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

namespace FieldLogger.Services;

/// <summary>
/// Joins UM receiver log packets with the current GNSS fix and persists them
/// under the active job. Runs for the lifetime of the app.
/// </summary>
public sealed class PointLogger
{
    private readonly UmReceiverService _locator;
    private readonly MaglinkService _gps;
    private readonly AppDatabase _database;
    private readonly SettingsService _settings;
    private readonly ILogger<PointLogger> _logger;

    /// <summary>Raised (on the UI thread) after a point is saved.</summary>
    public event EventHandler<LoggedPoint>? PointSaved;

    /// <summary>Raised when a packet arrives but no active job is selected, so the point was dropped.</summary>
    public event EventHandler? PacketIgnoredNoJob;

    public PointLogger(UmReceiverService locator, MaglinkService gps, AppDatabase database,
        SettingsService settings, ILogger<PointLogger> logger)
    {
        _locator = locator;
        _gps = gps;
        _database = database;
        _settings = settings;
        _logger = logger;

        _locator.PacketReceived += OnPacketReceived;
    }

    private void OnPacketReceived(object? sender, UmLogPacket packet)
    {
        _ = HandlePacketAsync(packet);
    }

    private async Task HandlePacketAsync(UmLogPacket packet)
    {
        try
        {
            var jobId = _settings.ActiveJobId;
            if (jobId is null)
            {
                _logger.LogWarning("Log packet received but no active job; point dropped");
                MainThread.BeginInvokeOnMainThread(() => PacketIgnoredNoJob?.Invoke(this, EventArgs.Empty));
                return;
            }

            var fix = _gps.FreshFix();
            var point = LoggedPoint.From(jobId.Value, packet, _locator.DeviceInfo, fix, _gps.DeviceInfo);
            await _database.AddPointAsync(point);

            _logger.LogInformation("Point {Id} saved to job {JobId} (gps valid: {GpsValid})",
                point.Id, jobId, point.GpsValid);
            MainThread.BeginInvokeOnMainThread(() => PointSaved?.Invoke(this, point));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to save logged point");
        }
    }
}