import { useState, useEffect, useRef } from 'react';
import { useRouter } from 'next/router';
import Link from 'next/link';
import Layout from '../components/Layout';
import CardItem from '../components/CardItem';
import BulkSelectionToolbar from '../components/BulkSelectionToolbar';
import CollectionSelectionModal from '../components/CollectionSelectionModal';
import { ManaCost, ColorFilterSymbol } from '../components/ManaSymbols';
import ManaSymbolSettings from '../components/ManaSymbolSettings';
import { Button, SearchBar } from '../components/ui';
import { useAuth } from '../lib/use-auth';
import { VOCAB } from '../lib/collection-vocabulary.js';

export default function MyCards() {
  const router = useRouter();
  const { user, loading: authLoading } = useAuth();

  const [cards, setCards] = useState([]);
  const [loading, setLoading] = useState(true);
  const [loadingMore, setLoadingMore] = useState(false);
  const [searchQuery, setSearchQuery] = useState('');
  const [selectedTCG, setSelectedTCG] = useState('all');
  const [selectedRarity, setSelectedRarity] = useState('all');
  const [selectedSet, setSelectedSet] = useState('all');
  const [selectedValueRange, setSelectedValueRange] = useState('all');
  const [sortBy, setSortBy] = useState('name');
  const [sortOrder, setSortOrder] = useState('asc');
  const [viewMode, setViewMode] = useState('grid'); // grid or list
  const [pagination, setPagination] = useState({
    page: 1,
    limit: 50,
    total: 0,
    pages: 0
  });
  const [filters, setFilters] = useState({
    games: [],
    rarities: [],
    sets: []
  });
  const [hasMore, setHasMore] = useState(true);
  const loadingMoreRef = useRef(false);
  const hasMoreRef = useRef(true);
  
  // Bulk selection state
  const [selectedCards, setSelectedCards] = useState([]);
  const [favoritedCards, setFavoritedCards] = useState(new Set());
  
  // Modal states
  const [showCollectionModal, setShowCollectionModal] = useState(false);
  const [cardsToAdd, setCardsToAdd] = useState([]);

  // Mana symbol settings
  const [manaSymbolSettings, setManaSymbolSettings] = useState({ useSVG: false });
  const [collectionSummary, setCollectionSummary] = useState(null);

  // Redirect to login if not authenticated
  useEffect(() => {
    if (!authLoading && !user) {
      router.push('/login');
    }
  }, [authLoading, user, router]);

  // Fetch owned cards from database
  const fetchCards = async (isLoadMore = false) => {
    try {
      if (isLoadMore) {
        setLoadingMore(true);
        loadingMoreRef.current = true;
      } else {
        setLoading(true);
        setPagination(prev => ({ ...prev, page: 1 }));
      }

      const currentPage = isLoadMore ? pagination.page + 1 : 1;
      
      // Build query parameters for owned cards only
      const params = new URLSearchParams({
        page: currentPage.toString(),
        limit: pagination.limit.toString(),
        sort: sortBy,
        order: sortOrder,
        ...(searchQuery && { search: searchQuery }),
        ...(selectedTCG !== 'all' && { tcg: selectedTCG }),
        ...(selectedRarity !== 'all' && { rarity: selectedRarity }),
        ...(selectedSet !== 'all' && { set: selectedSet }),
        ...(selectedValueRange !== 'all' && { valueRange: selectedValueRange })
      });

      const token = localStorage.getItem('auth_token');
      const headers = {
        'Content-Type': 'application/json',
      };
      
      if (token) {
        headers.Authorization = `Bearer ${token}`;
      }

      const response = await fetch(`/api/cards/owned?${params}`, { headers });
      
      if (response.ok) {
        const data = await response.json();
        
        if (isLoadMore) {
          setCards(prev => [...prev, ...data.cards]);
          setPagination(prev => ({ ...prev, page: currentPage }));
        } else {
          setCards(data.cards);
          setPagination(data.pagination);
        }

        // Update hasMore state
        const newHasMore = currentPage < data.pagination.pages;
        setHasMore(newHasMore);
        hasMoreRef.current = newHasMore;

