var objectKeys = require('object-keys');
var isArguments = require('is-arguments');
var is = require('object-is');
var isRegex = require('is-regex');
var flags = require('regexp.prototype.flags');
var isArray = require('isarray');
var isDate = require('is-date-object');
var whichBoxedPrimitive = require('which-boxed-primitive');
var GetIntrinsic = require('es-abstract/GetIntrinsic');
var callBound = require('es-abstract/helpers/callBound');
var whichCollection = require('which-collection');
var getIterator = require('es-get-iterator');
var getSideChannel = require('side-channel');

var $getTime = callBound('Date.prototype.getTime');
var gPO = Object.getPrototypeOf;
var $objToString = callBound('Object.prototype.toString');

var $Set = GetIntrinsic('%Set%', true);
var $mapHas = callBound('Map.prototype.has', true);
var $mapGet = callBound('Map.prototype.get', true);
var $mapSize = callBound('Map.prototype.size', true);
var $setAdd = callBound('Set.prototype.add', true);
var $setDelete = callBound('Set.prototype.delete', true);
var $setHas = callBound('Set.prototype.has', true);
var $setSize = callBound('Set.prototype.size', true);

// taken from https://github.com/browserify/commonjs-assert/blob/bba838e9ba9e28edf3127ce6974624208502f6bc/internal/util/comparisons.js#L401-L414
function setHasEqualElement(set, val1, strict, channel) {
  var i = getIterator(set);
  var result;
  while ((result = i.next()) && !result.done) {
    if (internalDeepEqual(val1, result.value, strict, channel)) { // eslint-disable-line no-use-before-define
      // Remove the matching element to make sure we do not check that again.
      $setDelete(set, result.value);
      return true;
    }
  }

  return false;
}

// taken from https://github.com/browserify/commonjs-assert/blob/bba838e9ba9e28edf3127ce6974624208502f6bc/internal/util/comparisons.js#L416-L439
function findLooseMatchingPrimitives(prim) {
  if (typeof prim === 'undefined') {
    return null;
  }
  if (typeof prim === 'object') { // Only pass in null as object!
    return void 0;
  }
  if (typeof prim === 'symbol') {
    return false;
  }
  if (typeof prim === 'string' || typeof prim === 'number') {
    // Loose equal entries exist only if the string is possible to convert to a regular number and not NaN.
    return +prim === +prim; // eslint-disable-line no-implicit-coercion
  }
  return true;
}

// taken from https://github.com/browserify/commonjs-assert/blob/bba838e9ba9e28edf3127ce6974624208502f6bc/internal/util/comparisons.js#L449-L460
function mapMightHaveLoosePrim(a, b, prim, item, channel) {
  var altValue = findLooseMatchingPrimitives(prim);
  if (altValue != null) {
    return altValue;
  }
  var curB = $mapGet(b, altValue);
  // eslint-disable-next-line no-use-before-define
  if ((typeof curB === 'undefined' && !$mapHas(b, altValue)) || !internalDeepEqual(item, curB, false, channel)) {
    return false;
  }
  // eslint-disable-next-line no-use-before-define
  return !$mapHas(a, altValue) && internalDeepEqual(item, curB, false, channel);
}

// taken from https://github.com/browserify/commonjs-assert/blob/bba838e9ba9e28edf3127ce6974624208502f6bc/internal/util/comparisons.js#L441-L447
function setMightHaveLoosePrim(a, b, prim) {
  var altValue = findLooseMatchingPrimitives(prim);
  if (altValue != null) {
    return altValue;
  }

  return $setHas(b, altValue) && !$setHas(a, altValue);
}

// taken from https://github.com/browserify/commonjs-assert/blob/bba838e9ba9e28edf3127ce6974624208502f6bc/internal/util/comparisons.js#L518-L533
function mapHasEqualEntry(set, map, key1, item1, strict, channel) {
  var i = getIterator(set);
  var result;
  var key2;
  while ((result = i.next()) && !result.done) {
    key2 = result.value;
    if (
      // eslint-disable-next-line no-use-before-define
      internalDeepEqual(key1, key2, strict, channel)
      // eslint-disable-next-line no-use-before-define
      && internalDeepEqual(item1, $mapGet(map, key2), strict, channel)
    ) {
      $setDelete(set, key2);
      return true;
    }
  }

  return false;
}

function internalDeepEqual(actual, expected, options, channel) {
  var opts = options || {};

