// lib/screens/challenges_screen.dart

import 'dart:math';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:google_fonts/google_fonts.dart';

import '../models/app_models.dart';
import '../services/firebase_service.dart';
import '../services/i18n_service.dart';

// KzEduca Palette
const _kGradientStart = Color(0xFF512DA8); // Roxo vibrante
const _kGradientEnd   = Color(0xFF000000); // Preto profundo
const _kAccent        = Color(0xFF00BFA5); // Verde água
const _kAction        = Color(0xFFFFD600); // Amarelo/dourado

class ChallengesScreen extends StatefulWidget {
  const ChallengesScreen({Key? key}) : super(key: key);

  @override
  State<ChallengesScreen> createState() => _ChallengesScreenState();
}

class _ChallengesScreenState extends State<ChallengesScreen> {
  List<FinancialChallenge> _publicChallenges = [];
  List<UserChallenge> _userChallenges = [];
  FinancialChallenge? _dailyChallenge;
  bool _isLoading = true;
  String _error = '';

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

  Future<void> _loadAll() async {
    setState(() {
      _isLoading = true;
      _error = '';
    });

    final service = Provider.of<FirebaseService>(context, listen: false);
    final uid = FirebaseAuth.instance.currentUser?.uid;
    if (uid == null) {
      setState(() {
        _error = 'Usuário não autenticado.';
        _isLoading = false;
      });
      return;
    }

    try {
      // 1) Carrega todos os desafios públicos
      _publicChallenges = await service.getAllChallenges();

      // 2) Carrega desafios aceitos pelo usuário e converte Timestamp para String
      final snapshot = await service.streamUserChallenges(uid).first;
      _userChallenges = snapshot.docs.map((doc) {
        final data = doc.data() as Map<String, dynamic>;

        // acceptedAt pode vir como Timestamp ou String
        final rawAccepted = data['acceptedAt'];
        final acceptedAtStr = rawAccepted is Timestamp
            ? rawAccepted.toDate().toIso8601String()
            : (rawAccepted?.toString() ?? '');

        // lastUpdated pode vir como Timestamp, String ou nulo
        final rawLast = data['lastUpdated'];
        final lastUpdatedStr = rawLast is Timestamp
            ? rawLast.toDate().toIso8601String()
            : rawLast?.toString();

        return UserChallenge(
          id: doc.id,
          challengeId: data['challengeId'] ?? '',
          nome: data['nome'] ?? '',
          meta: data['meta'] ?? '',
          progresso: (data['progresso'] as num?)?.toInt() ?? 0,
          acceptedAt: acceptedAtStr,
          lastUpdated: lastUpdatedStr,
        );
      }).toList();

      // 3) Escolhe um desafio do dia aleatório entre os não-aceitos
      final remaining = _publicChallenges.where(
        (c) => !_userChallenges.any((uc) => uc.challengeId == c.id),
      ).toList();

      if (remaining.isNotEmpty) {
        _dailyChallenge = remaining[Random().nextInt(remaining.length)];
      }

      setState(() {
        _isLoading = false;
      });
    } catch (e) {
      setState(() {
        _error = 'Erro ao carregar desafios: $e';
        _isLoading = false;
      });
    }
  }

  Future<void> _acceptChallenge(FinancialChallenge challenge) async {
    final service = Provider.of<FirebaseService>(context, listen: false);
    final uid = FirebaseAuth.instance.currentUser?.uid;
    if (uid == null) return;

    await service.acceptChallenge(uid, {
      'challengeId': challenge.id,
      'nome': challenge.nome,
      'meta': challenge.meta,
      'progresso': 0,
      'acceptedAt': DateTime.now().toIso8601String(),
    });

    await _loadAll();
    if (mounted) {
      final msg = Provider.of<I18nService>(context, listen: false)
          .t('challenge_accepted');
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(msg)),
      );
    }
  }

  Future<void> _updateProgress(UserChallenge uc) async {
    final service = Provider.of<FirebaseService>(context, listen: false);
    final uid = FirebaseAuth.instance.currentUser?.uid;
    if (uid == null) return;

    int newProgress = uc.progresso;
    await showModalBottomSheet(
      context: context,
      backgroundColor: Colors.grey[900],
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(16)),
      ),
      builder: (ctx) {
        return StatefulBuilder(builder: (ctx, setSheet) {
          return Padding(
            padding: const EdgeInsets.all(24),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  uc.nome,
                  style: GoogleFonts.montserrat(
                    color: Colors.white,
                    fontSize: 20,
                    fontWeight: FontWeight.w600,
                  ),
                ),
                const SizedBox(height: 16),
                Text(
                  Provider.of<I18nService>(context, listen: false)
                      .t('update_progress'),
                  style: GoogleFonts.montserrat(color: Colors.white70),
                ),
                Slider(
                  value: newProgress.toDouble(),
                  min: 0,
                  max: 100,
                  divisions: 20,
                  activeColor: _kAccent,
                  inactiveColor: Colors.white12,
                  label: '$newProgress%',
                  onChanged: (v) => setSheet(() => newProgress = v.round()),
                ),
                const SizedBox(height: 16),
                ElevatedButton(
                  style: ElevatedButton.styleFrom(
                    foregroundColor: Colors.black87, backgroundColor: _kAction,
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(12),
                    ),
                  ),
                  onPressed: () async {
                    await service.updateChallengeProgress(
                        uid, uc.id, newProgress);
                    Navigator.pop(ctx);
                    await _loadAll();
                  },
                  child: Text(
                    Provider.of<I18nService>(context, listen: false).t('save'),
                    style: GoogleFonts.montserrat(fontWeight: FontWeight.w600),
                  ),
                ),
                const SizedBox(height: 16),
              ],
            ),
          );
        });
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final i18n = Provider.of<I18nService>(context);

