import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../../app/providers.dart';
import '../../../core/router/app_router.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/utils/extensions.dart';
import '../../../core/utils/formatters.dart';
import '../../../core/utils/validators.dart';
import '../../../core/widgets/glass_card.dart';
import '../../../core/widgets/primary_button.dart';
import '../../../domain/entities/customer.dart';
import '../../pos/providers/cart_controller.dart';
import '../providers/customer_providers.dart';

/// Screen 2 — registers a shopper and drops straight into billing.
class CustomerRegistrationScreen extends ConsumerStatefulWidget {
  const CustomerRegistrationScreen({super.key, this.prefillMobile});

  final String? prefillMobile;

  @override
  ConsumerState<CustomerRegistrationScreen> createState() =>
      _CustomerRegistrationScreenState();
}

class _CustomerRegistrationScreenState
    extends ConsumerState<CustomerRegistrationScreen> {
  final _formKey = GlobalKey<FormState>();
  late final TextEditingController _mobile;
  final _name = TextEditingController();
  final _email = TextEditingController();

  Gender _gender = Gender.unspecified;
  DateTime? _dob;
  bool _saving = false;
  String? _serverError;

  @override
  void initState() {
    super.initState();
    _mobile = TextEditingController(text: widget.prefillMobile ?? '');
  }

  @override
  void dispose() {
    _mobile.dispose();
    _name.dispose();
    _email.dispose();
    super.dispose();
  }

  Future<void> _save() async {
    setState(() => _serverError = null);
    if (!(_formKey.currentState?.validate() ?? false)) return;

    setState(() => _saving = true);
    try {
      final customer = await ref.read(customerRepositoryProvider).create(
            Customer(
              id: '',
              name: _name.text,
              mobile: _mobile.text,
              email: _email.text,
              gender: _gender,
              dateOfBirth: _dob,
            ),
          );

      ref.read(cartControllerProvider.notifier).attachCustomer(customer);
      ref.invalidate(recentCustomersProvider);

      if (!mounted) return;
      context.go(AppRoutes.pos);
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _saving = false;
        _serverError = e is StateError ? e.message : 'Could not save customer.';
      });
    }
  }

  Future<void> _pickDob() async {
    final now = DateTime.now();
    final picked = await showDatePicker(
      context: context,
      initialDate: _dob ?? DateTime(now.year - 25),
      firstDate: DateTime(now.year - 100),
      lastDate: now,
      helpText: 'Date of birth',
    );
    if (picked != null) setState(() => _dob = picked);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.background,
      appBar: AppBar(
        title: const Text('New Customer'),
        leading: IconButton(
          icon: const Icon(Icons.arrow_back_rounded),
          onPressed: () => context.pop(),
        ),
      ),
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(AppSpacing.xxl),
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 640),
            child: GlassCard(
              padding: const EdgeInsets.all(AppSpacing.xxxl),
              radius: AppRadius.xl,
              shadows: AppColors.shadowMd,
              child: Form(
                key: _formKey,
                autovalidateMode: AutovalidateMode.onUserInteraction,
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text('Register a shopper',
                        style: context.text.headlineSmall),
                    const SizedBox(height: AppSpacing.xs),
                    Text(
                      'Only the mobile number and name are required.',
                      style: context.text.bodySmall,
                    ),
                    const SizedBox(height: AppSpacing.xxl),

                    _Field(
                      label: 'Mobile Number',
                      required: true,
                      child: TextFormField(
                        controller: _mobile,
                        autofocus: true,
                        keyboardType: TextInputType.phone,
                        maxLength: 10,
                        validator: Validators.mobile,
                        inputFormatters: [
                          FilteringTextInputFormatter.digitsOnly,
                        ],
                        decoration: const InputDecoration(
                          hintText: '10-digit mobile number',
                          prefixText: '+91  ',
                          counterText: '',
                          prefixIcon: Icon(Icons.phone_outlined),
                        ),
                      ),
                    ),

