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

import '../../../app/providers.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/widgets/numeric_keypad.dart';
import '../../../domain/entities/store_account.dart';

/// Prompts for an admin PIN before a theft-sensitive cart action — taking a
/// scanned item back out of the bill, or clearing it — and resolves `true`
/// only once a PIN belonging to an [StaffRole.admin] account is verified.
///
/// A cashier can always start a brand new sale; what this exists to stop is
/// quietly taking something back out of a bill a customer has already been
/// shown, after it was rung up.
Future<bool> requireAdminPin(
  BuildContext context,
  WidgetRef ref, {
  required String reason,
}) async {
  final ok = await showDialog<bool>(
    context: context,
    barrierDismissible: false,
    builder: (_) => _AdminPinDialog(reason: reason),
  );
  return ok ?? false;
}

class _AdminPinDialog extends ConsumerStatefulWidget {
  const _AdminPinDialog({required this.reason});

  final String reason;

  @override
  ConsumerState<_AdminPinDialog> createState() => _AdminPinDialogState();
}

class _AdminPinDialogState extends ConsumerState<_AdminPinDialog> {
  String _pin = '';
  String? _error;
  bool _checking = false;

  void _key(String digit) {
    if (_checking || _pin.length >= 8) return;
    setState(() {
      _pin += digit;
      _error = null;
    });
  }

  void _backspace() {
    if (_checking || _pin.isEmpty) return;
    setState(() => _pin = _pin.substring(0, _pin.length - 1));
  }

  void _clear() {
    if (_checking) return;
    setState(() => _pin = '');
  }

  Future<void> _submit() async {
    if (_pin.isEmpty || _checking) return;
    setState(() {
      _checking = true;
      _error = null;
    });

    final store = ref.read(localStoreProvider);
    final user = await store.staff.authenticate(_pin);

    if (!mounted) return;

    if (user == null) {
      setState(() {
        _checking = false;
        _error = 'Incorrect PIN.';
        _pin = '';
      });
      return;
    }

    if (user.role != StaffRole.admin) {
      setState(() {
        _checking = false;
        _error = "${user.name}'s PIN is ${user.role.label.toLowerCase()} — "
            'this needs an admin.';
        _pin = '';
      });
      return;
    }

    Navigator.of(context).pop(true);
  }

  @override
  Widget build(BuildContext context) {
    return Dialog(
      shape: const RoundedRectangleBorder(borderRadius: AppRadius.brLg),
      child: Padding(
        padding: const EdgeInsets.all(AppSpacing.xl),
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 320),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Row(
                children: [
                  const Icon(Icons.lock_outline_rounded,
                      color: AppColors.danger, size: 20,),
                  const SizedBox(width: AppSpacing.sm),
                  const Expanded(
                    child: Text(
                      'Admin PIN required',
                      style: TextStyle(
                        fontSize: 16,
                        fontWeight: FontWeight.w700,
                      ),
                    ),
                  ),
                  InkWell(
                    onTap: () => Navigator.of(context).pop(false),
                    borderRadius: AppRadius.brSm,
                    child: const Padding(
                      padding: EdgeInsets.all(4),
                      child: Icon(Icons.close_rounded,
                          size: 20, color: AppColors.textSecondary,),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: AppSpacing.xs),
              Text(
                widget.reason,
                style: const TextStyle(
                  fontSize: 13,
                  color: AppColors.textSecondary,
                  height: 1.4,
                ),
              ),
              const SizedBox(height: AppSpacing.lg),
              SizedBox(
                height: 20,
                child: _pin.isEmpty
                    ? const Center(
                        child: Text(
                          'Enter PIN',
                          style: TextStyle(
                            fontSize: 13,
                            color: AppColors.textTertiary,
                          ),
                        ),
                      )
                    : Wrap(
                        alignment: WrapAlignment.center,
                        spacing: 10,
                        children: [
                          for (var i = 0; i < _pin.length; i++)
                            Container(
                              width: 12,
                              height: 12,
                              decoration: const BoxDecoration(
                                color: AppColors.primary,
                                shape: BoxShape.circle,
                              ),
                            ),
                        ],
                      ),
              ),
              if (_error != null) ...[
                const SizedBox(height: AppSpacing.sm),
                Text(
                  _error!,
                  textAlign: TextAlign.center,
                  style: const TextStyle(
                    fontSize: 12.5,
                    color: AppColors.danger,
                    fontWeight: FontWeight.w600,
                  ),
                ),
              ],
              const SizedBox(height: AppSpacing.lg),
              NumericKeypad(
                onKey: _key,
                onBackspace: _backspace,
                onClear: _clear,
                onSubmit: _checking ? null : _submit,
                submitLabel: _checking ? 'Checking…' : 'Approve',
              ),
            ],
          ),
        ),
      ),
    );
  }
}