        // Load filter options on first load
        if (!isLoadMore && data.filters) {
          setFilters(data.filters);
        }
      } else {
        console.error('Failed to fetch owned cards');
      }
    } catch (error) {
      console.error('Error fetching owned cards:', error);
    } finally {
      setLoading(false);
      setLoadingMore(false);
      loadingMoreRef.current = false;
    }
  };

  // Load favorited cards
  const loadFavoritedCards = async () => {
    try {
      const token = localStorage.getItem('auth_token');
      const headers = {
        'Content-Type': 'application/json',
      };
      
      if (token) {
        headers.Authorization = `Bearer ${token}`;
      }

      const response = await fetch('/api/favorites?type=card', { headers });
      if (response.ok) {
        const data = await response.json();
        // Handle both array and object responses
        const favorites = Array.isArray(data) ? data : (data.favorites || []);
        setFavoritedCards(new Set(favorites.map(fav => fav.item_id)));
      }
    } catch (error) {
      console.error('Error loading favorited cards:', error);
      // Set empty set on error to prevent crashes
      setFavoritedCards(new Set());
    }
  };

  // Load collection summary for header line
  useEffect(() => {
    if (!user) return;
    let cancelled = false;

    const loadSummary = async () => {
      try {
        const token = localStorage.getItem('auth_token');
        const headers = { 'Content-Type': 'application/json' };
        if (token) headers.Authorization = `Bearer ${token}`;

        const response = await fetch('/api/user/stats', { headers });
        if (response.ok && !cancelled) {
          setCollectionSummary(await response.json());
        }
      } catch (error) {
        console.error('Error loading collection summary:', error);
      }
    };

    loadSummary();
    return () => {
      cancelled = true;
    };
  }, [user]);

  // Initial load
  useEffect(() => {
    if (user) {
      // eslint-disable-next-line react-hooks/set-state-in-effect -- filter-driven reload via async fetchCards
      fetchCards();
      loadFavoritedCards();
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps -- filter-driven reload; fetchCards closes over latest search state
  }, [user, searchQuery, selectedTCG, selectedRarity, selectedSet, selectedValueRange, sortBy, sortOrder]);

  // Infinite scroll
  useEffect(() => {
    const observer = new IntersectionObserver(
      (entries) => {
        const target = entries[0];
        if (target.isIntersecting && hasMoreRef.current && !loadingMoreRef.current) {
          fetchCards(true);
        }
      },
      { threshold: 0.1 }
    );

    const sentinel = document.getElementById('scroll-sentinel');
    if (sentinel) {
      observer.observe(sentinel);
    }

    return () => {
      if (sentinel) {
        observer.unobserve(sentinel);
      }
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps -- rebind observer when card list length changes
  }, [cards]);

  // Handle favorite toggle
  const handleFavoriteToggle = async (cardId) => {
    try {
      const token = localStorage.getItem('auth_token');
      const headers = {
        'Content-Type': 'application/json',
      };
      
      if (token) {
        headers.Authorization = `Bearer ${token}`;
      }

      const isFavorited = favoritedCards.has(cardId);
      
      if (isFavorited) {
        // Remove from favorites
        const response = await fetch('/api/favorites', {
          method: 'DELETE',
          headers,
          body: JSON.stringify({
            itemType: 'card',
            itemId: cardId
          })
        });
        
        if (response.ok) {
          setFavoritedCards(prev => {
            const newSet = new Set(prev);
            newSet.delete(cardId);
            return newSet;
          });
        }
      } else {
        // Add to favorites
        const response = await fetch('/api/favorites', {
          method: 'POST',
          headers,
          body: JSON.stringify({
            itemType: 'card',
            itemId: cardId
          })
        });
        
        if (response.ok) {
          setFavoritedCards(prev => {
            const newSet = new Set(prev);
            newSet.add(cardId);
            return newSet;
          });
        }
      }
    } catch (error) {
      console.error('Error toggling favorite:', error);
    }
  };

