import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import '../models/lesson.dart';
import '../models/school.dart';
import '../services/lessons_api.dart';
import 'select_school_page.dart';
import 'home_page.dart';
import 'meditation_page.dart';
import '../widgets/app_drawer.dart';
import '../widgets/app_bottom_nav.dart';
import '../widgets/yogibook_background.dart';
import 'reschedule_page.dart';
import 'orders_page.dart';

class LessonsPage extends StatefulWidget {
  final String token;
  final School school;
  final String? userFirstName;

  const LessonsPage({
    super.key,
    required this.token,
    required this.school,
    this.userFirstName,
  });

  @override
  State<LessonsPage> createState() => _LessonsPageState();
}

class _LessonsPageState extends State<LessonsPage> {
  bool loading = true;
  String error = '';

  String currentMonth = DateFormat('yyyy-MM').format(DateTime.now());

  LessonsSummary? summary;
  List<Lesson> lessons = [];

  int bottomIndex = 1;

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

  Future<void> _load() async {
    setState(() {
      loading = true;
      error = '';
    });

    try {
      final data = await LessonsApi.fetchMyLessons(
        token: widget.token,
        month: currentMonth,
      );

      setState(() {
        summary = data.summary;
        lessons = data.lessons;
      });
    } catch (e) {
      setState(() => error = 'Errore: $e');
    } finally {
      setState(() => loading = false);
    }
  }

  // Navigazione mesi calcolata lato client (l'API non restituisce prev/next).
  String _shiftMonth(String yyyyMm, int delta) {
    final dt = DateFormat('yyyy-MM').parse(yyyyMm);
    final shifted = DateTime(dt.year, dt.month + delta, 1);
    return DateFormat('yyyy-MM').format(shifted);
  }

  void _goPrevMonth() {
    setState(() => currentMonth = _shiftMonth(currentMonth, -1));
    _load();
  }

  void _goNextMonth() {
    setState(() => currentMonth = _shiftMonth(currentMonth, 1));
    _load();
  }

  String _monthLabel(String yyyyMm) {
    final dt = DateFormat('yyyy-MM').parse(yyyyMm);
    return DateFormat('MMMM yyyy', 'it_IT').format(dt);
  }

  String _weekdayLabel(String ymd) {
    final dt = DateFormat('yyyy-MM-dd').parse(ymd);
    final s = DateFormat('EEEE', 'it_IT').format(dt);
    return s[0].toUpperCase() + s.substring(1);
  }

  String _dayNum(String ymd) {
    final dt = DateFormat('yyyy-MM-dd').parse(ymd);
    return DateFormat('dd').format(dt);
  }

  String get _name => (widget.userFirstName ?? '').trim();
  String get _avatarLetter => _name.isNotEmpty ? _name[0].toUpperCase() : 'U';

  void _handleBottomNav(int i) {
    if (i == bottomIndex) return;
    setState(() => bottomIndex = i);

    if (i == 0) {
      Navigator.pushReplacement(
        context,
        MaterialPageRoute(
          builder: (_) => HomePage(
            token: widget.token,
            school: widget.school,
            userFirstName: widget.userFirstName,
          ),
        ),
      );
      return;
    }

    if (i == 1) return; // sei già su Lezioni

    if (i == 2) {
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('TODO: vai ad Account')));
      return;
    }

    if (i == 3) {
      Navigator.pushReplacement(
        context,
        MaterialPageRoute(
          builder: (_) => MeditationPage(
            token: widget.token,
            school: widget.school,
            userFirstName: widget.userFirstName,
          ),
        ),
      );
      return;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      drawer: AppDrawer(
        token: widget.token,
        school: widget.school,
        userFirstName: widget.userFirstName,
      ),

      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        centerTitle: true,
        title: Column(
          children: [
            const Text(
              'Le mie lezioni',
              style: TextStyle(fontWeight: FontWeight.w800, fontSize: 18),
            ),
            const SizedBox(height: 2),
            Text(
              widget.school.name,
              style: const TextStyle(
                fontSize: 12,
                fontWeight: FontWeight.w600,
                color: Colors.black54,
              ),
            ),
          ],
        ),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: 12),
            child: CircleAvatar(
              radius: 16,
              backgroundColor: const Color(0xFF10B981),
              child: Text(
                _avatarLetter,
                style: const TextStyle(
                  color: Colors.white,
                  fontWeight: FontWeight.w900,
                  fontSize: 12,
                ),
              ),
            ),
          ),
        ],
      ),
      bottomNavigationBar: AppBottomNav(
        currentIndex: bottomIndex,
        onTap: _handleBottomNav,
      ),

      body: YogibookBackground(
        child: SafeArea(
          top: false,
          child: Column(
            children: [
              // Riepilogo conteggi (le card pastello della webapp)
              if (summary != null)
                Padding(
                  padding: const EdgeInsets.fromLTRB(12, 8, 12, 4),
                  child: _SummaryStrip(summary: summary!),
                ),

