/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "vm/EqualityOperations.h"  // js::LooselyEqual, js::StrictlyEqual, js::SameValue

#include "mozilla/Assertions.h"  // MOZ_ASSERT, MOZ_ASSERT_IF

#include "jstypes.h"  // JS_PUBLIC_API

#include "builtin/Number.h"  // js::StringToNumber
#include "js/Context.h"      // js::AssertHeapIsIdle
#include "js/Equality.h"  // JS::LooselyEqual, JS::StrictlyEqual, JS::SameValue
#include "js/Result.h"    // JS_TRY_VAR_OR_RETURN_FALSE
#include "js/RootingAPI.h"  // JS::Rooted
#include "js/Value.h"       // JS::Int32Value, JS::SameType, JS::Value
#include "vm/BigIntType.h"  // JS::BigInt
#include "vm/ConstantCompareOperand.h"
#include "vm/JSContext.h"   // CHECK_THREAD
#include "vm/JSObject.h"    // js::ToPrimitive
#include "vm/StringType.h"  // js::EqualStrings

#include "builtin/Boolean-inl.h"  // js::EmulatesUndefined
#include "vm/JSContext-inl.h"     // JSContext::check

static bool EqualGivenSameType(JSContext* cx, const JS::Value& lval,
                               const JS::Value& rval, bool* equal) {
  MOZ_ASSERT(JS::SameType(lval, rval));

  if (lval.isString()) {
    return js::EqualStrings(cx, lval.toString(), rval.toString(), equal);
  }

  if (lval.isDouble()) {
    *equal = (lval.toDouble() == rval.toDouble());
    return true;
  }

  if (lval.isBigInt()) {
    *equal = JS::BigInt::equal(lval.toBigInt(), rval.toBigInt());
    return true;
  }

  // Note: we can do a bitwise comparison even for Int32Value because both
  // Values have the same type.
  MOZ_ASSERT(js::CanUseBitwiseCompareForStrictlyEqual(lval) || lval.isInt32());

  *equal = (lval.asRawBits() == rval.asRawBits());
  MOZ_ASSERT_IF(lval.isUndefined() || lval.isNull(), *equal);
  return true;
}

static bool LooselyEqualBooleanAndOther(JSContext* cx,
                                        JS::Handle<JS::Value> lval,
                                        JS::Handle<JS::Value> rval,
                                        bool* result) {
  MOZ_ASSERT(!rval.isBoolean());

  JS::Rooted<JS::Value> lvalue(cx, JS::Int32Value(lval.toBoolean() ? 1 : 0));

  // The tail-call would end up in Step 3.
  if (rval.isNumber()) {
    *result = (lvalue.toNumber() == rval.toNumber());
    return true;
  }
  // The tail-call would end up in Step 6.
  if (rval.isString()) {
    double num;
    if (!StringToNumber(cx, rval.toString(), &num)) {
      return false;
    }
    *result = (lvalue.toNumber() == num);
    return true;
  }

  return js::LooselyEqual(cx, lvalue, rval, result);
}

// ES2026 Draft rev e936549f1c05ac1b206ad4c5817e77ee3ecbc787
//
// IsLooselyEqual ( x, y )
// https://tc39.es/ecma262/#sec-islooselyequal
bool js::LooselyEqual(JSContext* cx, JS::Handle<JS::Value> lval,
                      JS::Handle<JS::Value> rval, bool* result) {
  // Step 1. If SameType(x, y) is true, then
  if (JS::SameType(lval, rval)) {
    // Step 1.a. Return IsStrictlyEqual(x, y).
    return EqualGivenSameType(cx, lval, rval, result);
  }

  // NOTE: JS::SameType distinguishes between Int32 vs Double,
  //       but the spec's SameType doesn't.
  if (lval.isNumber() && rval.isNumber()) {
    *result = (lval.toNumber() == rval.toNumber());
    return true;
  }

