import { useState, useEffect, useRef } from 'react';
import { useRouter } from 'next/router';
import Layout from '../components/Layout';
import CameraScanner from '../components/CameraScanner';
import ScannerDestinationPicker from '../components/ScannerDestinationPicker';
import ScannedCardItem, { CONDITION_OPTIONS } from '../components/ScannedCardItem';
import OCRSettings from '../components/OCRSettings';
import { useAuth } from '../lib/use-auth';
import { useFocusTrap } from '../lib/use-focus-trap.js';
import { VOCAB } from '../lib/collection-vocabulary.js';
import {
  addScannedCardToCollection,
  addScannedCardToDeck,
  addScannedCardToOwned,
  createScannerCollection,
  fetchScannerCollections,
  fetchScannerDecks,
  routeScannedCardToDestination,
} from '../lib/scanner-route-api.js';
import {
  DEFAULT_SCANNER_DESTINATION,
  destinationActionKey,
  loadSavedScannerSession,
  mergeScannedCardEntry,
  saveScannerSession,
} from '../lib/scanner-session.js';

export default function Scanner() {
  const { user, loading: authLoading } = useAuth();
  const router = useRouter();
  const [scannedCards, setScannedCards] = useState([]);
  const [collections, setCollections] = useState([]);
  const [decks, setDecks] = useState([]);
  const [showCreateCollection, setShowCreateCollection] = useState(false);
  const [newCollectionName, setNewCollectionName] = useState('');
  const createCollectionDialogRef = useFocusTrap(showCreateCollection);
  const [showOCRSettings, setShowOCRSettings] = useState(false);
  
  // Bulk action states
  const [selectedCards, setSelectedCards] = useState(new Set());
  const [bulkAction, setBulkAction] = useState(''); // 'owned', 'collection', 'deck'
  const [bulkTarget, setBulkTarget] = useState('');
  const [isProcessing, setIsProcessing] = useState(false);
  const addingInFlightRef = useRef(new Set());
  const [addingCardIds, setAddingCardIds] = useState(() => new Set());
  const [sessionDestination, setSessionDestination] = useState(
    () => loadSavedScannerSession().destination
  );
  const [gameFilter, setGameFilter] = useState(() => loadSavedScannerSession().gameFilter);
  const [scanDefaults, setScanDefaults] = useState(() => loadSavedScannerSession().scanDefaults);
  const [autoRouteError, setAutoRouteError] = useState(null);

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

  useEffect(() => {
    saveScannerSession({ destination: sessionDestination, gameFilter, scanDefaults });
  }, [sessionDestination, gameFilter, scanDefaults]);

  useEffect(() => {
    if (!user) return;

    let cancelled = false;

    (async () => {
      try {
        const [loadedCollections, loadedDecks] = await Promise.all([
          fetchScannerCollections(),
          fetchScannerDecks(),
        ]);
        if (cancelled) return;
        setCollections(loadedCollections);
        setDecks(loadedDecks);
      } catch (error) {
        console.error('Error loading scanner destinations:', error);
      }
    })();

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

  const handleGameFilterChange = (nextFilter) => {
    setGameFilter(nextFilter);
    setSessionDestination((current) => {
      if (!current || current.type === 'owned') return current;
      return DEFAULT_SCANNER_DESTINATION;
    });
  };

  const handleCardScanned = async (cardData) => {
    setAutoRouteError(null);

    const { cardEntry, scannedCards: nextQueue } = mergeScannedCardEntry(
      scannedCards,
      cardData,
      scanDefaults
    );
    setScannedCards(nextQueue);

    if (!sessionDestination) return;

    if (!cardEntry.databaseId) {
      setAutoRouteError(`"${cardEntry.name}" was queued but is not in the catalog yet — add it manually after review.`);
      return;
    }

    try {
      if (!tryBeginAdding(cardEntry.id)) return;
      await routeScannedCardToDestination(cardEntry, sessionDestination);
      markCardAsProcessed(cardEntry.id, destinationActionKey(sessionDestination));
    } catch (error) {
      console.error('Auto-route failed:', error);
      setAutoRouteError(`Could not add "${cardEntry.name}" to ${sessionDestination.label}. Use the card actions below.`);
    } finally {
      endAdding(cardEntry.id);
    }
  };

