import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:intl/intl.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/loading_button.dart';
import '../../core/api/api_client.dart';
import '../../shared/providers/lookup_providers.dart';
import 'contracts_provider.dart';

class ContractFormScreen extends ConsumerStatefulWidget {
  final int editId;
  const ContractFormScreen({super.key, required this.editId});

  @override
  ConsumerState<ContractFormScreen> createState() => _ContractFormScreenState();
}

class _ContractFormScreenState extends ConsumerState<ContractFormScreen> {
  final _formKey = GlobalKey<FormState>();
  final _titleCtrl = TextEditingController();
  DateTime? _periodStart;
  DateTime? _periodEnd;
  int? _companyId;
  int? _vendorId;
  bool _loading = false;
  bool _initDone = false;

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

  Future<void> _init() async {
    if (_initDone) return;
    _initDone = true;
    try {
      final resp = await apiDio.get('/contracts/${widget.editId}');
      final d = resp.data as Map<String, dynamic>;
      setState(() {
        _titleCtrl.text = d['title'] ?? '';
        _companyId = d['company_id'];
        _vendorId = d['vendor_id'];
        if (d['period_start'] != null) _periodStart = DateTime.tryParse(d['period_start']);
        if (d['period_end'] != null)   _periodEnd   = DateTime.tryParse(d['period_end']);
      });
    } catch (_) {}
  }

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;
    setState(() => _loading = true);
    try {
      await updateContract(widget.editId, {
        'title': _titleCtrl.text.trim(),
        'company_id': _companyId,
        'vendor_id': _vendorId,
        if (_periodStart != null) 'period_start': DateFormat('yyyy-MM-dd').format(_periodStart!),
        if (_periodEnd != null)   'period_end':   DateFormat('yyyy-MM-dd').format(_periodEnd!),
      });
      if (mounted) context.pop();
    } on ApiException catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message), backgroundColor: AppColors.danger));
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _pickDate(bool isStart) async {
    final picked = await showDatePicker(
      context: context,
      initialDate: (isStart ? _periodStart : _periodEnd) ?? DateTime.now(),
      firstDate: DateTime(2000), lastDate: DateTime(2035),
    );
    if (picked != null) setState(() => isStart ? _periodStart = picked : _periodEnd = picked);
  }

  @override
  Widget build(BuildContext context) {
    _init();
    final companiesAsync = ref.watch(companiesProvider);
    final vendorsAsync = ref.watch(vendorsProvider);

    return Scaffold(
      appBar: AppBar(title: const Text('Edit Contract')),
      body: Form(
        key: _formKey,
        child: ListView(
          padding: const EdgeInsets.all(16),
          children: [
            _label('Contract Title'),
            TextFormField(controller: _titleCtrl,
                decoration: const InputDecoration(hintText: 'Contract title'),
                validator: (v) => (v == null || v.isEmpty) ? 'Title is required' : null),
            const SizedBox(height: 16),

            _label('Company'),
            companiesAsync.when(
              loading: () => const LinearProgressIndicator(),
              error: (_, __) => const Text('Failed'),
              data: (list) => DropdownButtonFormField<int>(
                value: _companyId,
                decoration: const InputDecoration(hintText: 'Select company'),
                items: list.map((c) => DropdownMenuItem(value: c.id, child: Text(c.name))).toList(),
                onChanged: (v) => setState(() => _companyId = v),
              ),
            ),
            const SizedBox(height: 16),

            _label('Vendor (optional)'),
            vendorsAsync.when(
              loading: () => const LinearProgressIndicator(),
              error: (_, __) => const Text('Failed'),
              data: (list) => DropdownButtonFormField<int>(
                value: _vendorId,
                decoration: const InputDecoration(hintText: 'Select vendor'),
                items: [
                  const DropdownMenuItem(value: null, child: Text('None')),
                  ...list.map((v) => DropdownMenuItem(value: v.id, child: Text(v.name))),
                ],
                onChanged: (v) => setState(() => _vendorId = v),
              ),
            ),
            const SizedBox(height: 16),

            Row(children: [
              Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
                _label('Start Date'),
                _datePicker(_periodStart, () => _pickDate(true)),
              ])),
              const SizedBox(width: 12),
              Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
                _label('End Date'),
                _datePicker(_periodEnd, () => _pickDate(false)),
              ])),
            ]),
            const SizedBox(height: 32),
            LoadingButton(loading: _loading, label: 'Save', onPressed: _submit),
          ],
        ),
      ),
    );
  }

  Widget _datePicker(DateTime? date, VoidCallback onTap) => GestureDetector(
    onTap: onTap,
    child: Container(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 14),
      decoration: BoxDecoration(
        color: AppColors.surface, border: Border.all(color: AppColors.border),
        borderRadius: BorderRadius.circular(10),
      ),
      child: Text(
        date != null ? DateFormat('d MMM yyyy').format(date) : 'Select date',
        style: TextStyle(fontSize: 13, color: date != null ? AppColors.text : AppColors.textSub),
      ),
    ),
  );

  Widget _label(String text) => Padding(
    padding: const EdgeInsets.only(bottom: 6),
    child: Text(text, style: const TextStyle(fontSize: 13, fontWeight: FontWeight.w600, color: AppColors.text)),
  );
}