/*
 * Copyright (c) 2024-2025, stelar7 <dudedbz@gmail.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/AnyOf.h>
#include <LibWeb/Bindings/IDBDatabase.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Crypto/Crypto.h>
#include <LibWeb/HTML/EventNames.h>
#include <LibWeb/IndexedDB/IDBDatabase.h>
#include <LibWeb/IndexedDB/IDBObjectStore.h>
#include <LibWeb/IndexedDB/Internal/Algorithms.h>

namespace Web::IndexedDB {

GC_DEFINE_ALLOCATOR(IDBDatabase);

IDBDatabase::IDBDatabase(JS::Realm& realm, Database& db)
    : EventTarget(realm)
    , m_name(db.name())
    , m_associated_database(db)
    , m_uuid(Crypto::generate_random_uuid())
{
    db.associate(*this);
    m_object_store_set = Vector<GC::Ref<ObjectStore>> { db.object_stores() };
}

IDBDatabase::~IDBDatabase() = default;

void IDBDatabase::finalize()
{
    Base::finalize();

    m_associated_database->dissociate(*this);
    heap().enqueue_post_gc_task([database = GC::Weak(m_associated_database)] {
        if (!database)
            return;
        database->check_pending_connection_wait();
    });
}

GC::Ref<IDBDatabase> IDBDatabase::create(JS::Realm& realm, Database& db)
{
    return realm.create<IDBDatabase>(realm, db);
}

void IDBDatabase::initialize(JS::Realm& realm)
{
    WEB_SET_PROTOTYPE_FOR_INTERFACE(IDBDatabase);
    Base::initialize(realm);
}

void IDBDatabase::visit_edges(Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_object_store_set);
    visitor.visit(m_associated_database);
    visitor.visit(m_transactions);

    for (auto& wait : m_pending_transaction_waits) {
        visitor.visit(wait.transactions);
        visitor.visit(wait.callback);
    }
}

void IDBDatabase::set_onabort(WebIDL::CallbackType* event_handler)
{
    set_event_handler_attribute(HTML::EventNames::abort, event_handler);
}

WebIDL::CallbackType* IDBDatabase::onabort()
{
    return event_handler_attribute(HTML::EventNames::abort);
}

void IDBDatabase::set_onerror(WebIDL::CallbackType* event_handler)
{
    set_event_handler_attribute(HTML::EventNames::error, event_handler);
}

WebIDL::CallbackType* IDBDatabase::onerror()
{
    return event_handler_attribute(HTML::EventNames::error);
}

void IDBDatabase::set_onclose(WebIDL::CallbackType* event_handler)
{
    set_event_handler_attribute(HTML::EventNames::close, event_handler);
}

WebIDL::CallbackType* IDBDatabase::onclose()
{
    return event_handler_attribute(HTML::EventNames::close);
}

void IDBDatabase::set_onversionchange(WebIDL::CallbackType* event_handler)
{
    set_event_handler_attribute(HTML::EventNames::versionchange, event_handler);
}

WebIDL::CallbackType* IDBDatabase::onversionchange()
{
    return event_handler_attribute(HTML::EventNames::versionchange);
}

// https://w3c.github.io/IndexedDB/#dom-idbdatabase-close
void IDBDatabase::close()
{
    // 1. Run close a database connection with this connection.
    close_a_database_connection(*this);
}

// https://w3c.github.io/IndexedDB/#dom-idbdatabase-createobjectstore
WebIDL::ExceptionOr<GC::Ref<IDBObjectStore>> IDBDatabase::create_object_store(String const& name, IDBObjectStoreParameters const& options)
{
    auto& realm = this->realm();

    // 1. Let database be this's associated database.
    auto database = associated_database();

    // 2. Let transaction be database’s upgrade transaction if it is not null, or throw an "InvalidStateError" DOMException otherwise.
    auto transaction = database->upgrade_transaction();
    if (!transaction)
        return WebIDL::InvalidStateError::create(realm, "Upgrade transaction is null"_utf16);

    // 3. If transaction’s state is not active, then throw a "TransactionInactiveError" DOMException.
    if (!transaction->is_active())
        return WebIDL::TransactionInactiveError::create(realm, "Transaction is not active while creating object store"_utf16);

    // 4. Let keyPath be options’s keyPath member if it is not undefined or null, or null otherwise.
    auto const& nullable_key_path = options.key_path;
    Optional<KeyPath> key_path;
    if (!nullable_key_path.has<Empty>())
        key_path = nullable_key_path.downcast<String, Vector<String>>();

    // 5. If keyPath is not null and is not a valid key path, throw a "SyntaxError" DOMException.
    if (key_path.has_value() && !is_valid_key_path(key_path.value()))
        return WebIDL::SyntaxError::create(realm, "Invalid key path"_utf16);

    // 6. If an object store named name already exists in database throw a "ConstraintError" DOMException.
    if (database->object_store_with_name(name))
        return WebIDL::ConstraintError::create(realm, "Object store already exists"_utf16);