  // Quantity management functions
  const incrementCardQuantity = (cardId) => {
    setScannedCards(prev => prev.map(card => 
      card.id === cardId 
        ? { ...card, quantity: (card.quantity || 1) + 1 }
        : card
    ));
  };

  const decrementCardQuantity = (cardId) => {
    setScannedCards(prev => prev.map(card => 
      card.id === cardId 
        ? { ...card, quantity: Math.max(1, (card.quantity || 1) - 1) }
        : card
    ));
  };

  const handleError = (error) => {
    console.error('Scanner error:', error);
    // You could show a toast notification here
  };

  const syncAddingState = () => {
    setAddingCardIds(new Set(addingInFlightRef.current));
  };

  const tryBeginAdding = (cardId) => {
    if (addingInFlightRef.current.has(cardId)) return false;
    addingInFlightRef.current.add(cardId);
    syncAddingState();
    return true;
  };

  const endAdding = (cardId) => {
    addingInFlightRef.current.delete(cardId);
    syncAddingState();
  };

  // Individual card actions
  const addSingleCardToOwned = async (card) => {
    if (!tryBeginAdding(card.id)) return;
    try {
      await addScannedCardToOwned(card);
      markCardAsProcessed(card.id, 'owned');
    } catch (error) {
      console.error('Error adding card to owned:', error);
    } finally {
      endAdding(card.id);
    }
  };

  const addSingleCardToCollection = async (card, collectionId) => {
    if (!tryBeginAdding(card.id)) return;
    try {
      await addScannedCardToCollection(card, collectionId);
      markCardAsProcessed(card.id, 'collection');
    } catch (error) {
      console.error('Error adding card to collection:', error);
    } finally {
      endAdding(card.id);
    }
  };

  const addSingleCardToDeck = async (card, deckId) => {
    if (!tryBeginAdding(card.id)) return;
    try {
      await addScannedCardToDeck(card, deckId);
      markCardAsProcessed(card.id, 'deck');
    } catch (error) {
      console.error('Error adding card to deck:', error);
    } finally {
      endAdding(card.id);
    }
  };

  // Bulk actions
  const handleBulkAction = async (actionOverride, targetOverride) => {
    const action = actionOverride ?? bulkAction;
    const target = targetOverride ?? bulkTarget;
    if (!action || selectedCards.size === 0) return;

    setIsProcessing(true);
    try {
      const cardsToProcess = scannedCards.filter(card => selectedCards.has(card.id));

      for (const card of cardsToProcess) {
        if (action === 'owned') {
          if (!tryBeginAdding(card.id)) continue;
          try {
            await addScannedCardToOwned(card);
          } finally {
            endAdding(card.id);
          }
        } else if (action === 'collection' && target) {
          if (!tryBeginAdding(card.id)) continue;
          try {
            await addScannedCardToCollection(card, target);
          } finally {
            endAdding(card.id);
          }
        } else if (action === 'deck' && target) {
          if (!tryBeginAdding(card.id)) continue;
          try {
            await addScannedCardToDeck(card, target);
          } finally {
            endAdding(card.id);
          }
        } else {
          continue;
        }
        markCardAsProcessed(card.id, action);
      }

      setSelectedCards(new Set());
      setBulkAction('');
      setBulkTarget('');
    } catch (error) {
      console.error('Error processing bulk action:', error);
    } finally {
      setIsProcessing(false);
    }
  };

  const markCardAsProcessed = (cardId, action) => {
    setScannedCards(prev => prev.map(card => 
      card.id === cardId 
        ? { ...card, processed: true, processedAction: action }
        : card
    ));
  };

  const updateCardMetadata = (cardId, patch) => {
    setScannedCards((prev) =>
      prev.map((card) => (card.id === cardId ? { ...card, ...patch } : card))
    );
  };

  const createCollection = async () => {
    if (!newCollectionName.trim()) return;

    try {
      const newCollection = await createScannerCollection(newCollectionName.trim());
      setCollections((prev) => [newCollection, ...prev]);
      setBulkTarget(newCollection.id.toString());
      setNewCollectionName('');
      setShowCreateCollection(false);
    } catch (error) {
      console.error('Error creating collection:', error);
    }
  };

  const clearScannedCards = () => {
    setScannedCards([]);
    setSelectedCards(new Set());
  };

  const removeScannedCard = (cardId) => {
    setScannedCards(prev => prev.filter(card => card.id !== cardId));
    setSelectedCards(prev => {
      const newSet = new Set(prev);
      newSet.delete(cardId);
      return newSet;
    });
  };

