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

import '../../../app/providers.dart';
import '../../../core/config/sync_config.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/widgets/primary_button.dart';

/// Points this terminal at a back office, and names it.
///
/// Until this existed a store was wired up by editing `syncConfigProvider` and
/// rebuilding — which is not something a shop can do, and made every terminal
/// in a fleet a separate build.
Future<void> showBackOfficeDialog(BuildContext context) => showDialog<void>(
      context: context,
      builder: (_) => const _BackOfficeDialog(),
    );

class _BackOfficeDialog extends ConsumerStatefulWidget {
  const _BackOfficeDialog();

  @override
  ConsumerState<_BackOfficeDialog> createState() => _BackOfficeDialogState();
}

class _BackOfficeDialogState extends ConsumerState<_BackOfficeDialog> {
  final _formKey = GlobalKey<FormState>();

  late TransportKind _kind;
  late final TextEditingController _terminalName;
  late final TextEditingController _storeId;
  late final TextEditingController _host;
  late final TextEditingController _port;
  late final TextEditingController _username;
  late final TextEditingController _password;
  late final TextEditingController _httpUrl;
  late final TextEditingController _apiKey;
  late bool _useTls;

  bool _saving = false;

  @override
  void initState() {
    super.initState();
    final config = ref.read(syncConfigProvider);
    final terminal = ref.read(terminalIdentityProvider);

    _kind = config.transport;
    _useTls = config.useTls;
    _terminalName = TextEditingController(text: terminal.name);
    _storeId = TextEditingController(text: terminal.storeId);
    _host = TextEditingController(text: config.brokerHost);
    _port = TextEditingController(text: '${config.brokerPort}');
    _username = TextEditingController(text: config.username ?? '');
    _password = TextEditingController(text: config.password ?? '');
    _httpUrl = TextEditingController(text: config.httpBaseUrl);
    _apiKey = TextEditingController(text: config.apiKey ?? '');
  }

  @override
  void dispose() {
    for (final c in [
      _terminalName,
      _storeId,
      _host,
      _port,
      _username,
      _password,
      _httpUrl,
      _apiKey,
    ]) {
      c.dispose();
    }
    super.dispose();
  }

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

    final store = ref.read(localStoreProvider);

    // Name and store id are the terminal's own, and live in its database — a
    // reinstall must not lose which shop this till belongs to.
    await store.identityStore.rename(
      name: _terminalName.text.trim(),
      storeId: _storeId.text.trim(),
    );
    await store.hydrate();

    if (!mounted) return;

    // Deliberately left out of the identity store: credentials belong to the
    // route, not to the machine, and re-pointing a terminal should not rewrite
    // who it is.
    ref.read(syncConfigProvider.notifier).state =
        ref.read(syncConfigProvider).copyWith(
              transport: _kind,
              storeId: _storeId.text.trim(),
              brokerHost: _host.text.trim(),
              brokerPort: int.tryParse(_port.text.trim()) ?? 8883,
              useTls: _useTls,
              username: _username.text.trim().isEmpty
                  ? null
                  : _username.text.trim(),
              password: _password.text.isEmpty ? null : _password.text,
              httpBaseUrl: _httpUrl.text.trim(),
              apiKey: _apiKey.text.trim().isEmpty ? null : _apiKey.text.trim(),
            );

    if (mounted) Navigator.of(context).pop();
  }

  @override
  Widget build(BuildContext context) {
    final terminal = ref.watch(terminalIdentityProvider);

    return AlertDialog(
      title: const Text('Back office connection'),
      content: SizedBox(
        width: 520,
        child: Form(
          key: _formKey,
          child: SingleChildScrollView(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                _IdentityBanner(code: terminal.code, deviceId: terminal.deviceId),
                const SizedBox(height: AppSpacing.lg),

                TextFormField(
                  controller: _terminalName,
                  decoration: const InputDecoration(
                    labelText: 'Terminal name',
                    helperText: 'What staff call this till, e.g. "Counter 2"',
                  ),
                ),
                const SizedBox(height: AppSpacing.md),

                TextFormField(
                  controller: _storeId,
                  decoration: const InputDecoration(
                    labelText: 'Store ID',
                    helperText: 'Namespaces this shop on the broker',
                  ),
                  validator: (v) => (v == null || v.trim().isEmpty)
                      ? 'Every terminal must belong to a store'
                      : null,
                ),
                const SizedBox(height: AppSpacing.lg),