  // Step 2. If x is null and y is undefined, return true.
  // Step 3. If x is undefined and y is null, return true.
  // Step 4. Normative Optional
  //         If the host is a web browser or otherwise supports The
  //         [[IsHTMLDDA]] Internal Slot, then
  // Step 4.a. If x is an Object, x has an [[IsHTMLDDA]] internal slot, and y
  //           is either undefined or null, return true.
  // Step 4.b. If x is either undefined or null, y is an Object, and y has an
  //           [[IsHTMLDDA]] internal slot, return true.
  if (lval.isNullOrUndefined()) {
    *result = rval.isNullOrUndefined() ||
              (rval.isObject() && EmulatesUndefined(&rval.toObject()));
    return true;
  }
  if (rval.isNullOrUndefined()) {
    MOZ_ASSERT(!lval.isNullOrUndefined());
    *result = lval.isObject() && EmulatesUndefined(&lval.toObject());
    return true;
  }

  // Step 5. If x is a Number and y is a String, return ! IsLooselyEqual(x, !
  //         ToNumber(y)).
  if (lval.isNumber() && rval.isString()) {
    double num;
    if (!StringToNumber(cx, rval.toString(), &num)) {
      return false;
    }
    *result = (lval.toNumber() == num);
    return true;
  }

  // Step 6. If x is a String and y is a Number, return ! IsLooselyEqual(!
  //         ToNumber(x), y).
  if (lval.isString() && rval.isNumber()) {
    double num;
    if (!StringToNumber(cx, lval.toString(), &num)) {
      return false;
    }
    *result = (num == rval.toNumber());
    return true;
  }

  // Step 7. If x is a BigInt and y is a String, then
  if (lval.isBigInt() && rval.isString()) {
    // Step 7.a. Let n be StringToBigInt(y).
    BigInt* n;
    JS::Rooted<JSString*> str(cx, rval.toString());
    JS_TRY_VAR_OR_RETURN_FALSE(cx, n, StringToBigInt(cx, str));
    if (!n) {
      // Step 7.b. If n is undefined, return false.
      *result = false;
      return true;
    }
    // Step 7.c. Return ! IsLooselyEqual(x, n).
    *result = JS::BigInt::equal(lval.toBigInt(), n);
    return true;
  }

  // Step 8. If x is a String and y is a BigInt, return ! IsLooselyEqual(y,
  //         x).
  if (lval.isString() && rval.isBigInt()) {
    BigInt* n;
    JS::Rooted<JSString*> str(cx, lval.toString());
    JS_TRY_VAR_OR_RETURN_FALSE(cx, n, StringToBigInt(cx, str));
    if (!n) {
      *result = false;
      return true;
    }
    *result = JS::BigInt::equal(rval.toBigInt(), n);
    return true;
  }

  // Step 9. If x is a Boolean, return ! IsLooselyEqual(! ToNumber(x), y).
  if (lval.isBoolean()) {
    return LooselyEqualBooleanAndOther(cx, lval, rval, result);
  }

  // Step 10. If y is a Boolean, return ! IsLooselyEqual(x, ! ToNumber(y)).
  if (rval.isBoolean()) {
    return LooselyEqualBooleanAndOther(cx, rval, lval, result);
  }

  // Step 11. If x is either a String, a Number, a BigInt, or a Symbol and y
  //          is an Object, return ! IsLooselyEqual(x, ? ToPrimitive(y)).
  if ((lval.isString() || lval.isNumber() || lval.isBigInt() ||
       lval.isSymbol()) &&
      rval.isObject()) {
    JS::Rooted<JS::Value> rvalue(cx, rval);
    if (!ToPrimitive(cx, &rvalue)) {
      return false;
    }
    return js::LooselyEqual(cx, lval, rvalue, result);
  }

  // Step 12. If x is an Object and y is either a String, a Number, a BigInt,
  //          or a Symbol, return ! IsLooselyEqual(? ToPrimitive(x), y).
  if (lval.isObject() && (rval.isString() || rval.isNumber() ||
                          rval.isBigInt() || rval.isSymbol())) {
    JS::Rooted<JS::Value> lvalue(cx, lval);
    if (!ToPrimitive(cx, &lvalue)) {
      return false;
    }
    return js::LooselyEqual(cx, lvalue, rval, result);
  }

