// Utilities
//
'use strict';


function _class(obj) { return Object.prototype.toString.call(obj); }

function isString(obj) { return _class(obj) === '[object String]'; }

var _hasOwnProperty = Object.prototype.hasOwnProperty;

function has(object, key) {
  return _hasOwnProperty.call(object, key);
}

// Merge objects
//
function assign(obj /*from1, from2, from3, ...*/) {
  var sources = Array.prototype.slice.call(arguments, 1);

  sources.forEach(function (source) {
    if (!source) { return; }

    if (typeof source !== 'object') {
      throw new TypeError(source + 'must be object');
    }

    Object.keys(source).forEach(function (key) {
      obj[key] = source[key];
    });
  });

  return obj;
}

// Remove element from array and put another array at those position.
// Useful for some operations with tokens
function arrayReplaceAt(src, pos, newElements) {
  return [].concat(src.slice(0, pos), newElements, src.slice(pos + 1));
}

////////////////////////////////////////////////////////////////////////////////

var UNESCAPE_MD_RE = /\\([!"#$%&'()*+,\-.\/:;<=>?@[\\\]^_`{|}~])/g;

function unescapeMd(str) {
  if (str.indexOf('\\') < 0) { return str; }
  return str.replace(UNESCAPE_MD_RE, '$1');
}

////////////////////////////////////////////////////////////////////////////////

function isValidEntityCode(c) {
  /*eslint no-bitwise:0*/
  // broken sequence
  if (c >= 0xD800 && c <= 0xDFFF) { return false; }
  // never used
  if (c >= 0xFDD0 && c <= 0xFDEF) { return false; }
  if ((c & 0xFFFF) === 0xFFFF || (c & 0xFFFF) === 0xFFFE) { return false; }
  // control codes
  if (c >= 0x00 && c <= 0x08) { return false; }
  if (c === 0x0B) { return false; }
  if (c >= 0x0E && c <= 0x1F) { return false; }
  if (c >= 0x7F && c <= 0x9F) { return false; }
  // out of range
  if (c > 0x10FFFF) { return false; }
  return true;
}

function fromCodePoint(c) {
  /*eslint no-bitwise:0*/
  if (c > 0xffff) {
    c -= 0x10000;
    var surrogate1 = 0xd800 + (c >> 10),
        surrogate2 = 0xdc00 + (c & 0x3ff);

    return String.fromCharCode(surrogate1, surrogate2);
  }
  return String.fromCharCode(c);
}

var NAMED_ENTITY_RE   = /&([a-z#][a-z0-9]{1,31});/gi;
var DIGITAL_ENTITY_TEST_RE = /^#((?:x[a-f0-9]{1,8}|[0-9]{1,8}))/i;
var entities = require('./entities');

function replaceEntityPattern(match, name) {
  var code = 0;

  if (has(entities, name)) {
    return entities[name];
  } else if (name.charCodeAt(0) === 0x23/* # */ && DIGITAL_ENTITY_TEST_RE.test(name)) {
    code = name[1].toLowerCase() === 'x' ?
      parseInt(name.slice(2), 16)
    :
      parseInt(name.slice(1), 10);
    if (isValidEntityCode(code)) {
      return fromCodePoint(code);
    }
  }
  return match;
}

function replaceEntities(str) {
  if (str.indexOf('&') < 0) { return str; }

  return str.replace(NAMED_ENTITY_RE, replaceEntityPattern);
}

////////////////////////////////////////////////////////////////////////////////

var HTML_ESCAPE_TEST_RE = /[&<>"]/;
var HTML_ESCAPE_REPLACE_RE = /[&<>"]/g;
var HTML_REPLACEMENTS = {
  '&': '&amp;',
  '<': '&lt;',
  '>': '&gt;',
  '"': '&quot;'
};

function replaceUnsafeChar(ch) {
  return HTML_REPLACEMENTS[ch];
}

function escapeHtml(str) {
  if (HTML_ESCAPE_TEST_RE.test(str)) {
    return str.replace(HTML_ESCAPE_REPLACE_RE, replaceUnsafeChar);
  }
  return str;
}

////////////////////////////////////////////////////////////////////////////////

var SURRORATE_TEST_RE   = /[\uD800-\uDFFF]/;
var SURRORATE_SEARCH_RE = /[\uD800-\uDFFF]/g;

function replaceBadSurrogate(ch, pos, orig) {
  var code = ch.charCodeAt(0);

  if (code >= 0xD800 && code <= 0xDBFF) {
    // high surrogate
    if (pos >= orig.length - 1) { return '\uFFFD'; }
    code = orig.charCodeAt(pos + 1);
    if (code < 0xDC00 || code > 0xDFFF) { return '\uFFFD'; }

    return ch;
  }

  // low surrogate
  if (pos === 0) { return '\uFFFD'; }
  code = orig.charCodeAt(pos - 1);
  if (code < 0xD800 || code > 0xDBFF) { return '\uFFFD'; }
  return ch;
}

function fixBrokenSurrogates(str) {
  if (!SURRORATE_TEST_RE.test(str)) { return str; }

  return str.replace(SURRORATE_SEARCH_RE, replaceBadSurrogate);
}

////////////////////////////////////////////////////////////////////////////////


// Incoming link can be partially encoded. Convert possible combinations to
// unified form.
//
// TODO: Rewrite it. Should use:
//
// - encodeURIComponent for query
// - encodeURI for path
// - (?) punicode for domain mame (but encodeURI seems to work in real world)
//
function normalizeLink(url) {
  var normalized = replaceEntities(url);

