLASH;
  } else if (c_str === "?") {
    this.url.username = this.base.username;
    this.url.password = this.base.password;
    this.url.host = this.base.host;
    this.url.port = this.base.port;
    this.url.path = this.base.path.slice();
    this.url.query = "";
    this.state = STATES.QUERY;
  } else if (c_str === "#") {
    this.url.username = this.base.username;
    this.url.password = this.base.password;
    this.url.host = this.base.host;
    this.url.port = this.base.port;
    this.url.path = this.base.path.slice();
    this.url.query = this.base.query;
    this.url.fragment = "";
    this.state = STATES.FRAGMENT;
  } else if (specialSchemas[this.url.scheme] !== undefined && c_str === "\\") {
    this.parse_error = true;
    this.state = STATES.RELATIVE_SLASH;
  } else {
    let nextChar = at(this.input, this.pointer + 1);
    let nextNextChar = at(this.input, this.pointer + 2);
    if (this.url.scheme !== "file" || !isASCIIAlpha(c) || !(nextChar === ":" || nextChar === "|") ||
      this.input.length - this.pointer === 1 || !(nextNextChar === "/" || nextNextChar === "\\" ||
        nextNextChar === "?" || nextNextChar === "#")) {
      this.url.username = this.base.username;
      this.url.password = this.base.password;
      this.url.host = this.base.host;
      this.url.port = this.base.port;
      this.url.path = this.base.path.slice(0, this.base.path.length - 1);
    }

    this.state = STATES.PATH;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.RELATIVE_SLASH] =
    function parseRelativeSlash(c, c_str) {
  if (c_str === "/" || (specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
    if (c_str === "\\") {
      this.parse_error = true;
    }
    if (this.url.scheme === "file") {
      this.state = STATES.FILE_HOST;
    } else {
      this.state = STATES.SPECIAL_AUTHORITY_IGNORE_SLASHES;
    }
  } else {
    if (this.url.scheme !== "file") {
      this.url.username = this.base.username;
      this.url.password = this.base.password;
      this.url.host = this.base.host;
      this.url.port = this.base.port;
    }
    this.state = STATES.PATH;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.SPECIAL_AUTHORITY_SLASHES] =
    function parseSpecialAuthoritySlashes(c, c_str) {
  if (c_str === "/" && at(this.input, this.pointer + 1) === "/") {
    this.state = STATES.SPECIAL_AUTHORITY_IGNORE_SLASHES;
    ++this.pointer;
  } else {
    this.parse_error = true;
    this.state = STATES.SPECIAL_AUTHORITY_IGNORE_SLASHES;
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.SPECIAL_AUTHORITY_IGNORE_SLASHES] =
    function parseSpecialAuthorityIgnoreSlashes(c, c_str) {
  if (c_str !== "/" && c_str !== "\\") {
    this.state = STATES.AUTHORITY;
    --this.pointer;
  } else {
    this.parse_error = true;
  }
};

URLStateMachine.prototype["parse" + STATES.AUTHORITY] =
    function parseAuthority(c, c_str) {
  if (c_str === "@") {
    this.parse_error = true;
    if (this.at_flag) {
      this.buffer = "%40" + this.buffer;
    }
    this.at_flag = true;

    // careful, this is based on buffer and has its own pointer (this.pointer != pointer) and inner chars
    const len = countSymbols(this.buffer);
    for (let pointer = 0; pointer < len; ++pointer) {
      /* jshint -W004 */
      const c = this.buffer.codePointAt(pointer);
      const c_str = String.fromCodePoint(c);
      /* jshint +W004 */

      if (c === 0x9 || c === 0xA || c === 0xD) {
        continue;
      }

      if (c_str === ":" && this.url.password === null) {
        this.url.password = "";
        continue;
      }
      if (this.url.password !== null) {
        this.url.password += passwordEncode(c);
      } else {
        this.url.username += usernameEncode(c);
      }
    }
    this.buffer = "";
  } else if (isNaN(c) || c_str === "/" || c_str === "?" || c_str === "#" ||
             (specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
    this.pointer -= countSymbols(this.buffer) + 1;
    this.buffer = "";
    this.state = STATES.HOST;
  } else {
    this.buffer += c_str;
  }
};