  // Step 13. If x is a BigInt and y is a Number, or if x is a Number and y
  //          is a BigInt, then
  if (lval.isBigInt() && rval.isNumber()) {
    // Step 13.a. If x is not finite or y is not finite, return false.
    // Step 13.b. If ℝ(x) = ℝ(y), return true; otherwise return false.
    *result = BigInt::equal(lval.toBigInt(), rval.toNumber());
    return true;
  }
  if (lval.isNumber() && rval.isBigInt()) {
    *result = BigInt::equal(rval.toBigInt(), lval.toNumber());
    return true;
  }

  // Step 14. Return false.
  *result = false;
  return true;
}

JS_PUBLIC_API bool JS::LooselyEqual(JSContext* cx, Handle<Value> value1,
                                    Handle<Value> value2, bool* equal) {
  js::AssertHeapIsIdle();
  CHECK_THREAD(cx);
  cx->check(value1, value2);
  MOZ_ASSERT(equal);
  return js::LooselyEqual(cx, value1, value2, equal);
}

bool js::ConstantStrictEqual(const JS::Value& val, uint16_t operand) {
  ConstantCompareOperand constant =
      ConstantCompareOperand::fromRawValue(operand);

  switch (constant.type()) {
    case ConstantCompareOperand::EncodedType::Int32:
      return val.isNumber() && val.toNumber() == double(constant.toInt32());
    case ConstantCompareOperand::EncodedType::Boolean:
      return val == BooleanValue(constant.toBoolean());
    case ConstantCompareOperand::EncodedType::Undefined:
      return val.isUndefined();
    case ConstantCompareOperand::EncodedType::Null:
      return val.isNull();
  }
  MOZ_CRASH("Unknown constant compare operand type");
}

bool js::StrictlyEqual(JSContext* cx, const JS::Value& lval,
                       const JS::Value& rval, bool* equal) {
  if (SameType(lval, rval)) {
    return EqualGivenSameType(cx, lval, rval, equal);
  }

  if (lval.isNumber() && rval.isNumber()) {
    *equal = (lval.toNumber() == rval.toNumber());
    return true;
  }

  *equal = false;
  return true;
}

JS_PUBLIC_API bool JS::StrictlyEqual(JSContext* cx, Handle<Value> value1,
                                     Handle<Value> value2, bool* equal) {
  js::AssertHeapIsIdle();
  CHECK_THREAD(cx);
  cx->check(value1, value2);
  MOZ_ASSERT(equal);
  return js::StrictlyEqual(cx, value1, value2, equal);
}

static inline bool IsNegativeZero(const JS::Value& v) {
  return v.isDouble() && mozilla::IsNegativeZero(v.toDouble());
}

static inline bool IsNaN(const JS::Value& v) {
  return v.isDouble() && std::isnan(v.toDouble());
}

bool js::SameValue(JSContext* cx, const JS::Value& v1, const JS::Value& v2,
                   bool* same) {
  if (IsNegativeZero(v1)) {
    *same = IsNegativeZero(v2);
    return true;
  }

  if (IsNegativeZero(v2)) {
    *same = false;
    return true;
  }

  return js::SameValueZero(cx, v1, v2, same);
}

JS_PUBLIC_API bool JS::SameValue(JSContext* cx, Handle<Value> value1,
                                 Handle<Value> value2, bool* same) {
  js::AssertHeapIsIdle();
  CHECK_THREAD(cx);
  cx->check(value1, value2);
  MOZ_ASSERT(same);
  return js::SameValue(cx, value1, value2, same);
}

bool js::SameValueZero(JSContext* cx, const Value& v1, const Value& v2,
                       bool* same) {
  if (IsNaN(v1) && IsNaN(v2)) {
    *same = true;
    return true;
  }

  return js::StrictlyEqual(cx, v1, v2, same);
}