import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

import '../services/teacher_api.dart';
import '../widgets/yogibook_background.dart';

/// Aggiungi partecipante a una classe (vista insegnante).
/// Flusso: cerca/crea utente -> scegli modalità -> conferma.
/// Ritorna `true` (Navigator.pop) se l'inserimento è avvenuto.
class TeacherAddParticipantPage extends StatefulWidget {
  final String token;
  final TeacherClass cls;

  const TeacherAddParticipantPage({
    super.key,
    required this.token,
    required this.cls,
  });

  @override
  State<TeacherAddParticipantPage> createState() =>
      _TeacherAddParticipantPageState();
}

class _TeacherAddParticipantPageState extends State<TeacherAddParticipantPage> {
  static const Color kGreen = Color(0xFF10B981);

  final _firstCtrl = TextEditingController();
  final _lastCtrl = TextEditingController();
  final _emailCtrl = TextEditingController();

  // ricerca
  List<TeacherUser> _results = [];
  bool _searching = false;

  // utente selezionato (null = nuovo utente da creare)
  TeacherUser? _selectedUser;
  bool _isNewUser = false;

  // ordini dell'utente selezionato
  List<TeacherOrder> _orders = [];
  bool _loadingOrders = false;

  // modalità: 'scala' | 'omaggio' | 'nuovo'
  String _mode = 'omaggio';
  int? _selectedOrderId;
  DateTime _newExpiry = DateTime.now().add(const Duration(days: 90));

  bool _submitting = false;

  @override
  void dispose() {
    _firstCtrl.dispose();
    _lastCtrl.dispose();
    _emailCtrl.dispose();
    super.dispose();
  }

  void _snack(String msg) {
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(msg)));
  }

  Future<void> _search() async {
    final f = _firstCtrl.text.trim();
    final l = _lastCtrl.text.trim();
    if (f.length < 2 && l.length < 2) {
      setState(() => _results = []);
      return;
    }
    setState(() => _searching = true);
    try {
      final r = await TeacherApi.searchUsers(
        token: widget.token,
        first: f,
        last: l,
      );
      if (!mounted) return;
      setState(() => _results = r);
    } catch (e) {
      _snack('$e');
    } finally {
      if (mounted) setState(() => _searching = false);
    }
  }

  Future<void> _selectUser(TeacherUser u) async {
    setState(() {
      _selectedUser = u;
      _isNewUser = false;
      _results = [];
      _firstCtrl.text = u.firstName;
      _lastCtrl.text = u.lastName;
      _emailCtrl.text = u.email;
      _loadingOrders = true;
      _orders = [];
    });
    try {
      final o = await TeacherApi.userOrders(token: widget.token, userId: u.id);
      if (!mounted) return;
      // default modalità: scala se ha pacchetti con residui, altrimenti omaggio
      final usable = o.where((x) => x.remaining > 0).toList();
      setState(() {
        _orders = o;
        if (usable.isNotEmpty) {
          _mode = 'scala';
          _selectedOrderId = usable.first.idOrderBook;
        } else {
          _mode = 'omaggio';
        }
      });
      // DEBUG temporaneo — rimuovere dopo diagnosi
      _snack('DEBUG ordini: ${o.length} totali, ${usable.length} con residui');
      // DEBUG temporaneo
      _snack('DEBUG: ${o.length} ordini totali, ${usable.length} con residui');
    } catch (e) {
      _snack('$e');
    } finally {
      if (mounted) setState(() => _loadingOrders = false);
    }
  }

  // segna che vogliamo creare un nuovo utente coi dati digitati
  void _useAsNewUser() {
    final f = _firstCtrl.text.trim();
    final l = _lastCtrl.text.trim();
    if (f.isEmpty || l.isEmpty) {
      _snack('Inserisci nome e cognome del nuovo utente.');
      return;
    }
    setState(() {
      _selectedUser = null;
      _isNewUser = true;
      _results = [];
      _orders = [];
      _mode = 'omaggio'; // nuovo utente non ha pacchetti
    });
  }

  void _clearSelection() {
    setState(() {
      _selectedUser = null;
      _isNewUser = false;
      _orders = [];
      _selectedOrderId = null;
      _mode = 'omaggio';
    });
  }