  // Handle bulk actions
  const handleAddToCollections = async (selectedCollectionIds) => {
    // Implementation for adding cards to collections
    console.log('Adding cards to collections:', selectedCollectionIds);
    setShowCollectionModal(false);
    setSelectedCards([]);
  };

  if (loading && cards.length === 0) {
    return (
      <Layout user={user}>
        <div className="flex items-center justify-center min-h-screen">
          <div className="animate-spin rounded-full h-32 w-32 border-b-2" style={{ borderColor: 'var(--accent-ember)' }}></div>
        </div>
      </Layout>
    );
  }

  return (
    <Layout user={user}>
      <div className="p-4 sm:p-6 max-w-[1500px] mx-auto space-y-6">
      {/* Header */}
      <div className="pt-2">
        <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-4">
          <div>
            <h1 className="text-2xl sm:text-3xl font-bold mb-2" style={{ color: 'var(--text-primary)' }}>
              {VOCAB.MY_COLLECTION}
            </h1>
            {collectionSummary && (
              <p className="text-sm mb-1" style={{ color: 'var(--text-secondary)' }}>
                {collectionSummary.totalCards.toLocaleString()} cards
                {' · '}
                ${collectionSummary.totalValue.toLocaleString(undefined, {
                  minimumFractionDigits: 0,
                  maximumFractionDigits: 0,
                })}{' '}
                estimated value
              </p>
            )}
            <p className="text-base sm:text-lg" style={{ color: 'var(--text-secondary)' }}>
              Browse and manage cards in {VOCAB.MY_COLLECTION}
            </p>
          </div>
          <div className="flex space-x-2 sm:space-x-4">
            <button 
              onClick={() => setViewMode('grid')}
              className={`p-2 rounded-xl transition-all duration-200 ${
                viewMode === 'grid' 
                  ? 'shadow-lg' 
                  : 'hover:shadow-md'
              }`}
              style={{
                backgroundColor: viewMode === 'grid' ? 'var(--accent-ember)' : 'var(--bg-tertiary)',
                color: viewMode === 'grid' ? 'white' : 'var(--text-primary)'
              }}
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 6a2 2 0 012-2h2a2 2 0 012 2v2a2 2 0 01-2 2H6a2 2 0 01-2-2V6zM14 6a2 2 0 012-2h2a2 2 0 012 2v2a2 2 0 01-2 2h-2a2 2 0 01-2-2V6zM4 16a2 2 0 012-2h2a2 2 0 012 2v2a2 2 0 01-2 2H6a2 2 0 01-2-2v-2zM14 16a2 2 0 012-2h2a2 2 0 012 2v2a2 2 0 01-2 2h-2a2 2 0 01-2-2v-2z" />
              </svg>
            </button>
            <button 
              onClick={() => setViewMode('list')}
              className={`p-2 rounded-xl transition-all duration-200 ${
                viewMode === 'list' 
                  ? 'shadow-lg' 
                  : 'hover:shadow-md'
              }`}
              style={{
                backgroundColor: viewMode === 'list' ? 'var(--accent-ember)' : 'var(--bg-tertiary)',
                color: viewMode === 'list' ? 'white' : 'var(--text-primary)'
              }}
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 6h16M4 10h16M4 14h16M4 18h16" />
              </svg>
            </button>
          </div>
        </div>
      </div>

      {/* Filters */}
      <div>
        <div className="glass-panel rounded-2xl p-4 mb-6">
          <div className="flex flex-wrap gap-4">
            <div className="flex-1 w-full sm:min-w-[200px]">
              <SearchBar
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                onClear={() => setSearchQuery('')}
                placeholder="Search your cards…"
              />
            </div>

            <select
              value={selectedTCG}
              onChange={(e) => setSelectedTCG(e.target.value)}
              className="input-field"
            >
              <option value="all">All Games</option>
              {filters.games.map(game => (
                <option key={game} value={game}>{game}</option>
              ))}
            </select>

            <select
              value={selectedRarity}
              onChange={(e) => setSelectedRarity(e.target.value)}
              className="input-field"
            >
              <option value="all">All Rarities</option>
              {filters.rarities.map(rarity => (
                <option key={rarity} value={rarity}>{rarity}</option>
              ))}
            </select>

            <select
              value={sortBy}
              onChange={(e) => setSortBy(e.target.value)}
              className="input-field"
              aria-label="Sort cards"
            >
              <option value="name">Sort by Name</option>
              <option value="price">Sort by Price</option>
              <option value="rarity">Sort by Rarity</option>
              <option value="date">Sort by Date Added</option>
            </select>

