import 'package:flutter/material.dart';
import 'package:flutter/services.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/primary_button.dart';
import '../../../data/local/staff_dao.dart';
import '../../../domain/entities/store_account.dart';
import '../../auth/providers/auth_controller.dart';

/// Manage who can sign in at this till.
Future<void> showStaffDialog(BuildContext context) => showDialog<void>(
      context: context,
      builder: (_) => const _StaffDialog(),
    );

class _StaffDialog extends ConsumerWidget {
  const _StaffDialog();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final me = ref.watch(currentUserProvider);
    final storeAsync = ref.watch(storeAccountProvider);

    // Only an admin can change who works here, or what they may do.
    if (me?.role != StaffRole.admin) {
      return AlertDialog(
        title: const Text('Users & roles'),
        content: const Text(
          'Only an admin can add or change staff accounts. Ask a manager to '
          'sign in first.',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: const Text('Close'),
          ),
        ],
      );
    }

    return AlertDialog(
      title: const Text('Users & roles'),
      content: SizedBox(
        width: 560,
        child: storeAsync.when(
          loading: () => const Center(child: CircularProgressIndicator()),
          error: (e, _) => Text('Could not load staff: $e'),
          data: (store) => SingleChildScrollView(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                for (final user in store.staff)
                  _StaffRow(user: user, isMe: user.id == me?.id),
                const SizedBox(height: AppSpacing.md),
                OutlinedButton.icon(
                  onPressed: () => _openEditor(context, ref, null),
                  icon: const Icon(Icons.person_add_alt_1_rounded, size: 17),
                  label: const Text('Add staff member'),
                ),
              ],
            ),
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: const Text('Done'),
        ),
      ],
    );
  }
}

class _StaffRow extends ConsumerWidget {
  const _StaffRow({required this.user, required this.isMe});

  final StaffUser user;
  final bool isMe;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: AppSpacing.xs),
      child: Row(
        children: [
          Expanded(
            flex: 4,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  user.name,
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
                Text(
                  user.role.label,
                  style: const TextStyle(
                    fontSize: 12,
                    color: AppColors.textSecondary,
                  ),
                ),
              ],
            ),
          ),
          if (user.mustChangePin)
            const Tooltip(
              message: 'Still on the PIN this terminal was set up with',
              child: Icon(Icons.warning_amber_rounded,
                  size: 17, color: AppColors.warning,),
            ),
          if (isMe)
            const Padding(
              padding: EdgeInsets.symmetric(horizontal: AppSpacing.sm),
              child: Text(
                'Signed in',
                style: TextStyle(fontSize: 11, color: AppColors.success),
              ),
            ),
          IconButton(
            tooltip: 'Edit',
            icon: const Icon(Icons.edit_outlined, size: 17),
            onPressed: () => _openEditor(context, ref, user),
          ),
          IconButton(
            tooltip: 'Remove',
            icon: const Icon(Icons.person_off_outlined, size: 17),
            color: AppColors.danger,
            onPressed: () => _confirmDeactivate(context, ref, user),
          ),
        ],
      ),
    );
  }
}

Future<void> _confirmDeactivate(
  BuildContext context,
  WidgetRef ref,
  StaffUser user,
) async {
  final confirmed = await showDialog<bool>(
    context: context,
    builder: (dialogContext) => AlertDialog(
      title: Text('Remove ${user.name}?'),
      content: const Text(
        'They will no longer be able to sign in. Bills they have already rung '
        'keep their name, so shift reports stay correct.',
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(dialogContext).pop(false),
          child: const Text('Cancel'),
        ),
        TextButton(
          onPressed: () => Navigator.of(dialogContext).pop(true),
          style: TextButton.styleFrom(foregroundColor: AppColors.danger),
          child: const Text('Remove'),
        ),
      ],
    ),
  );

  if (confirmed != true || !context.mounted) return;

  try {
    await ref.read(localStoreProvider).staff.deactivate(user.id);
    await ref.read(authControllerProvider.notifier).refreshStore();
  } on StaffException catch (e) {
    if (context.mounted) _showError(context, e.message);
  }
}

Future<void> _openEditor(
  BuildContext context,
  WidgetRef ref,
  StaffUser? existing,
) =>
    showDialog<void>(
      context: context,
      builder: (_) => _StaffEditor(existing: existing),
    );

void _showError(BuildContext context, String message) {
  ScaffoldMessenger.of(context)
    ..hideCurrentSnackBar()
    ..showSnackBar(SnackBar(
      backgroundColor: AppColors.danger,
      content: Text(message),
    ),);
}

