// The following are types that are internal to the SDK

type BaseFunctionsFactory = {
    callFunction(name: string, args: unknown[]): Promise<unknown>;
};

type DefaultFunctionsFactory = BaseFunctionsFactory & {
    [name: string]: (...args: unknown[]) => Promise<unknown>;
};

type BaseAppTypes = {
    FunctionsFactory: unknown,
    CustomUserDataType: unknown,
    ProfileDataType: unknown
};

type AppTypes<T extends Partial<BaseAppTypes>> = T & BaseAppTypes;

declare class User<T extends BaseAppTypes> {
    get functions(): T["FunctionsFactory"];
    get data(): T["CustomUserDataType"];
}

class App<T extends BaseAppTypes> {
    currentUser: User<T> | null = null;
}

// Below are the types as used from an app

// The user can declare their own app's types, wrapping them in AppTypes to allow defaults to be applied for (sub)types that is not declared.
type MyAppTypes = AppTypes<{
    FunctionsFactory: {
        echo: () => Promise<void>
    },
}>;

// Using the types
const app = new App<MyAppTypes>();
if (app.currentUser) {
    app.currentUser.functions.echo();
}