Express REST API

import express from "express";
import { z } from "zod";

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

type Todo = { id: number; title: string; done: boolean };
const todos: Todo[] = [{ id: 1, title: "Describe your API in the Codexa chat", done: false }];
let nextId = 2;

const TodoInput = z.object({ title: z.string().min(1).max(200), done: z.boolean().optional() });

app.get("/", (_req, res) => {
  res.json({ name: "codexa-api", endpoints: ["GET /api/todos", "POST /api/todos", "PATCH /api/todos/:id", "DELETE /api/todos/:id"] });
});
app.get("/api/todos", (_req, res) => res.json(todos));
app.post("/api/todos", (req, res) => {
  const parsed = TodoInput.safeParse(req.body);
  if (!parsed.success) return res.status(400).json({ error: parsed.error.flatten() });
  const todo: Todo = { id: nextId++, title: parsed.data.title, done: parsed.data.done ?? false };
  todos.push(todo);
  res.status(201).json(todo);
});
app.patch("/api/todos/:id", (req, res) => {
  const todo = todos.find((t) => t.id === Number(req.params.id));
  if (!todo) return res.status(404).json({ error: "Not found" });
  const parsed = TodoInput.partial().safeParse(req.body);
  if (!parsed.success) return res.status(400).json({ error: parsed.error.flatten() });
  Object.assign(todo, parsed.data);
  res.json(todo);
});
app.delete("/api/todos/:id", (req, res) => {
  const i = todos.findIndex((t) => t.id === Number(req.params.id));
  if (i === -1) return res.status(404).json({ error: "Not found" });
  todos.splice(i, 1);
  res.status(204).end();
});

const port = Number(process.env.PORT) || 3000;
app.listen(port, "0.0.0.0", () => console.log(`API listening on http://localhost:${port}`));