@steambrew/api/src/index.ts

A support library for creating plugins with Millennium.

const isSteamLoopbackHost = window.location.hostname === 'steamloopback.host';

declare global {
    interface Window {
        Millennium: Millennium,
        PLUGIN_LIST: any,
        MILLENNIUM_BACKEND_IPC: any,
        MILLENNIUM_IPC_SOCKET: WebSocket,
        CURRENT_IPC_CALL_COUNT: number
    }
}

/** Returnable IPC types */
type IPC_types = (string | number | boolean)

declare const g_PopupManager: any;

window.MILLENNIUM_BACKEND_IPC = {
    postMessage: (messageId: number, contents: string) => new Promise((resolve) => {
        const message = { id: messageId, iteration: window.CURRENT_IPC_CALL_COUNT++, data: contents };

        const messageHandler = (data: MessageEvent) => {
            let json;
            try {
                json = JSON.parse(data.data);
            } catch {
                console.error('Failed to parse JSON from backend IPC', data.data, contents);
                return;
            }

            if (json.id !== message.iteration) return;

            resolve(json);
            window.MILLENNIUM_IPC_SOCKET.removeEventListener('message', messageHandler);
        };

        window.MILLENNIUM_IPC_SOCKET.addEventListener('message', messageHandler);
        window.MILLENNIUM_IPC_SOCKET.send(JSON.stringify(message));
    })
}

window.Millennium = {
    // @ts-ignore (ignore overloaded function)
    callServerMethod: (pluginName: string, methodName: string, kwargs: any) =>  new Promise((resolve, reject) => {
        const query = { pluginName, methodName, ...(kwargs && { argumentList: kwargs }) };

        window.MILLENNIUM_BACKEND_IPC.postMessage(0, query).then((response: any) => {
            if (response?.failedRequest) {
                return reject(`IPC call failed [plugin: ${pluginName}, method: ${methodName}] -> ${response.failMessage}`);
            }

            resolve(typeof response.returnValue === 'string' ? atob(response.returnValue) : response.returnValue);
        });
    }),
    findElement: (privateDocument: Document, querySelector: string, timeout?: number): Promise<NodeListOf<Element>> => new Promise((resolve, reject) => {
        const matchedElements = privateDocument.querySelectorAll(querySelector);
        if (matchedElements.length) return resolve(matchedElements);

        const observer = new MutationObserver(() => {
            const elements = privateDocument.querySelectorAll(querySelector);
            if (elements.length) {
                observer.disconnect();
                if (timer) clearTimeout(timer);
                resolve(elements);
            }
        });

        observer.observe(privateDocument.body, { childList: true, subtree: true });

        const timer = timeout && setTimeout(() => {
            observer.disconnect();
            reject();
        }, timeout);
    }),

    // Only define exposeObj and AddWindowCreateHook if the current URL host is steamloopback.host
    ...(isSteamLoopbackHost ? {
        exposeObj: function<T extends object>(exports: any, obj: T): void {
            for (const key in obj) {
                exports[key] = obj[key];
            }
        },
        AddWindowCreateHook: (callback: any) => {
            // used to have extended functionality but removed since it was shotty
            g_PopupManager.AddPopupCreatedCallback((e: any) => {
                callback(e)
            });
        }
    } : {})
}

/*
 Global Millennium API for developers. 
*/
type Millennium = {
    /**
     * @brief Call a method on the backend
     * @deprecated Use `callable` instead. 
     * Example usage: 
     * ```typescript
     * // before
     * const result = await Millennium.callServerMethod('methodName', { arg1: 'value' });
     * // after
     * const method = callable<[{ arg1: string }]>("methodName");
     * 
     * const result1 = await method({ arg1: 'value1' });
     * const result2 = await method({ arg1: 'value2' });
     * ```
     */
    callServerMethod: (methodName: string, kwargs?: object) => Promise<any>,
    findElement: (privateDocument: Document, querySelector: string, timeOut?: number) => Promise<NodeListOf<Element>>,
    exposeObj?: <T extends object>(obj: T) => any,
    AddWindowCreateHook?: (callback: (context: object) => void) => void
};

// callable function definition
const callable = <Args extends any[] = [], Return = (void | IPC_types)>(
    cb: (route: string, ...args: Args) => Promise<Return>,
    route: string
): ((...args: Args) => Promise<Return>) => {
    return (...args: Args) => cb(route, ...args);
};

// Only define and export pluginSelf if the current URL host is steamloopback.host
const m_private_context: any = undefined;
export const pluginSelf = isSteamLoopbackHost ? m_private_context : undefined;

const Millennium: Millennium = window.Millennium;
export { Millennium, callable };