/**
 * Example: using backend-toolkit inside an Express app.
 *
 * Requires express to be installed separately:
 *   npm install express
 *
 * Run with: node examples/express.js
 */
const express = require("express");
const { z } = require("zod");
const {
  success,
  error,
  asyncHandler,
  validate,
  rules,
  hashPassword,
  signToken,
  paginate,
  getPaginationParams,
  logger,
} = require("../src/index");

const app = express();
app.use(express.json());

const users = [];
const createUserSchema = z.object({ email: rules.email, password: rules.password });

app.post(
  "/users",
  asyncHandler(async (req, res) => {
    const result = validate(createUserSchema, req.body);

    if (!result.success) {
      return res.status(400).json(error("Validation failed", 400, result.errors));
    }

    const passwordHash = await hashPassword(result.data.password);
    const user = { id: users.length + 1, email: result.data.email, passwordHash };
    users.push(user);

    const token = signToken({ userId: user.id }, process.env.JWT_SECRET || "dev-secret", {
      expiresIn: "1h",
    });

    logger.info(`Created user #${user.id}`);
    return res.status(201).json(success({ id: user.id, token }, "User created", 201));
  })
);

app.get(
  "/users",
  asyncHandler(async (req, res) => {
    const { page, limit } = getPaginationParams(req.query);
    const meta = paginate({ page, limit, totalItems: users.length });
    const items = users
      .slice(meta.offset, meta.offset + meta.limit)
      .map((u) => ({ id: u.id, email: u.email }));

    return res.json(success({ items, meta }, "Users fetched"));
  })
);

// Central error handler — every asyncHandler-wrapped route lands here on failure.
app.use((err, req, res, _next) => {
  logger.error(err.message);
  res.status(500).json(error(err.message, 500));
});

const port = process.env.PORT || 3000;
app.listen(port, () => logger.info(`Example app listening on port ${port}`));