    return Scaffold(
      backgroundColor: Colors.black,
      body: Container(
        decoration: const BoxDecoration(
          gradient: LinearGradient(
            colors: [_kGradientStart, _kGradientEnd],
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
          ),
        ),
        child: SafeArea(
          child: _isLoading
              ? const Center(child: CircularProgressIndicator(color: _kAccent))
              : _error.isNotEmpty
                  ? Center(
                      child: Text(
                        _error,
                        style: GoogleFonts.montserrat(
                          color: Colors.redAccent,
                          fontSize: 16,
                        ),
                      ),
                    )
                  : SingleChildScrollView(
                      padding: const EdgeInsets.symmetric(
                          horizontal: 20, vertical: 16),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          // Header
                          Row(
                            children: [
                              IconButton(
                                icon: const Icon(Icons.arrow_back_rounded,
                                    color: Colors.white),
                                onPressed: () => Navigator.pop(context),
                              ),
                              const SizedBox(width: 8),
                              Text(
                                i18n.t('challenges_title'),
                                style: GoogleFonts.montserrat(
                                  color: Colors.white,
                                  fontSize: 28,
                                  fontWeight: FontWeight.w700,
                                ),
                              ),
                            ],
                          ),
                          const SizedBox(height: 24),

                          // Daily Challenge
                          if (_dailyChallenge != null) ...[
                            _DailyCard(
                              challenge: _dailyChallenge!,
                              onAccept: () => _acceptChallenge(_dailyChallenge!),
                            ),
                            const SizedBox(height: 32),
                          ],

                          // Public Challenges
                          Text(
                            i18n.t('public_challenges_title'),
                            style: GoogleFonts.montserrat(
                              color: Colors.white,
                              fontSize: 22,
                              fontWeight: FontWeight.w600,
                            ),
                          ),
                          const SizedBox(height: 16),
                          Column(
                            children: _publicChallenges
                                .where((c) => c.id != _dailyChallenge?.id)
                                .map((c) => _PublicCard(
                                      challenge: c,
                                      onAccept: () => _acceptChallenge(c),
                                    ))
                                .toList(),
                          ),
                          const SizedBox(height: 32),

                          // My Challenges
                          Text(
                            i18n.t('accepted_challenges_title'),
                            style: GoogleFonts.montserrat(
                              color: Colors.white,
                              fontSize: 22,
                              fontWeight: FontWeight.w600,
                            ),
                          ),
                          const SizedBox(height: 16),
                          if (_userChallenges.isEmpty)
                            _EmptyState(
                              icon: Icons.hourglass_empty_rounded,
                              message: i18n.t('no_accepted_challenges'),
                            )
                          else
                            Column(
                              children: _userChallenges
                                  .map((uc) => _ProgressCard(
                                        uc: uc,
                                        onTap: () => _updateProgress(uc),
                                      ))
                                  .toList(),
                            ),
                          const SizedBox(height: 40),
                        ],
                      ),
                    ),
        ),
      ),
    );
  }
}

// Daily Challenge Card
class _DailyCard extends StatelessWidget {
  final FinancialChallenge challenge;
  final VoidCallback onAccept;

  const _DailyCard({
    required this.challenge,
    required this.onAccept,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext c) {
    final i18n = Provider.of<I18nService>(c, listen: false);

    return Container(
      padding: const EdgeInsets.all(24),
      decoration: BoxDecoration(
        gradient: const LinearGradient(colors: [_kAccent, _kGradientStart]),
        borderRadius: BorderRadius.circular(24),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.5),
            blurRadius: 14,
            offset: const Offset(0, 8),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            i18n.t('daily_challenge_new'),
            style: GoogleFonts.montserrat(
              color: Colors.white70,
              fontSize: 14,
              letterSpacing: 1.2,
            ),
          ),
          const SizedBox(height: 8),
          Text(
            challenge.nome,
            style: GoogleFonts.montserrat(
              color: Colors.white,
              fontSize: 26,
              fontWeight: FontWeight.w700,
            ),
          ),
          const SizedBox(height: 12),
          Text(
            challenge.meta,
            style: GoogleFonts.montserrat(
              color: Colors.white70,
              fontSize: 16,
              height: 1.4,
            ),
          ),
          const SizedBox(height: 24),
          Center(
            child: ElevatedButton(
              style: ElevatedButton.styleFrom(
                foregroundColor: Colors.black87, backgroundColor: _kAction,
                padding: const EdgeInsets.symmetric(
                    horizontal: 36, vertical: 14),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(12),
                ),
              ),
              onPressed: onAccept,
              child: Text(
                i18n.t('accept_challenge'),
                style: GoogleFonts.montserrat(
                  fontWeight: FontWeight.w600,
                  fontSize: 16,
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

