/*
 * Copyright (c) 2021-2023, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibJS/Bytecode/CommonImplementations.h>
#include <LibJS/Bytecode/Interpreter.h>
#include <LibJS/Bytecode/Op.h>
#include <LibJS/Runtime/DeclarativeEnvironment.h>
#include <LibJS/Runtime/ECMAScriptFunctionObject.h>
#include <LibJS/Runtime/GlobalEnvironment.h>
#include <LibJS/Runtime/ObjectEnvironment.h>

namespace JS::Bytecode {

ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(Bytecode::Interpreter& interpreter, Value base_value)
{
    auto& vm = interpreter.vm();
    if (base_value.is_object())
        return base_value.as_object();

    // OPTIMIZATION: For various primitives we can avoid actually creating a new object for them.
    if (base_value.is_string())
        return vm.current_realm()->intrinsics().string_prototype();
    if (base_value.is_number())
        return vm.current_realm()->intrinsics().number_prototype();
    if (base_value.is_boolean())
        return vm.current_realm()->intrinsics().boolean_prototype();

    return base_value.to_object(vm);
}

ThrowCompletionOr<Value> get_by_id(Bytecode::Interpreter& interpreter, IdentifierTableIndex property, Value base_value, Value this_value, u32 cache_index)
{
    auto& vm = interpreter.vm();
    auto const& name = interpreter.current_executable().get_identifier(property);
    auto& cache = interpreter.current_executable().property_lookup_caches[cache_index];

    if (base_value.is_string()) {
        auto string_value = TRY(base_value.as_string().get(vm, name));
        if (string_value.has_value())
            return *string_value;
    }

    auto base_obj = TRY(base_object_for_get(interpreter, base_value));

    // OPTIMIZATION: If the shape of the object hasn't changed, we can use the cached property offset.
    // NOTE: Unique shapes don't change identity, so we compare their serial numbers instead.
    auto& shape = base_obj->shape();
    if (&shape == cache.shape
        && (!shape.is_unique() || shape.unique_shape_serial_number() == cache.unique_shape_serial_number)) {
        return base_obj->get_direct(cache.property_offset.value());
    }

    CacheablePropertyMetadata cacheable_metadata;
    auto value = TRY(base_obj->internal_get(name, this_value, &cacheable_metadata));

    if (cacheable_metadata.type == CacheablePropertyMetadata::Type::OwnProperty) {
        cache.shape = shape;
        cache.property_offset = cacheable_metadata.property_offset.value();
        cache.unique_shape_serial_number = shape.unique_shape_serial_number();
    }

    return value;
}

ThrowCompletionOr<Value> get_by_value(Bytecode::Interpreter& interpreter, Value base_value, Value property_key_value)
{
    auto& vm = interpreter.vm();
    auto object = TRY(base_object_for_get(interpreter, base_value));

    // OPTIMIZATION: Fast path for simple Int32 indexes in array-like objects.
    if (property_key_value.is_int32()
        && property_key_value.as_i32() >= 0
        && !object->may_interfere_with_indexed_property_access()
        && object->indexed_properties().has_index(property_key_value.as_i32())) {
        auto value = object->indexed_properties().get(property_key_value.as_i32())->value;
        if (!value.is_accessor())
            return value;
    }

    auto property_key = TRY(property_key_value.to_property_key(vm));

    if (base_value.is_string()) {
        auto string_value = TRY(base_value.as_string().get(vm, property_key));
        if (string_value.has_value())
            return *string_value;
    }

    return TRY(object->internal_get(property_key, base_value));
}

ThrowCompletionOr<Value> get_global(Bytecode::Interpreter& interpreter, IdentifierTableIndex identifier, u32 cache_index)
{
    auto& vm = interpreter.vm();
    auto& realm = *vm.current_realm();

    auto& cache = interpreter.current_executable().global_variable_caches[cache_index];
    auto& binding_object = realm.global_environment().object_record().binding_object();
    auto& declarative_record = realm.global_environment().declarative_record();