              // Selettore mese
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 6, 16, 4),
                child: _MonthPillCompact(
                  label: _monthLabel(currentMonth),
                  onPrev: _goPrevMonth,
                  onNext: _goNextMonth,
                ),
              ),

              // Bottone "Programma lezioni" (solo se ci sono ticket residui)
              if (summary != null && summary!.toSchedule > 0)
                Padding(
                  padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
                  child: SizedBox(
                    width: double.infinity,
                    child: ElevatedButton.icon(
                      style: ElevatedButton.styleFrom(
                        backgroundColor: const Color(0xFF10B981),
                        padding: const EdgeInsets.symmetric(vertical: 12),
                        shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(14),
                        ),
                      ),
                      icon: const Icon(Icons.add, color: Colors.white),
                      label: Text(
                        'Programma lezioni (${summary!.toSchedule} disponibili)',
                        style: const TextStyle(
                          color: Colors.white,
                          fontWeight: FontWeight.w800,
                        ),
                      ),
                      onPressed: () async {
                        await Navigator.push(
                          context,
                          MaterialPageRoute(
                            builder: (_) => OrdersPage(token: widget.token),
                          ),
                        );
                        _load();
                      },
                    ),
                  ),
                ),

              Expanded(
                child: loading
                    ? const Center(child: CircularProgressIndicator())
                    : error.isNotEmpty
                    ? _ErrorBox(message: error, onRetry: _load)
                    : lessons.isEmpty
                    ? _EmptyState(
                        onBrowse: () {
                          ScaffoldMessenger.of(context).showSnackBar(
                            const SnackBar(content: Text('TODO: vedi corsi')),
                          );
                        },
                      )
                    : ListView.builder(
                        padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
                        itemCount: lessons.length + 1,
                        itemBuilder: (_, i) {
                          if (i == lessons.length) {
                            return Padding(
                              padding: const EdgeInsets.only(top: 8, bottom: 6),
                              child: Center(
                                child: Image.asset(
                                  'assets/images/yogibook_logo.png',
                                  height: 56,
                                ),
                              ),
                            );
                          }

                          final l = lessons[i];
                          return _LessonGreenCardCompact(
                            lesson: l,
                            weekday: _weekdayLabel(l.date),
                            dayNum: _dayNum(l.date),
                            onReschedule: l.canReschedule
                                ? () async {
                                    await Navigator.push(
                                      context,
                                      MaterialPageRoute(
                                        builder: (_) => ReschedulePage(
                                          token: widget.token,
                                          bookingId: l.bookingId,
                                          serviceId: l.serviceId,
                                          className: l.className,
                                        ),
                                      ),
                                    );
                                    _load();
                                  }
                                : null,
                            onCancel: l.canDelete
                                ? () async {
                                    final conferma = await showDialog<bool>(
                                      context: context,
                                      builder: (dialogCtx) => AlertDialog(
                                        title: const Text(
                                          'Cancellare la lezione?',
                                        ),
                                        content: Text(
                                          'Vuoi cancellare "${l.className}" del ${l.date}? '
                                          'Ricordati di riprogrammarla entro la scadenza.',
                                        ),
                                        actions: [
                                          TextButton(
                                            onPressed: () =>
                                                Navigator.pop(dialogCtx, false),
                                            child: const Text('Annulla'),
                                          ),
                                          ElevatedButton(
                                            onPressed: () =>
                                                Navigator.pop(dialogCtx, true),
                                            child: const Text('Cancella'),
                                          ),
                                        ],
                                      ),
                                    );
                                    if (conferma != true) return;
                                    try {
                                      await LessonsApi.cancelLesson(
                                        token: widget.token,
                                        bookingId: l.bookingId,
                                      );
                                      if (!mounted) return;
                                      ScaffoldMessenger.of(
                                        context,
                                      ).showSnackBar(
                                        const SnackBar(
                                          content: Text('Lezione cancellata'),
                                        ),
                                      );
                                      _load();
                                    } catch (e) {
                                      if (!mounted) return;
                                      ScaffoldMessenger.of(
                                        context,
                                      ).showSnackBar(
                                        SnackBar(content: Text('$e')),
                                      );
                                    }
                                  }
                                : null,
                          );
                        },
                      ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _SummaryStrip extends StatelessWidget {
  final LessonsSummary summary;
  const _SummaryStrip({required this.summary});

