import 'dart:async';
import 'dart:io' show Platform;

import 'package:flutter/material.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';
import 'package:provider/provider.dart';

import '../connector/meshcore_connector.dart';
import '../l10n/l10n.dart';
import '../widgets/adaptive_app_bar_title.dart';
import '../widgets/device_tile.dart';
import 'contacts_screen.dart';

/// Screen for scanning and connecting to MeshCore devices
class ScannerScreen extends StatefulWidget {
  const ScannerScreen({super.key});

  @override
  State<ScannerScreen> createState() => _ScannerScreenState();
}

class _ScannerScreenState extends State<ScannerScreen> {
  bool _changedNavigation = false;
  late final VoidCallback _connectionListener;
  BluetoothAdapterState _bluetoothState = BluetoothAdapterState.unknown;
  late StreamSubscription<BluetoothAdapterState> _bluetoothStateSubscription;

  @override
  void initState() {
    super.initState();
    final connector = Provider.of<MeshCoreConnector>(context, listen: false);

    _connectionListener = () {
      if (connector.state == MeshCoreConnectionState.disconnected) {
        _changedNavigation = false;
      } else if (connector.state == MeshCoreConnectionState.connected &&
          !_changedNavigation) {
        _changedNavigation = true;
        if (mounted) {
          Navigator.of(context).push(
            MaterialPageRoute(builder: (context) => const ContactsScreen()),
          );
        }
      }
    };

    connector.addListener(_connectionListener);

    _bluetoothStateSubscription = FlutterBluePlus.adapterState.listen((state) {
      if (mounted) {
        setState(() {
          _bluetoothState = state;
        });
        // Cancel scan if Bluetooth turns off while scanning
        if (state != BluetoothAdapterState.on) {
          unawaited(connector.stopScan());
        }
      }
    });
  }

  @override
  void dispose() {
    final connector = Provider.of<MeshCoreConnector>(context, listen: false);
    connector.removeListener(_connectionListener);
    unawaited(_bluetoothStateSubscription.cancel());
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: AdaptiveAppBarTitle(context.l10n.scanner_title),
        centerTitle: true,
        automaticallyImplyLeading: false,
      ),
      body: SafeArea(
        top: false,
        child: Consumer<MeshCoreConnector>(
          builder: (context, connector, child) {
            return Column(
              children: [
                // Bluetooth off warning
                if (_bluetoothState == BluetoothAdapterState.off)
                  _bluetoothOffWarning(context),

                // Status bar
                _buildStatusBar(context, connector),

                // Device list
                Expanded(child: _buildDeviceList(context, connector)),
              ],
            );
          },
        ),
      ),
      floatingActionButton: Consumer<MeshCoreConnector>(
        builder: (context, connector, child) {
          final isScanning =
              connector.state == MeshCoreConnectionState.scanning;
          final isBluetoothOff = _bluetoothState == BluetoothAdapterState.off;

          return FloatingActionButton.extended(
            onPressed: isBluetoothOff
                ? null
                : () {
                    if (isScanning) {
                      connector.stopScan();
                    } else {
                      connector.startScan();
                    }
                  },
            icon: isScanning
                ? const SizedBox(
                    width: 20,
                    height: 20,
                    child: CircularProgressIndicator(
                      strokeWidth: 2,
                      color: Colors.white,
                    ),
                  )
                : const Icon(Icons.bluetooth_searching),
            label: Text(
              isScanning
                  ? context.l10n.scanner_stop
                  : context.l10n.scanner_scan,
            ),
          );
        },
      ),
    );
  }

  Widget _buildStatusBar(BuildContext context, MeshCoreConnector connector) {
    String statusText;
    Color statusColor;

    final l10n = context.l10n;
    switch (connector.state) {
      case MeshCoreConnectionState.scanning:
        statusText = l10n.scanner_scanning;
        statusColor = Colors.blue;
        break;
      case MeshCoreConnectionState.connecting:
        statusText = l10n.scanner_connecting;
        statusColor = Colors.orange;
        break;
      case MeshCoreConnectionState.connected:
        statusText = l10n.scanner_connectedTo(connector.deviceDisplayName);
        statusColor = Colors.green;
        break;
      case MeshCoreConnectionState.disconnecting:
        statusText = l10n.scanner_disconnecting;
        statusColor = Colors.orange;
        break;
      case MeshCoreConnectionState.disconnected:
        statusText = l10n.scanner_notConnected;
        statusColor = Colors.grey;
        break;
    }

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
      color: statusColor.withValues(alpha: 0.1),
      child: Row(
        children: [
          Icon(Icons.circle, size: 12, color: statusColor),
          const SizedBox(width: 8),
          Text(
            statusText,
            style: TextStyle(color: statusColor, fontWeight: FontWeight.w500),
          ),
        ],
      ),
    );
  }

  Widget _buildDeviceList(BuildContext context, MeshCoreConnector connector) {
    if (connector.scanResults.isEmpty) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(Icons.bluetooth, size: 64, color: Colors.grey[400]),
            const SizedBox(height: 16),
            Text(
              connector.state == MeshCoreConnectionState.scanning
                  ? context.l10n.scanner_searchingDevices
                  : context.l10n.scanner_tapToScan,
              style: TextStyle(fontSize: 16, color: Colors.grey[600]),
            ),
          ],
        ),
      );
    }

    return ListView.separated(
      padding: const EdgeInsets.all(8),
      itemCount: connector.scanResults.length,
      separatorBuilder: (context, index) => const Divider(),
      itemBuilder: (context, index) {
        final result = connector.scanResults[index];
        return DeviceTile(
          scanResult: result,
          onTap: () => _connectToDevice(context, connector, result),
        );
      },
    );
  }

  Future<void> _connectToDevice(
    BuildContext context,
    MeshCoreConnector connector,
    ScanResult result,
  ) async {
    try {
      final name = result.device.platformName.isNotEmpty
          ? result.device.platformName
          : result.advertisementData.advName;
      await connector.connect(result.device, displayName: name);
    } catch (e) {
      if (context.mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(context.l10n.scanner_connectionFailed(e.toString())),
            backgroundColor: Colors.red,
          ),
        );
      }
    }
  }

  Widget _bluetoothOffWarning(BuildContext context) {
    final errorColor = Theme.of(context).colorScheme.error;
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(vertical: 12, horizontal: 16),
      color: errorColor.withValues(alpha: 0.15),
      child: Row(
        children: [
          Icon(Icons.bluetooth_disabled, size: 24, color: errorColor),
          const SizedBox(width: 12),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  context.l10n.scanner_bluetoothOff,
                  style: TextStyle(
                    color: errorColor,
                    fontWeight: FontWeight.w600,
                    fontSize: 14,
                  ),
                ),
                const SizedBox(height: 4),
                Text(
                  context.l10n.scanner_bluetoothOffMessage,
                  style: TextStyle(
                    color: errorColor.withValues(alpha: 0.85),
                    fontSize: 12,
                  ),
                ),
              ],
            ),
          ),
          if (Platform.isAndroid)
            TextButton(
              onPressed: () => FlutterBluePlus.turnOn(),
              child: Text(context.l10n.scanner_enableBluetooth),
            ),
        ],
      ),
    );
  }
}