import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../theme/app_colors.dart';
import '../theme/app_text_styles.dart';
import 'home_screen.dart';
import '../services/encouragement_service.dart';

/// Onboarding Screen - Shows on first launch
class OnboardingScreen extends StatefulWidget {
  final EncouragementService encouragementService;

  const OnboardingScreen({
    super.key,
    required this.encouragementService,
  });

  /// Check if user has completed onboarding
  static Future<bool> hasCompletedOnboarding() async {
    final prefs = await SharedPreferences.getInstance();
    return prefs.getBool(_onboardingKey) ?? false;
  }

  /// Mark onboarding as completed
  static Future<void> setOnboardingCompleted() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setBool(_onboardingKey, true);
  }

  static const String _onboardingKey = 'onboarding_completed';

  @override
  State<OnboardingScreen> createState() => _OnboardingScreenState();
}

class _OnboardingScreenState extends State<OnboardingScreen> {
  final PageController _pageController = PageController();
  int _currentPage = 0;

  final List<OnboardingPage> _pages = [
    OnboardingPage(
      emoji: '💚',
      title: 'Focus without guilt',
      description:
          "This app is different — it won't punish you for losing focus.\n\nPerfect for ADHD, anxiety, or anyone who finds traditional timers too harsh.",
    ),
    OnboardingPage(
      emoji: '🤚',
      title: 'Tap when you get distracted',
      description:
          "We'll gently remind you to come back.\n\nNo shame. No stress. Just a friendly nudge.",
    ),
    OnboardingPage(
      emoji: '📊',
      title: 'Track your progress',
      description:
          "See how you're improving, one session at a time.\n\nEvery distraction is just data — not failure.",
    ),
  ];

  void _onPageChanged(int page) {
    setState(() {
      _currentPage = page;
    });
  }

  void _nextPage() {
    if (_currentPage < _pages.length - 1) {
      _pageController.animateToPage(
        _currentPage + 1,
        duration: const Duration(milliseconds: 300),
        curve: Curves.easeInOut,
      );
    } else {
      _completeOnboarding();
    }
  }

  void _skipOnboarding() {
    _completeOnboarding();
  }

  Future<void> _completeOnboarding() async {
    await OnboardingScreen.setOnboardingCompleted();

    if (!mounted) return;

    Navigator.pushReplacement(
      context,
      MaterialPageRoute(
        builder: (context) => HomeScreen(
          encouragementService: widget.encouragementService,
        ),
      ),
    );
  }

  @override
  void dispose() {
    _pageController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.background,
      body: SafeArea(
        child: Column(
          children: [
            // Skip button
            Align(
              alignment: Alignment.topRight,
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: TextButton(
                  onPressed: _skipOnboarding,
                  child: const Text(
                    'Skip',
                    style: TextStyle(
                      fontFamily: 'Nunito',
                      fontSize: 16,
                      fontWeight: FontWeight.w600,
                      color: AppColors.textSecondary,
                    ),
                  ),
                ),
              ),
            ),

            // PageView
            Expanded(
              child: PageView.builder(
                controller: _pageController,
                onPageChanged: _onPageChanged,
                itemCount: _pages.length,
                itemBuilder: (context, index) {
                  return _buildPage(_pages[index]);
                },
              ),
            ),

            // Page indicators
            Padding(
              padding: const EdgeInsets.symmetric(vertical: 24.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: List.generate(
                  _pages.length,
                  (index) => _buildIndicator(index == _currentPage),
                ),
              ),
            ),

            // Next/Get Started button
            Padding(
              padding: const EdgeInsets.all(24.0),
              child: SizedBox(
                width: double.infinity,
                child: ElevatedButton(
                  onPressed: _nextPage,
                  child: Text(
                    _currentPage == _pages.length - 1
                        ? 'Get Started'
                        : 'Next',
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildPage(OnboardingPage page) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 32.0),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          // Emoji
          Text(
            page.emoji,
            style: const TextStyle(fontSize: 80),
          ),

          const SizedBox(height: 48),

          // Title
          Text(
            page.title,
            style: const TextStyle(
              fontFamily: 'Nunito',
              fontSize: 32,
              fontWeight: FontWeight.w700,
              color: AppColors.textPrimary,
            ),
            textAlign: TextAlign.center,
          ),

          const SizedBox(height: 24),

          // Description
          Text(
            page.description,
            style: AppTextStyles.bodyText.copyWith(
              fontSize: 18,
              height: 1.6,
            ),
            textAlign: TextAlign.center,
          ),

          const SizedBox(height: 40),
        ],
      ),
    );
  }

  Widget _buildIndicator(bool isActive) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 4),
      width: isActive ? 24 : 8,
      height: 8,
      decoration: BoxDecoration(
        color: isActive ? AppColors.primary : AppColors.divider,
        borderRadius: BorderRadius.circular(4),
      ),
    );
  }
}

/// Data class for onboarding page
class OnboardingPage {
  final String emoji;
  final String title;
  final String description;

  OnboardingPage({
    required this.emoji,
    required this.title,
    required this.description,
  });
}