URLStateMachine.prototype["parse" + STATES.HOST_NAME] =
URLStateMachine.prototype["parse" + STATES.HOST] =
    function parseHostName(c, c_str) {
  if (c_str === ":" && !this.arr_flag) {
    if (specialSchemas[this.url.scheme] !== undefined && this.buffer === "") {
      throw new TypeError("Invalid URL");
    }

    let host = parseHost(this.buffer);
    this.url.host = host;
    this.buffer = "";
    this.state = STATES.PORT;
    if (this.state_override === STATES.HOST_NAME) {
      return false;
    }
  } else if (isNaN(c) || c_str === "/" || c_str === "?" || c_str === "#" ||
             (specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
    --this.pointer;
    if (specialSchemas[this.url.scheme] !== undefined && this.buffer === "") {
      throw new TypeError("Invalid URL");
    }

    let host = parseHost(this.buffer);
    this.url.host = host;
    this.buffer = "";
    this.state = STATES.PATH_START;
    if (this.state_override) {
      return false;
    }
  } else if (c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    if (c_str === "[") {
      this.arr_flag = true;
    } else if (c_str === "]") {
      this.arr_flag = false;
    }
    this.buffer += c_str;
  }
};

URLStateMachine.prototype["parse" + STATES.FILE_HOST] =
    function parseFileHost(c, c_str) {
  if (isNaN(c) || c_str === "/" || c_str === "\\" || c_str === "?" || c_str === "#") {
    --this.pointer;
    // don't need to count symbols here since we check ASCII values
    if (this.buffer.length === 2 &&
      isASCIIAlpha(this.buffer.codePointAt(0)) && (this.buffer[1] === ":" || this.buffer[1] === "|")) {
      this.state = STATES.PATH;
    } else if (this.buffer === "") {
      this.state = STATES.PATH_START;
    } else {
      let host = parseHost(this.buffer);
      this.url.host = host;
      this.buffer = "";
      this.state = STATES.PATH_START;
    }
  } else if (c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    this.buffer += c_str;
  }
};

URLStateMachine.prototype["parse" + STATES.PORT] =
    function parsePort(c, c_str) {
  if (isASCIIDigit(c)) {
    this.buffer += c_str;
  } else if (isNaN(c) || c_str === "/" || c_str === "?" || c_str === "#" ||
             (specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
    while (this.buffer[0] === "0" && this.buffer.length > 1) {
      this.buffer = this.buffer.substr(1);
    }
    if (this.buffer === specialSchemas[this.url.scheme]) {
      this.buffer = "";
    }
    this.url.port = this.buffer;
    if (this.state_override) {
      return false;
    }
    this.buffer = "";
    this.state = STATES.PATH_START;
    --this.pointer;
  } else if (c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    this.parse_error = true;
    throw new TypeError("Invalid URL");
  }
};

URLStateMachine.prototype["parse" + STATES.PATH_START] =
    function parsePathStart(c, c_str) {
  if (specialSchemas[this.url.scheme] !== undefined && c_str === "\\") {
    this.parse_error = true;
  }
  this.state = STATES.PATH;
  if (c_str !== "/" && !(specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
    --this.pointer;
  }
};

URLStateMachine.prototype["parse" + STATES.PATH] =
    function parsePath(c, c_str) {
  if (isNaN(c) || c_str === "/" || (specialSchemas[this.url.scheme] !== undefined && c_str === "\\") ||
      (!this.state_override && (c_str === "?" || c_str === "#"))) {
    if (specialSchemas[this.url.scheme] !== undefined && c_str === "\\") {
      this.parse_error = true;
    }

    this.buffer = bufferReplacement[this.buffer.toLowerCase()] || this.buffer;
    if (this.buffer === "..") {
      this.url.path.pop();
      if (c_str !== "/" && !(specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
        this.url.path.push("");
      }
    } else if (this.buffer === "." && c_str !== "/" &&
               !(specialSchemas[this.url.scheme] !== undefined && c_str === "\\")) {
      this.url.path.push("");
    } else if (this.buffer !== ".") {
      if (this.url.scheme === "file" && this.url.path.length === 0 &&
        this.buffer.length === 2 && isASCIIAlpha(this.buffer.codePointAt(0)) && this.buffer[1] === "|") {
        this.buffer = this.buffer[0] + ":";
      }
      this.url.path.push(this.buffer);
    }
    this.buffer = "";
    if (c_str === "?") {
      this.url.query = "";
      this.state = STATES.QUERY;
    }
    if (c_str === "#") {
      this.url.fragment = "";
      this.state = STATES.FRAGMENT;
    }
  } else if (c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    //TODO:If c is not a URL code point and not "%", parse error.
    if (c_str === "%" &&
      (!isASCIIHex(at(this.input, this.pointer + 1)) ||
        !isASCIIHex(at(this.input, this.pointer + 2)))) {
      this.parse_error = true;
    }

    this.buffer += defaultEncode(c);
  }
};

