using Windows.Devices.Bluetooth;
using Windows.Devices.Bluetooth.GenericAttributeProfile;
using Windows.Devices.Enumeration;
using Windows.Storage.Streams;

namespace Substation;

public class CoyoteDevice : IDisposable
{
    static readonly Guid ServiceUuid   = Guid.Parse("0000180c-0000-1000-8000-00805f9b34fb");
    static readonly Guid WriteCharUuid = Guid.Parse("0000150a-0000-1000-8000-00805f9b34fb");
    static readonly Guid NotifyCharUuid= Guid.Parse("0000150b-0000-1000-8000-00805f9b34fb");

    BluetoothLEDevice?     _device;
    GattCharacteristic?    _write;
    GattCharacteristic?    _notify;

    public bool   IsConnected => _write != null;
    public int    StrengthA   { get; private set; }
    public int    StrengthB   { get; private set; }
    public string DeviceName  { get; private set; } = "";

    public event Action<int, int>? StrengthChanged;
    public event Action<bool>? ConnectionChanged;

    public async Task ConnectAsync(string nameFilter = "47L121000")
    {
        var selector = BluetoothLEDevice.GetDeviceSelectorFromDeviceName(nameFilter);
        var devices  = await DeviceInformation.FindAllAsync(selector);

        if (devices.Count == 0)
        {
            selector = BluetoothLEDevice.GetDeviceSelectorFromPairingState(false);
            devices  = await DeviceInformation.FindAllAsync(selector);
            var match = devices.FirstOrDefault(d =>
                d.Name.Contains(nameFilter, StringComparison.OrdinalIgnoreCase) ||
                d.Name.Contains("DG-LAB",   StringComparison.OrdinalIgnoreCase) ||
                d.Name.Contains("Coyote",   StringComparison.OrdinalIgnoreCase));
            if (match == null)
                throw new InvalidOperationException(
                    $"Coyote 3.0 not found (filter='{nameFilter}'). Ensure it's powered on and BLE is enabled.");
            // fallback path
            var fallback = await BluetoothLEDevice.FromIdAsync(match.Id);
            await ConnectDeviceAsync(fallback, match.Name);
            return;
        }

        var dev = await BluetoothLEDevice.FromIdAsync(devices[0].Id);
        await ConnectDeviceAsync(dev, devices[0].Name);
    }

    async Task ConnectDeviceAsync(BluetoothLEDevice dev, string name)
    {
        _device = dev;
        DeviceName = name;
        _device.ConnectionStatusChanged += OnConnectionStatusChanged;

        var svcResult = await dev.GetGattServicesForUuidAsync(ServiceUuid, BluetoothCacheMode.Uncached);
        if (svcResult.Status != GattCommunicationStatus.Success || svcResult.Services.Count == 0)
            throw new InvalidOperationException($"GATT service {ServiceUuid} not found on {name}.");

        var svc = svcResult.Services[0];

        var charResult = await svc.GetCharacteristicsAsync();
        if (charResult.Status != GattCommunicationStatus.Success)
            throw new InvalidOperationException($"Failed to enumerate characteristics on {name}.");

        _write  = charResult.Characteristics.FirstOrDefault(c => c.Uuid == WriteCharUuid)
                  ?? throw new InvalidOperationException("Write characteristic 0x150A not found.");
        _notify = charResult.Characteristics.FirstOrDefault(c => c.Uuid == NotifyCharUuid)
                  ?? throw new InvalidOperationException("Notify characteristic 0x150B not found.");

        _notify.ValueChanged += OnNotify;
        var subStatus = await _notify.WriteClientCharacteristicConfigurationDescriptorAsync(
            GattClientCharacteristicConfigurationDescriptorValue.Notify);
        if (subStatus != GattCommunicationStatus.Success)
            throw new InvalidOperationException("Failed to subscribe to 0x150B notifications.");

        await SendBF(200, 200, 128, 128, 128, 128);
        ConnectionChanged?.Invoke(true);
    }

    void OnConnectionStatusChanged(BluetoothLEDevice sender, object args)
    {
        if (sender.ConnectionStatus == Windows.Devices.Bluetooth.BluetoothConnectionStatus.Disconnected)
        {
            _write = null;
            _notify = null;
            ConnectionChanged?.Invoke(false);
        }
    }

    void OnNotify(GattCharacteristic sender, GattValueChangedEventArgs args)
    {
        var reader = DataReader.FromBuffer(args.CharacteristicValue);
        if (reader.UnconsumedBufferLength < 1) return;

        var head = reader.ReadByte();
        if (head == 0xB1 && reader.UnconsumedBufferLength >= 3)
        {
            reader.ReadByte();
            StrengthA = reader.ReadByte();
            StrengthB = reader.ReadByte();
            StrengthChanged?.Invoke(StrengthA, StrengthB);
        }
    }

    public async Task SendB0(byte[] frame)
    {
        if (_write == null) return;
        var writer = new DataWriter();
        writer.WriteBytes(frame);
        var status = await _write.WriteValueAsync(writer.DetachBuffer(), GattWriteOption.WriteWithoutResponse);
        if (status != GattCommunicationStatus.Success)
            Console.Error.WriteLine($"[BLE] B0 write failed: {status}");
    }

    public async Task SendBF(byte capA, byte capB, byte freqBalA, byte freqBalB, byte intBalA, byte intBalB)
    {
        if (_write == null) return;
        var frame  = BF.Build(capA, capB, freqBalA, freqBalB, intBalA, intBalB);
        var writer = new DataWriter();
        writer.WriteBytes(frame);
        var status = await _write.WriteValueAsync(writer.DetachBuffer(), GattWriteOption.WriteWithoutResponse);
        if (status != GattCommunicationStatus.Success)
            Console.Error.WriteLine($"[BLE] BF write failed: {status}");
    }

    public void Dispose()
    {
        if (_notify != null)
            _notify.ValueChanged -= OnNotify;
        _device?.Dispose();
    }
}