  // 7.1. All identical values are equivalent, as determined by ===.
  if (opts.strict ? is(actual, expected) : actual === expected) {
    return true;
  }

  var actualBoxed = whichBoxedPrimitive(actual);
  var expectedBoxed = whichBoxedPrimitive(expected);
  if (actualBoxed !== expectedBoxed) {
    return false;
  }

  // 7.3. Other pairs that do not both pass typeof value == 'object', equivalence is determined by ==.
  if (!actual || !expected || (typeof actual !== 'object' && typeof expected !== 'object')) {
    if ((actual === false && expected) || (actual && expected === false)) { return false; }
    return opts.strict ? is(actual, expected) : actual == expected; // eslint-disable-line eqeqeq
  }

  /*
   * 7.4. For all other Object pairs, including Array objects, equivalence is
   * determined by having the same number of owned properties (as verified
   * with Object.prototype.hasOwnProperty.call), the same set of keys
   * (although not necessarily the same order), equivalent values for every
   * corresponding key, and an identical 'prototype' property. Note: this
   * accounts for both named and indexed properties on Arrays.
   */
  // see https://github.com/nodejs/node/commit/d3aafd02efd3a403d646a3044adcf14e63a88d32 for memos/channel inspiration

  var hasActual = channel.has(actual);
  var hasExpected = channel.has(expected);
  var sentinel;
  if (hasActual && hasExpected) {
    if (channel.get(actual) === channel.get(expected)) {
      return true;
    }
  } else {
    sentinel = {};
  }
  if (!hasActual) { channel.set(actual, sentinel); }
  if (!hasExpected) { channel.set(expected, sentinel); }

  // eslint-disable-next-line no-use-before-define
  return objEquiv(actual, expected, opts, channel);
}

function isBuffer(x) {
  if (!x || typeof x !== 'object' || typeof x.length !== 'number') {
    return false;
  }
  if (typeof x.copy !== 'function' || typeof x.slice !== 'function') {
    return false;
  }
  if (x.length > 0 && typeof x[0] !== 'number') {
    return false;
  }
  return true;
}

function setEquiv(a, b, opts, channel) {
  if ($setSize(a) !== $setSize(b)) {
    return false;
  }
  var iA = getIterator(a);
  var iB = getIterator(b);
  var resultA;
  var resultB;
  var set;
  while ((resultA = iA.next()) && !resultA.done) {
    if (resultA.value && typeof resultA.value === 'object') {
      if (!set) { set = new $Set(); }
      $setAdd(set, resultA.value);
    } else if (!$setHas(b, resultA.value)) {
      if (opts.strict) { return false; }
      if (!setMightHaveLoosePrim(a, b, resultA.value)) {
        return false;
      }
      if (!set) { set = new $Set(); }
      $setAdd(set, resultA.value);
    }
  }
  if (set) {
    while ((resultB = iB.next()) && !resultB.done) {
      // We have to check if a primitive value is already matching and only if it's not, go hunting for it.
      if (resultB.value && typeof resultB.value === 'object') {
        if (!setHasEqualElement(set, resultB.value, opts.strict, channel)) {
          return false;
        }
      } else if (
        !opts.strict
        && !$setHas(a, resultB.value)
        && !setHasEqualElement(set, resultB.value, opts.strict, channel)
      ) {
        return false;
      }
    }
    return $setSize(set) === 0;
  }
  return true;
}

function mapEquiv(a, b, opts, channel) {
  if ($mapSize(a) !== $mapSize(b)) {
    return false;
  }
  var iA = getIterator(a);
  var iB = getIterator(b);
  var resultA;
  var resultB;
  var set;
  var key;
  var item1;
  var item2;
  while ((resultA = iA.next()) && !resultA.done) {
    key = resultA.value[0];
    item1 = resultA.value[1];
    if (key && typeof key === 'object') {
      if (!set) { set = new $Set(); }
      $setAdd(set, key);
    } else {
      item2 = $mapGet(b, key);
      // if (typeof curB === 'undefined' && !$mapHas(b, altValue) || !internalDeepEqual(item, curB, false, channel)) {
      if ((typeof item2 === 'undefined' && !$mapHas(b, key)) || !internalDeepEqual(item1, item2, opts.strict, channel)) {
        if (opts.strict) {
          return false;
        }
        if (!mapMightHaveLoosePrim(a, b, key, item1, channel)) {
          return false;
        }
        if (!set) { set = new $Set(); }
        $setAdd(set, key);
      }
    }
  }