    // OPTIMIZATION: If the shape of the object hasn't changed, we can use the cached property offset.
    // NOTE: Unique shapes don't change identity, so we compare their serial numbers instead.
    auto& shape = binding_object.shape();
    if (cache.environment_serial_number == declarative_record.environment_serial_number()
        && &shape == cache.shape
        && (!shape.is_unique() || shape.unique_shape_serial_number() == cache.unique_shape_serial_number)) {
        return binding_object.get_direct(cache.property_offset.value());
    }

    cache.environment_serial_number = declarative_record.environment_serial_number();

    auto const& name = interpreter.current_executable().get_identifier(identifier);
    if (vm.running_execution_context().script_or_module.has<NonnullGCPtr<Module>>()) {
        // NOTE: GetGlobal is used to access variables stored in the module environment and global environment.
        //       The module environment is checked first since it precedes the global environment in the environment chain.
        auto& module_environment = *vm.running_execution_context().script_or_module.get<NonnullGCPtr<Module>>()->environment();
        if (TRY(module_environment.has_binding(name))) {
            // TODO: Cache offset of binding value
            return TRY(module_environment.get_binding_value(vm, name, vm.in_strict_mode()));
        }
    }

    if (TRY(declarative_record.has_binding(name))) {
        // TODO: Cache offset of binding value
        return TRY(declarative_record.get_binding_value(vm, name, vm.in_strict_mode()));
    }

    if (TRY(binding_object.has_property(name))) {
        CacheablePropertyMetadata cacheable_metadata;
        auto value = TRY(binding_object.internal_get(name, js_undefined(), &cacheable_metadata));
        if (cacheable_metadata.type == CacheablePropertyMetadata::Type::OwnProperty) {
            cache.shape = shape;
            cache.property_offset = cacheable_metadata.property_offset.value();
            cache.unique_shape_serial_number = shape.unique_shape_serial_number();
        }
        return value;
    }

    return vm.throw_completion<ReferenceError>(ErrorType::UnknownIdentifier, name);
}

ThrowCompletionOr<void> put_by_property_key(VM& vm, Value base, Value this_value, Value value, PropertyKey name, Op::PropertyKind kind)
{
    auto object = TRY(base.to_object(vm));
    if (kind == Op::PropertyKind::Getter || kind == Op::PropertyKind::Setter) {
        // The generator should only pass us functions for getters and setters.
        VERIFY(value.is_function());
    }
    switch (kind) {
    case Op::PropertyKind::Getter: {
        auto& function = value.as_function();
        if (function.name().is_empty() && is<ECMAScriptFunctionObject>(function))
            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(DeprecatedString::formatted("get {}", name));
        object->define_direct_accessor(name, &function, nullptr, Attribute::Configurable | Attribute::Enumerable);
        break;
    }
    case Op::PropertyKind::Setter: {
        auto& function = value.as_function();
        if (function.name().is_empty() && is<ECMAScriptFunctionObject>(function))
            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(DeprecatedString::formatted("set {}", name));
        object->define_direct_accessor(name, nullptr, &function, Attribute::Configurable | Attribute::Enumerable);
        break;
    }
    case Op::PropertyKind::KeyValue: {
        bool succeeded = TRY(object->internal_set(name, value, this_value));
        if (!succeeded && vm.in_strict_mode())
            return vm.throw_completion<TypeError>(ErrorType::ReferenceNullishSetProperty, name, base.to_string_without_side_effects());
        break;
    }
    case Op::PropertyKind::DirectKeyValue:
        object->define_direct_property(name, value, Attribute::Enumerable | Attribute::Writable | Attribute::Configurable);
        break;
    case Op::PropertyKind::Spread:
        TRY(object->copy_data_properties(vm, value, {}));
        break;
    case Op::PropertyKind::ProtoSetter:
        if (value.is_object() || value.is_null())
            MUST(object->internal_set_prototype_of(value.is_object() ? &value.as_object() : nullptr));
        break;
    }

    return {};
}

}