// The blob store behind blob.ts and blob-global.ts: one SQLite file,
// blobs.db, with the same methods and errors as Val Town's std/blob.
import { DatabaseSync } from "node:sqlite";

export class ValTownBlobError extends Error {}
export class ValTownBlobNotFoundError extends ValTownBlobError {
  constructor() {
    super("Blob not found");
  }
}

export function openBlobs(dir: string) {
  Deno.mkdirSync(dir, { recursive: true });
  const db = new DatabaseSync(`${dir}/blobs.db`);
  db.exec("PRAGMA journal_mode = WAL; PRAGMA busy_timeout = 5000");
  db.exec(`CREATE TABLE IF NOT EXISTS blobs (key TEXT PRIMARY KEY,
    value BLOB NOT NULL, last_modified TEXT NOT NULL)`);

  async function get(key: string): Promise<Response> {
    const row = db.prepare("SELECT value FROM blobs WHERE key = ?").get(key) as
      | { value: Uint8Array }
      | undefined;
    if (!row) throw new ValTownBlobNotFoundError();
    return new Response(row.value);
  }
  async function set(key: string, value: BodyInit): Promise<void> {
    if (key.length < 1 || key.length > 512) throw new ValTownBlobError("Invalid key");
    const bytes = new Uint8Array(await new Response(value).arrayBuffer());
    db.prepare(`INSERT INTO blobs (key, value, last_modified) VALUES (?, ?, ?)
      ON CONFLICT (key) DO UPDATE SET value = excluded.value,
      last_modified = excluded.last_modified`).run(key, bytes, new Date().toISOString());
  }
  async function list(prefix = "") {
    return (db.prepare(`SELECT key, length(value) AS size, last_modified AS lastModified
      FROM blobs WHERE substr(key, 1, length(?)) = ? ORDER BY key`).all(prefix, prefix)) as {
      key: string;
      size: number;
      lastModified: string;
    }[];
  }
  async function delete_(key: string) {
    db.prepare("DELETE FROM blobs WHERE key = ?").run(key);
  }
  async function copy(previous: string, next: string) {
    await set(next, await (await get(previous)).arrayBuffer());
  }
  async function move(previous: string, next: string) {
    await copy(previous, next);
    await delete_(previous);
  }
  async function getJSON(key: string) {
    try {
      return await (await get(key)).json();
    } catch (e) {
      if (e instanceof ValTownBlobNotFoundError) return undefined;
      throw e;
    }
  }
  async function setJSON(key: string, value: unknown) {
    return await set(key, JSON.stringify(value));
  }
  return { get, set, copy, move, list, delete: delete_, getJSON, setJSON };
}