            <select
              value={sortOrder}
              onChange={(e) => setSortOrder(e.target.value)}
              className="input-field"
              aria-label="Sort order"
            >
              <option value="asc">Ascending</option>
              <option value="desc">Descending</option>
            </select>
          </div>
        </div>

        {/* Results Summary */}
        <div className="flex items-center justify-between mb-4">
          <p style={{ color: 'var(--text-secondary)' }}>
            {pagination.total} cards in {VOCAB.MY_COLLECTION}
          </p>
          {selectedCards.length > 0 && (
            <p style={{ color: 'var(--text-primary)' }}>
              {selectedCards.length} cards selected
            </p>
          )}
        </div>

        {/* Bulk Selection Toolbar */}
        {selectedCards.length > 0 && (
          <BulkSelectionToolbar
            selectedCount={selectedCards.length}
            onAddToCollection={() => {
              setCardsToAdd(selectedCards);
              setShowCollectionModal(true);
            }}
            onClearSelection={() => setSelectedCards([])}
          />
        )}

        {/* Cards Grid */}
        <div className={`
          ${viewMode === 'grid'
            ? 'grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 lg:grid-cols-4 xl:grid-cols-5 2xl:grid-cols-6 gap-4'
            : 'space-y-4'
          }
        `}>
          {cards.length === 0 && !loading && (
            <div className="col-span-full text-center py-12" style={{ color: 'var(--text-secondary)' }}>
              <p>No cards loaded from /api/cards/owned (summary shows {collectionSummary?.totalCards ?? 'N/A'} via /api/user/stats).</p>
            </div>
          )}
          {cards.map((card) => (
            <CardItem
              key={card.id}
              card={card}
              viewMode={viewMode}
              isSelected={selectedCards.includes(card.id)}
              isFavorited={favoritedCards.has(card.id)}
              onSelect={(cardId) => {
                setSelectedCards(prev => 
                  prev.includes(cardId) 
                    ? prev.filter(id => id !== cardId)
                    : [...prev, cardId]
                );
              }}
              onFavorite={(cardId) => {
                handleFavoriteToggle(cardId);
              }}
            />
          ))}
        </div>

        {/* Loading More */}
        {loadingMore && (
          <div className="flex justify-center py-8">
            <div className="animate-spin rounded-full h-8 w-8 border-b-2" style={{ borderColor: 'var(--accent-ember)' }}></div>
          </div>
        )}

        {/* Infinite Scroll Sentinel */}
        {hasMore && <div id="scroll-sentinel" className="h-4"></div>}

        {/* No More Cards */}
        {!hasMore && cards.length > 0 && (
          <div className="text-center py-8">
            <p style={{ color: 'var(--text-secondary)' }}>
              You&apos;ve reached the end of {VOCAB.MY_COLLECTION}!
            </p>
          </div>
        )}

        {/* No Cards Found */}
        {cards.length === 0 && !loading && (
          <div className="text-center py-20" data-testid="my-cards-empty-state">
            <div className="glass-panel w-16 h-16 mx-auto mb-4 rounded-2xl flex items-center justify-center">
              <svg className="w-8 h-8" fill="none" stroke="currentColor" viewBox="0 0 24 24" style={{ color: 'var(--text-secondary)' }}>
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 10h18M7 15h1m4 0h1m-7 4h12a3 3 0 003-3V8a3 3 0 00-3-3H6a3 3 0 00-3 3v8a3 3 0 003 3z" />
              </svg>
            </div>
            <h3 className="text-lg font-semibold mb-2" style={{ color: 'var(--text-primary)' }}>No cards in {VOCAB.MY_COLLECTION}</h3>
            <p className="mb-4" style={{ color: 'var(--text-secondary)' }}>
              {searchQuery ? 'Try adjusting your search filters' : `Start adding cards to ${VOCAB.MY_COLLECTION} by browsing available cards`}
            </p>
            <Link href="/cards">
              <Button variant="primary" size="lg">
                Browse All Cards
              </Button>
            </Link>
          </div>
        )}
      </div>

      {/* Collection Selection Modal */}
      <CollectionSelectionModal
        isOpen={showCollectionModal}
        onClose={() => setShowCollectionModal(false)}
        cards={cardsToAdd}
        onAddToCollections={handleAddToCollections}
      />
      </div>
    </Layout>
  );
}