  @override
  Widget build(BuildContext context) {
    final items = <_SummaryItem>[
      _SummaryItem('Acquistate', summary.purchased, const Color(0xFFE2C4FB)),
      _SummaryItem('Praticate', summary.practiced, const Color(0xFFC4E1FB)),
      _SummaryItem('Prenotate', summary.booked, const Color(0xFFCDFBC4)),
      _SummaryItem('Da confermare', summary.pending, const Color(0xFFFBFAC4)),
      _SummaryItem(
        'Da programmare',
        summary.toSchedule,
        const Color(0xFFFBE4C4),
      ),
      _SummaryItem('Perse', summary.lost, const Color(0xFFFBC7C4)),
    ];

    return SizedBox(
      height: 76,
      child: ListView.separated(
        scrollDirection: Axis.horizontal,
        itemCount: items.length,
        separatorBuilder: (_, __) => const SizedBox(width: 8),
        itemBuilder: (_, i) {
          final it = items[i];
          return Container(
            width: 96,
            padding: const EdgeInsets.all(8),
            decoration: BoxDecoration(
              color: it.color,
              borderRadius: BorderRadius.circular(12),
            ),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Text(
                  '${it.value}',
                  style: const TextStyle(
                    fontSize: 22,
                    fontWeight: FontWeight.w900,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  it.label,
                  textAlign: TextAlign.center,
                  style: const TextStyle(
                    fontSize: 10,
                    fontWeight: FontWeight.w700,
                  ),
                  maxLines: 2,
                  overflow: TextOverflow.ellipsis,
                ),
              ],
            ),
          );
        },
      ),
    );
  }
}

class _SummaryItem {
  final String label;
  final int value;
  final Color color;
  _SummaryItem(this.label, this.value, this.color);
}

class _MonthPillCompact extends StatelessWidget {
  final String label;
  final VoidCallback? onPrev;
  final VoidCallback? onNext;

  const _MonthPillCompact({
    required this.label,
    required this.onPrev,
    required this.onNext,
  });

  @override
  Widget build(BuildContext context) {
    const green = Color(0xFF10B981);

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 6),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(16),
        boxShadow: const [
          BoxShadow(
            blurRadius: 14,
            color: Color(0x11000000),
            offset: Offset(0, 8),
          ),
        ],
      ),
      child: Row(
        children: [
          IconButton(
            onPressed: onPrev,
            icon: const Icon(Icons.chevron_left),
            iconSize: 22,
            padding: EdgeInsets.zero,
            constraints: const BoxConstraints(minWidth: 40, minHeight: 40),
            color: onPrev == null ? Colors.black26 : green,
          ),
          Expanded(
            child: Text(
              label,
              textAlign: TextAlign.center,
              style: const TextStyle(fontSize: 15, fontWeight: FontWeight.w900),
            ),
          ),
          IconButton(
            onPressed: onNext,
            icon: const Icon(Icons.chevron_right),
            iconSize: 22,
            padding: EdgeInsets.zero,
            constraints: const BoxConstraints(minWidth: 40, minHeight: 40),
            color: onNext == null ? Colors.black26 : green,
          ),
        ],
      ),
    );
  }
}

class _LessonGreenCardCompact extends StatelessWidget {
  final Lesson lesson;
  final String weekday;
  final String dayNum;
  final VoidCallback? onReschedule;
  final VoidCallback? onCancel;

  const _LessonGreenCardCompact({
    required this.lesson,
    required this.weekday,
    required this.dayNum,
    required this.onReschedule,
    required this.onCancel,
  });

  @override
  Widget build(BuildContext context) {
    const green = Color(0xFF10B981);
    const darkGreen = Color(0xFF065F46);

    final time = _shortTime(lesson.time);
    final canModify = lesson.canReschedule || lesson.canDelete;

    return Container(
      margin: const EdgeInsets.only(bottom: 12),
      decoration: BoxDecoration(
        color: const Color(0xFFE7F8F1),
        borderRadius: BorderRadius.circular(18),
        boxShadow: const [
          BoxShadow(
            blurRadius: 18,
            color: Color(0x12000000),
            offset: Offset(0, 10),
          ),
        ],
      ),
      child: ClipRRect(
        borderRadius: BorderRadius.circular(18),
        child: Row(
          children: [
            // left panel
            Container(
              width: 92,
              color: const Color(0xFFBFF3DE),
              padding: const EdgeInsets.fromLTRB(10, 12, 10, 12),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    dayNum,
                    style: const TextStyle(
                      fontSize: 28,
                      height: 1,
                      fontWeight: FontWeight.w900,
                      color: darkGreen,
                    ),
                  ),
                  const SizedBox(height: 4),
                  Text(
                    weekday,
                    style: const TextStyle(
                      fontSize: 11,
                      fontWeight: FontWeight.w800,
                      color: darkGreen,
                    ),
                  ),
                  const SizedBox(height: 8),
                  Container(
                    padding: const EdgeInsets.symmetric(
                      horizontal: 8,
                      vertical: 6,
                    ),
                    decoration: BoxDecoration(
                      color: Colors.white.withOpacity(0.6),
                      borderRadius: BorderRadius.circular(12),
                    ),
                    child: Row(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        const Icon(
                          Icons.schedule,
                          size: 14,
                          color: Colors.black54,
                        ),
                        const SizedBox(width: 6),
                        FittedBox(
                          fit: BoxFit.scaleDown,
                          child: Text(
                            time,
                            style: const TextStyle(
                              fontSize: 11,
                              fontWeight: FontWeight.w800,
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ],
              ),
            ),

