success pt. 3

src/lib/db/client-db/seed.ts

@@ -0,0 +1,94 @@
+import { browser } from "$app/environment";
+import { asset } from "$app/paths";
+import { overwriteDatabaseFile } from "$lib/db/client-db";
+
+/**
+ * Version-keyed seeding for the client-side SQLocal database.
+ *
+ * Your shipped snapshot lives at:
+ * - `static/data/amq.sqlite` -> `/data/amq.sqlite`
+ *
+ * SQLocal stores its own managed DB file (named in `client-db.ts`), and we
+ * overwrite its contents from the shipped snapshot when needed.
+ *
+ * This is intended for READ-ONLY browsing. Bump the version when you ship a new
+ * snapshot so clients refresh.
+ */
+export const AMQ_DB_SEED_VERSION = 1;
+
+const SEED_ASSET_PATH = "/data/amq.sqlite";
+const seededStorageKey = (version: number) => `amq.sqlocal.seeded.v${version}`;
+
+let seedPromise: Promise<void> | null = null;
+
+function ensureBrowser() {
+	if (!browser) {
+		throw new Error("Client DB seeding can only run in the browser.");
+	}
+}
+
+/**
+ * Ensure the client DB has been seeded for the given version.
+ *
+ * - Uses `localStorage` to skip reseeding once done.
+ * - Uses a shared promise to avoid races across multiple callers.
+ * - Uses streaming (ReadableStream) when available for large DB files.
+ *
+ * @param opts.version Bump to force users to refresh from the shipped snapshot
+ * @param opts.force If true, reseed even if already seeded for this version
+ */
+export async function ensureSeeded(
+	opts: { version?: number; force?: boolean } = {},
+): Promise<void> {
+	ensureBrowser();
+
+	const version = opts.version ?? AMQ_DB_SEED_VERSION;
+	const key = seededStorageKey(version);
+
+	if (!opts.force && localStorage.getItem(key) === "1") return;
+
+	// Serialize seeding work so multiple callers don't overwrite concurrently.
+	if (seedPromise) return seedPromise;
+
+	seedPromise = (async () => {
+		// Re-check inside the serialized section in case another caller finished first.
+		if (!opts.force && localStorage.getItem(key) === "1") return;
+
+		const url = asset(SEED_ASSET_PATH);
+
+		const res = await fetch(url, { cache: "no-cache" });
+		if (!res.ok) {
+			throw new Error(
+				`Failed to fetch seed DB from ${url}: ${res.status} ${res.statusText}`,
+			);
+		}
+
+		// Prefer streaming when possible.
+		if (res.body) {
+			await overwriteDatabaseFile(res.body);
+		} else {
+			const blob = await res.blob();
+			await overwriteDatabaseFile(blob);
+		}
+
+		localStorage.setItem(key, "1");
+	})();
+
+	try {
+		await seedPromise;
+	} finally {
+		// If seeding failed, allow future attempts (and let the error surface).
+		if (localStorage.getItem(key) !== "1") {
+			seedPromise = null;
+		}
+	}
+}
+
+/**
+ * Utility for debugging / support: clears the seeded marker for a given version.
+ * This does NOT delete SQLocal's stored DB file; it only forces reseed on next call.
+ */
+export function clearSeedMarker(version = AMQ_DB_SEED_VERSION) {
+	ensureBrowser();
+	localStorage.removeItem(seededStorageKey(version));
+}