URLStateMachine.prototype["parse" + STATES.NON_RELATIVE_PATH] =
    function parseNonRelativePath(c, c_str) {
  if (c_str === "?") {
    this.url.query = "";
    this.state = STATES.QUERY;
  } else if (c_str === "#") {
    this.url.fragment = "";
    this.state = STATES.FRAGMENT;
  } else {
    // TODO: Add: not a URL code point
    if (!isNaN(c) && c_str !== "%") {
      this.parse_error = true;
    }

    if (c_str === "%" &&
        (!isASCIIHex(at(this.input, this.pointer + 1)) ||
         !isASCIIHex(at(this.input, this.pointer + 2)))) {
      this.parse_error = true;
    }

    if (!isNaN(c) && c !== 0x9 && c !== 0xA && c !== 0xD) {
      this.url.path[0] = this.url.path[0] + simpleEncode(c);
    }
  }
};

URLStateMachine.prototype["parse" + STATES.QUERY] =
    function parseQuery(c, c_str) {
  if (isNaN(c) || (!this.state_override && c_str === "#")) {
    if (specialSchemas[this.url.scheme] === undefined || this.url.scheme === "ws" || this.url.scheme === "wss") {
      this.encoding_override = "utf-8";
    }

    const buffer = new Buffer(this.buffer); //TODO: Use encoding override instead
    for (let i = 0; i < buffer.length; ++i) {
      if (buffer[i] < 0x21 || buffer[i] > 0x7E || buffer[i] === 0x22 || buffer[i] === 0x23 ||
          buffer[i] === 0x3C || buffer[i] === 0x3E) {
        this.url.query += percentEncode(buffer[i]);
      } else {
        this.url.query += String.fromCodePoint(buffer[i]);
      }
    }

    this.buffer = "";
    if (c_str === "#") {
      this.url.fragment = "";
      this.state = STATES.FRAGMENT;
    }
  } else if (c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    //TODO: If c is not a URL code point and not "%", parse error.
    if (c_str === "%" &&
      (!isASCIIHex(at(this.input, this.pointer + 1)) ||
        !isASCIIHex(at(this.input, this.pointer + 2)))) {
      this.parse_error = true;
    }

    this.buffer += c_str;
  }
};

URLStateMachine.prototype["parse" + STATES.FRAGMENT] =
    function parseFragment(c, c_str) {
  if (isNaN(c)) { // do nothing
  } else if (c === 0x0 || c === 0x9 || c === 0xA || c === 0xD) {
    this.parse_error = true;
  } else {
    //TODO: If c is not a URL code point and not "%", parse error.
    if (c_str === "%" &&
      (!isASCIIHex(at(this.input, this.pointer + 1)) ||
        !isASCIIHex(at(this.input, this.pointer + 2)))) {
      this.parse_error = true;
    }

    this.url.fragment += c_str;
  }
};

function serializeURL(url, excludeFragment) {
  let output = url.scheme + ":";
  if (url.host !== null) {
    output += "//" + url.username;
    if (url.password !== null) {
      output += ":" + url.password;
    }
    if (url.username !== "" || url.password !== null) {
      output += "@";
    }
    output += serializeHost(url.host);
    if (url.port !== "") {
      output += ":" + url.port;
    }
  }

  if (url.scheme === "file" && url.host === null) {
    output += "//";
  }

  if (url.nonRelative) {
    output += url.path[0];
  } else {
    output += "/" + url.path.join("/");
  }

  if (url.query !== null) {
    output += "?" + url.query;
  }

  if (!excludeFragment && url.fragment !== null) {
    output += "#" + url.fragment;
  }

  return output;
}

function serializeOrigin(tuple) {
  if (tuple.scheme === undefined || tuple.host === undefined || tuple.port === undefined) {
    return "null";
  }

  let result = tuple.scheme + "://";
  result += tr46.toUnicode(tuple.host, false).domain;

  if (specialSchemas[tuple.scheme] && tuple.port !== specialSchemas[tuple.scheme]) {
    result += ":" + tuple.port;
  }

  return result;
}

function mixin(src, target) {
  const props = Object.getOwnPropertyNames(src);
  const descriptors = {};

  for (let i = 0; i < props.length; ++i) {
    descriptors[props[i]] = Object.getOwnPropertyDescriptor(src, props[i]);
  }

