import 'package:flutter/material.dart';
import 'package:practice_engine/practice_engine.dart';
import '../routes.dart';
import '../services/deck_storage.dart';

class DeckOverviewScreen extends StatefulWidget {
  const DeckOverviewScreen({super.key});

  @override
  State<DeckOverviewScreen> createState() => _DeckOverviewScreenState();
}

class _DeckOverviewScreenState extends State<DeckOverviewScreen> {
  Deck? _deck;
  final DeckStorage _deckStorage = DeckStorage();

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    // Get deck from route arguments
    final args = ModalRoute.of(context)?.settings.arguments;
    if (args is Deck) {
      // ALWAYS load the latest version from storage to ensure we have the most up-to-date deck
      // This is critical for getting the latest incomplete attempt state
      // Don't rely on route arguments - they might be stale
      final storedDeck = _deckStorage.getDeckSync(args.id);
      final deckToUse = storedDeck ?? args;
      
      // Always update to get the latest state from storage
      // This ensures we always have the most up-to-date incomplete attempt state
      setState(() {
        _deck = deckToUse;
      });
    }
  }

  void _saveDeck() {
    if (_deck != null) {
      _deckStorage.saveDeckSync(_deck!);
    }
  }

  @override
  void initState() {
    super.initState();
  }

  void _startAttempt() async {
    // Force reload from storage before checking for incomplete attempts to ensure we have latest state
    Deck? deckToCheck = _deck;
    if (_deck != null) {
      final freshDeck = _deckStorage.getDeckSync(_deck!.id);
      if (freshDeck != null) {
        setState(() {
          _deck = freshDeck;
        });
        deckToCheck = freshDeck; // Use the fresh deck for the check
      }
    }
    
    if (deckToCheck == null || deckToCheck.questions.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('Cannot start attempt: No questions in deck'),
          backgroundColor: Colors.red,
        ),
      );
      return;
    }

    // Check for incomplete attempt first - use the fresh deck we just loaded
    if (deckToCheck.incompleteAttempt != null) {
      final incomplete = deckToCheck.incompleteAttempt!;
      final progress = incomplete.currentQuestionIndex + 1;
      final total = incomplete.questionIds.length;
      
      final action = await showDialog<String>(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('Incomplete Attempt Found'),
          content: Text(
            'You have an incomplete attempt (Question $progress of $total).\n\n'
            'Would you like to continue where you left off, or start a new attempt?',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context, 'ignore'),
              child: const Text('Start Fresh'),
            ),
            FilledButton(
              onPressed: () => Navigator.pop(context, 'continue'),
              child: const Text('Continue'),
            ),
          ],
        ),
      );

      if (action == 'continue') {
        // Continue the incomplete attempt
        if (!mounted) return;
        Navigator.pushNamed(
          context,
          Routes.attempt,
          arguments: {
            'deck': deckToCheck,
            'resumeAttempt': true,
          },
        ).then((_) {
          // Refresh deck state when returning from attempt
          _refreshDeck();
        });
        return;
      } else if (action == 'ignore') {
        // Clear incomplete attempt and start fresh
        // Clear incomplete attempt - create a fresh copy without it
        final updatedDeck = deckToCheck.copyWith(clearIncompleteAttempt: true);
        
        // Save to storage multiple times to ensure it's persisted
        _deckStorage.saveDeckSync(updatedDeck);
        _deckStorage.saveDeckSync(updatedDeck); // Save twice to be sure
        
        // Update local state immediately with cleared deck
        setState(() {
          _deck = updatedDeck;
        });
        
        // Force reload from storage multiple times to verify it's cleared
        Deck? finalClearedDeck = updatedDeck;
        for (int i = 0; i < 3; i++) {
          final verifiedDeck = _deckStorage.getDeckSync(updatedDeck.id);
          
          if (verifiedDeck != null) {
            // Ensure incomplete attempt is null even if storage had it
            if (verifiedDeck.incompleteAttempt != null) {
              final clearedDeck = verifiedDeck.copyWith(clearIncompleteAttempt: true);
              _deckStorage.saveDeckSync(clearedDeck);
              setState(() {
                _deck = clearedDeck;
              });
              finalClearedDeck = clearedDeck;
            } else {
              // Already cleared, update state
              setState(() {
                _deck = verifiedDeck;
              });
              finalClearedDeck = verifiedDeck;
              break; // Exit loop if already cleared
            }
          }
        }
        // CRITICAL: Update deckToCheck to use the cleared deck for the rest of the flow
        deckToCheck = finalClearedDeck ?? updatedDeck;
        // Continue to normal flow below - the deck should now have no incomplete attempt
      } else {
        // User cancelled
        return;
      }
    }

