// queue storage that persists to IndexedDB across sessions

class QueueStorage {
	constructor() {
		this.db = null;
	}

	async ensureDB() {
		if (this.db) return this.db;

		try {
			return await new Promise((resolve) => {
				const req = indexedDB.open("tinysub", 2);

				req.onsuccess = () => {
					this.db = req.result;
					resolve(this.db);
				};

				req.onupgradeneeded = (e) => {
					const db = e.target.result;
					if (!db.objectStoreNames.contains("queueStorage")) {
						db.createObjectStore("queueStorage");
					}
				};

				req.onerror = () => resolve(null);
			});
		} catch (error) {
			console.error("[QueueStorage] IndexedDB initialization failed:", error);
			return null;
		}
	}
	async save(songs, queueIndex) {
		const db = await this.ensureDB();
		if (!db) return;

		return new Promise((resolve) => {
			try {
				const tx = db.transaction(["queueStorage"], "readwrite");
				const store = tx.objectStore("queueStorage");

				store.put(songs, "songs");
				store.put(queueIndex, "queueIndex");

				tx.onerror = () => {
					console.error("[QueueStorage] Failed to save queue");
					resolve();
				};
				tx.oncomplete = () => resolve();
			} catch (error) {
				console.error("[QueueStorage] Save failed:", error);
				resolve();
			}
		});
	}

	async load() {
		const db = await this.ensureDB();
		if (!db) return { songs: [], queueIndex: -1 };

		return new Promise((resolve) => {
			try {
				const tx = db.transaction(["queueStorage"], "readonly");
				const store = tx.objectStore("queueStorage");

				const songsReq = store.get("songs");
				const indexReq = store.get("queueIndex");

				tx.onerror = () => {
					console.error("[QueueStorage] Failed to load queue");
					resolve({ songs: [], queueIndex: -1 });
				};
				tx.oncomplete = () => {
					resolve({
						songs: songsReq.result || [],
						queueIndex: indexReq.result ?? -1,
					});
				};
			} catch (error) {
				console.error("[QueueStorage] Load failed:", error);
				resolve({ songs: [], queueIndex: -1 });
			}
		});
	}
}

const queueStorage = new QueueStorage();