  Object.defineProperties(target, descriptors);

  const symbols = Object.getOwnPropertySymbols(src);
  for (var i = 0; i < symbols.length; ++i) {
    target[symbols[i]] = src[symbols[i]];
  }
}

const inputSymbol = Symbol("input");
const encodingSymbol = Symbol("queryEncoding");
const querySymbol = Symbol("queryObject");
const urlSymbol = Symbol("url");

const baseSymbol = Symbol("base");
const isURLSymbol = Symbol("isURL");
const updateStepsSymbol = Symbol("updateSteps");

function setTheInput(obj, input, url) {
  if (url) {
    obj[urlSymbol] = url;
    obj[inputSymbol] = input;
  } else {
    obj[urlSymbol] = null;
    if (input === null) {
      obj[inputSymbol] = "";
    } else {
      obj[inputSymbol] = input;

      try {
        if (typeof obj[baseSymbol] === "function") {
          obj[urlSymbol] = new URLStateMachine(input, new URLStateMachine(obj[baseSymbol]()).url);
        } else {
          obj[urlSymbol] = new URLStateMachine(input, obj[baseSymbol]);
        }
      } catch (e) {}
    }
  }

  const query = obj[urlSymbol] !== null && obj[urlSymbol].url.query !== null ? obj[urlSymbol].url.query : "";
  // TODO: Update URLSearchParams
}

const URLUtils = {
  get href() {
    if (this[urlSymbol] === null) {
      return this[inputSymbol];
    }

    return serializeURL(this[urlSymbol].url);
  },
  set href(val) {
    let input = String(val);

    if (this[isURLSymbol]) {
      // SPEC: says to use "get the base" algorithm,
      // but the base might've already been provided by the constructor.
      // Clarify!
      // Can't set base symbol to function in URL constructor, so don't need to check this
      const parsedURL = new URLStateMachine(input, this[baseSymbol]);
      input = "";
      setTheInput(this, "", parsedURL);
    } else {
      setTheInput(this, input);
      preUpdateSteps(this, input);
    }
  },

  get origin() {
    if (this[urlSymbol] === null) {
      return "";
    }

    const url = this[urlSymbol].url;
    switch (url.scheme) {
      case "blob":
        try {
          return module.exports.createURLConstructor()(url.scheme_data).origin;
        } catch (e) {
          // serializing an opaque identifier returns "null"
          return "null";
        }
        break;
      case "ftp":
      case "gopher":
      case "http":
      case "https":
      case "ws":
      case "wss":
        return serializeOrigin({
          scheme: url.scheme,
          host: serializeHost(url.host),
          port: url.port === "" ? specialSchemas[url.scheme] : url.port
        });
      case "file":
        // spec says "exercise to the reader", chrome says "file://"
        return "file://";
      default:
        // serializing an opaque identifier returns "null"
        return "null";
    }
  },

  get protocol() {
    if (this[urlSymbol] === null) {
      return ":";
    }
    return this[urlSymbol].url.scheme + ":";
  },
  set protocol(val) {
    if (this[urlSymbol] === null) {
      return;
    }
    this[urlSymbol] = new URLStateMachine(val + ":", null, null, this[urlSymbol].url, STATES.SCHEME_START);
    preUpdateSteps(this);
  },

  get username() {
    return this[urlSymbol] === null ? "" : this[urlSymbol].url.username;
  },
  set username(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.host === null || this[urlSymbol].url.nonRelative) {
      return;
    }

    this[urlSymbol].url.username = "";
    const decoded = punycode.ucs2.decode(val);
    for (let i = 0; i < decoded.length; ++i) {
      this[urlSymbol].url.username += usernameEncode(decoded[i]);
    }
    preUpdateSteps(this);
  },

  get password() {
    return this[urlSymbol] === null || this[urlSymbol].url.password === null ? "" : this[urlSymbol].url.password;
  },
  set password(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.host === null || this[urlSymbol].url.nonRelative) {
      return;
    }

    this[urlSymbol].url.password = "";
    const decoded = punycode.ucs2.decode(val);
    for (let i = 0; i < decoded.length; ++i) {
      this[urlSymbol].url.password += passwordEncode(decoded[i]);
    }
    preUpdateSteps(this);
  },

  get host() {
    if (this[urlSymbol] === null || this[urlSymbol].url.host === null) {
      return "";
    }
    return serializeHost(this[urlSymbol].url.host) +
           (this[urlSymbol].url.port === "" ? "" : ":" + this[urlSymbol].url.port);
  },
  set host(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.nonRelative) {
      return;
    }
    this[urlSymbol] = new URLStateMachine(val, null, null, this[urlSymbol].url, STATES.HOST);
    preUpdateSteps(this);
  },

  get hostname() {
    if (this[urlSymbol] === null || this[urlSymbol].url.host === null) {
      return "";
    }
    return serializeHost(this[urlSymbol].url.host);
  },
  set hostname(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.nonRelative) {
      return;
    }
    this[urlSymbol] = new URLStateMachine(val, null, null, this[urlSymbol].url, STATES.HOST_NAME);
    preUpdateSteps(this);
  },

