ulapp/FieldLogger/ViewModels/HomeViewModel.cs

using System.Collections.ObjectModel;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using FieldLogger.Models;
using FieldLogger.Services;
using FieldLogger.Services.Data;
using FieldLogger.Services.Sync;

namespace FieldLogger.ViewModels;

public sealed partial class HomeViewModel : ObservableObject
{
    private readonly DeviceConnectionManager _manager;
    private readonly MaglinkService _gps;
    private readonly PointLogger _pointLogger;
    private readonly AppDatabase _database;
    private readonly SettingsService _settings;
    private readonly IMqttSyncService _sync;

    public DeviceConnectionManager Manager => _manager;

    [ObservableProperty]
    private string _activeJobName = "No active job";

    [ObservableProperty]
    private bool _hasActiveJob;

    [ObservableProperty]
    private int _pointCount;

    [ObservableProperty]
    private string _fixSummary = "Waiting for GPS…";

    [ObservableProperty]
    private string _fixStatusLabel = "—";

    [ObservableProperty]
    private string _fixAccuracy = "";

    [ObservableProperty]
    private string _syncStatus = "";

    public ObservableCollection<LoggedPoint> RecentPoints { get; } = new();

    public HomeViewModel(DeviceConnectionManager manager, MaglinkService gps,
        PointLogger pointLogger, AppDatabase database, SettingsService settings, IMqttSyncService sync)
    {
        _manager = manager;
        _gps = gps;
        _pointLogger = pointLogger;
        _database = database;
        _settings = settings;
        _sync = sync;
        SyncStatus = sync.Status;

        _gps.FixReceived += OnFixReceived;
        _pointLogger.PointSaved += OnPointSaved;
        _pointLogger.PacketIgnoredNoJob += OnPacketIgnoredNoJob;
        _sync.StatusChanged += OnSyncStatusChanged;
        _sync.PointRejected += OnPointRejected;
    }

    /// <summary>Called from the page's OnAppearing.</summary>
    public async Task InitializeAsync()
    {
        // First launch: nothing saved yet, send the user to device selection.
        if (!_manager.HasSavedDevice(DeviceKind.Locator) && !_manager.HasSavedDevice(DeviceKind.RtkGps))
        {
            await Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.Locator}");
            return;
        }

        _manager.Start();
        await RefreshJobAsync();
    }

    public async Task RefreshJobAsync()
    {
        var jobId = _settings.ActiveJobId;
        if (jobId is null)
        {
            HasActiveJob = false;
            ActiveJobName = "No active job";
            PointCount = 0;
            RecentPoints.Clear();
            return;
        }

        var job = await _database.GetJobAsync(jobId.Value);
        if (job is null)
        {
            _settings.ActiveJobId = null;
            await RefreshJobAsync();
            return;
        }

        HasActiveJob = true;
        ActiveJobName = job.Name;
        PointCount = await _database.GetPointCountAsync(job.Id);

        var points = await _database.GetPointsAsync(job.Id);
        RecentPoints.Clear();
        foreach (var p in points.OrderByDescending(p => p.TimestampUtc).Take(10))
            RecentPoints.Add(p);
    }

    [RelayCommand]
    private async Task NewJobAsync()
    {
        var name = await Shell.Current.DisplayPromptAsync("New Job", "Job name:",
            placeholder: $"Job {DateTime.Now:yyyy-MM-dd}");
        if (string.IsNullOrWhiteSpace(name))
            return;

        var job = await _database.CreateJobAsync(name.Trim());
        _settings.ActiveJobId = job.Id;
        await RefreshJobAsync();
    }

    [RelayCommand]
    private Task SelectJobAsync() => Shell.Current.GoToAsync("//jobs");

    [RelayCommand]
    private Task SelectLocatorAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.Locator}");

    [RelayCommand]
    private Task SelectGpsAsync() => Shell.Current.GoToAsync($"devicescan?kind={DeviceKind.RtkGps}");

    [RelayCommand]
    private Task ViewMapAsync() => Shell.Current.GoToAsync("//map");

    private void OnFixReceived(object? sender, GnssFix fix)
    {
        MainThread.BeginInvokeOnMainThread(() =>
        {
            FixStatusLabel = fix.StatusLabel;
            FixSummary = fix.HasPosition
                ? $"{fix.Latitude:F8}, {fix.Longitude:F8}  ·  {fix.AltitudeCorrected:F2} m"
                : "No position";
            FixAccuracy = $"H ±{fix.Hrms:F3} m · V ±{fix.Vrms:F3} m · {fix.SatellitesUsed} sats · batt {fix.BatteryPercent}%";
        });
    }

    private void OnPointSaved(object? sender, LoggedPoint point)
    {
        RecentPoints.Insert(0, point);
        while (RecentPoints.Count > 10)
            RecentPoints.RemoveAt(RecentPoints.Count - 1);
        PointCount++;
    }

    private async void OnPacketIgnoredNoJob(object? sender, EventArgs e)
    {
        await Shell.Current.DisplayAlert("No Active Job",
            "A point was logged on the receiver, but no job is active so it was not saved. Create or select a job first.",
            "OK");
    }

    private void OnSyncStatusChanged(object? sender, string status) =>
        MainThread.BeginInvokeOnMainThread(() => SyncStatus = status);

    private void OnPointRejected(object? sender, PointSyncFailureEventArgs e) =>
        MainThread.BeginInvokeOnMainThread(async () =>
            await Shell.Current.DisplayAlert(
                "Point Saved Locally — Sync Needs Attention",
                $"Point #{e.Point.Id} remains on this device and was not uploaded. Reason: {e.ReasonCode}.",
                "OK"));
}