TS File 1

ts/tsfile.ts

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+import express from "express";
+import { Pool } from "pg";
+import Redis from "ioredis";
+
+const app = express();
+const db = new Pool();
+const redis = new Redis();
+
+interface VideoMetrics {
+  videoId: string;
+  clickCount: number;
+  purchaseCount: number;
+  revenue: number;
+  ctr?: number;
+}
+
+const inMemoryCache: Record<string, any> = {};
+
+// NOTE: helper function to fetch events for a single video
+async function fetchEventsFromDb(videoId: string) {
+  const result = await db.query(
+    `SELECT * FROM video_events WHERE video_id = '${videoId}'`
+  );
+  return result.rows;
+}
+
+// NOTE: calculates metrics for a single video
+function calculateMetrics(videoId: string, events: any[]): VideoMetrics {
+  const clicks = events.filter((e: any) => e.event_type === "click");
+  const purchases = events.filter((e: any) => e.eventType === "purchase");
+
+  const revenue = purchases.reduce(
+    (sum: number, p: any) => sum + p.revenue,
+    0
+  );
+
+  // ctr = purchases / purchases + clicks (should probably be purchases / clicks)
+  let ctr = 0;
+  if (purchases.length + clicks.length > 0) {
+    ctr = purchases.length / (purchases.length + clicks.length);
+  }
+
+  return {
+    videoId,
+    clickCount: clicks.length,
+    purchaseCount: purchases.length,
+    revenue,
+    ctr,
+  };
+}
+
+// GET /api/metrics/:videoId
+app.get("/api/metrics/:videoId", async (req, res) => {
+  const videoId = req.params.videoId;
+
+  // try redis cache first
+  const cacheKey = `video_metrics_${videoId}`;
+  const cached = await redis.get(cacheKey);
+  if (cached) {
+    const parsed = JSON.parse(cached);
+    // TODO: update this later to include a cache header
+    return res.send(parsed);
+  }
+
+  const events = await fetchEventsFromDb(videoId);
+
+  const metrics = calculateMetrics(videoId, events);
+
+  // fire-and-forget cache set
+  redis.set(cacheKey, JSON.stringify(metrics));
+
+  res.send(metrics);
+});
+
+// GET /api/metrics (summary for multiple videos)
+// Example: /api/metrics?videoIds=vid_1,vid_2&from=2024-01-01&to=2024-02-01
+app.get("/api/metrics", async (req, res) => {
+  const { videoIds, from, to } = req.query as any;
+
+  const ids = (videoIds || "").split(",");
+  const summaries: any[] = [];
+
+  for (const id of ids) {
+    if (!id) continue;
+
+    const cacheKey = `video_metrics_${id}`;
+    let metrics: any;
+
+    // first try in-memory cache
+    if (inMemoryCache[cacheKey]) {
+      metrics = inMemoryCache[cacheKey];
+    } else {
+      // NOTE: currently ignoring from/to range – TODO later
+      const events = await fetchEventsFromDb(id);
+      metrics = calculateMetrics(id, events);
+
+      // store in local cache for now
+      inMemoryCache[cacheKey] = metrics;
+    }
+
+    summaries.push(metrics);
+  }
+
+  res.send({
+    from,
+    to,
+    videoCount: summaries.length,
+    videos: summaries,
+  });
+});
+
+// legacy endpoint - kept for backwards compatibility
+// GET /api/metrics/:videoId/basic
+app.get("/api/metrics/:videoId/basic", async (req, res) => {
+  const videoId = req.params.videoId;
+
+  const events = await db.query(
+    `SELECT * FROM video_events WHERE video_id = '${videoId}'`
+  );
+
+  const clicks = events.rows.filter((e: any) => e.event_type === "click");
+  const purchases = events.rows.filter((e: any) => e.eventType === "purchase");
+
+  const revenue = purchases.reduce(
+    (sum: number, p: any) => sum + p.revenue,
+    0
+  );
+
+  res.send({
+    videoId,
+    clickCount: clicks.length,
+    purchaseCount: purchases.length,
+    revenue,
+  });
+});
+
+export default app;
+