/**
 * Example: Authenticated Streaming Handler
 *
 * This example shows how to use authentication with streaming handlers.
 * Works with any Flink auth plugin (JWT, BankID, OAuth, etc.)
 */

import { StreamHandler, StreamingRouteProps } from "@flink-app/streaming-plugin";
import { FlinkContext } from "@flink-app/flink";

// Route configuration with permissions
export const Route: StreamingRouteProps = {
    path: "/admin/live-metrics",
    format: "sse",
    skipAutoRegister: true,
    permissions: ["admin"], // Only users with 'admin' role can access
};

interface MetricEvent {
    metric: string;
    value: number;
    timestamp: number;
    userId: string;
}

/**
 * Authenticated streaming handler
 * Only accessible to users with 'admin' permission
 */
const GetLiveMetrics: StreamHandler<FlinkContext, MetricEvent> = async ({ req, stream }) => {
    // req.user is populated by the auth plugin after successful authentication
    const userId = (req as any).user?.userId || "unknown";

    console.log(`Admin user ${userId} connected to live metrics stream`);

    let count = 0;
    const maxMetrics = 20;

    // Stream metrics every second
    const interval = setInterval(() => {
        if (!stream.isOpen() || count >= maxMetrics) {
            clearInterval(interval);
            stream.end();
            console.log(`User ${userId} disconnected from metrics stream`);
            return;
        }

        // Send metric with user context
        stream.write({
            metric: "cpu_usage",
            value: Math.random() * 100,
            timestamp: Date.now(),
            userId,
        });

        count++;
    }, 1000);
};

export default GetLiveMetrics;

/**
 * CLIENT USAGE:
 *
 * ```typescript
 * // Must include authentication header (depends on your auth plugin)
 * const eventSource = new EventSource('/admin/live-metrics', {
 *     headers: {
 *         'Authorization': 'Bearer your-jwt-token'
 *     }
 * });
 *
 * eventSource.onmessage = (event) => {
 *     const metric = JSON.parse(event.data);
 *     console.log(`Metric from user ${metric.userId}:`, metric);
 * };
 *
 * eventSource.onerror = (error) => {
 *     console.error('Authentication failed or connection lost');
 * };
 * ```
 *
 * Note: EventSource API doesn't support custom headers in browsers.
 * For authenticated SSE, you may need to:
 * 1. Pass token as query parameter: `/admin/live-metrics?token=...`
 * 2. Use cookie-based authentication
 * 3. Use Fetch API with ReadableStream instead of EventSource
 */