    // Check if all questions are known and includeKnownInAttempts is disabled
    final allKnown = deckToCheck.knownCount == deckToCheck.numberOfQuestions && deckToCheck.numberOfQuestions > 0;
    final includeKnownDisabled = !deckToCheck.config.includeKnownInAttempts;

    if (allKnown && includeKnownDisabled) {
      // Show confirmation dialog
      final shouldIncludeKnown = await showDialog<bool>(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('All Questions Known'),
          content: const Text(
            'All questions are known, attempt with known questions?',
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context, false),
              child: const Text('No'),
            ),
            FilledButton(
              onPressed: () => Navigator.pop(context, true),
              child: const Text('Yes'),
            ),
          ],
        ),
      );

      if (shouldIncludeKnown == null || !shouldIncludeKnown) {
        // User cancelled or said No
        return;
      }

      // Pass the deck with a flag to include known questions
      // Ensure we're using a deck without incomplete attempt
      if (!mounted) return;
      final deckToUse = deckToCheck.copyWith(clearIncompleteAttempt: true);
      Navigator.pushNamed(
        context,
        Routes.attempt,
        arguments: {
          'deck': deckToUse,
          'includeKnown': true,
        },
      ).then((_) {
        // Refresh deck state when returning from attempt
        _refreshDeck();
      });
    } else {
      // Normal flow - ensure we're using a deck without incomplete attempt
      if (!mounted) return;
      // Always use a fresh deck copy without incomplete attempt to prevent stale state
      // Also ensure storage has the cleared state
      final deckToUse = deckToCheck.copyWith(clearIncompleteAttempt: true);
      // Ensure storage also has the cleared state
      _deckStorage.saveDeckSync(deckToUse);
      Navigator.pushNamed(
        context,
        Routes.attempt,
        arguments: deckToUse,
      ).then((_) {
        // Refresh deck state when returning from attempt
        _refreshDeck();
      });
    }
  }

  void _refreshDeck() {
    if (_deck != null) {
      // Reload the deck from storage to get the latest state (including incomplete attempts)
      final refreshedDeck = _deckStorage.getDeckSync(_deck!.id);
      if (refreshedDeck != null && mounted) {
        setState(() {
          _deck = refreshedDeck;
        });
      }
    }
  }

  void _openConfig() {
    if (_deck == null) return;
    
    Navigator.pushNamed(context, Routes.deckConfig, arguments: _deck)
        .then((updatedDeck) {
      if (updatedDeck != null && updatedDeck is Deck) {
        final wasReset = updatedDeck.attemptHistory.isEmpty && 
                        updatedDeck.currentAttemptIndex == 0 &&
                        _deck != null &&
                        _deck!.attemptHistory.isNotEmpty;
        
        setState(() {
          _deck = updatedDeck;
        });
        _saveDeck(); // Save to storage
        
        // Show confirmation message
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text(wasReset 
                  ? 'Deck has been reset successfully'
                  : 'Deck settings have been updated'),
              backgroundColor: Colors.green,
              duration: const Duration(seconds: 2),
            ),
          );
        }
      }
    });
  }

  String _formatTime(int milliseconds) {
    final seconds = milliseconds ~/ 1000;
    final minutes = seconds ~/ 60;
    final hours = minutes ~/ 60;
    final remainingMinutes = minutes % 60;
    final remainingSeconds = seconds % 60;
    
    if (hours > 0) {
      return '${hours}h ${remainingMinutes}m';
    } else if (minutes > 0) {
      return '${minutes}m ${remainingSeconds}s';
    } else {
      return '${remainingSeconds}s';
    }
  }

  Widget _buildProgressStats(BuildContext context) {
    if (_deck == null) return const SizedBox.shrink();
    
    final totalQuestions = _deck!.numberOfQuestions;
    final knownCount = _deck!.knownCount;
    final unknownCount = totalQuestions - knownCount;
    final unknownPercentage = totalQuestions > 0 
        ? (unknownCount / totalQuestions * 100.0) 
        : 0.0;
    final knownPercentage = totalQuestions > 0 
        ? (knownCount / totalQuestions * 100.0) 
        : 0.0;
    
