using FieldLogger.Models;
using FieldLogger.Services.Ble;
using Microsoft.Extensions.Logging;

namespace FieldLogger.Services;

/// <summary>
/// Manages the connection to an Underground Magnetics locating receiver and
/// its push-button data-logging (PBDL) protocol.
/// </summary>
public sealed class UmReceiverService : IAsyncDisposable
{
    // UM Receiver BLE External Logging API v1.2:
    // serial port service with notify (RX) and write-no-response (TX) characteristics.
    public static readonly Guid ServiceUuid = Guid.Parse("554d0000-261f-677e-a6f1-54c57aa996d4");
    public static readonly Guid NotifyUuid = Guid.Parse("554d0001-261f-677e-a6f1-54c57aa996d4");
    public static readonly Guid WriteUuid = Guid.Parse("554d0002-261f-677e-a6f1-54c57aa996d4");

    private readonly BleSerialClient _client = new();
    private readonly ILogger<UmReceiverService> _logger;

    public UmDeviceInfo? DeviceInfo { get; private set; }
    public bool IsConnected => _client.IsConnected;
    public string? DeviceName => _client.DeviceName;

    /// <summary>Raised when the operator presses the log button on the receiver.</summary>
    public event EventHandler<UmLogPacket>? PacketReceived;
    public event EventHandler<UmDeviceInfo>? DeviceInfoReceived;
    public event EventHandler? Disconnected;

    public UmReceiverService(ILogger<UmReceiverService> logger)
    {
        _logger = logger;
        _client.LineReceived += OnLineReceived;
        _client.Disconnected += (_, _) => Disconnected?.Invoke(this, EventArgs.Empty);
    }

    /// <summary>Device-name filter for scan results (UMRX_* for most brands, DT100_* for Leica).</summary>
    public static bool IsUmReceiverName(string? name) =>
        name is not null &&
        (name.StartsWith("UMRX", StringComparison.OrdinalIgnoreCase) ||
         name.StartsWith("DT100", StringComparison.OrdinalIgnoreCase));

    public async Task ConnectAsync(Guid deviceId, CancellationToken cancellationToken = default)
    {
        await _client.ConnectAsync(deviceId, ServiceUuid, NotifyUuid, WriteUuid, cancellationToken);
        await EnableLoggingAsync(cancellationToken);
    }

    /// <summary>Enables push-button data logging. The first enable triggers the info string.</summary>
    public Task EnableLoggingAsync(CancellationToken cancellationToken = default)
        => _client.WriteLineAsync("$UMPBDL,1", cancellationToken);

    public Task DisableLoggingAsync(CancellationToken cancellationToken = default)
        => _client.WriteLineAsync("$UMPBDL,0", cancellationToken);

    public Task DisconnectAsync() => _client.DisconnectAsync();

    private void OnLineReceived(object? sender, string line)
    {
        _logger.LogDebug("UM rx: {Line}", line);

        // Bare command acknowledgements.
        var trimmed = line.Trim();
        if (trimmed.Equals("OK", StringComparison.OrdinalIgnoreCase) ||
            trimmed.Equals("ERROR", StringComparison.OrdinalIgnoreCase))
            return;

        var packet = UmLogPacket.TryParse(line);
        if (packet is not null)
        {
            PacketReceived?.Invoke(this, packet);
            return;
        }

        var info = UmDeviceInfo.TryParse(line);
        if (info is not null)
        {
            DeviceInfo = info;
            DeviceInfoReceived?.Invoke(this, info);
            return;
        }

        _logger.LogWarning("UM receiver sent unrecognized line: {Line}", line);
    }

    public ValueTask DisposeAsync() => _client.DisposeAsync();
}