    // 7. Let autoIncrement be options’s autoIncrement member.
    auto auto_increment = options.auto_increment;

    bool is_empty_key_path_or_sequence = key_path.has_value() && key_path.value().visit([](String const& value) -> bool { return value.is_empty(); }, [](Vector<String> const&) -> bool { return true; });

    // 8. If autoIncrement is true and keyPath is an empty string or any sequence (empty or otherwise), throw an "InvalidAccessError" DOMException.
    if (auto_increment && is_empty_key_path_or_sequence)
        return WebIDL::InvalidAccessError::create(realm, "Auto increment is true and key path is empty or sequence"_utf16);

    // 9. Let store be a new object store in database.
    //    Set the created object store's name to name.
    //    If autoIncrement is true, then the created object store uses a key generator.
    //    If keyPath is not null, set the created object store's key path to keyPath.
    auto object_store = ObjectStore::create(realm, database, name, auto_increment, key_path);

    // AD-HOC: Add newly created object store to this's object store set.
    add_to_object_store_set(object_store);

    // AD-HOC: Set up a mutation log for this store and log its creation for potential revert on abort.
    transaction->set_up_mutation_log_for_new_store(object_store);

    // 10. Return a new object store handle associated with store and transaction.
    transaction->add_to_scope(object_store);
    return transaction->get_or_create_object_store_handle(object_store);
}

// https://w3c.github.io/IndexedDB/#dom-idbdatabase-objectstorenames
GC::Ref<HTML::DOMStringList> IDBDatabase::object_store_names()
{
    // 1. Let names be a list of the names of the object stores in this's object store set.
    Vector<String> names;
    for (auto const& object_store : this->object_store_set())
        names.append(object_store->name());

    // 2. Return the result (a DOMStringList) of creating a sorted name list with names.
    return create_a_sorted_name_list(realm(), names);
}

// https://w3c.github.io/IndexedDB/#dom-idbdatabase-deleteobjectstore
WebIDL::ExceptionOr<void> IDBDatabase::delete_object_store(String const& name)
{
    auto& realm = this->realm();

    // 1. Let database be this's associated database.
    auto database = associated_database();

    // 2. Let transaction be database’s upgrade transaction if it is not null, or throw an "InvalidStateError" DOMException otherwise.
    auto transaction = database->upgrade_transaction();
    if (!transaction)
        return WebIDL::InvalidStateError::create(realm, "Upgrade transaction is null"_utf16);

    // 3. If transaction’s state is not active, then throw a "TransactionInactiveError" DOMException.
    if (!transaction->is_active())
        return WebIDL::TransactionInactiveError::create(realm, "Transaction is not active while deleting object store"_utf16);

    // 4. Let store be the object store named name in database, or throw a "NotFoundError" DOMException if none.
    auto store = database->object_store_with_name(name);
    if (!store)
        return WebIDL::NotFoundError::create(realm, "Object store not found while trying to delete"_utf16);

    // 5. Remove store from this's object store set.
    this->remove_from_object_store_set(*store);

    // NB: Upgrade transactions' scope is always the entire database. Since we removed this store from the database,
    //     it no longer belongs in the scope.
    transaction->remove_from_scope(*store);

    // 6. If there is an object store handle associated with store and transaction, remove all entries from its index set.
    if (auto handle = transaction->object_store_handle_for(*store))
        handle->index_set().clear();

    // AD-HOC: Mark the store and its indexes as deleted so that stale handles throw InvalidStateError.
    store->set_deleted(true);
    for (auto const& [_, index] : store->index_set())
        index->set_deleted(true);

    // AD-HOC: Log the deletion for potential revert on abort.
    store->mutation_log()->note_object_store_deleted();

    // 7. Destroy store.
    database->remove_object_store(*store);

    return {};
}

// https://w3c.github.io/IndexedDB/#dom-idbdatabase-transaction
WebIDL::ExceptionOr<GC::Ref<IDBTransaction>> IDBDatabase::transaction(Variant<String, Vector<String>> store_names, Bindings::IDBTransactionMode mode, IDBTransactionOptions options)
{
    auto& realm = this->realm();

    // 1. If a live upgrade transaction is associated with the connection, throw an "InvalidStateError" DOMException.
    auto database = associated_database();
    if (database->upgrade_transaction())
        return WebIDL::InvalidStateError::create(realm, "Upgrade transaction is live"_utf16);

    // 2. If this's close pending flag is true, then throw an "InvalidStateError" DOMException.
    if (close_pending())
        return WebIDL::InvalidStateError::create(realm, "Close pending"_utf16);

    // 3. Let scope be the set of unique strings in storeNames if it is a sequence, or a set containing one string equal to storeNames otherwise.
    Vector<String> scope;
    if (store_names.has<Vector<String>>()) {
        scope = store_names.get<Vector<String>>();
    } else {
        scope.append(store_names.get<String>());
    }

