// Persists uploaded tables (and their optional ROM zip) in the browser via
// IndexedDB, so a returning visitor can replay a table without re-uploading
// it. Blobs are stored as-is (File objects are Blobs) rather than converted
// to ArrayBuffer up front — IndexedDB clones Blobs without loading their
// bytes into JS memory, so a large library doesn't sit resident until a
// specific entry is actually played.

const DB_NAME = "vpinball-library";
const DB_VERSION = 1;
const STORE = "tables";

export interface LibraryEntry {
  id: string;
  name: string;
  sizeBytes: number;
  addedAt: number;
  vpxBlob: Blob;
  romFileName?: string;
  romBlob?: Blob;
}

export type LibraryEntryMeta = Omit<LibraryEntry, "vpxBlob" | "romBlob">;

function openDb(): Promise<IDBDatabase> {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open(DB_NAME, DB_VERSION);
    request.onupgradeneeded = () => {
      request.result.createObjectStore(STORE, { keyPath: "id" });
    };
    request.onsuccess = () => resolve(request.result);
    request.onerror = () => reject(request.error);
  });
}

async function withStore<T>(mode: IDBTransactionMode, fn: (store: IDBObjectStore) => IDBRequest<T>): Promise<T> {
  const db = await openDb();
  try {
    return await new Promise<T>((resolve, reject) => {
      const tx = db.transaction(STORE, mode);
      const request = fn(tx.objectStore(STORE));
      request.onsuccess = () => resolve(request.result);
      request.onerror = () => reject(request.error);
    });
  } finally {
    db.close();
  }
}

export async function saveToLibrary(entry: LibraryEntry): Promise<void> {
  await withStore("readwrite", (store) => store.put(entry));
}

export async function listLibrary(): Promise<LibraryEntryMeta[]> {
  const entries = await withStore<LibraryEntry[]>("readonly", (store) => store.getAll());
  return entries
    .map((entry): LibraryEntryMeta => ({
      id: entry.id,
      name: entry.name,
      sizeBytes: entry.sizeBytes,
      addedAt: entry.addedAt,
      romFileName: entry.romFileName,
    }))
    .sort((a, b) => b.addedAt - a.addedAt);
}

export async function getLibraryEntry(id: string): Promise<LibraryEntry | undefined> {
  return withStore<LibraryEntry | undefined>("readonly", (store) => store.get(id));
}

export async function deleteFromLibrary(id: string): Promise<void> {
  await withStore("readwrite", (store) => store.delete(id));
}