/*

 * Copyright (c) 2020-2023, Linus Groh <linusg@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <AK/Math/Exponentials.h>

#include <LibJS/Runtime/AbstractOperations.h>

#include <LibJS/Runtime/BigInt.h>

#include <LibJS/Runtime/Error.h>

#include <LibJS/Runtime/GlobalObject.h>

#include <LibJS/Runtime/NumberConstructor.h>

#include <LibJS/Runtime/NumberObject.h>

#include <LibJS/Runtime/ValueInlines.h>

#if defined(AK_COMPILER_CLANG)

#    define EPSILON_VALUE AK::exp2(-52.)

#    define MAX_SAFE_INTEGER_VALUE AK::exp2(53.) - 1

#    define MIN_SAFE_INTEGER_VALUE -(AK::exp2(53.) - 1)

#else

constexpr double const EPSILON_VALUE { __builtin_exp2(-52) };

constexpr double const MAX_SAFE_INTEGER_VALUE { __builtin_exp2(53) - 1 };

constexpr double const MIN_SAFE_INTEGER_VALUE { -(__builtin_exp2(53) - 1) };

#endif

namespace JS {

JS_DEFINE_ALLOCATOR(NumberConstructor);

NumberConstructor::NumberConstructor(Realm& realm)

    : NativeFunction(realm.vm().names.Number.as_string(), realm.intrinsics().function_prototype())

{

}

void NumberConstructor::initialize(Realm& realm)

{

    auto& vm = this->vm();

    Base::initialize(realm);

    // 21.1.2.15 Number.prototype, https://tc39.es/ecma262/#sec-number.prototype

    define_direct_property(vm.names.prototype, realm.intrinsics().number_prototype(), 0);

    u8 attr = Attribute::Writable | Attribute::Configurable;

    define_native_function(realm, vm.names.isFinite, is_finite, 1, attr);

    define_native_function(realm, vm.names.isInteger, is_integer, 1, attr);

    define_native_function(realm, vm.names.isNaN, is_nan, 1, attr);

    define_native_function(realm, vm.names.isSafeInteger, is_safe_integer, 1, attr);

    define_direct_property(vm.names.parseInt, realm.intrinsics().parse_int_function(), attr);

    define_direct_property(vm.names.parseFloat, realm.intrinsics().parse_float_function(), attr);

    define_direct_property(vm.names.EPSILON, Value(EPSILON_VALUE), 0);

    define_direct_property(vm.names.MAX_VALUE, Value(NumericLimits<double>::max()), 0);

    define_direct_property(vm.names.MIN_VALUE, Value(NumericLimits<double>::min_denormal()), 0);

    define_direct_property(vm.names.MAX_SAFE_INTEGER, Value(MAX_SAFE_INTEGER_VALUE), 0);

    define_direct_property(vm.names.MIN_SAFE_INTEGER, Value(MIN_SAFE_INTEGER_VALUE), 0);

    define_direct_property(vm.names.NEGATIVE_INFINITY, js_negative_infinity(), 0);

    define_direct_property(vm.names.POSITIVE_INFINITY, js_infinity(), 0);

    define_direct_property(vm.names.NaN, js_nan(), 0);

    define_direct_property(vm.names.length, Value(1), Attribute::Configurable);

}

// Most of 21.1.1.1 Number ( value ) factored into a separate function for sharing between call() and construct().

static ThrowCompletionOr<Value> get_value_from_constructor_argument(VM& vm)

{

    Value number;

    // 1. If value is present, then

    if (vm.argument_count() > 0) {

        // a. Let prim be ? ToNumeric(value).

        auto primitive = TRY(vm.argument(0).to_numeric(vm));

        // b. If Type(prim) is BigInt, let n be 𝔽(ℝ(prim)).

        if (primitive.is_bigint()) {

            number = Value(primitive.as_bigint().big_integer().to_double(Crypto::UnsignedBigInteger::RoundingMode::ECMAScriptNumberValueFor));

        }

        // c. Otherwise, let n be prim.

        else {

            number = primitive;

        }

    }

    // 2. Else,

    else {

        // a. Let n be +0𝔽.

        number = Value(0);

    }

    return number;

}

// 21.1.1.1 Number ( value ), https://tc39.es/ecma262/#sec-number-constructor-number-value

ThrowCompletionOr<Value> NumberConstructor::call()

{

    // NOTE: get_value_from_constructor_argument performs steps 1 and 2 and returns n.

    // 3. If NewTarget is undefined, return n.

    return get_value_from_constructor_argument(vm());

}

// 21.1.1.1 Number ( value ), https://tc39.es/ecma262/#sec-number-constructor-number-value

ThrowCompletionOr<NonnullGCPtr<Object>> NumberConstructor::construct(FunctionObject& new_target)

{

    auto& vm = this->vm();

    // NOTE: get_value_from_constructor_argument performs steps 1 and 2 and returns n.

    auto number = TRY(get_value_from_constructor_argument(vm));

    // 4. Let O be ? OrdinaryCreateFromConstructor(NewTarget, "%Number.prototype%", « [[NumberData]] »).

    // 5. Set O.[[NumberData]] to n.

    // 6. Return O.

    return TRY(ordinary_create_from_constructor<NumberObject>(vm, new_target, &Intrinsics::number_prototype, number.as_double()));

}

// 21.1.2.2 Number.isFinite ( number ), https://tc39.es/ecma262/#sec-number.isfinite

JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_finite)

{

    auto number = vm.argument(0);

    // 1. If number is not a Number, return false.

    // 2. If number is not finite, return false.

    // 3. Otherwise, return true.

    return Value(number.is_finite_number());

}

// 21.1.2.3 Number.isInteger ( number ), https://tc39.es/ecma262/#sec-number.isinteger

JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_integer)

{

    auto number = vm.argument(0);

    // 1. Return IsIntegralNumber(number).

    return Value(number.is_integral_number());

}

// 21.1.2.4 Number.isNaN ( number ), https://tc39.es/ecma262/#sec-number.isnan

JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_nan)

{

    auto number = vm.argument(0);

    // 1. If number is not a Number, return false.

    // 2. If number is NaN, return true.

    // 3. Otherwise, return false.

    return Value(number.is_nan());

}

// 21.1.2.5 Number.isSafeInteger ( number ), https://tc39.es/ecma262/#sec-number.issafeinteger

JS_DEFINE_NATIVE_FUNCTION(NumberConstructor::is_safe_integer)

{

    auto number = vm.argument(0);

    // 1. If IsIntegralNumber(number) is true, then

    if (number.is_integral_number()) {

        // a. If abs(ℝ(number)) ≤ 2^53 - 1, return true.

        if (fabs(number.as_double()) <= MAX_SAFE_INTEGER_VALUE)

            return Value(true);

    }

    // 2. Return false.

    return Value(false);

}

}