/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
// SPDX-FileCopyrightText: 2017 Philip Chimento <philip.chimento@gmail.com>

#include <config.h>

#include <stddef.h>     // for size_t
#include <string.h>

#include <string>
#include <vector>  // for vector

#include <gio/gio.h>
#include <glib-object.h>
#include <glib.h>

#include <js/CallAndConstruct.h>
#include <js/CallArgs.h>
#include <js/CharacterEncoding.h>  // for ConstUTF8CharsZ
#include <js/Class.h>
#include <js/CompilationAndEvaluation.h>
#include <js/CompileOptions.h>
#include <js/Conversions.h>
#include <js/EnvironmentChain.h>
#include <js/ErrorReport.h>  // for JS_ReportOutOfMemory
#include <js/Exception.h>
#include <js/GlobalObject.h>  // for CurrentGlobalOrNull
#include <js/Id.h>
#include <js/Modules.h>
#include <js/Object.h>
#include <js/Promise.h>
#include <js/PropertyAndElement.h>
#include <js/PropertyDescriptor.h>
#include <js/RootingAPI.h>
#include <js/ScriptPrivate.h>
#include <js/SourceText.h>
#include <js/String.h>
#include <js/TypeDecls.h>
#include <js/Utility.h>  // for UniqueChars
#include <js/Value.h>
#include <js/ValueArray.h>
#include <jsapi.h>        // for JS_GetFunctionObject, JS_Ne...
#include <jsfriendapi.h>  // for NewFunctionWithReserved
#include <mozilla/Maybe.h>

#include "cjs/atoms.h"
#include "cjs/auto.h"
#include "cjs/context-private.h"
#include "cjs/deprecation.h"
#include "cjs/gerror-result.h"
#include "cjs/global.h"
#include "cjs/jsapi-util-args.h"
#include "cjs/jsapi-util.h"
#include "cjs/macros.h"
#include "cjs/mem-private.h"
#include "cjs/module.h"
#include "cjs/native.h"
#include "util/log.h"
#include "util/misc.h"

namespace mozilla {
union Utf8Unit;
}

class GjsScriptModule {
    Gjs::AutoChar m_name;

    // Reserved slots
    static const size_t POINTER = 0;

    explicit GjsScriptModule(const char* name) : m_name(g_strdup(name)) {
        GJS_INC_COUNTER(module);
    }

    ~GjsScriptModule() { GJS_DEC_COUNTER(module); }

    // Private data accessors

    [[nodiscard]]
    static GjsScriptModule* priv(JSObject* module) {
        return JS::GetMaybePtrFromReservedSlot<GjsScriptModule>(
            module, GjsScriptModule::POINTER);
    }

    // Creates a JS module object. Use instead of the class's constructor
    [[nodiscard]]
    static JSObject* create(JSContext* cx, const char* name) {
        JSObject* module = JS_NewObject(cx, &GjsScriptModule::klass);
        JS::SetReservedSlot(module, GjsScriptModule::POINTER,
                            JS::PrivateValue(new GjsScriptModule(name)));
        return module;
    }

    // Defines the empty module as a property on the importer
    GJS_JSAPI_RETURN_CONVENTION
    bool define_import(JSContext* cx, JS::HandleObject module,
                       JS::HandleObject importer, JS::HandleId name) const {
        if (!JS_DefinePropertyById(cx, importer, name, module,
                                   GJS_MODULE_PROP_FLAGS & ~JSPROP_PERMANENT)) {
            gjs_debug(GJS_DEBUG_IMPORTER, "Failed to define '%s' in importer",
                      m_name.get());
            return false;
        }

        return true;
    }

    // Carries out the actual execution of the module code
    GJS_JSAPI_RETURN_CONVENTION
    bool evaluate_import(JSContext* cx, JS::HandleObject module,
                         const char* source, size_t source_len,
                         const char* filename, const char* uri) {
        JS::SourceText<mozilla::Utf8Unit> buf;
        if (!buf.init(cx, source, source_len, JS::SourceOwnership::Borrowed))
            return false;

