import type { NextFunction, Request, Response } from "express";
import express from "express";
import cors from "cors";
import dotenv from "dotenv";
import mysql, { type ResultSetHeader, type RowDataPacket } from "mysql2";
import { readFile } from "fs/promises"; // frontend routes
import userRouter from "./routes/app/users.route";
import productRouter from "./routes/app/products.route";
import storageRouter from "./routes/app/storage.route";
import path from "node:path";

dotenv.config();
const app = express();
app.set("view engine", "ejs");

const port = 8004;

app.use(cors());
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

const pool = mysql
  .createPool({
    host: process.env.DB_HOST!,
    user: process.env.DB_USER!,
    password: process.env.DB_PASSWORD!,
    database: process.env.DB_NAME!,
  })
  .promise();

app.use("/users", userRouter);

app.use("/products", productRouter);

app.use("/storage", storageRouter);

app.listen(port, () => {
  runStartup(port);
});

// Startup code
const runStartup = async (port: number) => {
  let firstStartupValue: string | null = null;
  try {
    const [firstResponse] = await pool.query<RowDataPacket[]>(
      `SELECT value
             FROM app_settings
             WHERE name = "first-startup";`,
    );
    firstStartupValue = firstResponse[0]?.value ?? null;
  } catch (err: unknown) {
    if (
      err instanceof Error &&
      (err as NodeJS.ErrnoException & { code?: string }).code !==
        "ER_NO_SUCH_TABLE"
    ) {
      throw err;
    }
  }

  if (firstStartupValue !== "false") {
    const schemaPath = path.join(__dirname, "database.scheme.sql");
    const schemaSql = await readFile(schemaPath, "utf8");
    const statements = schemaSql
      .split(";")
      .map((statement: string) => statement.trim())
      .filter((statement: string) => statement.length > 0);

    for (const statement of statements) {
      await pool.query(statement);
    }

    const [result] = await pool.query<RowDataPacket[]>(
      `SELECT value
             FROM app_settings
             WHERE name = "first-startup";`,
    );

    if (result[0]?.value === "true") {
      const insertResult = await insertFirstData();

      if (insertResult.affectedRows > 0) {
        console.log("Successfully created admin user!");
        console.log("Username: admin");
        console.log("Password: admin");

        const [scndResponse] = await pool.query<ResultSetHeader>(
          `UPDATE app_settings
                     SET value = "false"
                     WHERE name = "first-startup";`,
        );

        if (scndResponse.affectedRows > 0) {
          console.log("Database settet up successfully!");
        } else {
          console.error("There was an error while setting up the database!");
        }
      } else {
        console.error("Error while creating admin user.");
      }
    }
  }

  console.log("Everything is settet up successfully!");
  console.log(`Backend is running on http://localhost:${port}`);
};

const insertFirstData = async (): Promise<ResultSetHeader> => {
  const [insertResult] = await pool.query<ResultSetHeader>(
    `INSERT INTO users (username, first_name, last_name, email, password, is_admin)
         VALUES ("admin", "admin", "admin", "admin@example.com", "admin", 1)`,
  );

  await pool.query(
    `INSERT INTO storage_locations (name, description)
         VALUES (?, ?);`,
    ["Default Storage", "Initial storage location"],
  );

  const [storageRows] = await pool.query<RowDataPacket[]>(
    `SELECT uuid
         FROM storage_locations
         WHERE name = ? LIMIT 1;`,
    ["Default Storage"],
  );

  const storageUuid: string | null = storageRows[0]?.uuid ?? null;
  if (storageUuid) {
    await pool.query(
      `INSERT INTO products (name, description, price, amount, storage_location, picture)
             VALUES (?, ?, ?, ?, ?, ?);`,
      [
        "Welcome Product",
        "Your first item in Stockhome",
        "0.00",
        1,
        storageUuid,
        null,
      ],
    );
  }

  console.log("Welcome product is ready...");
  return insertResult;
};

// error handling code
app.use((err: Error, req: Request, res: Response, next: NextFunction) => {
  console.error(err.stack);
  res.status(500).send("Something broke!");
});