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

import '../../../../core/errors/failure.dart';
import '../../../../core/utils/validators.dart';
import '../../../../shared/models/permission_matrix_models.dart';
import '../../../../shared/models/user_management_models.dart';
import '../../../../shared/widgets/app_button.dart';
import '../../../../shared/widgets/app_loading_view.dart';
import '../../../../shared/widgets/app_text_field.dart';
import '../../../../shared/widgets/error_view.dart';
import '../../../../shared/widgets/app_side_panel.dart';
import '../providers/role_form_provider.dart';
import 'rbac_widgets.dart';
import '../../../../shared/widgets/app_toast.dart';

class RoleFormPanel extends ConsumerStatefulWidget {
  const RoleFormPanel({super.key, this.roleId});

  final String? roleId;

  bool get isEditing => roleId != null;

  @override
  ConsumerState<RoleFormPanel> createState() => _RoleFormPanelState();
}

class _RoleFormPanelState extends ConsumerState<RoleFormPanel> {
  final _formKey = GlobalKey<FormState>();
  final _nameController = TextEditingController();
  final _descriptionController = TextEditingController();
  final Map<String, bool> _viewPermissions = {};
  bool _prefilled = false;
  bool _permissionsInitialized = false;

  @override
  void dispose() {
    _nameController.dispose();
    _descriptionController.dispose();
    super.dispose();
  }

  void _prefillFromRole(RoleCardModel role) {
    if (_prefilled) return;
    _prefilled = true;
    _nameController.text = role.name;
    _descriptionController.text = role.description ?? '';
  }

  Future<void> _save() async {
    if (!_formKey.currentState!.validate()) return;

    final formState = ref.read(roleFormProvider(widget.roleId)).valueOrNull;
    if (formState == null) return;

    final notifier = ref.read(roleFormProvider(widget.roleId).notifier);
    final bool success;

    if (widget.isEditing) {
      success = await notifier.submitUpdate(
        widget.roleId!,
        UpdateRoleRequest(
          name: _nameController.text.trim(),
          description: _descriptionController.text.trim(),
        ),
      );
    } else {
      success = await notifier.submitCreate(
        buildCreateRoleRequest(
          name: _nameController.text.trim(),
          description: _descriptionController.text.trim(),
          selectedModules: _viewPermissions,
          catalog: formState.permissionCatalog,
        ),
      );
    }

    if (!mounted) return;

    if (success) {
      Navigator.of(context, rootNavigator: true).pop(true);
      return;
    }

    final error = ref.read(roleFormProvider(widget.roleId)).valueOrNull?.errorMessage;
    showAppToastFromSnackBar(context, 
      SnackBar(
        content: Text(
          error ??
              (widget.isEditing ? 'Failed to update role' : 'Failed to create role'),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final formAsync = ref.watch(roleFormProvider(widget.roleId));
    final isSubmitting = formAsync.valueOrNull?.isSubmitting ?? false;

    return SidePanelScaffold(
      title: widget.isEditing ? 'Edit Role' : 'Create New Role',
      footer: Row(
        children: [
          Expanded(
            child: OutlinedButton(
              onPressed: isSubmitting
                  ? null
                  : () => Navigator.of(context, rootNavigator: true).pop(),
              child: const Text('Cancel'),
            ),
          ),
          const SizedBox(width: 12),
          Expanded(
            child: AppButton(
              label: widget.isEditing ? 'Update Role' : 'Save Role',
              expand: true,
              isLoading: isSubmitting,
              onPressed: isSubmitting ? null : _save,
            ),
          ),
        ],
      ),
      child: formAsync.when(
        loading: () => AppLoadingView(
          message: widget.isEditing ? 'Loading role...' : 'Loading form...',
        ),
        error: (error, _) => ErrorView.fromFailure(
          error is Failure ? error : Failure.unknown(message: error.toString()),
          onRetry: () => ref.invalidate(roleFormProvider(widget.roleId)),
        ),
        data: (formState) {
          if (!widget.isEditing &&
              !_permissionsInitialized &&
              formState.selectableModules.isNotEmpty) {
            WidgetsBinding.instance.addPostFrameCallback((_) {
              if (!mounted || _permissionsInitialized) return;
              setState(() {
                _permissionsInitialized = true;
                for (final module in formState.selectableModules) {
                  _viewPermissions.putIfAbsent(module.code, () => false);
                }
              });
            });
          }

          if (formState.editingRole != null && !_prefilled) {
            WidgetsBinding.instance.addPostFrameCallback((_) {
              if (!mounted || _prefilled) return;
              setState(() => _prefillFromRole(formState.editingRole!));
            });
          }

          return Form(
            key: _formKey,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                AppTextField(
                  controller: _nameController,
                  label: 'Role Name *',
                  hint: 'e.g. QC Manager',
                  validator: Validators.roleName,
                  inputFormatters: Validators.roleNameInput,
                ),
                const SizedBox(height: 16),
                AppTextField(
                  controller: _descriptionController,
                  label: 'Description',
                  hint: 'What does this role do?',
                  maxLines: 3,
                ),
                if (!widget.isEditing) ...[
                  const SizedBox(height: 24),
                  Text(
                    'INITIAL PERMISSIONS',
                    style: Theme.of(context).textTheme.labelSmall?.copyWith(
                          fontWeight: FontWeight.w700,
                          letterSpacing: 0.8,
                          color: Theme.of(context).colorScheme.onSurfaceVariant,
                        ),
                  ),
                  const SizedBox(height: 8),
                  Text(
                    'You can fine-tune permissions in the Permission Matrix tab after creating the role.',
                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
                          color: Theme.of(context).colorScheme.onSurfaceVariant,
                        ),
                  ),
                  const SizedBox(height: 16),
                  if (formState.selectableModules.isEmpty)
                    Text(
                      'No view permissions available from the server.',
                      style: Theme.of(context).textTheme.bodySmall?.copyWith(
                            color: Theme.of(context).colorScheme.onSurfaceVariant,
                          ),
                    )
                  else
                    ...formState.selectableModules.asMap().entries.map((entry) {
                      final module = entry.value;
                      final appearance =
                          permissionModuleAppearance(module.code, entry.key);
                      return ModulePermissionRow(
                        icon: appearance.icon,
                        color: appearance.color,
                        label: module.name,
                        value: _viewPermissions[module.code] ?? false,
                        onChanged: (v) =>
                            setState(() => _viewPermissions[module.code] = v),
                      );
                    }),
                ],
              ],
            ),
          );
        },
      ),
    );
  }
}

/// Backwards-compatible alias.
typedef CreateRolePanel = RoleFormPanel;