  const toggleCardSelection = (cardId) => {
    setSelectedCards(prev => {
      const newSet = new Set(prev);
      if (newSet.has(cardId)) {
        newSet.delete(cardId);
      } else {
        newSet.add(cardId);
      }
      return newSet;
    });
  };

  if (authLoading) {
    return (
      <Layout user={null}>
        <div className="flex items-center justify-center min-h-[50vh]">
          <div className="animate-spin rounded-full h-12 w-12 border-b-2" style={{ borderColor: 'var(--text-accent)' }} />
        </div>
      </Layout>
    );
  }

  if (!user) {
    return <div>Redirecting to login...</div>;
  }

  return (
    <Layout user={user}>
      <div className="h-full flex flex-col">
        {/* Header */}
        <div className="px-6 pt-6 pb-4">
          <h1 className="text-3xl font-bold mb-2" style={{ color: 'var(--text-primary)' }}>
            🃏 Card Scanner
          </h1>
          <p className="text-lg" style={{ color: 'var(--text-secondary)' }}>
            Pick a destination once — every scan lands there until you change it
          </p>
        </div>

        <ScannerDestinationPicker
          gameFilter={gameFilter}
          onGameFilterChange={handleGameFilterChange}
          destination={sessionDestination}
          onDestinationChange={setSessionDestination}
          collections={collections}
          decks={decks}
          disabled={isProcessing}
        />

        {autoRouteError && (
          <div
            className="mx-6 mb-4 px-4 py-3 rounded-lg border text-sm"
            style={{
              backgroundColor: 'var(--bg-secondary)',
              borderColor: 'var(--accent-flame)',
              color: 'var(--text-primary)',
            }}
            role="alert"
          >
            {autoRouteError}
          </div>
        )}

        <div
          className="mx-6 mb-4 rounded-xl border p-4 flex flex-wrap items-end gap-4"
          style={{ backgroundColor: 'var(--bg-secondary)', borderColor: 'var(--border)' }}
        >
          <div>
            <h2 className="text-sm font-semibold uppercase tracking-wide mb-1" style={{ color: 'var(--text-secondary)' }}>
              Defaults for new scans
            </h2>
            <p className="text-xs" style={{ color: 'var(--text-secondary)' }}>
              Applied to each card when it enters the queue
            </p>
          </div>
          <label className="flex flex-col gap-1 text-sm">
            <span style={{ color: 'var(--text-secondary)' }}>Condition</span>
            <select
              value={scanDefaults.condition}
              onChange={(e) => setScanDefaults((current) => ({ ...current, condition: e.target.value }))}
              className="px-3 py-2 rounded-lg border"
              style={{
                backgroundColor: 'var(--bg-tertiary)',
                borderColor: 'var(--border)',
                color: 'var(--text-primary)',
              }}
            >
              {CONDITION_OPTIONS.map((option) => (
                <option key={option} value={option}>
                  {option}
                </option>
              ))}
            </select>
          </label>
          <label className="flex items-center gap-2 text-sm pb-2 cursor-pointer" style={{ color: 'var(--text-primary)' }}>
            <input
              type="checkbox"
              checked={scanDefaults.isFoil}
              onChange={(e) => setScanDefaults((current) => ({ ...current, isFoil: e.target.checked }))}
              style={{ accentColor: 'var(--accent-ember)' }}
            />
            Foil
          </label>
        </div>

        {/* Main Content - Full Height */}
        <div className="flex-1 grid grid-cols-1 lg:grid-cols-5 gap-6 px-6 pb-6">
          {/* Camera Scanner */}
          <div className="lg:col-span-3 flex flex-col">
            <div className="flex-1 rounded-xl p-6 flex flex-col" style={{ backgroundColor: 'var(--bg-secondary)', border: '1px solid var(--border)' }}>
              <div className="flex justify-between items-center mb-4">
                <h2 className="text-xl font-semibold" style={{ color: 'var(--text-primary)' }}>
                  Camera Scanner
                </h2>
                <button
                  onClick={() => setShowOCRSettings(true)}
                  className="px-4 py-2 rounded-xl font-medium border transition-all duration-200 hover:opacity-80"
                  style={{
                    borderColor: 'var(--border)',
                    color: 'var(--text-primary)'
                  }}
                >
                  ⚙️ OCR Settings
                </button>
              </div>