        JS::EnvironmentChain scope_chain{cx, JS::SupportUnscopables::No};
        if (!scope_chain.append(module)) {
            JS_ReportOutOfMemory(cx);
            return false;
        }

        JS::CompileOptions options(cx);
        options.setFileAndLine(filename, 1).setNonSyntacticScope(true);

        JS::RootedObject priv(cx, build_private(cx, uri));
        if (!priv)
            return false;

        JS::RootedScript script(cx, JS::Compile(cx, options, buf));
        if (!script)
            return false;

        JS::SetScriptPrivate(script, JS::ObjectValue(*priv));
        JS::RootedValue ignored_retval(cx);
        if (!JS_ExecuteScript(cx, scope_chain, script, &ignored_retval))
            return false;

        GjsContextPrivate* gjs = GjsContextPrivate::from_cx(cx);
        gjs->schedule_gc_if_needed();

        gjs_debug(GJS_DEBUG_IMPORTER, "Importing module %s succeeded",
                  m_name.get());

        return true;
    }

    // Loads JS code from a file and imports it
    GJS_JSAPI_RETURN_CONVENTION
    bool import_file(JSContext* cx, JS::HandleObject module, GFile* file) {
        Gjs::AutoError error;
        Gjs::AutoChar script;
        size_t script_len = 0;

        if (!(g_file_load_contents(file, nullptr, script.out(), &script_len,
                                   nullptr, &error)))
            return gjs_throw_gerror_message(cx, error);
        g_assert(script);

        Gjs::AutoChar full_path{g_file_get_parse_name(file)};
        Gjs::AutoChar uri{g_file_get_uri(file)};
        return evaluate_import(cx, module, script, script_len, full_path, uri);
    }

    // JSClass operations

    GJS_JSAPI_RETURN_CONVENTION
    bool resolve_impl(JSContext* cx, JS::HandleObject module, JS::HandleId id,
                      bool* resolved) {
        JS::RootedObject lexical(cx, JS_ExtensibleLexicalEnvironment(module));
        if (!lexical) {
            *resolved = false;
            return true;  // nothing imported yet
        }

        JS::Rooted<mozilla::Maybe<JS::PropertyDescriptor>> maybe_desc(cx);
        JS::RootedObject holder(cx);
        if (!JS_GetPropertyDescriptorById(cx, lexical, id, &maybe_desc,
                                          &holder))
            return false;
        if (maybe_desc.isNothing())
            return true;

        /* The property is present in the lexical environment. This should not
         * be supported according to ES6. For compatibility with earlier GJS, we
         * treat it as if it were a real property, but warn about it. */

        gjs_warn_deprecated_once_per_callsite(
            cx, GjsDeprecationMessageId::ModuleExportedLetOrConst,
            {gjs_debug_id(id), m_name.get()});

        JS::Rooted<JS::PropertyDescriptor> desc(cx, maybe_desc.value());
        return JS_DefinePropertyById(cx, module, id, desc);
    }

    GJS_JSAPI_RETURN_CONVENTION
    static bool resolve(JSContext* cx, JS::HandleObject module, JS::HandleId id,
                        bool* resolved) {
        return priv(module)->resolve_impl(cx, module, id, resolved);
    }

    static void finalize(JS::GCContext*, JSObject* module) {
        delete priv(module);
    }

    static constexpr JSClassOps class_ops = {
        nullptr,  // addProperty
        nullptr,  // deleteProperty
        nullptr,  // enumerate
        nullptr,  // newEnumerate
        &GjsScriptModule::resolve,
        nullptr,  // mayResolve
        &GjsScriptModule::finalize,
    };

    static constexpr JSClass klass = {
        "GjsScriptModule",
        JSCLASS_HAS_RESERVED_SLOTS(1) | JSCLASS_BACKGROUND_FINALIZE,
        &GjsScriptModule::class_ops,
    };

 public:
    /* Creates a JS object to pass to JS::SetScriptPrivate as a script's
     * private.
     */
    GJS_JSAPI_RETURN_CONVENTION
    static JSObject* build_private(JSContext* cx, const char* script_uri) {
        JS::RootedObject priv(cx, JS_NewPlainObject(cx));
        const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);