                SegmentedButton<TransportKind>(
                  segments: const [
                    ButtonSegment(
                      value: TransportKind.simulated,
                      label: Text('Offline demo'),
                    ),
                    ButtonSegment(
                      value: TransportKind.http,
                      label: Text('HTTP'),
                    ),
                    ButtonSegment(
                      value: TransportKind.mqtt,
                      label: Text('MQTT'),
                    ),
                  ],
                  selected: {_kind},
                  onSelectionChanged: (s) => setState(() => _kind = s.first),
                ),
                const SizedBox(height: AppSpacing.lg),

                if (_kind == TransportKind.mqtt) ..._mqttFields(),
                if (_kind == TransportKind.http) ..._httpFields(),
                if (_kind == TransportKind.simulated)
                  const _Note(
                    'Bills queue and drain against a local stub. Nothing '
                    'leaves this terminal — use it to rehearse a shift '
                    'without a server.',
                  ),
              ],
            ),
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: _saving ? null : () => Navigator.of(context).pop(),
          child: const Text('Cancel'),
        ),
        PrimaryButton(
          label: 'Save',
          expanded: false,
          busy: _saving,
          onPressed: _save,
        ),
      ],
    );
  }

  List<Widget> _mqttFields() => [
        Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Expanded(
              flex: 3,
              child: TextFormField(
                controller: _host,
                decoration: const InputDecoration(
                  labelText: 'Broker host',
                  hintText: 'nats.example.com',
                ),
                validator: (v) => (v == null || v.trim().isEmpty)
                    ? 'A broker host is required'
                    : null,
              ),
            ),
            const SizedBox(width: AppSpacing.md),
            Expanded(
              child: TextFormField(
                controller: _port,
                keyboardType: TextInputType.number,
                inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                decoration: const InputDecoration(labelText: 'Port'),
                validator: (v) {
                  final port = int.tryParse(v?.trim() ?? '');
                  return (port == null || port < 1 || port > 65535)
                      ? '1–65535'
                      : null;
                },
              ),
            ),
          ],
        ),
        const SizedBox(height: AppSpacing.md),
        Row(
          children: [
            Expanded(
              child: TextFormField(
                controller: _username,
                decoration: const InputDecoration(labelText: 'Username'),
              ),
            ),
            const SizedBox(width: AppSpacing.md),
            Expanded(
              child: TextFormField(
                controller: _password,
                obscureText: true,
                decoration: const InputDecoration(labelText: 'Password'),
              ),
            ),
          ],
        ),
        SwitchListTile(
          contentPadding: EdgeInsets.zero,
          value: _useTls,
          onChanged: (v) => setState(() => _useTls = v),
          title: const Text('Use TLS'),
          subtitle: const Text(
            'Bills carry customer names and mobile numbers. Turn this off only '
            'on a closed network you control.',
            style: TextStyle(fontSize: 12),
          ),
        ),
        const _Note(
          'Works against NATS with its MQTT gateway enabled, or any MQTT 3.1.1 '
          'broker. Topics arrive as NATS subjects with "/" replaced by "." — '
          'see docs/sync-contract.md.',
        ),
      ];

  List<Widget> _httpFields() => [
        TextFormField(
          controller: _httpUrl,
          decoration: const InputDecoration(
            labelText: 'Base URL',
            hintText: 'https://api.example.com',
            helperText: 'Bills are posted to {base}/orders',
          ),
          validator: (v) {
            final text = v?.trim() ?? '';
            if (text.isEmpty) return 'A base URL is required';
            final uri = Uri.tryParse(text);
            if (uri == null || !uri.isAbsolute) return 'Not a valid URL';
            return null;
          },
        ),
        const SizedBox(height: AppSpacing.md),
        TextFormField(
          controller: _apiKey,
          obscureText: true,
          decoration: const InputDecoration(
            labelText: 'API key',
            helperText: 'Sent as a bearer token',
          ),
        ),
      ];
}

/// The two identifiers a support call needs, and neither is editable.
class _IdentityBanner extends StatelessWidget {
  const _IdentityBanner({required this.code, required this.deviceId});

  final String code;
  final String deviceId;

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.all(AppSpacing.md),
      decoration: const BoxDecoration(
        color: AppColors.primarySurface,
        borderRadius: AppRadius.brSm,
      ),
      child: Row(
        children: [
          const Icon(Icons.point_of_sale_rounded,
              size: 18, color: AppColors.primary,),
          const SizedBox(width: AppSpacing.sm),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'Terminal $code',
                  style: const TextStyle(
                    fontWeight: FontWeight.w700,
                    color: AppColors.primary,
                  ),
                ),
                Text(
                  'Device $deviceId',
                  style: const TextStyle(
                    fontSize: 11,
                    color: AppColors.textSecondary,
                  ),
                ),
              ],
            ),
          ),
          IconButton(
            tooltip: 'Copy device ID',
            icon: const Icon(Icons.copy_rounded, size: 16),
            onPressed: () => Clipboard.setData(ClipboardData(text: deviceId)),
          ),
        ],
      ),
    );
  }
}

class _Note extends StatelessWidget {
  const _Note(this.text);

  final String text;

  @override
  Widget build(BuildContext context) => Padding(
        padding: const EdgeInsets.only(top: AppSpacing.sm),
        child: Text(
          text,
          style: const TextStyle(
            fontSize: 12,
            color: AppColors.textTertiary,
            height: 1.45,
          ),
        ),
      );
}