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, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');

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

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

  try {
    const { identifier } = req.query;

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

    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));
    
    // Verify user has access to this collection
    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.length === 0) {
      return res.status(404).json({ error: 'Collection not found or access denied' });
    }

    const collection = collectionResult[0];

    // Get the top 5 rarest cards from the collection
    const thumbnailsResult = await sql`
      SELECT DISTINCT
        cards.id,
        cards.name,
        cards.rarity,
        cards.image_url,
        cards.stock_image_url,
        cards.market_price,
        cards.game,
        cards.set_name,
        cc.quantity
      FROM collection_cards cc
      JOIN cards ON cc.card_id = cards.id
      WHERE cc.collection_id = ${collection.id}
        AND (cards.image_url IS NOT NULL OR cards.stock_image_url IS NOT NULL)
      ORDER BY 
        CASE cards.rarity
          WHEN 'mythic' THEN 8
          WHEN 'legendary' THEN 7
          WHEN 'rare' THEN 6
          WHEN 'uncommon' THEN 5
          WHEN 'common' THEN 4
          WHEN 'special' THEN 3
          WHEN 'promo' THEN 2
          WHEN 'token' THEN 1
          ELSE 0
        END DESC,
        cards.market_price DESC NULLS LAST,
        cards.name ASC
      LIMIT 5
    `;

    const thumbnails = thumbnailsResult.map(card => ({
      id: card.id,
      name: card.name,
      rarity: card.rarity,
      image_url: card.image_url,
      stock_image_url: card.stock_image_url,
      market_price: parseFloat(card.market_price) || 0,
      game: card.game,
      set_name: card.set_name,
      quantity: parseInt(card.quantity) || 1
    }));

    res.status(200).json(thumbnails);

  } catch (error) {
    console.error('Error fetching collection thumbnails:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
}