        JS::RootedValue val(cx);
        if (!gjs_string_from_utf8(cx, script_uri, &val) ||
            !JS_SetPropertyById(cx, priv, atoms.uri(), val))
            return nullptr;

        return priv;
    }

    // Carries out the import operation
    GJS_JSAPI_RETURN_CONVENTION
    static JSObject* import(JSContext* cx, JS::HandleObject importer,
                            JS::HandleId id, const char* name, GFile* file) {
        JS::RootedObject module(cx, GjsScriptModule::create(cx, name));
        if (!module ||
            !priv(module)->define_import(cx, module, importer, id) ||
            !priv(module)->import_file(cx, module, file))
            return nullptr;

        return module;
    }

    GjsScriptModule(GjsScriptModule&) = delete;
    GjsScriptModule& operator=(GjsScriptModule&) = delete;
};

/**
 * gjs_script_module_build_private:
 * @cx: the #JSContext
 * @uri: the URI this script module is loaded from
 *
 * To support dynamic imports from scripts, we need to provide private data when
 * we compile scripts which is compatible with our module resolution hooks in
 * modules/internal/loader.js
 *
 * Returns: a JSObject which can be used for a JSScript's private data.
 */
JSObject* gjs_script_module_build_private(JSContext* cx, const char* uri) {
    return GjsScriptModule::build_private(cx, uri);
}

/**
 * gjs_module_import:
 * @cx: the JS context
 * @importer: the JS importer object, parent of the module to be imported
 * @id: module name in the form of a jsid
 * @name: module name, used for logging and identification
 * @file: location of the file to import
 *
 * Carries out an import of a GJS module.
 * Defines a property @name on @importer pointing to the module object, which
 * is necessary in the case of cyclic imports.
 * This property is not permanent; the caller is responsible for making it
 * permanent if the import succeeds.
 *
 * Returns: the JS module object, or nullptr on failure.
 */
JSObject* gjs_module_import(JSContext* cx, JS::HandleObject importer,
                            JS::HandleId id, const char* name, GFile* file) {
    return GjsScriptModule::import(cx, importer, id, name, file);
}

/**
 * gjs_get_native_registry:
 * @global: The JS global object
 *
 * Retrieves a global's native registry from the NATIVE_REGISTRY slot.
 * Registries are JS Map objects created with JS::NewMapObject instead of
 * GCHashMaps (used elsewhere in GJS) because the objects need to be exposed to
 * internal JS code and accessed from native C++ code.
 *
 * Returns: the native module registry, a JS Map object.
 */
JSObject* gjs_get_native_registry(JSObject* global) {
    JS::Value native_registry =
        gjs_get_global_slot(global, GjsGlobalSlot::NATIVE_REGISTRY);

    g_assert(native_registry.isObject());
    return &native_registry.toObject();
}

/**
 * gjs_get_module_registry:
 * @global: the JS global object
 *
 * Retrieves a global's module registry from the MODULE_REGISTRY slot.
 * Registries are JS Maps. See gjs_get_native_registry() for more detail.
 *
 * Returns: the module registry, a JS Map object
 */
JSObject* gjs_get_module_registry(JSObject* global) {
    JS::Value esm_registry =
        gjs_get_global_slot(global, GjsGlobalSlot::MODULE_REGISTRY);

    g_assert(esm_registry.isObject());
    return &esm_registry.toObject();
}

/**
 * gjs_get_source_map_registry:
 * @global: The JS global object
 *
 * Retrieves a global's source map registry from the SOURCE_MAP_REGISTRY slot.
 * Registries are JS Maps.
 *
 * Returns: the source map registry, a JS Map object
 */
JSObject* gjs_get_source_map_registry(JSObject* global) {
    JS::Value source_map_registry =
        gjs_get_global_slot(global, GjsGlobalSlot::SOURCE_MAP_REGISTRY);

    g_assert(source_map_registry.isObject());
    return &source_map_registry.toObject();
}

