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

import '../../data/sources/ble/ble_provisioner.dart';
import '../../providers.dart';

enum _Step { scan, configure, done }

// Shared bottom sheet used by onboarding and the main sensor screens.
// Flow: scan -> select device (slides to configure) -> provision -> done.
class BleProvisionSheet extends ConsumerStatefulWidget {
  const BleProvisionSheet({super.key});

  @override
  ConsumerState<BleProvisionSheet> createState() => _BleProvisionSheetState();
}

class _BleProvisionSheetState extends ConsumerState<BleProvisionSheet> {
  final _provisioner = BleProvisioner();
  final _ssidController = TextEditingController();
  final _wifiPasswordController = TextEditingController();
  late final PageController _pageController;

  late Stream<BleScanResult> _scanStream;
  int _scanGeneration = 0;

  _Step _step = _Step.scan;
  BleScanResult? _selected;
  bool _provisioning = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    _pageController = PageController();
    _scanStream = _provisioner.scan();
  }

  @override
  void dispose() {
    _provisioner.dispose();
    _ssidController.dispose();
    _wifiPasswordController.dispose();
    _pageController.dispose();
    super.dispose();
  }

  Future<void> _provision() async {
    if (_selected == null) return;
    setState(() {
      _provisioning = true;
      _error = null;
    });
    try {
      final mqttBroker = await ref.read(mqttBrokerProvider.future);
      await _provisioner.provision(
        _selected!.deviceId,
        ssid: _ssidController.text.trim(),
        wifiPassword: _wifiPasswordController.text,
        mqttHost: mqttBroker?.host,
        mqttPort: mqttBroker?.port,
      );
      await ref
          .read(sensorRepositoryProvider)
          .createSensor(_selected!.name, name: _selected!.name);
      if (mounted) {
        setState(() => _step = _Step.done);
        _pageController.animateToPage(
          2,
          duration: const Duration(milliseconds: 300),
          curve: Curves.easeInOut,
        );
      }
    } catch (e) {
      if (mounted) setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _provisioning = false);
    }
  }

  void _selectDevice(BleScanResult r) {
    setState(() {
      _selected = r;
      _step = _Step.configure;
    });
    _pageController.animateToPage(
      1,
      duration: const Duration(milliseconds: 300),
      curve: Curves.easeInOut,
    );
  }

  void _goBack() {
    setState(() {
      _step = _Step.scan;
      _selected = null;
      _error = null;
      _scanGeneration++;
    });
    _pageController.animateToPage(
      0,
      duration: const Duration(milliseconds: 300),
      curve: Curves.easeInOut,
    );
  }

  void _reset() {
    setState(() {
      _step = _Step.scan;
      _selected = null;
      _error = null;
      _ssidController.clear();
      _wifiPasswordController.clear();
      _scanGeneration++;
    });
    _pageController.animateToPage(
      0,
      duration: const Duration(milliseconds: 300),
      curve: Curves.easeInOut,
    );
  }

  @override
  Widget build(BuildContext context) {
    return DraggableScrollableSheet(
      expand: false,
      initialChildSize: 0.6,
      maxChildSize: 0.9,
      builder: (context, scrollController) => Padding(
        padding: const EdgeInsets.symmetric(horizontal: 0),
        child: Column(
          children: [
            if (_step != _Step.done) ...[
              Padding(
                padding: const .fromLTRB(12, 12, 12, 0),
                child: Column(
                  children: [
                    Padding(
                      padding: const .fromLTRB(0, 0, 12, 4),
                      child: Row(
                        children: [
                          if (_step == _Step.configure)
                            IconButton(
                              icon: const Icon(Icons.arrow_back),
                              onPressed: _goBack,
                            )
                          else
                            const SizedBox(width: 0, height: 48),
                          Expanded(
                            child: Padding(
                              padding: const .only(left: 12),
                              child: Text(
                                _step == _Step.scan
                                    ? 'Add sensor'
                                    : (_selected?.name ?? 'Configure'),
                                style: Theme.of(context).textTheme.titleLarge,
                              ),
                            ),
                          ),
                        ],
                      ),
                    ),

                    const Divider(height: 0),
                  ],
                ),
              ),
            ],
            Expanded(
              child: PageView(
                controller: _pageController,
                physics: const NeverScrollableScrollPhysics(),
                children:
                    [
                          _ScanPage(
                            scrollController: scrollController,
                            scanStream: _scanStream,
                            generation: _scanGeneration,
                            selected: _selected,
                            onSelected: _selectDevice,
                          ),
                          _ConfigurePage(
                            ssidController: _ssidController,
                            wifiPasswordController: _wifiPasswordController,
                            provisioning: _provisioning,
                            error: _error,
                            onProvision: _provision,
                          ),
                          _DoneStep(
                            onGoToFloorPlan: () {
                              final router = GoRouter.of(context);
                              Navigator.of(context).pop();
                              router.go('/floorplan');
                            },
                            onAddAnother: _reset,
                            onDone: () => Navigator.of(context).pop(),
                          ),
                        ]
                        .map(
                          (page) => Padding(
                            padding: const .symmetric(horizontal: 24),
                            child: page,
                          ),
                        )
                        .toList(),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _ScanPage extends StatefulWidget {
  const _ScanPage({
    required this.scrollController,
    required this.scanStream,
    required this.generation,
    required this.selected,
    required this.onSelected,
  });

  final ScrollController scrollController;
  final Stream<BleScanResult> scanStream;
  final int generation;
  final BleScanResult? selected;
  final ValueChanged<BleScanResult> onSelected;

  @override
  State<_ScanPage> createState() => _ScanPageState();
}

class _ScanPageState extends State<_ScanPage>
    with AutomaticKeepAliveClientMixin {
  @override
  bool get wantKeepAlive => true;

  final _discovered = <String, BleScanResult>{};

