update

landing/functions/api/download-stats.ts

@@ -0,0 +1,34 @@
+import type { CounterDatabase, PagesHandler } from "../types";
+import { DOWNLOAD_COUNT_SEED } from "../../lib/downloads";
+
+interface Env {
+  DOWNLOAD_COUNTER_DB: CounterDatabase;
+}
+
+async function readDownloadCount(db: CounterDatabase) {
+  const result = await db
+    .prepare(`
+      SELECT
+        COALESCE(
+          (SELECT value FROM download_counter_settings WHERE key = 'base_downloads'),
+          ?
+        ) + COUNT(*) AS downloads
+      FROM unique_download_windows
+    `)
+    .bind(DOWNLOAD_COUNT_SEED)
+    .first<{ downloads: number }>();
+
+  return result?.downloads ?? DOWNLOAD_COUNT_SEED;
+}
+
+export const onRequestGet: PagesHandler<Env> = async (context) => {
+  const downloads = await readDownloadCount(context.env.DOWNLOAD_COUNTER_DB);
+  return Response.json(
+    { downloads },
+    {
+      headers: {
+        "Cache-Control": "no-store",
+      },
+    },
+  );
+};

landing/functions/api/download.ts

@@ -0,0 +1,73 @@
+import {
+  DOWNLOAD_DEDUP_WINDOW_MS,
+  getDownloadAsset,
+} from "../../lib/downloads";
+import type { CounterDatabase, PagesHandler } from "../types";
+
+interface Env {
+  DOWNLOAD_COUNTER_DB: CounterDatabase;
+  DOWNLOAD_COUNTER_SALT?: string;
+}
+
+function getClientIp(request: Request) {
+  const cfConnectingIp = request.headers.get("CF-Connecting-IP")?.trim();
+  if (cfConnectingIp) {
+    return cfConnectingIp;
+  }
+
+  const forwardedFor = request.headers.get("X-Forwarded-For")?.split(",")[0]?.trim();
+  return forwardedFor || null;
+}
+
+function getWindowKey(now = Date.now()) {
+  return Math.floor(now / DOWNLOAD_DEDUP_WINDOW_MS);
+}
+
+async function sha256Hex(input: string) {
+  const buffer = await crypto.subtle.digest("SHA-256", new TextEncoder().encode(input));
+  return Array.from(new Uint8Array(buffer), (byte) => byte.toString(16).padStart(2, "0")).join("");
+}
+
+async function countUniqueDownload(db: CounterDatabase, request: Request, assetId: string, salt: string | undefined) {
+  const clientIp = getClientIp(request);
+  if (!clientIp) {
+    return;
+  }
+
+  const ipHash = await sha256Hex(`${salt ?? ""}:${clientIp}`);
+  const windowKey = getWindowKey();
+
+  await db
+    .prepare(`
+      INSERT OR IGNORE INTO unique_download_windows (
+        ip_hash,
+        window_key,
+        first_asset_id,
+        created_at
+      ) VALUES (?, ?, ?, datetime('now'))
+    `)
+    .bind(ipHash, windowKey, assetId)
+    .run();
+}
+
+export const onRequestGet: PagesHandler<Env> = async (context) => {
+  const url = new URL(context.request.url);
+  const assetId = url.searchParams.get("asset")?.trim();
+  if (!assetId) {
+    return new Response("Missing asset parameter.", { status: 400 });
+  }
+
+  const asset = getDownloadAsset(assetId);
+  if (!asset) {
+    return new Response("Unknown asset.", { status: 404 });
+  }
+
+  await countUniqueDownload(
+    context.env.DOWNLOAD_COUNTER_DB,
+    context.request,
+    asset.id,
+    context.env.DOWNLOAD_COUNTER_SALT,
+  );
+
+  return Response.redirect(asset.href, 302);
+};