  if (set) {
    while ((resultB = iB.next()) && !resultB.done) {
      key = resultB.value[0];
      item1 = resultB.value[1];
      if (key && typeof key === 'object') {
        if (!mapHasEqualEntry(set, a, key, item1, opts.strict, channel)) {
          return false;
        }
      } else if (
        !opts.strict
        && (!a.has(key) || !internalDeepEqual($mapGet(a, key), item1, false, channel))
        && !mapHasEqualEntry(set, a, key, item1, false, channel)
      ) {
        return false;
      }
    }
    return $setSize(set) === 0;
  }
  return true;
}

function objEquiv(a, b, opts, channel) {
  /* eslint max-statements: [2, 100], max-lines-per-function: [2, 120], max-depth: [2, 5] */
  var i, key;

  if (typeof a !== typeof b) { return false; }
  if (a == null || b == null) { return false; }

  // an identical 'prototype' property.
  if (a.prototype !== b.prototype) { return false; }

  if ($objToString(a) !== $objToString(b)) { return false; }

  if (isArguments(a) !== isArguments(b)) { return false; }

  var aIsArray = isArray(a);
  var bIsArray = isArray(b);
  if (aIsArray !== bIsArray) { return false; }

  // TODO: replace when a cross-realm brand check is available
  var aIsError = a instanceof Error;
  var bIsError = b instanceof Error;
  if (aIsError !== bIsError) { return false; }
  if (aIsError || bIsError) {
    if (a.name !== b.name || a.message !== b.message) { return false; }
  }

  var aIsRegex = isRegex(a);
  var bIsRegex = isRegex(b);
  if (aIsRegex !== bIsRegex) { return false; }
  if ((aIsRegex || bIsRegex) && (a.source !== b.source || flags(a) !== flags(b))) {
    return false;
  }

  var aIsDate = isDate(a);
  var bIsDate = isDate(b);
  if (aIsDate !== bIsDate) { return false; }
  if (aIsDate || bIsDate) { // && would work too, because both are true or both false here
    if ($getTime(a) !== $getTime(b)) { return false; }
  }
  if (opts.strict && gPO && gPO(a) !== gPO(b)) { return false; }

  var aIsBuffer = isBuffer(a);
  var bIsBuffer = isBuffer(b);
  if (aIsBuffer !== bIsBuffer) { return false; }
  if (aIsBuffer || bIsBuffer) { // && would work too, because both are true or both false here
    if (a.length !== b.length) { return false; }
    for (i = 0; i < a.length; i++) {
      if (a[i] !== b[i]) { return false; }
    }
    return true;
  }

  if (typeof a !== typeof b) { return false; }

  try {
    var ka = objectKeys(a);
    var kb = objectKeys(b);
  } catch (e) { // happens when one is a string literal and the other isn't
    return false;
  }
  // having the same number of owned properties (keys incorporates hasOwnProperty)
  if (ka.length !== kb.length) { return false; }

  // the same set of keys (although not necessarily the same order),
  ka.sort();
  kb.sort();
  // ~~~cheap key test
  for (i = ka.length - 1; i >= 0; i--) {
    if (ka[i] != kb[i]) { return false; } // eslint-disable-line eqeqeq
  }

  // equivalent values for every corresponding key, and ~~~possibly expensive deep test
  for (i = ka.length - 1; i >= 0; i--) {
    key = ka[i];
    if (!internalDeepEqual(a[key], b[key], opts, channel)) { return false; }
  }

  var aCollection = whichCollection(a);
  var bCollection = whichCollection(b);
  if (aCollection !== bCollection) {
    return false;
  }
  if (aCollection === 'Set' || bCollection === 'Set') { // aCollection === bCollection
    return setEquiv(a, b, opts, channel);
  }
  if (aCollection === 'Map') { // aCollection === bCollection
    return mapEquiv(a, b, opts, channel);
  }

  return true;
}

module.exports = function deepEqual(a, b, opts) {
  return internalDeepEqual(a, b, opts, getSideChannel());
};