@juspay/neurolink/dist/server/middleware/abortSignal.js

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/**
 * Abort Signal Middleware
 * Provides client disconnection handling for long-running requests
 */
/**
 * Create abort signal middleware for handling client disconnections.
 *
 * This middleware creates an AbortController and attaches its signal to the context,
 * allowing route handlers to check for client disconnection during long-running operations.
 *
 * @param options - Optional configuration
 * @returns Middleware that attaches abort signal to context
 *
 * @example
 * ```typescript
 * const abortMiddleware = createAbortSignalMiddleware();
 * server.registerMiddleware(abortMiddleware);
 *
 * // In route handler:
 * const signal = ctx.abortSignal;
 * await longRunningOperation({ signal });
 * ```
 */
export function createAbortSignalMiddleware(options) {
    const { onAbort, timeout } = options ?? {};
    return {
        name: "abort-signal",
        order: 5, // Early in middleware chain
        handler: async (ctx, next) => {
            const controller = new AbortController();
            let timeoutId;
            // Set up timeout if configured
            if (timeout && timeout > 0) {
                timeoutId = setTimeout(() => {
                    controller.abort(new Error(`Request timeout after ${timeout}ms`));
                }, timeout);
            }
            // Framework-specific abort handling
            setupFrameworkAbortHandler(ctx, controller, onAbort);
            // Attach signal to context
            ctx.abortSignal = controller.signal;
            ctx.abortController = controller;
            try {
                return await next();
            }
            finally {
                // Clean up timeout
                if (timeoutId) {
                    clearTimeout(timeoutId);
                }
            }
        },
    };
}
/**
 * Set up framework-specific abort handling
 */
function setupFrameworkAbortHandler(ctx, controller, onAbort) {
    const frameworkResponse = ctx.rawResponse;
    if (!frameworkResponse) {
        return;
    }
    // Express: res.on('close')
    if (typeof frameworkResponse.on === "function") {
        const res = frameworkResponse;
        res.on("close", () => {
            if (!res.writableFinished) {
                controller.abort(new Error("Client disconnected"));
                onAbort?.(ctx);
            }
        });
    }
    // Hono/Fastify: May have different event patterns
    // Add additional framework support as needed
}
/**
 * Express-specific middleware factory.
 * Use this directly with Express adapter for optimal handling.
 *
 * This is a lower-level middleware that works directly with Express
 * request/response objects rather than the unified ServerContext.
 *
 * @param options - Optional configuration
 * @returns Express middleware function
 *
 * @example
 * ```typescript
 * // In Express adapter
 * app.use(createExpressAbortMiddleware());
 *
 * // Access in route handler
 * app.get('/api/stream', (req, res) => {
 *   const signal = res.locals.abortSignal;
 *   // Use signal for cancellation
 * });
 * ```
 */
export function createExpressAbortMiddleware(options) {
    return (_req, res, next) => {
        const controller = new AbortController();
        res.on("close", () => {
            if (!res.writableFinished) {
                controller.abort(new Error("Client disconnected"));
                options?.onAbort?.({});
            }
        });
        res.locals.abortSignal = controller.signal;
        res.locals.abortController = controller;
        next();
    };
}