import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:provider/provider.dart';

import '../labels.dart';
import '../models/models.dart';
import '../services/auth_controller.dart';
import '../ui/feedback.dart';

class AdminScreen extends StatelessWidget {
  const AdminScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 2,
      child: Column(
        children: [
          const TabBar(
            tabs: [
              Tab(text: 'Dealers'),
              Tab(text: 'Sales reps'),
            ],
          ),
          const Expanded(
            child: TabBarView(
              children: [
                _DealersTab(),
                _RepsTab(),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

class _DealersTab extends StatefulWidget {
  const _DealersTab();

  @override
  State<_DealersTab> createState() => _DealersTabState();
}

class _DealersTabState extends State<_DealersTab> {
  final _name = TextEditingController();
  final _code = TextEditingController();
  final _address = TextEditingController();
  final _phone = TextEditingController();
  String? _district;
  int _districtField = 0;
  List<Dealer> _dealers = [];
  bool _loading = true;
  bool _saving = false;

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

  @override
  void dispose() {
    _name.dispose();
    _code.dispose();
    _address.dispose();
    _phone.dispose();
    super.dispose();
  }

  Future<void> _load() async {
    try {
      final dealers = await context.read<AuthController>().api.adminDealers();
      if (!mounted) return;
      setState(() {
        _dealers = dealers;
        _loading = false;
      });
    } catch (error) {
      if (!mounted) return;
      setState(() => _loading = false);
      showError(context, error);
    }
  }

  Future<void> _delete(Dealer dealer) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Delete dealer'),
        content: Text(
          'Delete ${dealer.name}? Its login, stock, and plans will be removed.',
        ),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context, false), child: const Text('Cancel')),
          FilledButton(onPressed: () => Navigator.pop(context, true), child: const Text('Delete')),
        ],
      ),
    );
    if (confirmed != true || !mounted) return;
    try {
      await context.read<AuthController>().api.deleteDealer(dealer.id);
      await _load();
    } catch (error) {
      if (mounted) showError(context, error);
    }
  }

  Future<void> _save() async {
    setState(() => _saving = true);
    try {
      await context.read<AuthController>().api.createDealer({
        'name': _name.text.trim(),
        'code': _code.text.trim(),
        'district': _district ?? '',
        'address': _address.text.trim(),
        'phone': _phone.text.trim(),
      });
      _name.clear();
      _code.clear();
      _address.clear();
      _phone.clear();
      _district = null;
      _districtField++;
      await _load();
    } catch (error) {
      if (mounted) showError(context, error);
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_loading) return const Center(child: CircularProgressIndicator());
    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        Text('New dealer', style: Theme.of(context).textTheme.titleMedium),
        const SizedBox(height: 12),
        TextField(controller: _name, decoration: const InputDecoration(labelText: 'Name')),
        const SizedBox(height: 12),
        TextField(controller: _code, decoration: const InputDecoration(labelText: 'Code')),
        const SizedBox(height: 12),
        DropdownButtonFormField<String>(
          key: ValueKey(_districtField),
          initialValue: _district,
          isExpanded: true,
          decoration: const InputDecoration(labelText: 'District'),
          items: [
            for (final district in sriLankaDistricts)
              DropdownMenuItem(value: district, child: Text(district)),
          ],
          onChanged: (value) => setState(() => _district = value),
        ),
        const SizedBox(height: 12),
        TextField(controller: _address, decoration: const InputDecoration(labelText: 'Address')),
        const SizedBox(height: 12),
        TextField(
          controller: _phone,
          keyboardType: TextInputType.phone,
          inputFormatters: [FilteringTextInputFormatter.digitsOnly],
          decoration: const InputDecoration(
            labelText: 'Contact phone',
            hintText: '0715127342',
            helperText: 'This number becomes the dealer login',
          ),
        ),
        const SizedBox(height: 12),
        FilledButton(
          onPressed: _saving ? null : _save,
          child: Text(_saving ? 'Saving' : 'Create dealer'),
        ),
        const SizedBox(height: 20),
        for (final dealer in _dealers)
          ListTile(
            contentPadding: EdgeInsets.zero,
            title: Text(dealer.name),
            subtitle: Text('${dealer.code}${dealer.district == null ? '' : ' · ${dealer.district}'}'),
            trailing: IconButton(
              tooltip: 'Delete',
              onPressed: () => _delete(dealer),
              icon: const Icon(Icons.delete_outline),
            ),
          ),
      ],
    );
  }
}

class _RepsTab extends StatefulWidget {
  const _RepsTab();

  @override
  State<_RepsTab> createState() => _RepsTabState();
}

class _RepsTabState extends State<_RepsTab> {
  final _name = TextEditingController();
  final _phone = TextEditingController();
  final _password = TextEditingController();
  List<Dealer> _dealers = [];
  List<AppUser> _reps = [];
  final Set<String> _selected = {};
  bool _loading = true;
  bool _saving = false;