  Future<void> _confirm() async {
    // deve esserci un utente selezionato o un nuovo utente valido
    if (_selectedUser == null && !_isNewUser) {
      _snack('Seleziona un utente o creane uno nuovo.');
      return;
    }
    if (_mode == 'scala' && _selectedOrderId == null) {
      _snack('Seleziona un pacchetto da cui scalare.');
      return;
    }

    setState(() => _submitting = true);
    try {
      await TeacherApi.addBooking(
        token: widget.token,
        scheduleId: widget.cls.scheduleId,
        serviceId: widget.cls.serviceId,
        bookingStart: widget.cls.dateTime,
        mode: _mode,
        userId: _selectedUser?.id ?? 0,
        name: _isNewUser ? _firstCtrl.text.trim() : '',
        surname: _isNewUser ? _lastCtrl.text.trim() : '',
        email: _emailCtrl.text.trim(),
        orderId: _mode == 'scala' ? _selectedOrderId : null,
        newExpiry: _mode == 'nuovo'
            ? DateFormat('yyyy-MM-dd').format(_newExpiry)
            : null,
      );
      if (!mounted) return;
      Navigator.pop(context, true);
    } catch (e) {
      _snack('$e');
      setState(() => _submitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final hasSelection = _selectedUser != null || _isNewUser;

    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        centerTitle: true,
        title: const Text(
          'Aggiungi partecipante',
          style: TextStyle(fontWeight: FontWeight.w800, fontSize: 18),
        ),
      ),
      body: YogibookBackground(
        child: SafeArea(
          top: false,
          child: ListView(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 24),
            children: [
              _classBanner(),
              const SizedBox(height: 14),
              _searchFields(),
              if (!hasSelection) ...[const SizedBox(height: 8), _resultsBox()],
              if (hasSelection) ...[
                const SizedBox(height: 14),
                _selectionCard(),
                const SizedBox(height: 14),
                _modeSection(),
                const SizedBox(height: 20),
                _confirmButton(),
              ],
            ],
          ),
        ),
      ),
    );
  }

  Widget _classBanner() {
    final dt = DateTime.tryParse(widget.cls.dateTime);
    final when = dt == null
        ? widget.cls.dateTime
        : DateFormat("EEE d MMM, HH:mm", 'it_IT').format(dt);
    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(14),
        boxShadow: const [
          BoxShadow(
            blurRadius: 12,
            color: Color(0x0F000000),
            offset: Offset(0, 6),
          ),
        ],
      ),
      child: Row(
        children: [
          const Icon(Icons.class_, color: kGreen),
          const SizedBox(width: 10),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  widget.cls.className,
                  style: const TextStyle(
                    fontWeight: FontWeight.w800,
                    fontSize: 15,
                  ),
                ),
                Text(
                  '$when · ${widget.cls.bookedCount}/${widget.cls.maxCapacity} posti',
                  style: const TextStyle(fontSize: 12, color: Colors.black54),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _searchFields() {
    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(14),
        boxShadow: const [
          BoxShadow(
            blurRadius: 12,
            color: Color(0x0F000000),
            offset: Offset(0, 6),
          ),
        ],
      ),
      child: Column(
        children: [
          Row(
            children: [
              Expanded(
                child: TextField(
                  controller: _firstCtrl,
                  onChanged: (_) => _search(),
                  decoration: const InputDecoration(
                    labelText: 'Nome',
                    isDense: true,
                    border: OutlineInputBorder(),
                  ),
                ),
              ),
              const SizedBox(width: 10),
              Expanded(
                child: TextField(
                  controller: _lastCtrl,
                  onChanged: (_) => _search(),
                  decoration: const InputDecoration(
                    labelText: 'Cognome',
                    isDense: true,
                    border: OutlineInputBorder(),
                  ),
                ),
              ),
            ],
          ),
          const SizedBox(height: 10),
          TextField(
            controller: _emailCtrl,
            keyboardType: TextInputType.emailAddress,
            decoration: const InputDecoration(
              labelText: 'Email (per nuovo utente)',
              isDense: true,
              border: OutlineInputBorder(),
            ),
          ),
        ],
      ),
    );
  }