    // Get progress trend if we have history
    // Attempt history is stored chronologically (oldest first), so first is oldest, last is newest
    String? trendText;
    if (_deck!.attemptHistory.isNotEmpty) {
      final oldestAttempt = _deck!.attemptHistory.first;
      final newestAttempt = _deck!.attemptHistory.last;
      final oldestUnknown = oldestAttempt.unknownPercentage;
      final newestUnknown = newestAttempt.unknownPercentage;
      final improvement = oldestUnknown - newestUnknown;
      
      if (improvement > 0) {
        trendText = 'Improved by ${improvement.toStringAsFixed(1)}% since first attempt';
      } else if (improvement < 0) {
        trendText = '${improvement.abs().toStringAsFixed(1)}% more to learn since first attempt';
      } else {
        trendText = 'No change since first attempt';
      }
    }
    
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        // Main stat: Unknown percentage
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'Questions to Learn',
                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.7),
                      ),
                ),
                const SizedBox(height: 4),
                Text(
                  '${unknownPercentage.toStringAsFixed(1)}%',
                  style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                        fontWeight: FontWeight.bold,
                        color: Theme.of(context).colorScheme.primary,
                      ),
                ),
                Text(
                  '$unknownCount of $totalQuestions questions',
                  style: Theme.of(context).textTheme.bodySmall,
                ),
              ],
            ),
            Column(
              crossAxisAlignment: CrossAxisAlignment.end,
              children: [
                Text(
                  'Questions Known',
                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.7),
                      ),
                ),
                const SizedBox(height: 4),
                Text(
                  '${knownPercentage.toStringAsFixed(1)}%',
                  style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                        fontWeight: FontWeight.bold,
                        color: Theme.of(context).colorScheme.secondary,
                      ),
                ),
                Text(
                  '$knownCount of $totalQuestions questions',
                  style: Theme.of(context).textTheme.bodySmall,
                ),
              ],
            ),
          ],
        ),
        const SizedBox(height: 16),
        // Progress bar
        Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  'Progress',
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.7),
                      ),
                ),
                Text(
                  '${knownPercentage.toStringAsFixed(1)}%',
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                        fontWeight: FontWeight.bold,
                      ),
                ),
              ],
            ),
            const SizedBox(height: 8),
            ClipRRect(
              borderRadius: BorderRadius.circular(8),
              child: LinearProgressIndicator(
                value: knownPercentage / 100.0,
                minHeight: 12,
                backgroundColor: Theme.of(context).colorScheme.surfaceContainerHighest,
                valueColor: AlwaysStoppedAnimation<Color>(
                  Theme.of(context).colorScheme.primary,
                ),
              ),
            ),
          ],
        ),
        if (trendText != null) ...[
          const SizedBox(height: 12),
          Text(
            trendText,
            style: Theme.of(context).textTheme.bodySmall?.copyWith(
                  color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.6),
                ),
          ),
        ],
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    if (_deck == null) {
      return const Scaffold(
        body: Center(child: CircularProgressIndicator()),
      );
    }

    return Scaffold(
      appBar: AppBar(
        title: Text(_deck!.title),
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            // Deck Description
            Card(
              child: Padding(
                padding: const EdgeInsets.all(12),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'Description',
                      style: Theme.of(context).textTheme.titleSmall,
                    ),
                    const SizedBox(height: 4),
                    Text(
                      _deck!.description,
                      style: Theme.of(context).textTheme.bodySmall,
                    ),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 12),

            // Practice Progress
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Row(
                  children: [
                    SizedBox(
                      width: 80,
                      height: 80,
                      child: CircularProgressIndicator(
                        value: _deck!.practicePercentage / 100,
                        strokeWidth: 6,
                      ),
                    ),
                    const SizedBox(width: 16),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text(
                            '${_deck!.practicePercentage.toStringAsFixed(1)}%',
                            style: Theme.of(context).textTheme.headlineSmall?.copyWith(
                                  fontWeight: FontWeight.bold,
                                ),
                          ),
                          const SizedBox(height: 4),
                          Text(
                            '${_deck!.knownCount} of ${_deck!.numberOfQuestions} questions known',
                            style: Theme.of(context).textTheme.bodySmall,
                          ),
                        ],
                      ),
                    ),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 12),