  get port() {
    if (this[urlSymbol] === null) {
      return "";
    }
    return this[urlSymbol].url.port;
  },
  set port(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.nonRelative || this[urlSymbol].url.scheme === "file") {
      return;
    }
    this[urlSymbol] = new URLStateMachine(val, null, null, this[urlSymbol].url, STATES.PORT);
    preUpdateSteps(this);
  },

  get pathname() {
    if (this[urlSymbol] === null) {
      return "";
    }
    if (this[urlSymbol].url.nonRelative) {
      return this[urlSymbol].url.path[0];
    }

    return "/" + this[urlSymbol].url.path.join("/");
  },
  set pathname(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.nonRelative) {
      return;
    }
    this[urlSymbol].url.path = [];
    this[urlSymbol] = new URLStateMachine(val, null, null, this[urlSymbol].url, STATES.PATH_START);
    preUpdateSteps(this);
  },

  get search() {
    if (this[urlSymbol] === null || !this[urlSymbol].url.query) {
      return "";
    }

    return "?" + this[urlSymbol].url.query;
  },
  set search(val) {
    if (this[urlSymbol] === null) {
      return;
    }
    if (val === "") {
      this[urlSymbol].url.query = null;
      // TODO: empty query object
      preUpdateSteps(this);
      return;
    }

    const input = val[0] === "?" ? val.substr(1) : val;
    this[urlSymbol].url.query = "";

    // TODO: Add query encoding
    this[urlSymbol] = new URLStateMachine(input, null, null, this[urlSymbol].url, STATES.QUERY);

    // TODO: Update query object
    // Since the query object isn't implemented, call updateSteps manually for now
    preUpdateSteps(this);
  },

  get hash() {
    if (this[urlSymbol] === null || !this[urlSymbol].url.fragment) {
      return "";
    }

    return "#" + this[urlSymbol].url.fragment;
  },
  set hash(val) {
    if (this[urlSymbol] === null || this[urlSymbol].url.scheme === "javascript") {
      return;
    }
    if (val === "") {
      this[urlSymbol].url.fragment = null;
      preUpdateSteps(this);
      return;
    }

    const input = val[0] === "#" ? val.substr(1) : val;
    this[urlSymbol].url.fragment = "";
    this[urlSymbol] = new URLStateMachine(input, null, null, this[urlSymbol].url, STATES.FRAGMENT);
    preUpdateSteps(this);
  },

  toString() {
    return this.href;
  }
};

function urlToASCII(domain) {
  try {
    const asciiDomain = parseHost(domain);
    return asciiDomain;
  } catch (e) {
    return "";
  }
}

function urlToUnicode(domain) {
  try {
    const unicodeDomain = parseHost(domain, true);
    return unicodeDomain;
  } catch (e) {
    return "";
  }
}

function init(url, base) {
  /*jshint validthis:true */
  if (this === undefined) {
    throw new TypeError("Failed to construct 'URL': Please use the 'new' operator, " +
      "this DOM object constructor cannot be called as a function.");
  }
  if (arguments.length === 0) {
    throw new TypeError("Failed to construct 'URL': 1 argument required, but only 0 present.");
  }

  let parsedBase = null;
  if (base) {
    parsedBase = new URLStateMachine(base);
    this[baseSymbol] = parsedBase.url;
  }

  const parsedURL = new URLStateMachine(url, parsedBase ? parsedBase.url : undefined);
  setTheInput(this, "", parsedURL);
}

function preUpdateSteps(obj, value) {
  if (value === undefined) {
    value = serializeURL(obj[urlSymbol].url);
  }

  obj[updateStepsSymbol].call(obj, value);
}

module.exports.createURLConstructor = function () {
  function URL() {
    this[isURLSymbol] = true;
    this[updateStepsSymbol] = function () {};
    init.apply(this, arguments);
  }

  mixin(URLUtils, URL.prototype);
  URL.toASCII = urlToASCII;
  URL.toUnicode = urlToUnicode;

  return URL;
};

module.exports.mixinURLUtils = function (obj, base, updateSteps) {
  obj[isURLSymbol] = false;
  if (typeof base === "function") {
    obj[baseSymbol] = base;
  } else {
    obj[baseSymbol] = new URLStateMachine(base).url;
  }
  obj[updateStepsSymbol] = updateSteps || function () {};

  setTheInput(obj, null, null);

  mixin(URLUtils, obj);
};

module.exports.setTheInput = function (obj, input) {
  setTheInput(obj, input, null);
};

module.exports.reparse = function (obj) {
  setTheInput(obj, obj[inputSymbol]);
};