import fs from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { pool } from "./pool.ts";

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const MIGRATIONS_DIR = path.join(__dirname, "migrations");

/**
 * Aplica en orden alfabético los .sql que aún no estén en schema_migrations.
 * Cada archivo corre dentro de su propia transacción: si falla a la mitad, no
 * queda registrado y la siguiente corrida lo reintenta entero.
 */
export async function runMigrations(): Promise<string[]> {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      filename    text PRIMARY KEY,
      applied_at  timestamptz NOT NULL DEFAULT now()
    )
  `);

  const files = fs
    .readdirSync(MIGRATIONS_DIR)
    .filter((f) => f.endsWith(".sql"))
    .sort();

  const { rows } = await pool.query<{ filename: string }>(
    `SELECT filename FROM schema_migrations`
  );
  const applied = new Set(rows.map((r) => r.filename));

  const ran: string[] = [];
  for (const file of files) {
    if (applied.has(file)) continue;
    const sql = fs.readFileSync(path.join(MIGRATIONS_DIR, file), "utf8");
    const client = await pool.connect();
    try {
      await client.query("BEGIN");
      await client.query(sql);
      await client.query(`INSERT INTO schema_migrations (filename) VALUES ($1)`, [file]);
      await client.query("COMMIT");
      ran.push(file);
      console.log(`[migrate] aplicada ${file}`);
    } catch (e) {
      await client.query("ROLLBACK");
      throw new Error(`Migración ${file} falló: ${(e as Error).message}`);
    } finally {
      client.release();
    }
  }
  return ran;
}

// Permite `node scripts/run-tsx.mjs platform/db/migrate.ts` desde la línea de comandos.
if (process.argv[1] && fileURLToPath(import.meta.url) === path.resolve(process.argv[1])) {
  runMigrations()
    .then((ran) => {
      console.log(ran.length ? `[migrate] ${ran.length} aplicadas` : "[migrate] al día");
      return pool.end();
    })
    .catch((e) => {
      console.error(e.message);
      process.exit(1);
    });
}