            // right body
            Expanded(
              child: Container(
                padding: const EdgeInsets.fromLTRB(10, 10, 10, 10),
                color: const Color(0xFFE7F8F1),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      lesson.className,
                      style: const TextStyle(
                        fontSize: 15,
                        fontWeight: FontWeight.w900,
                      ),
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                    ),
                    const SizedBox(height: 6),

                    Row(
                      children: [
                        const Icon(
                          Icons.place_outlined,
                          size: 16,
                          color: Colors.black54,
                        ),
                        const SizedBox(width: 6),
                        Expanded(
                          child: Text(
                            lesson.location.trim().isEmpty
                                ? 'Sala da definire'
                                : lesson.location,
                            style: const TextStyle(
                              fontSize: 12,
                              color: Color(0xFF404040),
                              fontWeight: FontWeight.w600,
                            ),
                            maxLines: 2,
                            overflow: TextOverflow.ellipsis,
                          ),
                        ),
                      ],
                    ),

                    const SizedBox(height: 8),

                    Row(
                      children: [
                        Expanded(
                          child: SizedBox(
                            height: 30,
                            child: ElevatedButton(
                              onPressed: onReschedule,
                              style: ElevatedButton.styleFrom(
                                backgroundColor: green,
                                padding: EdgeInsets.zero,
                                shape: RoundedRectangleBorder(
                                  borderRadius: BorderRadius.circular(12),
                                ),
                              ),
                              child: const Text(
                                'Riprogramma',
                                style: TextStyle(
                                  fontSize: 12,
                                  fontWeight: FontWeight.w800,
                                ),
                              ),
                            ),
                          ),
                        ),
                        const SizedBox(width: 8),
                        Expanded(
                          child: SizedBox(
                            height: 30,
                            child: OutlinedButton(
                              onPressed: onCancel,
                              style: OutlinedButton.styleFrom(
                                foregroundColor: green,
                                side: const BorderSide(color: green, width: 2),
                                padding: EdgeInsets.zero,
                                shape: RoundedRectangleBorder(
                                  borderRadius: BorderRadius.circular(12),
                                ),
                              ),
                              child: const Text(
                                'Cancella',
                                style: TextStyle(
                                  fontSize: 12,
                                  fontWeight: FontWeight.w800,
                                ),
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),

                    if (!canModify) ...[
                      const SizedBox(height: 6),
                      const Text(
                        'Non modificabile',
                        style: TextStyle(fontSize: 11, color: Colors.black54),
                      ),
                    ],
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  static String _shortTime(String t) => t.length >= 5 ? t.substring(0, 5) : t;
}

class _EmptyState extends StatelessWidget {
  final VoidCallback onBrowse;
  const _EmptyState({required this.onBrowse});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(18),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.event_busy, size: 64, color: Colors.black26),
            const SizedBox(height: 14),
            const Text(
              'Nessuna lezione prenotata',
              style: TextStyle(
                fontSize: 18,
                fontWeight: FontWeight.w800,
                color: Colors.black54,
              ),
            ),
            const SizedBox(height: 6),
            const Text(
              'Le tue lezioni appariranno qui',
              style: TextStyle(color: Colors.black45),
            ),
            const SizedBox(height: 14),
            ElevatedButton(
              onPressed: onBrowse,
              style: ElevatedButton.styleFrom(
                backgroundColor: const Color(0xFF10B981),
                padding: const EdgeInsets.symmetric(
                  horizontal: 18,
                  vertical: 12,
                ),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(14),
                ),
              ),
              child: const Text('Vedi i corsi'),
            ),
          ],
        ),
      ),
    );
  }
}

class _ErrorBox extends StatelessWidget {
  final String message;
  final VoidCallback onRetry;
  const _ErrorBox({required this.message, required this.onRetry});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(18),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.error_outline, size: 58, color: Colors.redAccent),
            const SizedBox(height: 10),
            Text(message, textAlign: TextAlign.center),
            const SizedBox(height: 12),
            ElevatedButton(onPressed: onRetry, child: const Text('Riprova')),
          ],
        ),
      ),
    );
  }
}