  // We don't care much about result of mailformed URIs,
  // but shoud not throw exception.
  try {
    normalized = decodeURI(normalized);
  } catch (__) {}

  // Encoder throws exception on broken surrogate pairs.
  // Fix those first.

  try {
    return encodeURI(fixBrokenSurrogates(normalized));
  } catch (__) {
    // This should never happen and left for safety only.
    /*istanbul ignore next*/
    return '';
  }
}

////////////////////////////////////////////////////////////////////////////////

var REGEXP_ESCAPE_RE = /[.?*+^$[\]\\(){}|-]/g;

function escapeRE (str) {
  return str.replace(REGEXP_ESCAPE_RE, '\\$&');
}

////////////////////////////////////////////////////////////////////////////////

// Zs (unicode class) || 09, 0A, 0D, 0C
function isWhiteSpace(code) {
  if (code >= 0x2000 && code <= 0x200A) { return true; }
  switch (code) {
    case 0x09:
    case 0x0A:
    case 0x0D:
    case 0x0C:
    case 0x20:
    case 0xA0:
    case 0x1680:
    case 0x202F:
    case 0x205F:
    case 0x3000:
      return true;
  }
  return false;
}

////////////////////////////////////////////////////////////////////////////////

/*eslint-disable max-len*/
var UNICODE_PUNCT_RE = require('uc.micro/categories/P/regex');

// Currently without astral characters support.
function isPunctChar(char) {
  return UNICODE_PUNCT_RE.test(char);
}


// Markdown ASCII punctuation characters.
//
// !, ", #, $, %, &, ', (, ), *, +, ,, -, ., /, :, ;, <, =, >, ?, @, [, \, ], ^, _, `, {, |, }, or ~
// http://spec.commonmark.org/0.15/#ascii-punctuation-character
//
// Don't confuse with unicode punctuation !!! It lacks some chars in ascii range.
//
function isMdAsciiPunct(ch) {
  switch (ch) {
    case 0x21/* ! */:
    case 0x22/* " */:
    case 0x23/* # */:
    case 0x24/* $ */:
    case 0x25/* % */:
    case 0x26/* & */:
    case 0x27/* ' */:
    case 0x28/* ( */:
    case 0x29/* ) */:
    case 0x2A/* * */:
    case 0x2B/* + */:
    case 0x2C/* , */:
    case 0x2D/* - */:
    case 0x2E/* . */:
    case 0x2F/* / */:
    case 0x3A/* : */:
    case 0x3B/* ; */:
    case 0x3C/* < */:
    case 0x3D/* = */:
    case 0x3E/* > */:
    case 0x3F/* ? */:
    case 0x40/* @ */:
    case 0x5B/* [ */:
    case 0x5C/* \ */:
    case 0x5D/* ] */:
    case 0x5E/* ^ */:
    case 0x5F/* _ */:
    case 0x60/* ` */:
    case 0x7B/* { */:
    case 0x7C/* | */:
    case 0x7D/* } */:
    case 0x7E/* ~ */:
      return true;
    default:
      return false;
  }
}

// Hepler to unify [reference labels].
//
function normalizeReference(str) {
  // use .toUpperCase() instead of .toLowerCase()
  // here to avoid a conflict with Object.prototype
  // members (most notably, `__proto__`)
  return str.trim().replace(/\s+/g, ' ').toUpperCase();
}

////////////////////////////////////////////////////////////////////////////////

exports.assign              = assign;
exports.isString            = isString;
exports.has                 = has;
exports.unescapeMd          = unescapeMd;
exports.isValidEntityCode   = isValidEntityCode;
exports.fromCodePoint       = fromCodePoint;
exports.replaceEntities     = replaceEntities;
exports.escapeHtml          = escapeHtml;
exports.arrayReplaceAt      = arrayReplaceAt;
exports.normalizeLink       = normalizeLink;
exports.isWhiteSpace        = isWhiteSpace;
exports.isMdAsciiPunct      = isMdAsciiPunct;
exports.isPunctChar         = isPunctChar;
exports.escapeRE            = escapeRE;
exports.normalizeReference  = normalizeReference;

// for testing only
exports.fixBrokenSurrogates = fixBrokenSurrogates;