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

  @override
  void dispose() {
    _name.dispose();
    _phone.dispose();
    _password.dispose();
    super.dispose();
  }

  Future<void> _load() async {
    final api = context.read<AuthController>().api;
    try {
      final results = await Future.wait([api.adminDealers(), api.salesReps()]);
      if (!mounted) return;
      setState(() {
        _dealers = results[0] as List<Dealer>;
        _reps = results[1] as List<AppUser>;
        _loading = false;
      });
    } catch (error) {
      if (!mounted) return;
      setState(() => _loading = false);
      showError(context, error);
    }
  }

  Future<void> _save() async {
    setState(() => _saving = true);
    try {
      await context.read<AuthController>().api.createSalesRep({
        'name': _name.text.trim(),
        'phone': _phone.text.trim(),
        'password': _password.text,
        'dealerIds': _selected.toList(),
      });
      _name.clear();
      _phone.clear();
      _password.clear();
      _selected.clear();
      await _load();
    } catch (error) {
      if (mounted) showError(context, error);
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  Future<void> _changeAssignment(AppUser rep, {required bool assign}) async {
    final choices = _dealers.where((dealer) {
      final has = rep.assignedDealerIds.contains(dealer.id);
      return assign ? !has : has;
    }).toList();
    if (choices.isEmpty) {
      showError(context, assign ? 'Every dealer is already assigned' : 'No dealers to remove');
      return;
    }
    String? dealerId = choices.first.id;
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(assign ? 'Assign dealer' : 'Remove dealer'),
        content: DropdownButtonFormField<String>(
          initialValue: dealerId,
          items: [
            for (final dealer in choices)
              DropdownMenuItem(value: dealer.id, child: Text(dealer.name)),
          ],
          onChanged: (value) => dealerId = value,
        ),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context, false), child: const Text('Cancel')),
          FilledButton(onPressed: () => Navigator.pop(context, true), child: const Text('Save')),
        ],
      ),
    );
    if (confirmed != true || dealerId == null || !mounted) return;
    try {
      await context.read<AuthController>().api.assignDealer(
        salesRepId: rep.id,
        dealerId: dealerId!,
        assigned: assign,
      );
      await _load();
    } catch (error) {
      if (mounted) showError(context, error);
    }
  }

  String _dealerNames(AppUser rep) {
    if (rep.assignedDealerIds.isEmpty) return 'No dealers assigned';
    return rep.assignedDealerIds
        .map((id) {
          for (final dealer in _dealers) {
            if (dealer.id == id) return dealer.name;
          }
          return id;
        })
        .join(', ');
  }

  @override
  Widget build(BuildContext context) {
    if (_loading) return const Center(child: CircularProgressIndicator());
    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        Text('New sales rep', style: Theme.of(context).textTheme.titleMedium),
        const SizedBox(height: 12),
        TextField(controller: _name, decoration: const InputDecoration(labelText: 'Name')),
        const SizedBox(height: 12),
        TextField(
          controller: _phone,
          keyboardType: TextInputType.phone,
          inputFormatters: [FilteringTextInputFormatter.digitsOnly],
          decoration: const InputDecoration(labelText: 'Phone', hintText: '0715127342'),
        ),
        const SizedBox(height: 12),
        TextField(
          controller: _password,
          obscureText: true,
          decoration: const InputDecoration(labelText: 'Password'),
        ),
        const SizedBox(height: 8),
        for (final dealer in _dealers)
          CheckboxListTile(
            contentPadding: EdgeInsets.zero,
            title: Text(dealer.name),
            value: _selected.contains(dealer.id),
            onChanged: (checked) {
              setState(() {
                if (checked == true) {
                  _selected.add(dealer.id);
                } else {
                  _selected.remove(dealer.id);
                }
              });
            },
          ),
        FilledButton(
          onPressed: _saving ? null : _save,
          child: Text(_saving ? 'Saving' : 'Create sales rep'),
        ),
        const SizedBox(height: 20),
        for (final rep in _reps)
          Card(
            child: Padding(
              padding: const EdgeInsets.all(12),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(rep.name, style: Theme.of(context).textTheme.titleMedium),
                  Text(rep.phone),
                  const SizedBox(height: 4),
                  Text(_dealerNames(rep)),
                  Row(
                    children: [
                      TextButton(
                        onPressed: () => _changeAssignment(rep, assign: true),
                        child: const Text('Assign'),
                      ),
                      TextButton(
                        onPressed: () => _changeAssignment(rep, assign: false),
                        child: const Text('Remove'),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ),
      ],
    );
  }
}