  Widget _resultsBox() {
    if (_searching) {
      return const Padding(
        padding: EdgeInsets.all(16),
        child: Center(child: CircularProgressIndicator()),
      );
    }
    final f = _firstCtrl.text.trim();
    final l = _lastCtrl.text.trim();
    if (f.length < 2 && l.length < 2) {
      return const Padding(
        padding: EdgeInsets.symmetric(vertical: 8),
        child: Text(
          'Digita almeno 2 lettere per cercare.',
          style: TextStyle(color: Colors.black45),
        ),
      );
    }

    return Column(
      children: [
        ..._results.map(
          (u) => Container(
            margin: const EdgeInsets.only(bottom: 8),
            decoration: BoxDecoration(
              color: Colors.white,
              borderRadius: BorderRadius.circular(12),
            ),
            child: ListTile(
              leading: CircleAvatar(
                backgroundColor: kGreen,
                child: Text(
                  ((u.firstName.isNotEmpty ? u.firstName[0] : '') +
                          (u.lastName.isNotEmpty ? u.lastName[0] : ''))
                      .toUpperCase(),
                  style: const TextStyle(
                    color: Colors.white,
                    fontWeight: FontWeight.w800,
                    fontSize: 13,
                  ),
                ),
              ),
              title: Text(
                u.fullName,
                style: const TextStyle(fontWeight: FontWeight.w700),
              ),
              subtitle: Text(u.email),
              onTap: () => _selectUser(u),
            ),
          ),
        ),
        // opzione "crea nuovo utente" con i dati digitati
        Container(
          margin: const EdgeInsets.only(top: 4),
          decoration: BoxDecoration(
            color: const Color(0xFFF3F0FF),
            borderRadius: BorderRadius.circular(12),
            border: Border.all(color: const Color(0xFFD9CFFB)),
          ),
          child: ListTile(
            leading: const Icon(Icons.person_add, color: Color(0xFF4F46E5)),
            title: const Text(
              'Crea nuovo utente',
              style: TextStyle(fontWeight: FontWeight.w800),
            ),
            subtitle: const Text('Usa nome, cognome ed email digitati sopra'),
            onTap: _useAsNewUser,
          ),
        ),
      ],
    );
  }

  Widget _selectionCard() {
    final title = _isNewUser
        ? '${_firstCtrl.text.trim()} ${_lastCtrl.text.trim()} (nuovo)'
        : _selectedUser!.fullName;
    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: const Color(0xFFE7F8F1),
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: kGreen),
      ),
      child: Row(
        children: [
          const Icon(Icons.check_circle, color: kGreen),
          const SizedBox(width: 10),
          Expanded(
            child: Text(
              title,
              style: const TextStyle(fontWeight: FontWeight.w800),
            ),
          ),
          TextButton(onPressed: _clearSelection, child: const Text('Cambia')),
        ],
      ),
    );
  }

  Widget _modeSection() {
    final usable = _orders.where((o) => o.remaining > 0).toList();

