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import { useState, useEffect, useCallback } from "react";
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const API_BASE = "http://localhost:8080/api/v1";
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interface Todo {
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  id: string;
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  text: string;
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  completed: boolean;
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  createdAt: string;
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  priority: "low" | "medium" | "high";
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}
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/* @gitian
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 * --group=clients
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 * useTodos hook — manages the full lifecycle of todos fetched
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 * from the Go API. Polls every 5 seconds for changes from
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 * other clients.
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 */
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function useTodos() {
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  const [todos, setTodos] = useState<Todo[]>([]);
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  const [loading, setLoading] = useState(true);
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  const refresh = useCallback(async () => {
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    // @gitian:todo Add error handling with retry + exponential backoff
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    const res = await fetch(`${API_BASE}/todos`);
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    setTodos(await res.json());
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    setLoading(false);
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  }, []);
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  useEffect(() => {
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    refresh();
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    // @gitian:perf Polling is simple but wasteful — switch to
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    // Server-Sent Events or WebSocket for real-time updates
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    const interval = setInterval(refresh, 5000);
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    return () => clearInterval(interval);
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  }, [refresh]);
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  const addTodo = useCallback(async (text: string) => {
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    const res = await fetch(`${API_BASE}/todos`, {
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      method: "POST",
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      headers: { "Content-Type": "application/json" },
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      body: JSON.stringify({ text }),
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    });
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    const todo = await res.json();
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    setTodos((prev) => [...prev, todo]);
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  }, []);
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  const toggleTodo = useCallback(async (id: string, completed: boolean) => {
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    await fetch(`${API_BASE}/todos/${id}`, {
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      method: "PUT",
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      headers: { "Content-Type": "application/json" },
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      body: JSON.stringify({ completed: !completed }),
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    });
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    setTodos((prev) =>
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      prev.map((t) => (t.id === id ? { ...t, completed: !t.completed } : t))
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    );
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  }, []);
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  return { todos, loading, addTodo, toggleTodo };
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}
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{/* @gitian
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  * --group=clients
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  * App component — renders the todo list with an add form.
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  * All data flows through the useTodos hook above.
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  */}
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export function App() {
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  const { todos, loading, addTodo, toggleTodo } = useTodos();
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  const completed = todos.filter((t) => t.completed).length;
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  // @gitian:warning No optimistic UI — toggles wait for the server
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  // round-trip before reflecting in the UI, causing visible lag
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  if (loading) return <p>Loading...</p>;
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  return (
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    <div style={{ maxWidth: 480, margin: "2rem auto", fontFamily: "system-ui" }}>
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      <h1>Todo App</h1>
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      <p>{completed}/{todos.length} completed</p>
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      <form onSubmit={(e) => {
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        e.preventDefault();
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        const input = e.currentTarget.elements.namedItem("text") as HTMLInputElement;
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        if (input.value.trim()) {
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          addTodo(input.value.trim());
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          input.value = "";
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        }
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      }}>
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        <input name="text" placeholder="What needs to be done?" />
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        <button type="submit">Add</button>
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      </form>
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      <ul>
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        {todos.map((t) => (
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          <li key={t.id} style={{ opacity: t.completed ? 0.5 : 1 }}>
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            <input
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              type="checkbox"
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              checked={t.completed}
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              onChange={() => toggleTodo(t.id, t.completed)}
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            />
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            <span>{t.text}</span>
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          </li>
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        ))}
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      </ul>
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    </div>
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  );
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}
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