junction/src/Junction.App/ViewModels/MachineRowViewModel.cs

using System;
using CommunityToolkit.Mvvm.ComponentModel;
using Junction.Domain.Models;

namespace Junction.App.ViewModels
{
    /// <summary>
    /// One dashboard row = one configured machine + its latest snapshot projection.
    /// Mutated only on the UI thread (see <see cref="DashboardViewModel"/> marshalling).
    /// </summary>
    public sealed partial class MachineRowViewModel : ViewModelBase
    {
        public Guid MachineId { get; }

        [ObservableProperty] private string _name;
        [ObservableProperty] private string _protocolId;
        [ObservableProperty] private ConnectionState _connectionState;
        [ObservableProperty] private string _lastDatum;
        [ObservableProperty] private string _lastUpdated;

        public MachineRowViewModel(Machine machine)
        {
            MachineId = machine.Id;
            _name = machine.Name;
            _protocolId = machine.ProtocolId;
            _connectionState = ConnectionState.Unknown;
            _lastDatum = "—";
            _lastUpdated = "—";
        }

        /// <summary>Projects a snapshot onto this row. Call on the UI thread.</summary>
        public void Apply(MachineSnapshot snapshot)
        {
            if (snapshot == null)
            {
                return;
            }

            ConnectionState = snapshot.ConnectionState;
            LastUpdated = snapshot.CapturedAt.LocalDateTime.ToString("HH:mm:ss");
            LastDatum = Representative(snapshot);
        }

        /// <summary>
        /// Picks a human-meaningful datum to show: prefer an availability/execution item,
        /// else the first item's value, else an em-dash placeholder.
        /// </summary>
        private static string Representative(MachineSnapshot snapshot)
        {
            if (snapshot.Items.Count == 0)
            {
                return "—";
            }

            DataItem? preferred = null;
            for (int i = 0; i < snapshot.Items.Count; i++)
            {
                var item = snapshot.Items[i];
                if (Matches(item.Id) || Matches(item.Name))
                {
                    preferred = item;
                    break;
                }
            }

            var chosen = preferred ?? snapshot.Items[0];
            var value = string.IsNullOrWhiteSpace(chosen.Value) ? "—" : chosen.Value;
            var label = string.IsNullOrWhiteSpace(chosen.Name) ? chosen.Id : chosen.Name;
            return string.IsNullOrWhiteSpace(label) ? value : label + " = " + value;
        }

        private static bool Matches(string s)
        {
            if (string.IsNullOrEmpty(s))
            {
                return false;
            }

            return s.IndexOf("avail", StringComparison.OrdinalIgnoreCase) >= 0
                || s.IndexOf("execution", StringComparison.OrdinalIgnoreCase) >= 0;
        }
    }
}