    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(14),
        boxShadow: const [
          BoxShadow(
            blurRadius: 12,
            color: Color(0x0F000000),
            offset: Offset(0, 6),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          const Text(
            'Modalità',
            style: TextStyle(fontWeight: FontWeight.w900, fontSize: 14),
          ),
          const SizedBox(height: 6),
          if (_loadingOrders)
            const Padding(
              padding: EdgeInsets.all(12),
              child: Center(child: CircularProgressIndicator()),
            )
          else ...[
            // scala (solo se ci sono pacchetti usabili)
            RadioListTile<String>(
              contentPadding: EdgeInsets.zero,
              activeColor: kGreen,
              value: 'scala',
              groupValue: _mode,
              onChanged: usable.isEmpty
                  ? null
                  : (v) => setState(() => _mode = v!),
              title: Text(
                usable.isEmpty
                    ? 'Scala da pacchetto (nessuno disponibile)'
                    : 'Scala da un pacchetto',
                style: TextStyle(
                  fontWeight: FontWeight.w700,
                  color: usable.isEmpty ? Colors.black38 : Colors.black87,
                ),
              ),
            ),
            if (_mode == 'scala' && usable.isNotEmpty)
              Padding(
                padding: const EdgeInsets.only(left: 12, bottom: 8),
                child: Column(
                  children: usable
                      .map(
                        (o) => RadioListTile<int>(
                          contentPadding: EdgeInsets.zero,
                          activeColor: kGreen,
                          value: o.idOrderBook,
                          groupValue: _selectedOrderId,
                          onChanged: (v) =>
                              setState(() => _selectedOrderId = v),
                          title: Text(
                            o.serviceName,
                            style: const TextStyle(
                              fontSize: 13,
                              fontWeight: FontWeight.w700,
                            ),
                          ),
                          subtitle: Text(
                            '${o.remaining}/${o.tickets} residui'
                            '${o.expireOn != null ? ' · scade ${o.expireOn}' : ''}',
                            style: const TextStyle(fontSize: 12),
                          ),
                        ),
                      )
                      .toList(),
                ),
              ),
            // omaggio
            RadioListTile<String>(
              contentPadding: EdgeInsets.zero,
              activeColor: kGreen,
              value: 'omaggio',
              groupValue: _mode,
              onChanged: (v) => setState(() => _mode = v!),
              title: const Text(
                'Aggiungi come omaggio',
                style: TextStyle(fontWeight: FontWeight.w700),
              ),
              subtitle: const Text(
                'Non consuma pacchetti, non spostabile',
                style: TextStyle(fontSize: 12),
              ),
            ),
            // nuovo ordine
            RadioListTile<String>(
              contentPadding: EdgeInsets.zero,
              activeColor: kGreen,
              value: 'nuovo',
              groupValue: _mode,
              onChanged: (v) => setState(() => _mode = v!),
              title: const Text(
                'Crea nuovo ordine (1 lezione)',
                style: TextStyle(fontWeight: FontWeight.w700),
              ),
            ),
            if (_mode == 'nuovo')
              Padding(
                padding: const EdgeInsets.only(left: 12, top: 4),
                child: Row(
                  children: [
                    const Icon(Icons.event, size: 18, color: Colors.black45),
                    const SizedBox(width: 8),
                    Text(
                      'Scadenza: ${DateFormat('dd/MM/yyyy').format(_newExpiry)}',
                      style: const TextStyle(fontWeight: FontWeight.w600),
                    ),
                    const Spacer(),
                    TextButton(
                      onPressed: () async {
                        final picked = await showDatePicker(
                          context: context,
                          initialDate: _newExpiry,
                          firstDate: DateTime.now(),
                          lastDate: DateTime.now().add(
                            const Duration(days: 730),
                          ),
                        );
                        if (picked != null) {
                          setState(() => _newExpiry = picked);
                        }
                      },
                      child: const Text('Cambia'),
                    ),
                  ],
                ),
              ),
          ],
        ],
      ),
    );
  }

  Widget _confirmButton() {
    return SizedBox(
      width: double.infinity,
      height: 50,
      child: ElevatedButton(
        style: ElevatedButton.styleFrom(
          backgroundColor: kGreen,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(14),
          ),
        ),
        onPressed: _submitting ? null : _confirm,
        child: _submitting
            ? const SizedBox(
                height: 18,
                width: 18,
                child: CircularProgressIndicator(
                  strokeWidth: 2,
                  color: Colors.white,
                ),
              )
            : const Text(
                'Aggiungi alla classe',
                style: TextStyle(
                  fontWeight: FontWeight.w900,
                  color: Colors.white,
                ),
              ),
      ),
    );
  }
}