                    _Field(
                      label: 'Customer Name',
                      required: true,
                      child: TextFormField(
                        controller: _name,
                        textCapitalization: TextCapitalization.words,
                        validator: Validators.name,
                        decoration: const InputDecoration(
                          hintText: 'Full name',
                          prefixIcon: Icon(Icons.person_outline_rounded),
                        ),
                      ),
                    ),

                    _Field(
                      label: 'Email',
                      child: TextFormField(
                        controller: _email,
                        keyboardType: TextInputType.emailAddress,
                        validator: Validators.emailOptional,
                        decoration: const InputDecoration(
                          hintText: 'name@example.com',
                          prefixIcon: Icon(Icons.mail_outline_rounded),
                        ),
                      ),
                    ),

                    _Field(
                      label: 'Gender',
                      child: Wrap(
                        spacing: AppSpacing.sm,
                        children: Gender.values
                            .map((g) => ChoiceChip(
                                  label: Text(g.label),
                                  selected: _gender == g,
                                  onSelected: (_) =>
                                      setState(() => _gender = g),
                                  labelStyle: TextStyle(
                                    color: _gender == g
                                        ? Colors.white
                                        : AppColors.textSecondary,
                                    fontWeight: FontWeight.w600,
                                  ),
                                ))
                            .toList(),
                      ),
                    ),

                    _Field(
                      label: 'Date of Birth',
                      child: InkWell(
                        onTap: _pickDob,
                        borderRadius: AppRadius.brMd,
                        child: InputDecorator(
                          decoration: const InputDecoration(
                            prefixIcon: Icon(Icons.cake_outlined),
                          ),
                          child: Text(
                            _dob == null
                                ? 'Select a date (optional)'
                                : Formatters.date(_dob!),
                            style: TextStyle(
                              color: _dob == null
                                  ? AppColors.textTertiary
                                  : AppColors.textPrimary,
                              fontSize: 15,
                            ),
                          ),
                        ),
                      ),
                    ),

                    if (_serverError != null) ...[
                      const SizedBox(height: AppSpacing.sm),
                      Container(
                        width: double.infinity,
                        padding: const EdgeInsets.all(AppSpacing.md),
                        decoration: BoxDecoration(
                          color: AppColors.dangerSurface,
                          borderRadius: AppRadius.brSm,
                        ),
                        child: Row(children: [
                          const Icon(Icons.error_outline_rounded,
                              color: AppColors.danger, size: 18),
                          const SizedBox(width: AppSpacing.sm),
                          Expanded(
                            child: Text(
                              _serverError!,
                              style: const TextStyle(
                                color: AppColors.danger,
                                fontSize: 13.5,
                              ),
                            ),
                          ),
                        ]),
                      ),
                    ],

                    const SizedBox(height: AppSpacing.xxl),
                    Row(children: [
                      Expanded(
                        child: PrimaryButton(
                          label: 'Cancel',
                          tone: ButtonTone.neutral,
                          onPressed:
                              _saving ? null : () => context.pop(),
                        ),
                      ),
                      const SizedBox(width: AppSpacing.md),
                      Expanded(
                        flex: 2,
                        child: PrimaryButton(
                          label: 'Save & Continue',
                          icon: Icons.check_rounded,
                          busy: _saving,
                          onPressed: _save,
                        ),
                      ),
                    ]),
                  ],
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _Field extends StatelessWidget {
  const _Field({
    required this.label,
    required this.child,
    this.required = false,
  });

  final String label;
  final Widget child;
  final bool required;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: AppSpacing.lg),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(children: [
            Text(label,
                style: context.text.labelMedium
                    ?.copyWith(color: AppColors.textSecondary)),
            if (required)
              const Text(' *',
                  style: TextStyle(color: AppColors.danger, fontSize: 13)),
            if (!required)
              Text('  optional',
                  style: context.text.labelSmall
                      ?.copyWith(color: AppColors.textTertiary)),
          ]),
          const SizedBox(height: AppSpacing.sm),
          child,
        ],
      ),
    );
  }
}