/*

 * Copyright (c) 2021-2022, Idan Horowitz <idan.horowitz@serenityos.org>

 *

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

 */

#include <LibJS/Runtime/AbstractOperations.h>

#include <LibJS/Runtime/FinalizationRegistry.h>

namespace JS {

JS_DEFINE_ALLOCATOR(FinalizationRegistry);

FinalizationRegistry::FinalizationRegistry(Realm& realm, NonnullGCPtr<JobCallback> cleanup_callback, Object& prototype)

    : Object(ConstructWithPrototypeTag::Tag, prototype)

    , WeakContainer(heap())

    , m_realm(realm)

    , m_cleanup_callback(cleanup_callback)

{

}

void FinalizationRegistry::add_finalization_record(Cell& target, Value held_value, Cell* unregister_token)

{

    VERIFY(!held_value.is_empty());

    m_records.append({ &target, held_value, unregister_token });

}

// Extracted from FinalizationRegistry.prototype.unregister ( unregisterToken )

bool FinalizationRegistry::remove_by_token(Cell& unregister_token)

{

    // 4. Let removed be false.

    auto removed = false;

    // 5. For each Record { [[WeakRefTarget]], [[HeldValue]], [[UnregisterToken]] } cell of finalizationRegistry.[[Cells]], do

    for (auto it = m_records.begin(); it != m_records.end(); ++it) {

        //  a. If cell.[[UnregisterToken]] is not empty and SameValue(cell.[[UnregisterToken]], unregisterToken) is true, then

        if (it->unregister_token == &unregister_token) {

            // i. Remove cell from finalizationRegistry.[[Cells]].

            it.remove(m_records);

            // ii. Set removed to true.

            removed = true;

        }

    }

    // 6. Return removed.

    return removed;

}

void FinalizationRegistry::remove_dead_cells(Badge<Heap>)

{

    auto any_cells_were_removed = false;

    for (auto& record : m_records) {

        if (!record.target || record.target->state() == Cell::State::Live)

            continue;

        record.target = nullptr;

        any_cells_were_removed = true;

        break;

    }

    if (any_cells_were_removed)

        vm().host_enqueue_finalization_registry_cleanup_job(*this);

}

// 9.13 CleanupFinalizationRegistry ( finalizationRegistry ), https://tc39.es/ecma262/#sec-cleanup-finalization-registry

ThrowCompletionOr<void> FinalizationRegistry::cleanup(JS::GCPtr<JobCallback> callback)

{

    auto& vm = this->vm();

    // 1. Assert: finalizationRegistry has [[Cells]] and [[CleanupCallback]] internal slots.

    // Note: Ensured by type.

    // 2. Let callback be finalizationRegistry.[[CleanupCallback]].

    auto cleanup_callback = callback ? callback : m_cleanup_callback;

    // 3. While finalizationRegistry.[[Cells]] contains a Record cell such that cell.[[WeakRefTarget]] is empty, an implementation may perform the following steps:

    for (auto it = m_records.begin(); it != m_records.end(); ++it) {

        // a. Choose any such cell.

        if (it->target != nullptr)

            continue;

        // b. Remove cell from finalizationRegistry.[[Cells]].

        MarkedVector<Value> arguments(vm.heap());

        arguments.append(it->held_value);

        it.remove(m_records);

        // c. Perform ? HostCallJobCallback(callback, undefined, « cell.[[HeldValue]] »).

        TRY(vm.host_call_job_callback(*cleanup_callback, js_undefined(), move(arguments)));

    }

    // 4. Return unused.

    return {};

}

void FinalizationRegistry::visit_edges(Cell::Visitor& visitor)

{

    Base::visit_edges(visitor);

    visitor.visit(m_realm);

    visitor.visit(m_cleanup_callback);

    for (auto& record : m_records) {

        visitor.visit(record.held_value);

        visitor.visit(record.unregister_token);

    }

}

}