/**
 * server.js — Node.js CRUD (Express + MariaDB).
 *
 * Переменные окружения:
 *   DB_HOST, DB_PORT, DB_NAME, DB_USER, DB_PASSWORD
 *   TABLE_NAME (по умолчанию crud_items)
 *   PORT (по умолчанию 3000)
 *
 * При старте: CREATE TABLE IF NOT EXISTS.
 */
const express = require("express");
const mysql = require("mysql2/promise");
const path = require("path");

const VERSION = "1.0.0";
const TABLE_NAME = process.env.TABLE_NAME || "crud_items";
if (!/^[A-Za-z_][A-Za-z0-9_]*$/.test(TABLE_NAME)) {
  throw new Error("TABLE_NAME must be a simple SQL identifier");
}
const TABLE_SQL = `\`${TABLE_NAME}\``;
// SERVICE_NAME — какое приложение добавило строку (колонка created_by).
// Задаётся в json_env манифеста для каждого сервиса (flask / lucee / nodejs).
const SERVICE_NAME = process.env.SERVICE_NAME || "nodejs";
const PORT = process.env.PORT || 3000;

const pool = mysql.createPool({
  host: process.env.DB_HOST || "127.0.0.1",
  port: Number.parseInt(process.env.DB_PORT || "3306", 10),
  database: process.env.DB_NAME || "maria",
  user: process.env.DB_USER || "",
  password: process.env.DB_PASSWORD || "",
  waitForConnections: true,
  connectionLimit: 5,
  queueLimit: 0,
  charset: "utf8mb4",
});

const app = express();
app.use(express.urlencoded({ extended: true }));
app.use(express.static(path.join(__dirname, "public")));
app.set("view engine", "ejs");
app.set("views", path.join(__dirname, "views"));

// --- Инициализация БД ---
// Таблица выставочная: кроме id/value — две метки: created_at (когда добавлено)
// и created_by (какое приложение добавило). ALTER ... IF NOT EXISTS досыпает
// колонки в таблицу, созданную прошлой версией приложения, не теряя данные.
async function initDB() {
  const client = await pool.getConnection();
  try {
    await client.query(`
      CREATE TABLE IF NOT EXISTS ${TABLE_SQL} (
        id         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
        \`value\`  TEXT NOT NULL,
        created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
        created_by VARCHAR(255) NOT NULL DEFAULT ''
      ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
    `);
    await client.query(
      `ALTER TABLE ${TABLE_SQL} ADD COLUMN IF NOT EXISTS created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP`
    );
    await client.query(
      `ALTER TABLE ${TABLE_SQL} ADD COLUMN IF NOT EXISTS created_by VARCHAR(255) NOT NULL DEFAULT ''`
    );
  } finally {
    client.release();
  }
}

// --- Главная страница (GET + POST) ---
app.get("/", async (req, res) => {
  try {
    let editRow = null;
    if (req.query.edit) {
      const [editRows] = await pool.execute(
        `SELECT id, \`value\`, created_at, created_by FROM ${TABLE_SQL} WHERE id = ?`,
        [parseInt(req.query.edit)]
      );
      if (editRows.length > 0) editRow = editRows[0];
    }

    const [rows] = await pool.execute(
      `SELECT id, \`value\`, created_at, created_by FROM ${TABLE_SQL} ORDER BY id`
    );

    res.render("index", {
      table_name: TABLE_NAME,
      rows,
      editRow,
      version: VERSION,
    });
  } catch (err) {
    res.status(500).send(err.message);
  }
});

app.post("/", async (req, res) => {
  try {
    const { action, value, id } = req.body;

    if (action === "create") {
      // created_at ставит СУБД (DEFAULT now()), created_by — имя этого сервиса
      await pool.execute(
        `INSERT INTO ${TABLE_SQL} (\`value\`, created_by) VALUES (?, ?)`,
        [value || "", SERVICE_NAME]
      );
    } else if (action === "update") {
      await pool.execute(`UPDATE ${TABLE_SQL} SET \`value\` = ? WHERE id = ?`, [
        value || "",
        parseInt(id || 0),
      ]);
    } else if (action === "delete") {
      await pool.execute(`DELETE FROM ${TABLE_SQL} WHERE id = ?`, [
        parseInt(id || 0),
      ]);
    }

    res.redirect("/");
  } catch (err) {
    res.status(500).send(err.message);
  }
});

// --- Старт ---
// Сервер стартует всегда, даже если PG недоступен.
// initDB — асинхронно, ошибка логируется но не роняет под.
initDB()
  .then(() => console.log("DB ready"))
  .catch((err) => console.error("DB init failed:", err.message));

app.listen(PORT, () => {
  console.log(`Node.js CRUD v${VERSION} — http://0.0.0.0:${PORT}`);
});