              <div className="flex-1">
                <CameraScanner 
                  onCardScanned={handleCardScanned}
                  onError={handleError}
                />
              </div>
            </div>
          </div>

          {/* Scanned Cards Queue */}
          <div className="lg:col-span-2 flex flex-col">
            <div className="flex-1 rounded-xl p-6 flex flex-col" style={{ backgroundColor: 'var(--bg-secondary)', border: '1px solid var(--border)' }}>
              <div className="flex justify-between items-center mb-4">
                <h2 className="text-xl font-semibold" style={{ color: 'var(--text-primary)' }}>
                  Scanned Cards
                </h2>
                <div className="flex items-center gap-2">
                  <div
                    className="text-sm"
                    style={{ color: 'var(--text-secondary)' }}
                    aria-live="polite"
                    aria-atomic="true"
                  >
                    {scannedCards.length} cards
                  </div>
                  {scannedCards.length > 0 && (
                    <button
                      onClick={clearScannedCards}
                      className="px-3 py-1 rounded-lg text-sm border hover:opacity-80"
                      style={{
                        borderColor: 'var(--border)',
                        color: 'var(--text-secondary)'
                      }}
                      aria-label="Clear all scanned cards from queue"
                    >
                      Clear All
                    </button>
                  )}
                </div>
              </div>

              {/* Scanned Cards Queue - Scrollable */}
              <div className="flex-1 overflow-y-auto">
                {scannedCards.length === 0 ? (
                  <div className="text-center py-8" style={{ color: 'var(--text-secondary)' }}>
                    <div className="text-4xl mb-2" aria-hidden="true">📱</div>
                    <div className="font-medium">No cards scanned yet</div>
                    <div className="text-sm">Start scanning to see cards here</div>
                  </div>
                ) : (
                  <ul className="space-y-3 list-none p-0 m-0" aria-label="Scanned cards queue">
                    {scannedCards.map((card) => (
                      <li key={card.id}>
                        <ScannedCardItem
                          card={card}
                          collections={collections}
                          decks={decks}
                          selected={selectedCards.has(card.id)}
                          onToggleSelect={() => toggleCardSelection(card.id)}
                          onIncrement={() => incrementCardQuantity(card.id)}
                          onDecrement={() => decrementCardQuantity(card.id)}
                          onUpdateMetadata={(patch) => updateCardMetadata(card.id, patch)}
                          onMarkOwned={() => addSingleCardToOwned(card)}
                          onAddToCollection={(collectionId) => addSingleCardToCollection(card, collectionId)}
                          onAddToDeck={(deckId) => addSingleCardToDeck(card, deckId)}
                          onRemove={() => removeScannedCard(card.id)}
                          isAdding={addingCardIds.has(card.id)}
                        />
                      </li>
                    ))}
                  </ul>
                )}
              </div>
            </div>
          </div>
        </div>

        {/* Floating Bulk Actions Toolbar */}
        {selectedCards.size > 0 && (
          <div className="fixed bottom-6 left-1/2 transform -translate-x-1/2 z-50">
            <div
              className="rounded-2xl shadow-2xl border px-6 py-4 flex items-center gap-4 max-w-4xl"
              role="toolbar"
              aria-label="Bulk actions for selected scanned cards"
              style={{
                backgroundColor: 'var(--bg-secondary)',
                borderColor: 'var(--border)',
                backdropFilter: 'blur(10px)',
              }}
            >
              
              {/* Selection Count */}
              <div className="flex items-center gap-2" aria-live="polite" aria-atomic="true">
                <div className="w-8 h-8 rounded-full flex items-center justify-center text-sm font-bold text-white"
                     style={{ backgroundColor: 'var(--accent-ember)' }}>
                  {selectedCards.size}
                </div>
                <span className="font-medium" style={{ color: 'var(--text-primary)' }}>
                  {selectedCards.size === 1 ? 'card selected' : 'cards selected'}
                </span>
              </div>

              {/* Divider */}
              <div className="w-px h-8" style={{ backgroundColor: 'var(--border)' }}></div>

