/*
 * Copyright (c) 2022, David Tuin <davidot@serenityos.org>
 * Copyright (c) 2023, networkException <networkexception@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <LibJS/Export.h>
#include <LibJS/Forward.h>
#include <LibJS/Module.h>

namespace JS {

enum class ModuleStatus {
    New,
    Unlinked,
    Linking,
    Linked,
    Evaluating,
    EvaluatingAsync,
    Evaluated
};

// 16.2.1.5 Cyclic Module Records, https://tc39.es/ecma262/#cyclic-module-record
class JS_API CyclicModule : public Module {
    GC_CELL(CyclicModule, Module);
    GC_DECLARE_ALLOCATOR(CyclicModule);

public:
    virtual ~CyclicModule() override;

    // Note: Do not call these methods directly unless you are HostResolveImportedModule.
    //       Badges cannot be used because other hosts must be able to call this (and it is called recursively)
    virtual ThrowCompletionOr<void> link(VM& vm) override final;
    virtual ThrowCompletionOr<GC::Ref<PromiseCapability>> evaluate(VM& vm) override final;

    virtual PromiseCapability& load_requested_modules(GC::Ptr<GraphLoadingState::HostDefined>) override;

    ModuleStatus status() const { return m_status; }
    void set_status(ModuleStatus status) { m_status = status; }

    Vector<ModuleRequest> const& requested_modules() const { return m_requested_modules; }
    Vector<LoadedModuleRequest> const& loaded_modules() const { return m_loaded_modules; }
    Vector<LoadedModuleRequest>& loaded_modules() { return m_loaded_modules; }

protected:
    CyclicModule(Realm& realm, StringView filename, bool has_top_level_await, Vector<ModuleRequest> requested_modules, Script::HostDefined* host_defined);

    virtual void visit_edges(Cell::Visitor&) override;
    virtual size_t external_memory_size() const override;

    virtual ThrowCompletionOr<u32> inner_module_linking(VM& vm, GC::RootVector<GC::Ref<Module>>& stack, u32 index) override final;
    virtual ThrowCompletionOr<u32> inner_module_evaluation(VM& vm, GC::RootVector<GC::Ref<Module>>& stack, u32 index) override final;

    virtual ThrowCompletionOr<void> initialize_environment(VM& vm);
    virtual ThrowCompletionOr<void> execute_module(VM& vm, GC::Ptr<PromiseCapability> capability = {});

    [[nodiscard]] GC::Ref<Module> get_imported_module(ModuleRequest const& request);

    void execute_async_module(VM& vm);
    void gather_available_ancestors(GC::RootVector<GC::Ptr<CyclicModule>>& exec_list);
    void async_module_execution_fulfilled(VM& vm);
    void async_module_execution_rejected(VM& vm, Value error);

    ModuleStatus m_status { ModuleStatus::New };          // [[Status]]
    ThrowCompletionOr<void> m_evaluation_error;           // [[EvaluationError]]
    Optional<u32> m_dfs_index;                            // [[DFSIndex]]
    Optional<u32> m_dfs_ancestor_index;                   // [[DFSAncestorIndex]]
    Vector<ModuleRequest> m_requested_modules;            // [[RequestedModules]]
    Vector<LoadedModuleRequest> m_loaded_modules;         // [[LoadedModules]]
    GC::Ptr<CyclicModule> m_cycle_root;                   // [[CycleRoot]]
    bool m_has_top_level_await { false };                 // [[HasTLA]]
    Optional<u64> m_async_evaluation_order;               // [[AsyncEvaluationOrder]]
    GC::Ptr<PromiseCapability> m_top_level_capability;    // [[TopLevelCapability]]
    Vector<GC::Ptr<CyclicModule>> m_async_parent_modules; // [[AsyncParentModules]]
    Optional<u32> m_pending_async_dependencies;           // [[PendingAsyncDependencies]]
};

void inner_module_loading(VM&, GraphLoadingState& state, GC::Ref<Module>);
void continue_module_loading(GraphLoadingState&, ThrowCompletionOr<GC::Ref<Module>> const&);
void continue_dynamic_import(GC::Ref<PromiseCapability>, ThrowCompletionOr<GC::Ref<Module>> const& module_completion);

}
