import { useOptimistic, startTransition } from 'react';

function MessageList({ messages, sendMessage }) {
  const [optimisticMessages, addOptimisticMessage] = useOptimistic(
    messages,
    (state, newMessage) => [...state, { ...newMessage, sending: true }]
  );

  const handleSend = async (text) => {
    addOptimisticMessage({ id: Date.now(), text });

    startTransition(async () => {
      await sendMessage(text);
    });
  };

  return (
    <ul>
      {optimisticMessages.map((msg) => (
        <li key={msg.id}>
          {msg.text} {msg.sending && <small>(Sending...)</small>}
        </li>
      ))}
    </ul>
  );
}

function LikeButton({ postId, initialLikes }) {
  const [optimisticLikes, addOptimisticLike] = useOptimistic(
    initialLikes,
    (state, amount) => state + amount
  );

  const handleLike = async () => {
    addOptimisticLike(1);

    startTransition(async () => {
      await fetch(`/api/posts/${postId}/like`, { method: 'POST' });
    });
  };

  return (
    <button onClick={handleLike}>
      ❤️ {optimisticLikes}
    </button>
  );
}