// Public Challenge Card
class _PublicCard extends StatelessWidget {
  final FinancialChallenge challenge;
  final VoidCallback onAccept;

  const _PublicCard({
    required this.challenge,
    required this.onAccept,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext c) {
    final i18n = Provider.of<I18nService>(c, listen: false);

    return Container(
      margin: const EdgeInsets.symmetric(vertical: 8),
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: Colors.grey[850],
        borderRadius: BorderRadius.circular(16),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.3),
            blurRadius: 10,
            offset: const Offset(0, 6),
          )
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(challenge.nome,
              style: GoogleFonts.montserrat(
                color: Colors.white,
                fontSize: 20,
                fontWeight: FontWeight.w600,
              )),
          const SizedBox(height: 8),
          Text(challenge.meta,
              style: GoogleFonts.montserrat(
                color: Colors.white70,
                fontSize: 16,
                height: 1.4,
              )),
          const SizedBox(height: 16),
          Align(
            alignment: Alignment.centerRight,
            child: TextButton(
              style: TextButton.styleFrom(
                backgroundColor: _kAccent,
                padding:
                    const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(12),
                ),
              ),
              onPressed: onAccept,
              child: Text(
                i18n.t('accept_challenge'),
                style: GoogleFonts.montserrat(
                  color: Colors.black87, fontWeight: FontWeight.w600,
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

// Progress Challenge Card with circular indicator
class _ProgressCard extends StatelessWidget {
  final UserChallenge uc;
  final VoidCallback onTap;

  const _ProgressCard({
    required this.uc,
    required this.onTap,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext c) {
    final progress = (uc.progresso / 100).clamp(0.0, 1.0);

    return GestureDetector(
      onTap: onTap,
      child: Container(
        margin: const EdgeInsets.symmetric(vertical: 8),
        padding: const EdgeInsets.all(20),
        decoration: BoxDecoration(
          color: Colors.grey[850],
          borderRadius: BorderRadius.circular(16),
          boxShadow: [
            BoxShadow(
              color: Colors.black.withOpacity(0.3),
              blurRadius: 10,
              offset: const Offset(0, 6),
            )
          ],
        ),
        child: Row(
          children: [
            CustomPaint(
              painter: _CircleProgressPainter(progress, _kAccent),
              size: const Size(60, 60),
              child: Center(
                child: Text('${uc.progresso}%',
                    style: GoogleFonts.montserrat(
                      color: Colors.white,
                      fontWeight: FontWeight.w600,
                    )),
              ),
            ),
            const SizedBox(width: 16),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(uc.nome,
                      style: GoogleFonts.montserrat(
                        color: Colors.white,
                        fontSize: 18,
                        fontWeight: FontWeight.w600,
                      )),
                  const SizedBox(height: 4),
                  Text(uc.meta,
                      style: GoogleFonts.montserrat(
                        color: Colors.white70,
                        fontSize: 14,
                        height: 1.3,
                      )),
                ],
              ),
            ),
            const Icon(Icons.edit, color: Colors.white54),
          ],
        ),
      ),
    );
  }
}

class _CircleProgressPainter extends CustomPainter {
  final double progress;
  final Color color;

  _CircleProgressPainter(this.progress, this.color);

  @override
  void paint(Canvas canvas, Size size) {
    final strokeWidth = 6.0;
    final center = Offset(size.width / 2, size.height / 2);
    final radius = (size.width - strokeWidth) / 2;

    final bgPaint = Paint()
      ..color = Colors.white12
      ..style = PaintingStyle.stroke
      ..strokeWidth = strokeWidth;

    final fgPaint = Paint()
      ..color = color
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round
      ..strokeWidth = strokeWidth;

    canvas.drawCircle(center, radius, bgPaint);
    final sweep = 2 * pi * progress;
    canvas.drawArc(
      Rect.fromCircle(center: center, radius: radius),
      -pi / 2,
      sweep,
      false,
      fgPaint,
    );
  }

  @override
  bool shouldRepaint(covariant _CircleProgressPainter old) =>
      old.progress != progress || old.color != color;
}

// Empty State Widget
class _EmptyState extends StatelessWidget {
  final IconData icon;
  final String message;

  const _EmptyState({
    required this.icon,
    required this.message,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext c) {
    return Column(
      children: [
        const SizedBox(height: 40),
        Icon(icon, size: 80, color: Colors.white24),
        const SizedBox(height: 20),
        Text(
          message,
          style: GoogleFonts.montserrat(
            color: Colors.white54,
            fontSize: 18,
            fontStyle: FontStyle.italic,
          ),
          textAlign: TextAlign.center,
        ),
      ],
    );
  }
}