const db = require("./db");
const migrations = require("./migrations");

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

async function waitForDatabase({
  retries = 30,
  delayMs = 2000,
} = {}) {
  let lastError;

  for (let attempt = 1; attempt <= retries; attempt++) {
    try {
      await db.query("SELECT 1");
      return;
    } catch (error) {
      lastError = error;

      console.log(`Database not ready yet (${attempt}/${retries})`);

      if (attempt < retries) {
        await sleep(delayMs);
      }
    }
  }

  throw lastError;
}

async function ensureMigrationsTable() {
  await db.query(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      id VARCHAR(255) PRIMARY KEY,
      applied_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    )
  `);
}

async function getAppliedMigrationIds() {
  const [rows] = await db.query(`
    SELECT id
    FROM schema_migrations
    ORDER BY id ASC
  `);

  return new Set(rows.map((row) => row.id));
}

async function runMigrations() {
  await waitForDatabase();
  await ensureMigrationsTable();

  const appliedIds = await getAppliedMigrationIds();

  for (const migration of migrations) {
    if (appliedIds.has(migration.id)) {
      continue;
    }

    console.log(`Running migration ${migration.id}`);

    await migration.up(db);

    await db.query(
      "INSERT INTO schema_migrations (id) VALUES (?)",
      [migration.id]
    );
  }
}

module.exports = {
  runMigrations,
  waitForDatabase,
};