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

export default async function handler(req, res) {
  // Set CORS headers
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');

  // Handle preflight requests
  if (req.method === 'OPTIONS') {
    res.status(200).end();
    return;
  }

  try {
    // Get authenticated user
    const user = await getUserFromRequest(req);
    if (!user) {
      return res.status(401).json({ error: 'Authentication required' });
    }

    const { identifier } = req.query;

    if (!identifier) {
      return res.status(400).json({ error: 'Collection identifier is required' });
    }

    // Determine if identifier is a slug or numeric ID
    const isSlug = isValidSlug(identifier) || isNaN(parseInt(identifier));
    
    // Get collection ID from identifier
    let collectionResult;
    if (isSlug) {
      collectionResult = await sql`
        SELECT c.*, cp.role as user_role
        FROM collections c
        LEFT JOIN collection_permissions cp ON c.id = cp.collection_id AND cp.user_id = ${user.userId} AND cp.status = 'active'
        WHERE c.slug = ${identifier}
          AND (
            c.user_id = ${user.userId} OR
            cp.id IS NOT NULL OR
            c.is_public = true
          )
      `;
    } else {
      const numericId = parseInt(identifier);
      collectionResult = await sql`
        SELECT c.*, cp.role as user_role
        FROM collections c
        LEFT JOIN collection_permissions cp ON c.id = cp.collection_id AND cp.user_id = ${user.userId} AND cp.status = 'active'
        WHERE c.id = ${numericId}
          AND (
            c.user_id = ${user.userId} OR
            cp.id IS NOT NULL OR
            c.is_public = true
          )
      `;
    }

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

    const collection = collectionResult.rows[0];

    if (req.method === 'GET') {
      // Get all cards in the collection
      const cardsResult = await sql`
        SELECT 
          cards.*,
          cc.quantity,
          cc.created_at as added_at
        FROM collection_cards cc
        JOIN cards ON cc.card_id = cards.id
        WHERE cc.collection_id = ${collection.id}
        ORDER BY cc.created_at DESC
      `;

      const cards = cardsResult.rows.map(card => ({
        id: card.id,
        name: card.name,
        set_name: card.set_name,
        set_code: card.set_code,
        card_number: card.card_number,
        rarity: card.rarity,
        game: card.game,
        mana_cost: card.mana_cost,
        cmc: card.cmc,
        card_type: card.card_type,
        colors: card.colors,
        oracle_text: card.oracle_text,
        power: card.power,
        toughness: card.toughness,
        image_url: card.image_url,
        stock_image_url: card.stock_image_url,
        current_price: parseFloat(card.current_price) || 0,
        market_price: parseFloat(card.market_price) || 0,
        quantity: parseInt(card.quantity) || 1,
        added_at: card.added_at
      }));

      res.status(200).json({ cards });

    } else if (req.method === 'POST') {
      // Add card to collection - only allow if user has write access
      const canWrite = collection.user_id === user.userId || 
                      ['owner', 'editor'].includes(collection.user_role);
      
      if (!canWrite) {
        return res.status(403).json({ error: 'You do not have permission to add cards to this collection' });
      }

      const { cardId, quantity = 1 } = req.body;

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

      // Check if card exists
      const cardCheck = await sql`SELECT id FROM cards WHERE id = ${cardId}`;
      if (cardCheck.length === 0) {
        return res.status(404).json({ error: 'Card not found' });
      }

      // Check if card already exists in collection
      const existingResult = await sql`
        SELECT * FROM collection_cards 
        WHERE collection_id = ${collection.id} AND card_id = ${cardId}
      `;

      if (existingResult.length > 0) {
        // Update quantity if card already exists
        const result = await sql`
          UPDATE collection_cards 
          SET quantity = quantity + ${quantity}, updated_at = CURRENT_TIMESTAMP
          WHERE collection_id = ${collection.id} AND card_id = ${cardId}
          RETURNING *
        `;

        res.status(200).json({ 
          message: 'Card quantity updated in collection',
          card: result[0]
        });
      } else {
        // Add new card to collection
        const result = await sql`
          INSERT INTO collection_cards (collection_id, card_id, quantity)
          VALUES (${collection.id}, ${cardId}, ${quantity})
          RETURNING *
        `;

        res.status(201).json({ 
          message: 'Card added to collection',
          card: result[0]
        });
      }

      // Update collection's updated_at timestamp
      await sql`
        UPDATE collections 
        SET updated_at = CURRENT_TIMESTAMP 
        WHERE id = ${collection.id}
      `;

    } else if (req.method === 'PUT') {
      // Update card quantity in collection
      const canWrite = collection.user_id === user.userId || 
                      ['owner', 'editor'].includes(collection.user_role);
      
      if (!canWrite) {
        return res.status(403).json({ error: 'You do not have permission to modify this collection' });
      }

      const { cardId, quantity } = req.body;

      if (!cardId || quantity === undefined) {
        return res.status(400).json({ error: 'Card ID and quantity are required' });
      }

      if (quantity <= 0) {
        // Remove card from collection if quantity is 0 or negative
        await sql`
          DELETE FROM collection_cards 
          WHERE collection_id = ${collection.id} AND card_id = ${cardId}
        `;

        res.status(200).json({ message: 'Card removed from collection' });
      } else {
        // Update quantity
        const result = await sql`
          UPDATE collection_cards 
          SET quantity = ${quantity}, updated_at = CURRENT_TIMESTAMP
          WHERE collection_id = ${collection.id} AND card_id = ${cardId}
          RETURNING *
        `;

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

        res.status(200).json({ 
          message: 'Card quantity updated',
          card: result.rows[0]
        });
      }

      // Update collection's updated_at timestamp
      await sql`
        UPDATE collections 
        SET updated_at = CURRENT_TIMESTAMP 
        WHERE id = ${collection.id}
      `;

    } else if (req.method === 'DELETE') {
      // Remove card from collection
      const canWrite = collection.user_id === user.userId || 
                      ['owner', 'editor'].includes(collection.user_role);
      
      if (!canWrite) {
        return res.status(403).json({ error: 'You do not have permission to modify this collection' });
      }

      const { cardId } = req.body;

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

      const result = await sql`
        DELETE FROM collection_cards 
        WHERE collection_id = ${collection.id} AND card_id = ${cardId}
        RETURNING *
      `;

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

      // Update collection's updated_at timestamp
      await sql`
        UPDATE collections 
        SET updated_at = CURRENT_TIMESTAMP 
        WHERE id = ${collection.id}
      `;

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

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

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