declare const System: {
    /**
     * Loads a javascript module from either a url or bare specifier that is in an import map.
     * You may optionally provide a parentUrl that will be used for resolving relative urls.
     */
    import: System.ImportFn;

    /**
     * Inserts a new module into the SystemJS module registry. The System.register format is
     * the underlying implementation that allows for ESM emulation.
     * See https://github.com/systemjs/systemjs/blob/master/docs/system-register.md for more details.
     * Register may be called with a name argument if you are using the named-register extra. (See
     * https://github.com/systemjs/systemjs#extras).
     */
    register(dependencies: string[], declare: System.DeclareFn): void;
    register(name: string, dependencies: string[], declare: System.DeclareFn): void;

    /**
     * Resolve any moduleId to its full URL. For a moduleId that is in the import map, this will resolve
     * the full import map URL. For a moduleId that is a relative url, the returned url will be resolved
     * relative to the parentUrl or the current browser page's base url. For a full url, resolve() is
     * a no-op.
     */
    resolve(moduleId: string, parentUrl?: string): string;

    /**
     * Delete a module from the module registry. Note that the moduleId almost always must be a full url and that
     * you might need to call System.resolve() to obtain the moduleId for modules in an import map.
     * The returned function is intended for use after re-importing the module. Calling the function
     * will re-bind all the exports of the re-imported module to every module that depends on the module.
     */
    delete(moduleId: string): false | System.UpdateModuleFn;

    /**
     * Get a module from the SystemJS module registry. Note that the moduleId almost always must be a full url
     * and that you might need to call System.resolve() to obtain the moduleId. If the module does not exist in
     * the registry, null is returned.
     */
    get(moduleId: string): System.Module | null;
    // eslint-disable-next-line @definitelytyped/no-unnecessary-generics
    get<T>(moduleId: string): T | null;

    /**
     * Indicates whether the SystemJS module registry contains a module. Note that the moduleId almost always
     * must be a full url and that you might need to call System.resolve() to obtain the moduleId.
     */
    has(moduleId: string): boolean;

    /**
     * An alternative to System.register(), this allows you to insert a module into the module registry. Note that
     * the moduleId you provide will go straight into the registry without being resolved first.
     */
    set(moduleId: string, module: System.Module): void;

    /**
     * Use for (let entry of System.entries()) to access all of the modules in the SystemJS registry.
     */
    entries(): Iterable<[string, System.Module]>;

    /**
     * Dynamically extend additional mappings into the import map at any time.
     * Any existing map entries will be overridden with the new values.
     */
    addImportMap(importMap: System.ImportMap): void;

    /**
     * Gets combined import map.
     */
    getImportMap(): System.ImportMap;
};

declare namespace System {
    // eslint-disable-next-line @definitelytyped/no-unnecessary-generics
    type ImportFn = <T extends Module>(moduleId: string, parentUrl?: string) => Promise<T>;

    type DeclareFn = (_export: ExportFn, _context: Context) => Declare;
    interface Declare {
        setters?: SetterFn[] | undefined;
        execute?(): any;
    }
    type SetterFn = (moduleValue: Module) => any;
    type ExecuteFn = () => any;

    interface ExportFn {
        (exportName: string, value: any): void;
        (exports: object): void;
    }

    type UpdateModuleFn = () => void;

    type GetFn = GetFnModule | GetFnGeneric;
    type GetFnModule = (moduleId: string) => Module;
    // eslint-disable-next-line @definitelytyped/no-unnecessary-generics
    type GetFnGeneric = <T>(moduleId: string) => T;

    interface Context {
        import: ImportFn;
        meta: {
            url: string;
        };
    }

    interface Module {
        default?: any;
        [exportName: string]: any;
    }

    /** The importmap standard is defined here: https://github.com/WICG/import-maps */
    interface ImportMap {
        imports?: Record<string, string>;
        scopes?: Record<string, Record<string, string>>;
        integrity?: Record<string, string>;
    }
}