/**
 * gjs_module_load:
 * @cx: the current JSContext
 * @identifier: specifier of the module to load
 * @file_uri: URI to load the module from
 *
 * Loads and registers a module given a specifier and URI.
 *
 * Returns: whether an error occurred while resolving the specifier.
 */
JSObject* gjs_module_load(JSContext* cx, const char* identifier,
                          const char* file_uri) {
    g_assert((gjs_global_is_type(cx, GjsGlobalType::DEFAULT) ||
              gjs_global_is_type(cx, GjsGlobalType::INTERNAL)) &&
             "gjs_module_load can only be called from module-enabled "
             "globals.");

    JS::RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
    JS::RootedValue v_loader(
        cx, gjs_get_global_slot(global, GjsGlobalSlot::MODULE_LOADER));
    g_assert(v_loader.isObject());
    JS::RootedObject loader(cx, &v_loader.toObject());

    JS::ConstUTF8CharsZ id_chars(identifier, strlen(identifier));
    JS::ConstUTF8CharsZ uri_chars(file_uri, strlen(file_uri));
    JS::RootedString id(cx, JS_NewStringCopyUTF8Z(cx, id_chars));
    if (!id)
        return nullptr;
    JS::RootedString uri(cx, JS_NewStringCopyUTF8Z(cx, uri_chars));
    if (!uri)
        return nullptr;

    JS::RootedValueArray<2> args(cx);
    args[0].setString(id);
    args[1].setString(uri);

    gjs_debug(GJS_DEBUG_IMPORTER,
              "Module load hook for module '%s' (%s), global %p", identifier,
              file_uri, global.get());

    JS::RootedValue result(cx);
    if (!JS::Call(cx, loader, "moduleLoadHook", args, &result))
        return nullptr;

    g_assert(result.isObject() && "Module hook failed to return an object!");
    return &result.toObject();
}

/**
 * import_native_module_sync:
 * @identifier: the specifier for the module to import
 *
 * JS function exposed as `import.meta.importSync` in internal modules only.
 *
 * Synchronously imports native "modules" from the import global's
 * native registry. This function does not do blocking I/O so it is
 * safe to call it synchronously for accessing native "modules" within
 * modules. This function is always called within the import global's
 * realm.
 *
 * Compare gjs_import_native_module() for the legacy importer.
 *
 * Returns: the imported JS module object.
 */
static bool import_native_module_sync(JSContext* cx, unsigned argc,
                                      JS::Value* vp) {
    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
    JS::UniqueChars id;
    if (!gjs_parse_call_args(cx, "importSync", args, "s", "identifier", &id))
        return false;

    Gjs::AutoMainRealm ar{cx};
    JS::RootedObject global{cx, JS::CurrentGlobalOrNull(cx)};

    JS::AutoSaveExceptionState exc_state(cx);

    JS::RootedObject native_registry(cx, gjs_get_native_registry(global));
    JS::RootedObject v_module(cx);

    JS::RootedId key(cx, gjs_intern_string_to_id(cx, id.get()));
    if (!gjs_global_registry_get(cx, native_registry, key, &v_module))
        return false;

    if (v_module) {
        args.rval().setObject(*v_module);
        return true;
    }

    JS::RootedObject native_obj(cx);
    if (!Gjs::NativeModuleDefineFuncs::get().define(cx, id.get(),
                                                    &native_obj)) {
        gjs_throw(cx, "Failed to load native module: %s", id.get());
        return false;
    }

    if (!gjs_global_registry_set(cx, native_registry, key, native_obj))
        return false;

    args.rval().setObject(*native_obj);
    return true;
}

/**
 * gjs_populate_module_meta:
 * @cx: the current JSContext
 * @private_ref: the JS private value for the #Module object, as a JS Object
 * @meta: the JS `import.meta` object
 *
 * Hook SpiderMonkey calls to populate the `import.meta` object.
 * Defines a property `import.meta.url`, and additionally a method
 * `import.meta.importSync` if this is an internal module.
 *
 * Returns: whether an error occurred while populating the module meta.
 */
bool gjs_populate_module_meta(JSContext* cx, JS::HandleValue private_ref,
                              JS::HandleObject meta) {
    g_assert(private_ref.isObject());
    JS::RootedObject module(cx, &private_ref.toObject());