    // 4. If any string in scope is not the name of an object store in the connected database, throw a "NotFoundError" DOMException.
    for (auto const& store_name : scope) {
        if (!database->object_store_with_name(store_name))
            return WebIDL::NotFoundError::create(realm, "Provided object store names does not exist in database"_utf16);
    }

    // 5. If scope is empty, throw an "InvalidAccessError" DOMException.
    if (scope.is_empty())
        return WebIDL::InvalidAccessError::create(realm, "Scope is empty"_utf16);

    // 6. If mode is not "readonly" or "readwrite", throw a TypeError.
    if (mode != Bindings::IDBTransactionMode::Readonly && mode != Bindings::IDBTransactionMode::Readwrite)
        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, "Invalid transaction mode"_string };

    // 7. Let transaction be a newly created transaction with this connection, mode, options’ durability member, and the set of object stores named in scope.
    Vector<GC::Ref<ObjectStore>> scope_stores;
    for (auto const& store_name : scope) {
        auto store = database->object_store_with_name(store_name);
        scope_stores.append(*store);
    }

    auto transaction = IDBTransaction::create(realm, *this, mode, options.durability, scope_stores);

    // 8. Set transaction’s cleanup event loop to the current event loop.
    transaction->set_cleanup_event_loop(HTML::main_thread_event_loop());

    block_on_conflicting_transactions(transaction);

    // 9. Return an IDBTransaction object representing transaction.
    return transaction;
}

void IDBDatabase::set_state(ConnectionState state)
{
    m_state = state;
}

void IDBDatabase::wait_for_transactions_to_finish(ReadonlySpan<GC::Ref<IDBTransaction>> transactions, GC::Ref<GC::Function<void()>> on_complete)
{
    auto all_finished = [&] {
        for (auto const& entry : transactions) {
            if (!entry->is_finished()) {
                return false;
                break;
            }
        }
        return true;
    }();

    if (all_finished) {
        queue_a_database_task(on_complete);
        return;
    }

    m_pending_transaction_waits.append(PendingTransactionWait {
        .transactions = Vector<GC::Ref<IDBTransaction>> { transactions },
        .callback = on_complete,
    });
}

void IDBDatabase::check_pending_transaction_waits()
{
    for (size_t i = 0; i < m_pending_transaction_waits.size();) {
        auto all_finished = [&] {
            for (auto const& transaction : m_pending_transaction_waits[i].transactions) {
                if (!transaction->is_finished())
                    return false;
            }
            return true;
        }();
        if (all_finished) {
            auto callback = m_pending_transaction_waits.take(i).callback;
            callback->function()();
            continue;
        }

        i++;
    }
}

// https://w3c.github.io/IndexedDB/#transaction-scheduling
void IDBDatabase::block_on_conflicting_transactions(GC::Ref<IDBTransaction> transaction)
{
    // The following constraints define when a transaction can be started:

    // - A read-only transactions tx can start when there are no read/write transactions which:
    // - A read/write transaction tx can start when there are no transactions which:

    Vector<GC::Ref<IDBTransaction>> blocking;
    for (auto const& other : m_transactions) {
        // - Were created before tx; and
        if (other.ptr() == transaction.ptr())
            break;

        // NB: According to the above conditions, we only block on transactions if one is read/write.
        if (transaction->is_readonly() && other->is_readonly())
            continue;

        // - have overlapping scopes with tx; and
        bool have_overlapping_scopes = any_of(transaction->scope(), [&](auto const& store) {
            return other->scope().contains_slow(store);
        });
        if (!have_overlapping_scopes)
            continue;

        // - are not finished.
        if (other->is_finished())
            continue;

        blocking.append(other);
    }

    if (blocking.is_empty()) {
        if (!transaction->is_readonly())
            transaction->set_up_mutation_logs();
        return;
    }

    transaction->request_list().block_execution();
    wait_for_transactions_to_finish(blocking, GC::create_function(realm().heap(), [transaction] {
        VERIFY(transaction->state() != IDBTransaction::TransactionState::Active);
        if (transaction->request_list().is_empty()) {
            // https://w3c.github.io/IndexedDB/#transaction-commit
            // The implementation must attempt to commit an inactive transaction when all requests placed
            // against the transaction have completed and their returned results handled, no new requests have
            // been placed against the transaction, and the transaction has not been aborted

            // If we were blocked, that means that the JS task has had its chance to make requests. If the request
            // list is empty, then the cleanup in the microtask checkpoint already ran, but skipped auto-committing.
            // We have to do it here instead.

            // FIXME: Update if this becomes explicit:
            //        https://github.com/w3c/IndexedDB/issues/489#issuecomment-3994928473
            commit_a_transaction(transaction->realm(), transaction);
            return;
        }
        if (!transaction->is_readonly())
            transaction->set_up_mutation_logs();
        transaction->request_list().unblock_execution();
    }));
}

}