/**
 * The database handle. Importing this module opens the database at
 * {@link DB_PATH}, applies the pending migrations and runs the startup tasks.
 *
 * @module
 */

import { DatabaseSync } from "node:sqlite";
import { DB_PATH } from "../config.ts";
import { runMigrations } from "./migrate.ts";
import { runStartupTasks } from "./startup.ts";

/** The one connection every service queries through. */
export const db: DatabaseSync = new DatabaseSync(DB_PATH);
// WAL lets readers run alongside a writer, and with synchronous = NORMAL a
// commit no longer waits on an fsync (a crash can lose the last transactions,
// never corrupt the file). busy_timeout covers the init/migration scripts and
// the test harness opening the same file.
db.exec(`
  PRAGMA journal_mode = WAL;
  PRAGMA synchronous = NORMAL;
  PRAGMA busy_timeout = 5000;
  PRAGMA foreign_keys = ON;
`);
runMigrations(db);
await runStartupTasks(db);

/**
 * Runs `fn` inside one transaction: several writes commit together (and cost
 * one commit rather than one each), and a throw rolls them all back. Nested
 * calls join the outer transaction.
 */
export function transaction<T>(fn: () => T): T {
  if (db.isTransaction) return fn();
  db.exec("BEGIN;");
  try {
    const result = fn();
    db.exec("COMMIT;");
    return result;
  } catch (err) {
    db.exec("ROLLBACK;");
    throw err;
  }
}