/// Add a staff member, or change one's name, role or PIN.
class _StaffEditor extends ConsumerStatefulWidget {
  const _StaffEditor({this.existing});

  final StaffUser? existing;

  @override
  ConsumerState<_StaffEditor> createState() => _StaffEditorState();
}

class _StaffEditorState extends ConsumerState<_StaffEditor> {
  final _formKey = GlobalKey<FormState>();
  late final TextEditingController _name;
  final _pin = TextEditingController();
  final _confirmPin = TextEditingController();

  late StaffRole _role;
  bool _saving = false;
  String? _error;

  bool get _isNew => widget.existing == null;

  @override
  void initState() {
    super.initState();
    _name = TextEditingController(text: widget.existing?.name ?? '');
    _role = widget.existing?.role ?? StaffRole.cashier;
  }

  @override
  void dispose() {
    _name.dispose();
    _pin.dispose();
    _confirmPin.dispose();
    super.dispose();
  }

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

    final staff = ref.read(localStoreProvider).staff;

    try {
      if (_isNew) {
        await staff.create(
          name: _name.text,
          role: _role,
          pin: _pin.text,
        );
      } else {
        await staff.updateDetails(
          id: widget.existing!.id,
          name: _name.text,
          role: _role,
        );
        // Blank means "leave it alone" — an admin editing a role should not be
        // forced to know or reset someone's PIN.
        if (_pin.text.isNotEmpty) {
          await staff.setPin(
            widget.existing!.id,
            _pin.text,
            // An admin setting someone else's PIN is a reset, so the person is
            // asked to choose their own at next sign-in.
            mustChangePin: widget.existing!.id !=
                ref.read(currentUserProvider)?.id,
          );
        }
      }

      await ref.read(authControllerProvider.notifier).refreshStore();
      if (mounted) Navigator.of(context).pop();
    } on StaffException catch (e) {
      setState(() {
        _saving = false;
        _error = e.message;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: Text(_isNew ? 'Add staff member' : 'Edit ${widget.existing!.name}'),
      content: SizedBox(
        width: 420,
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              TextFormField(
                controller: _name,
                autofocus: true,
                decoration: const InputDecoration(labelText: 'Name'),
                validator: (v) => (v == null || v.trim().isEmpty)
                    ? 'A staff member needs a name'
                    : null,
              ),
              const SizedBox(height: AppSpacing.md),

              DropdownButtonFormField<StaffRole>(
                initialValue: _role,
                // Without this the item is laid out at its natural width and
                // "Manager — Sales, inventory and reports" runs 222px past the
                // edge of the dialog.
                isExpanded: true,
                decoration: const InputDecoration(labelText: 'Role'),
                items: [
                  for (final role in StaffRole.values)
                    DropdownMenuItem(
                      value: role,
                      child: Text(
                        '${role.label} — ${role.description}',
                        overflow: TextOverflow.ellipsis,
                      ),
                    ),
                ],
                onChanged: (v) => setState(() => _role = v ?? _role),
              ),
              // Spelled out below rather than squeezed into the dropdown, so
              // the permissions being granted are actually readable.
              Padding(
                padding: const EdgeInsets.only(top: AppSpacing.xs),
                child: Text(
                  _role.description,
                  style: const TextStyle(
                    fontSize: 12,
                    color: AppColors.textSecondary,
                  ),
                ),
              ),
              const SizedBox(height: AppSpacing.md),

              TextFormField(
                controller: _pin,
                obscureText: true,
                keyboardType: TextInputType.number,
                inputFormatters: [
                  FilteringTextInputFormatter.digitsOnly,
                  LengthLimitingTextInputFormatter(6),
                ],
                decoration: InputDecoration(
                  labelText: _isNew ? 'PIN' : 'New PIN',
                  helperText: _isNew
                      ? 'At least four digits, and not guessable across a '
                          'counter'
                      : 'Leave blank to keep the current PIN',
                ),
                validator: (v) {
                  final text = v ?? '';
                  if (_isNew && text.isEmpty) return 'A PIN is required';
                  if (text.isNotEmpty && text.length < 4) {
                    return 'At least four digits';
                  }
                  return null;
                },
              ),
              const SizedBox(height: AppSpacing.md),