              {/* Quick Actions */}
              <div className="flex items-center gap-3">
                <button
                  onClick={() => handleBulkAction('owned')}
                  disabled={isProcessing}
                  className="px-4 py-2 rounded-lg font-medium hover:opacity-80 disabled:opacity-50 flex items-center gap-2"
                  style={{ backgroundColor: 'var(--accent-gold)', color: 'white' }}
                >
                  <span aria-hidden="true">💎 </span>
                  {VOCAB.ADD_TO_MY_COLLECTION}
                </button>

                {collections.length > 0 && (
                  <select
                    onChange={(e) => {
                      const collectionId = e.target.value;
                      e.target.value = '';
                      if (collectionId) {
                        handleBulkAction('collection', collectionId);
                      }
                    }}
                    disabled={isProcessing}
                    className="px-4 py-2 rounded-lg font-medium"
                    style={{ backgroundColor: 'var(--accent-ember)', color: 'white', border: 'none' }}
                    aria-label="Add selected cards to list"
                  >
                    <option value="">{`📚 ${VOCAB.ADD_TO_LIST}`}</option>
                    {collections.map(collection => (
                      <option key={collection.id} value={collection.id}>
                        {collection.name}
                      </option>
                    ))}
                  </select>
                )}

                {decks.length > 0 && (
                  <select
                    onChange={(e) => {
                      const deckId = e.target.value;
                      e.target.value = '';
                      if (deckId) {
                        handleBulkAction('deck', deckId);
                      }
                    }}
                    disabled={isProcessing}
                    className="px-4 py-2 rounded-lg font-medium"
                    style={{ backgroundColor: 'var(--accent-flame)', color: 'white', border: 'none' }}
                    aria-label="Add selected cards to deck"
                  >
                    <option value="">🃏 Add to Deck</option>
                    {decks.map(deck => (
                      <option key={deck.id} value={deck.id}>
                        {deck.name} ({deck.game})
                      </option>
                    ))}
                  </select>
                )}
              </div>

              {/* Divider */}
              <div className="w-px h-8" style={{ backgroundColor: 'var(--border)' }}></div>

              {/* Clear Selection */}
              <button
                onClick={() => setSelectedCards(new Set())}
                className="px-3 py-2 rounded-lg hover:opacity-80"
                style={{ color: 'var(--text-secondary)' }}
                aria-label="Clear selection"
              >
                <span aria-hidden="true">✕</span>
              </button>
            </div>
          </div>
        )}

        {/* Bulk Actions Modal */}
        {/* This modal is no longer needed as bulk actions are in a floating toolbar */}

        {/* Create List Modal */}
        {showCreateCollection && (
          <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50">
            <div
              ref={createCollectionDialogRef}
              className="rounded-xl p-6 max-w-md w-full mx-4"
              style={{ backgroundColor: 'var(--bg-secondary)' }}
              role="dialog"
              aria-modal="true"
              aria-labelledby="create-collection-title"
            >
              <h3 id="create-collection-title" className="text-lg font-semibold mb-4" style={{ color: 'var(--text-primary)' }}>
                Create New List
              </h3>
              <label htmlFor="create-collection-name" className="sr-only">
                List name
              </label>
              <input
                id="create-collection-name"
                type="text"
                placeholder="List name..."
                value={newCollectionName}
                onChange={(e) => setNewCollectionName(e.target.value)}
                className="w-full px-4 py-2 rounded-lg border mb-4"
                style={{
                  backgroundColor: 'var(--bg-tertiary)',
                  borderColor: 'var(--border)',
                  color: 'var(--text-primary)'
                }}
                onKeyPress={(e) => {
                  if (e.key === 'Enter') {
                    createCollection();
                  }
                }}
              />
              <div className="flex gap-3">
                <button
                  onClick={createCollection}
                  disabled={!newCollectionName.trim()}
                  className="flex-1 px-4 py-2 rounded-lg font-medium disabled:opacity-50"
                  style={{ backgroundColor: 'var(--accent-ember)', color: 'white' }}
                >
                  Create
                </button>
                <button
                  onClick={() => setShowCreateCollection(false)}
                  className="flex-1 px-4 py-2 rounded-lg border font-medium"
                  style={{ borderColor: 'var(--border)', color: 'var(--text-primary)' }}
                >
                  Cancel
                </button>
              </div>
            </div>
          </div>
        )}

        {/* OCR Settings Modal */}
        {showOCRSettings && (
          <OCRSettings onClose={() => setShowOCRSettings(false)} />
        )}
      </div>
    </Layout>
  );
}