import { createClient } from '@supabase/supabase-js';

export default async function handler(req, res) {
    if (req.method !== 'POST') {
        return res.status(405).json({ message: 'Method not allowed' });
    }

    const { code } = req.body;

    try {
        // Exchange GitHub code for access token
        const response = await fetch('https://github.com/login/oauth/access_token', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'Accept': 'application/json'
            },
            body: JSON.stringify({
                client_id: process.env.GITHUB_CLIENT_ID,
                client_secret: process.env.GITHUB_CLIENT_SECRET,
                code,
                redirect_uri: process.env.GITHUB_REDIRECT_URI
            })
        });

        const data = await response.json();
        
        if (data.error) {
            throw new Error(data.error_description || 'GitHub authentication failed');
        }

        // Store the token in Supabase (optional)
        const supabase = createClient(process.env.SUPABASE_URL, process.env.SUPABASE_KEY);
        await supabase
            .from('user_tokens')
            .upsert({
                user_id: req.session.user.id, // You'd need session management
                github_token: data.access_token,
                updated_at: new Date().toISOString()
            });

        res.status(200).json({
            access_token: data.access_token,
            token_type: data.token_type,
            scope: data.scope
        });
    } catch (error) {
        console.error('GitHub auth error:', error);
        res.status(500).json({ message: error.message });
    }
}