    gjs_debug(GJS_DEBUG_IMPORTER, "Module metadata hook for module %p",
              &private_ref.toObject());

    const GjsAtoms& atoms = GjsContextPrivate::atoms(cx);
    JS::RootedValue specifier{cx};
    if (!JS_GetProperty(cx, module, "id", &specifier) ||
        !JS_DefinePropertyById(cx, meta, atoms.url(), specifier,
                               GJS_MODULE_PROP_FLAGS))
        return false;

    JS::RootedValue v_internal(cx);
    if (!JS_GetPropertyById(cx, module, atoms.internal(), &v_internal))
        return false;
    if (JS::ToBoolean(v_internal)) {
        gjs_debug(GJS_DEBUG_IMPORTER, "Defining meta.importSync for module %p",
                  &private_ref.toObject());
        if (!JS_DefineFunctionById(cx, meta, atoms.importSync(),
                                   import_native_module_sync, 1,
                                   GJS_MODULE_PROP_FLAGS))
            return false;
    }

    return true;
}

// Canonicalize specifier so that differently-spelled specifiers referring to
// the same module don't result in duplicate entries in the registry
static bool canonicalize_specifier(JSContext* cx,
                                   JS::MutableHandleString specifier) {
    JS::UniqueChars specifier_utf8 = JS_EncodeStringToUTF8(cx, specifier);
    if (!specifier_utf8)
        return false;

    Gjs::AutoChar scheme, host, path, query;
    if (!g_uri_split(specifier_utf8.get(), G_URI_FLAGS_NONE, scheme.out(),
                     nullptr, host.out(), nullptr, path.out(), query.out(),
                     nullptr, nullptr))
        return false;

    if (g_strcmp0(scheme, "gi")) {
        // canonicalize without the query portion to avoid it being encoded
        Gjs::AutoChar for_file_uri{g_uri_join(G_URI_FLAGS_NONE, scheme.get(),
                                              nullptr, host.get(), -1,
                                              path.get(), nullptr, nullptr)};
        Gjs::AutoUnref<GFile> file{g_file_new_for_uri(for_file_uri.get())};
        for_file_uri = g_file_get_uri(file);
        host.reset();
        path.reset();
        if (!g_uri_split(for_file_uri.get(), G_URI_FLAGS_NONE, nullptr, nullptr,
                         host.out(), nullptr, path.out(), nullptr, nullptr,
                         nullptr))
            return false;
    }

    Gjs::AutoChar canonical_specifier{
        g_uri_join(G_URI_FLAGS_NONE, scheme.get(), nullptr, host.get(), -1,
                   path.get(), query.get(), nullptr)};
    JS::ConstUTF8CharsZ chars{canonical_specifier, strlen(canonical_specifier)};
    JS::RootedString new_specifier{cx, JS_NewStringCopyUTF8Z(cx, chars)};
    if (!new_specifier)
        return false;

    specifier.set(new_specifier);
    return true;
}

/**
 * gjs_module_resolve:
 * @cx: the current JSContext
 * @importing_module_priv: the private JS Object of the #Module object
 *   initiating the import, or a JS null value
 * @module_request: the module request object
 *
 * This function resolves import specifiers. It is called internally by
 * SpiderMonkey as a hook.
 *
 * Returns: whether an error occurred while resolving the specifier.
 */
JSObject* gjs_module_resolve(JSContext* cx,
                             JS::HandleValue importing_module_priv,
                             JS::HandleObject module_request) {
    g_assert((gjs_global_is_type(cx, GjsGlobalType::DEFAULT) ||
              gjs_global_is_type(cx, GjsGlobalType::INTERNAL)) &&
             "gjs_module_resolve can only be called from module-enabled "
             "globals.");
    JS::RootedString specifier(
        cx, JS::GetModuleRequestSpecifier(cx, module_request));

