import { sql } from '@vercel/postgres';
import { getUserFromRequest } from '../../../../lib/permission-middleware';

export default async function handler(req, res) {
  try {
    const user = await getUserFromRequest(req);
    if (!user) {
      return res.status(401).json({ error: 'Authentication required' });
    }

    const { id: deckId } = req.query;

    // Verify user owns this deck
    const deckResult = await sql`
      SELECT * FROM decks WHERE id = ${deckId} AND user_id = ${user.userId}
    `;

    if (deckResult.rows.length === 0) {
      return res.status(404).json({ error: 'Deck not found or access denied' });
    }

    if (req.method === 'POST') {
      const { cardId, quantity = 1 } = req.body;

      if (!cardId) {
        return res.status(400).json({ error: 'Card ID is required' });
      }

      // Check if card already exists in deck
      const existingResult = await sql`
        SELECT * FROM deck_cards 
        WHERE deck_id = ${deckId} AND card_id = ${cardId}
      `;

      if (existingResult.rows.length > 0) {
        // Update quantity
        const newQuantity = existingResult.rows[0].quantity + quantity;
        await sql`
          UPDATE deck_cards 
          SET quantity = ${newQuantity}, updated_at = CURRENT_TIMESTAMP
          WHERE deck_id = ${deckId} AND card_id = ${cardId}
        `;
      } else {
        // Insert new record
        await sql`
          INSERT INTO deck_cards (deck_id, card_id, quantity)
          VALUES (${deckId}, ${cardId}, ${quantity})
        `;
      }

      return res.status(200).json({ message: 'Card added to deck' });

    } else if (req.method === 'GET') {
      // Get cards in deck
      const result = await sql`
        SELECT dc.*, c.name, c.set_name, c.rarity, c.game, c.image_url, c.mana_cost, c.cmc, c.card_type, c.colors
        FROM deck_cards dc
        JOIN cards c ON dc.card_id = c.id
        WHERE dc.deck_id = ${deckId}
        ORDER BY c.name ASC
      `;

      return res.status(200).json(result.rows);

    } else if (req.method === 'DELETE') {
      const { cardId, quantity = 1 } = req.body;

      if (!cardId) {
        return res.status(400).json({ error: 'Card ID is required' });
      }

      // Check if card exists in deck
      const existingResult = await sql`
        SELECT * FROM deck_cards 
        WHERE deck_id = ${deckId} AND card_id = ${cardId}
      `;

      if (existingResult.rows.length === 0) {
        return res.status(404).json({ error: 'Card not found in deck' });
      }

      const currentQuantity = existingResult.rows[0].quantity;
      const newQuantity = currentQuantity - quantity;

      if (newQuantity <= 0) {
        // Remove card entirely
        await sql`
          DELETE FROM deck_cards 
          WHERE deck_id = ${deckId} AND card_id = ${cardId}
        `;
      } else {
        // Update quantity
        await sql`
          UPDATE deck_cards 
          SET quantity = ${newQuantity}, updated_at = CURRENT_TIMESTAMP
          WHERE deck_id = ${deckId} AND card_id = ${cardId}
        `;
      }

      return res.status(200).json({ message: 'Card removed from deck' });

    } else {
      return res.status(405).json({ error: 'Method not allowed' });
    }

  } catch (error) {
    console.error('Error in deck cards API:', error);
    return res.status(500).json({ error: 'Internal server error' });
  }
}