  @override
  void didUpdateWidget(_ScanPage old) {
    super.didUpdateWidget(old);
    if (old.generation != widget.generation ||
        old.scanStream != widget.scanStream) {
      _discovered.clear();
    }
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);
    return StreamBuilder<BleScanResult>(
      stream: widget.scanStream,
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          _discovered[snapshot.data!.deviceId] = snapshot.data!;
        }

        return ListView(
          controller: widget.scrollController,
          padding: const EdgeInsets.only(top: 16, bottom: 24),
          children: [
            Row(
              children: [
                Text(
                  'Nearby sensor devices',
                  style: Theme.of(context).textTheme.labelLarge,
                ),
                const SizedBox(width: 12),
                const SizedBox.square(
                  dimension: 12,
                  child: CircularProgressIndicator(strokeWidth: 1.5),
                ),
              ],
            ),
            const SizedBox(height: 4),
            if (_discovered.isEmpty)
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 12),
                child: Text(
                  'No devices found yet…',
                  style: TextStyle(
                    color: Theme.of(context).colorScheme.onSurfaceVariant,
                  ),
                ),
              )
            else
              ..._discovered.values.map((r) {
                final selected = widget.selected?.deviceId == r.deviceId;
                return ListTile(
                  contentPadding: EdgeInsets.zero,
                  leading: const Icon(Icons.sensors),
                  title: Text(r.name),
                  subtitle: Text('${r.rssi} dBm'),
                  selected: selected,
                  onTap: () => widget.onSelected(r),
                );
              }),
          ],
        );
      },
    );
  }
}

class _ConfigurePage extends StatefulWidget {
  const _ConfigurePage({
    required this.ssidController,
    required this.wifiPasswordController,
    required this.provisioning,
    required this.error,
    required this.onProvision,
  });

  final TextEditingController ssidController;
  final TextEditingController wifiPasswordController;
  final bool provisioning;
  final String? error;
  final VoidCallback onProvision;

  @override
  State<_ConfigurePage> createState() => _ConfigurePageState();
}

class _ConfigurePageState extends State<_ConfigurePage> {
  bool _obscurePassword = true;

  @override
  Widget build(BuildContext context) {
    final bottomInset = MediaQuery.of(context).viewInsets.bottom;
    // scrollPadding ensures the field scrolls fully clear of the keyboard.
    final fieldScrollPadding = EdgeInsets.only(bottom: bottomInset + 24);

    return SingleChildScrollView(
      padding: EdgeInsets.only(top: 16, bottom: bottomInset + 24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          TextField(
            controller: widget.ssidController,
            scrollPadding: fieldScrollPadding,
            decoration: const InputDecoration(
              labelText: 'WiFi SSID',
              border: OutlineInputBorder(),
            ),
            textInputAction: .next,
          ),
          const SizedBox(height: 12),
          TextField(
            controller: widget.wifiPasswordController,
            scrollPadding: fieldScrollPadding,
            decoration: InputDecoration(
              labelText: 'WiFi Password',
              border: const OutlineInputBorder(),
              suffixIcon: IconButton(
                icon: Icon(
                  _obscurePassword ? Icons.visibility_off : Icons.visibility,
                ),
                onPressed: () =>
                    setState(() => _obscurePassword = !_obscurePassword),
              ),
            ),
            obscureText: _obscurePassword,
            textInputAction: TextInputAction.done,
            onSubmitted: (_) {
              if (widget.ssidController.text.trim().isNotEmpty) {
                widget.onProvision();
              }
            },
          ),
          const SizedBox(height: 16),
          if (widget.error != null)
            Padding(
              padding: const EdgeInsets.only(bottom: 12),
              child: Text(
                widget.error!,
                style: TextStyle(color: Theme.of(context).colorScheme.error),
              ),
            ),
          ListenableBuilder(
            listenable: widget.ssidController,
            builder: (context, _) {
              final canProvision = widget.ssidController.text.trim().isNotEmpty;
              return FilledButton(
                onPressed: (widget.provisioning || !canProvision)
                    ? null
                    : widget.onProvision,
                child: widget.provisioning
                    ? const SizedBox.square(
                        dimension: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : const Text('Provision & add'),
              );
            },
          ),
        ],
      ),
    );
  }
}

class _DoneStep extends StatelessWidget {
  const _DoneStep({
    required this.onGoToFloorPlan,
    required this.onAddAnother,
    required this.onDone,
  });

  final VoidCallback onGoToFloorPlan;
  final VoidCallback onAddAnother;
  final VoidCallback onDone;

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      padding: const EdgeInsets.symmetric(vertical: 16),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          const Icon(Icons.check_circle_outline, size: 56),
          const SizedBox(height: 16),
          Text(
            'Sensor provisioned!',
            style: Theme.of(context).textTheme.titleLarge,
            textAlign: TextAlign.center,
          ),
          const SizedBox(height: 8),
          Text(
            'The sensor will appear in the list once it connects to the network. '
            'Open the floor plan to place it.',
            style: Theme.of(context).textTheme.bodyMedium,
            textAlign: TextAlign.center,
          ),
          const SizedBox(height: 32),
          FilledButton.icon(
            icon: const Icon(Icons.map_outlined),
            label: const Text('Place on floor plan'),
            onPressed: onGoToFloorPlan,
          ),
          const SizedBox(height: 12),
          OutlinedButton.icon(
            icon: const Icon(Icons.add),
            label: const Text('Add another sensor'),
            onPressed: onAddAnother,
          ),
          const SizedBox(height: 8),
          TextButton(onPressed: onDone, child: const Text('Done')),
        ],
      ),
    );
  }
}