            // Statistics
            Card(
              child: Padding(
                padding: const EdgeInsets.all(12),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: [
                    _StatItem(
                      label: 'Total',
                      value: '${_deck!.numberOfQuestions}',
                      icon: Icons.quiz,
                    ),
                    _StatItem(
                      label: 'Known',
                      value: '${_deck!.knownCount}',
                      icon: Icons.check_circle,
                    ),
                    _StatItem(
                      label: 'Practice',
                      value: '${_deck!.numberOfQuestions - _deck!.knownCount}',
                      icon: Icons.school,
                    ),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 12),

            // Attempts History
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Row(
                      children: [
                        Icon(
                          Icons.history,
                          size: 20,
                          color: Theme.of(context).colorScheme.primary,
                        ),
                        const SizedBox(width: 8),
                        Text(
                          'Attempts History',
                          style: Theme.of(context).textTheme.titleMedium?.copyWith(
                                fontWeight: FontWeight.bold,
                              ),
                        ),
                      ],
                    ),
                    const SizedBox(height: 16),
                    if (_deck!.attemptHistory.isEmpty)
                      Padding(
                        padding: const EdgeInsets.all(16),
                        child: Center(
                          child: Column(
                            children: [
                              Icon(
                                Icons.quiz_outlined,
                                size: 48,
                                color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.3),
                              ),
                              const SizedBox(height: 8),
                              Text(
                                'No attempts yet',
                                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                                      color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.6),
                                    ),
                              ),
                            ],
                          ),
                        ),
                      )
                    else ...[
                      // Summary Statistics
                      Row(
                        mainAxisAlignment: MainAxisAlignment.spaceAround,
                        children: [
                          _HistoryStatItem(
                            label: 'Attempts',
                            value: '${_deck!.attemptCount}',
                            icon: Icons.quiz,
                          ),
                          _HistoryStatItem(
                            label: 'Avg. Score',
                            value: '${_deck!.averagePercentageCorrect.toStringAsFixed(1)}%',
                            icon: Icons.trending_up,
                          ),
                          _HistoryStatItem(
                            label: 'Total Time',
                            value: _formatTime(_deck!.totalTimeSpent),
                            icon: Icons.timer,
                          ),
                        ],
                      ),
                      const SizedBox(height: 16),
                      const Divider(),
                      const SizedBox(height: 8),
                      Text(
                        'Learning Progress',
                        style: Theme.of(context).textTheme.titleSmall,
                      ),
                      const SizedBox(height: 12),
                      // Current progress
                      _buildProgressStats(context),
                    ],
                  ],
                ),
              ),
            ),
            const SizedBox(height: 12),

            // Action Buttons
            FilledButton.icon(
              onPressed: _startAttempt,
              icon: const Icon(Icons.play_arrow),
              label: const Text('Start Attempt'),
              style: FilledButton.styleFrom(
                padding: const EdgeInsets.symmetric(vertical: 12),
              ),
            ),
            const SizedBox(height: 8),
            OutlinedButton.icon(
              onPressed: _openConfig,
              icon: const Icon(Icons.settings),
              label: const Text('Configure Deck'),
              style: OutlinedButton.styleFrom(
                padding: const EdgeInsets.symmetric(vertical: 12),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _StatItem extends StatelessWidget {
  final String label;
  final String value;
  final IconData icon;

  const _StatItem({
    required this.label,
    required this.value,
    required this.icon,
  });

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        Icon(icon, size: 24),
        const SizedBox(height: 4),
        Text(
          value,
          style: Theme.of(context).textTheme.titleMedium?.copyWith(
                fontWeight: FontWeight.bold,
              ),
        ),
        Text(
          label,
          style: Theme.of(context).textTheme.bodySmall,
        ),
      ],
    );
  }
}

class _HistoryStatItem extends StatelessWidget {
  final String label;
  final String value;
  final IconData icon;

  const _HistoryStatItem({
    required this.label,
    required this.value,
    required this.icon,
  });

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        Icon(icon, size: 20, color: Theme.of(context).colorScheme.primary),
        const SizedBox(height: 4),
        Text(
          value,
          style: Theme.of(context).textTheme.titleSmall?.copyWith(
                fontWeight: FontWeight.bold,
              ),
        ),
        Text(
          label,
          style: Theme.of(context).textTheme.bodySmall,
        ),
      ],
    );
  }
}