    JS::RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
    JS::RootedValue v_loader(
        cx, gjs_get_global_slot(global, GjsGlobalSlot::MODULE_LOADER));
    g_assert(v_loader.isObject());
    JS::RootedObject loader(cx, &v_loader.toObject());

    if (!canonicalize_specifier(cx, &specifier))
        return nullptr;

    JS::RootedValueArray<2> args(cx);
    args[0].set(importing_module_priv);
    args[1].setString(specifier);

    gjs_debug(GJS_DEBUG_IMPORTER,
              "Module resolve hook for module %s (relative to %s), global %p",
              gjs_debug_string(specifier).c_str(),
              gjs_debug_value(importing_module_priv).c_str(), global.get());

    JS::RootedValue result(cx);
    if (!JS::Call(cx, loader, "moduleResolveHook", args, &result))
        return nullptr;

    g_assert(result.isObject() && "resolve hook failed to return an object!");
    return &result.toObject();
}

// Call JS::FinishDynamicModuleImport() with the values stashed in the function.
// Can fail in JS::FinishDynamicModuleImport(), but will assert if anything
// fails in fetching the stashed values, since that would be a serious GJS bug.
GJS_JSAPI_RETURN_CONVENTION
static bool finish_import(JSContext* cx, JS::HandleObject evaluation_promise,
                          const JS::CallArgs& args) {
    GjsContextPrivate* priv = GjsContextPrivate::from_cx(cx);
    priv->main_loop_release();

    JS::Value callback_priv = js::GetFunctionNativeReserved(&args.callee(), 0);
    g_assert(callback_priv.isObject() && "Wrong private value");
    JS::RootedObject callback_data(cx, &callback_priv.toObject());

    JS::RootedValue importing_module_priv(cx);
    JS::RootedValue v_module_request(cx);
    JS::RootedValue v_internal_promise(cx);
    bool ok GJS_USED_ASSERT =
        JS_GetProperty(cx, callback_data, "priv", &importing_module_priv) &&
        JS_GetProperty(cx, callback_data, "promise", &v_internal_promise) &&
        JS_GetProperty(cx, callback_data, "module_request", &v_module_request);
    g_assert(ok && "Wrong properties on private value");

    g_assert(v_module_request.isObject() && "Wrong type for module request");
    g_assert(v_internal_promise.isObject() && "Wrong type for promise");

    JS::RootedObject module_request(cx, &v_module_request.toObject());
    JS::RootedObject internal_promise(cx, &v_internal_promise.toObject());

    args.rval().setUndefined();

    return JS::FinishDynamicModuleImport(cx, evaluation_promise,
                                         importing_module_priv, module_request,
                                         internal_promise);
}

// Failing a JSAPI function may result either in an exception pending on the
// context, in which case we must call JS::FinishDynamicModuleImport() to reject
// the internal promise; or in an uncatchable exception such as OOM, in which
// case we must not call JS::FinishDynamicModuleImport().
GJS_JSAPI_RETURN_CONVENTION
static bool fail_import(JSContext* cx, const JS::CallArgs& args) {
    if (JS_IsExceptionPending(cx))
        return finish_import(cx, nullptr, args);
    return false;
}

GJS_JSAPI_RETURN_CONVENTION
static bool import_rejected(JSContext* cx, unsigned argc, JS::Value* vp) {
    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);

    gjs_debug(GJS_DEBUG_IMPORTER, "Async import promise rejected");

    // Throw the value that the promise is rejected with, so that
    // FinishDynamicModuleImport will reject the internal_promise with it.
    JS_SetPendingException(cx, args.get(0),
                           JS::ExceptionStackBehavior::DoNotCapture);

    return finish_import(cx, nullptr, args);
}

GJS_JSAPI_RETURN_CONVENTION
static bool import_resolved(JSContext* cx, unsigned argc, JS::Value* vp) {
    JS::CallArgs args = JS::CallArgsFromVp(argc, vp);

    gjs_debug(GJS_DEBUG_IMPORTER, "Async import promise resolved");

