export default async function handler(req, res) {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (req.method === 'OPTIONS') return res.status(200).end();
  if (req.method !== 'POST') return res.status(405).json({ error: 'Method not allowed' });

  const { prompt, messages } = req.body;

  if (!prompt && !messages) {
    return res.status(400).json({ error: 'No prompt provided' });
  }

  const apiKey = process.env.CLAUDE_API_KEY;
  if (!apiKey) {
    console.error('CLAUDE_API_KEY is not set');
    return res.status(500).json({ error: 'API key not configured' });
  }

  try {
    const msgArray = messages || [{ role: 'user', content: prompt }];

    const response = await fetch('https://api.anthropic.com/v1/messages', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'x-api-key': apiKey,
        'anthropic-version': '2023-06-01'
      },
      body: JSON.stringify({
        model: 'claude-haiku-4-5-20251001',
        max_tokens: 4096,
        messages: msgArray
      })
    });

    const data = await response.json();

    if (!response.ok) {
      console.error('Claude API error:', JSON.stringify(data));
      return res.status(500).json({ error: data.error?.message || 'Claude API error' });
    }

    const result = data.content[0].text;
    return res.status(200).json({ result });

  } catch (error) {
    console.error('Server error:', error.message);
    return res.status(500).json({ error: 'Server error: ' + error.message });
  }
}