              TextFormField(
                controller: _confirmPin,
                obscureText: true,
                keyboardType: TextInputType.number,
                inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                decoration: const InputDecoration(labelText: 'Confirm PIN'),
                validator: (v) {
                  // A mistyped PIN nobody can verify locks the account out —
                  // there is no email to reset it with.
                  if (_pin.text.isEmpty) return null;
                  return v != _pin.text ? 'The two PINs do not match' : null;
                },
              ),

              if (_error != null) ...[
                const SizedBox(height: AppSpacing.md),
                Text(
                  _error!,
                  style: const TextStyle(
                    color: AppColors.danger,
                    fontSize: 12.5,
                  ),
                ),
              ],
            ],
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: _saving ? null : () => Navigator.of(context).pop(),
          child: const Text('Cancel'),
        ),
        PrimaryButton(
          label: _isNew ? 'Add' : 'Save',
          expanded: false,
          busy: _saving,
          onPressed: _save,
        ),
      ],
    );
  }
}

/// Forces someone off a PIN they did not choose.
///
/// Shown after sign-in while [StaffUser.mustChangePin] is set. Not dismissable:
/// the seeded PINs are in the source of an open-source build, so a shop still
/// running one is effectively unprotected.
Future<void> showForcedPinChange(BuildContext context) => showDialog<void>(
      context: context,
      barrierDismissible: false,
      builder: (_) => const _ForcedPinChange(),
    );

class _ForcedPinChange extends ConsumerStatefulWidget {
  const _ForcedPinChange();

  @override
  ConsumerState<_ForcedPinChange> createState() => _ForcedPinChangeState();
}

class _ForcedPinChangeState extends ConsumerState<_ForcedPinChange> {
  final _formKey = GlobalKey<FormState>();
  final _pin = TextEditingController();
  final _confirm = TextEditingController();
  bool _saving = false;
  String? _error;

  @override
  void dispose() {
    _pin.dispose();
    _confirm.dispose();
    super.dispose();
  }

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

    final me = ref.read(currentUserProvider);
    if (me == null) return;

    try {
      await ref.read(localStoreProvider).staff.setPin(me.id, _pin.text);
      await ref.read(authControllerProvider.notifier).refreshStore();
      if (mounted) Navigator.of(context).pop();
    } on StaffException catch (e) {
      setState(() {
        _saving = false;
        _error = e.message;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final me = ref.watch(currentUserProvider);

    return PopScope(
      canPop: false,
      child: AlertDialog(
        title: const Text('Choose your PIN'),
        content: SizedBox(
          width: 420,
          child: Form(
            key: _formKey,
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Text(
                  '${me?.name ?? 'This account'} is still using the PIN this '
                  'terminal was set up with. Those are the same on every new '
                  'install, so please pick your own before ringing a sale.',
                  style: const TextStyle(
                    fontSize: 13,
                    height: 1.45,
                    color: AppColors.textSecondary,
                  ),
                ),
                const SizedBox(height: AppSpacing.lg),

                TextFormField(
                  controller: _pin,
                  autofocus: true,
                  obscureText: true,
                  keyboardType: TextInputType.number,
                  inputFormatters: [
                    FilteringTextInputFormatter.digitsOnly,
                    LengthLimitingTextInputFormatter(6),
                  ],
                  decoration: const InputDecoration(labelText: 'New PIN'),
                  validator: (v) => (v == null || v.length < 4)
                      ? 'At least four digits'
                      : null,
                ),
                const SizedBox(height: AppSpacing.md),

                TextFormField(
                  controller: _confirm,
                  obscureText: true,
                  keyboardType: TextInputType.number,
                  inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                  decoration: const InputDecoration(labelText: 'Confirm PIN'),
                  validator: (v) =>
                      v != _pin.text ? 'The two PINs do not match' : null,
                ),

                if (_error != null) ...[
                  const SizedBox(height: AppSpacing.md),
                  Text(
                    _error!,
                    style: const TextStyle(
                      color: AppColors.danger,
                      fontSize: 12.5,
                    ),
                  ),
                ],
              ],
            ),
          ),
        ),
        actions: [
          PrimaryButton(
            label: 'Set PIN',
            expanded: false,
            busy: _saving,
            onPressed: _save,
          ),
        ],
      ),
    );
  }
}