    Gjs::AutoMainRealm ar{cx};

    g_assert(args[0].isObject());
    JS::RootedObject module(cx, &args[0].toObject());

    JS::RootedValue evaluation_promise(cx);
    if (!JS::ModuleLink(cx, module) ||
        !JS::ModuleEvaluate(cx, module, &evaluation_promise))
        return fail_import(cx, args);

    g_assert(evaluation_promise.isObject() &&
             "got weird value from JS::ModuleEvaluate");
    JS::RootedObject evaluation_promise_object(cx,
                                               &evaluation_promise.toObject());
    return finish_import(cx, evaluation_promise_object, args);
}

bool gjs_dynamic_module_resolve(JSContext* cx,
                                JS::HandleValue importing_module_priv,
                                JS::HandleObject module_request,
                                JS::HandleObject internal_promise) {
    g_assert(gjs_global_is_type(cx, GjsGlobalType::DEFAULT) &&
             "gjs_dynamic_module_resolve can only be called from the default "
             "global.");

    JS::RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
    g_assert(global && "gjs_dynamic_module_resolve must be in a realm");

    JS::RootedValue v_loader(
        cx, gjs_get_global_slot(global, GjsGlobalSlot::MODULE_LOADER));
    g_assert(v_loader.isObject());
    JS::RootedObject loader(cx, &v_loader.toObject());
    JS::RootedString specifier(
        cx, JS::GetModuleRequestSpecifier(cx, module_request));

    if (!canonicalize_specifier(cx, &specifier))
        return false;

    JS::RootedObject callback_data(cx, JS_NewPlainObject(cx));
    if (!callback_data ||
        !JS_DefineProperty(cx, callback_data, "module_request", module_request,
                           JSPROP_PERMANENT) ||
        !JS_DefineProperty(cx, callback_data, "promise", internal_promise,
                           JSPROP_PERMANENT) ||
        !JS_DefineProperty(cx, callback_data, "priv", importing_module_priv,
                           JSPROP_PERMANENT))
        return false;

    if (importing_module_priv.isObject()) {
        gjs_debug(GJS_DEBUG_IMPORTER,
                  "Async module resolve hook for module %s (relative to %p), "
                  "global %p",
                  gjs_debug_string(specifier).c_str(),
                  &importing_module_priv.toObject(), global.get());
    } else {
        gjs_debug(GJS_DEBUG_IMPORTER,
                  "Async module resolve hook for module %s (unknown path), "
                  "global %p",
                  gjs_debug_string(specifier).c_str(), global.get());
    }

    JS::RootedValueArray<2> args(cx);
    args[0].set(importing_module_priv);
    args[1].setString(specifier);

    JS::RootedValue result(cx);
    if (!JS::Call(cx, loader, "moduleResolveAsyncHook", args, &result))
        return JS::FinishDynamicModuleImport(cx, nullptr, importing_module_priv,
                                             module_request, internal_promise);

    // Release in finish_import
    GjsContextPrivate* priv = GjsContextPrivate::from_cx(cx);
    priv->main_loop_hold();

    JS::RootedObject resolved(
        cx, JS_GetFunctionObject(js::NewFunctionWithReserved(
                cx, import_resolved, 1, 0, "async import resolved")));
    if (!resolved)
        return false;
    JS::RootedObject rejected(
        cx, JS_GetFunctionObject(js::NewFunctionWithReserved(
                cx, import_rejected, 1, 0, "async import rejected")));
    if (!rejected)
        return false;
    js::SetFunctionNativeReserved(resolved, 0, JS::ObjectValue(*callback_data));
    js::SetFunctionNativeReserved(rejected, 0, JS::ObjectValue(*callback_data));

    JS::RootedObject promise(cx, &result.toObject());

    // Calling JS::FinishDynamicModuleImport() at the end of the resolve and
    // reject handlers will also call the module resolve hook. The module will
    // already have been resolved, but that is how SpiderMonkey obtains the
    // module object.
    return JS::AddPromiseReactions(cx, promise, resolved, rejected);
}
