HC_APTBS/ViewModels/Pages/PumpPageViewModel.cs

using System.ComponentModel;
using CommunityToolkit.Mvvm.ComponentModel;
using HC_APTBS.Models;
using HC_APTBS.ViewModels.Dialogs;

namespace HC_APTBS.ViewModels.Pages
{
    /// <summary>Identifies the sub-section shown inside the Pump navigation page.</summary>
    public enum PumpSubPage
    {
        /// <summary>§3.a — Pump selection and K-Line ECU read.</summary>
        Identification = 0,
        /// <summary>§3.b — Diagnostic Trouble Codes.</summary>
        Dtcs           = 1,
        /// <summary>§3.c — Live pump CAN readings and status words.</summary>
        LiveData       = 2,
        /// <summary>§3.d — DFI calibration and ME/FBKW/PreIn manual control (auth-gated).</summary>
        Adaptation     = 3,
        /// <summary>§3.e — Ford VP44 immobilizer unlock (visible only when required).</summary>
        Unlock         = 4
    }

    /// <summary>
    /// ViewModel for the Pump navigation page.
    ///
    /// <para>Thin façade that groups the pump-related child ViewModels owned by
    /// <see cref="MainViewModel"/> and adds sub-page navigation, banner flags,
    /// and the Adaptation auth gate. Holds a <see cref="Root"/> reference so
    /// page XAML can bind to MainViewModel-owned properties (PumpRpm, PumpTemp,
    /// KLineState, …) via <c>{Binding Root.X}</c>.</para>
    /// </summary>
    public sealed partial class PumpPageViewModel : ObservableObject
    {
        /// <summary>Root ViewModel — owns services, live readings, and global commands.</summary>
        public MainViewModel Root { get; }

        // ── Child VM façades ──────────────────────────────────────────────────────

        /// <summary>Pump selector and K-Line read (§3.a).</summary>
        public PumpIdentificationViewModel Identification => Root.PumpIdentification;

        /// <summary>Diagnostic Trouble Code list (§3.b).</summary>
        public DtcListViewModel DtcList { get; }

        /// <summary>DFI management (§3.d).</summary>
        public DfiManageViewModel DfiViewModel => Root.DfiViewModel;

        /// <summary>Manual pump control sliders (§3.d).</summary>
        public PumpControlViewModel PumpControl => Root.PumpControl;

        /// <summary>First pump status display — Status word (§3.c).</summary>
        public StatusDisplayViewModel StatusDisplay1 => Root.StatusDisplay1;

        /// <summary>Second pump status display — Empf3 word (§3.c).</summary>
        public StatusDisplayViewModel StatusDisplay2 => Root.StatusDisplay2;

        /// <summary>Current immobilizer unlock VM (§3.e). Null when no unlock is in progress for this pump.</summary>
        public UnlockProgressViewModel? UnlockVm => Root.CurrentUnlockVm;

        // ── Navigation state ──────────────────────────────────────────────────────

        /// <summary>Currently selected Pump sub-section.</summary>
        [ObservableProperty] private PumpSubPage _selectedSubPage = PumpSubPage.Identification;

        // ── Banner flags (derived from Root state) ────────────────────────────────

        /// <summary>True when a pump has been loaded from the database.</summary>
        [ObservableProperty] private bool _isPumpSelected;

        /// <summary>True when the K-Line session is currently open.</summary>
        [ObservableProperty] private bool _isKLineSessionOpen;

        /// <summary>True when the K-Line session is in the failed state.</summary>
        [ObservableProperty] private bool _isKLineSessionFailed;

        /// <summary>True for pumps that require a Ford immobilizer unlock (Type 1 or 2).</summary>
        [ObservableProperty] private bool _isUnlockApplicable;

        /// <summary>Constructs the page VM and subscribes to relevant Root state changes.</summary>
        public PumpPageViewModel(
            MainViewModel root,
            DtcListViewModel dtcList)
        {
            Root   = root;
            DtcList = dtcList;

            // Initialise derived flags from the current Root state.
            RefreshDerivedFlags();

            // Keep the derived flags in sync with Root changes.
            Root.PropertyChanged += OnRootPropertyChanged;
            Root.PumpIdentification.PumpChanged += _ => RefreshDerivedFlags();
        }

        private void OnRootPropertyChanged(object? sender, PropertyChangedEventArgs e)
        {
            switch (e.PropertyName)
            {
                case nameof(MainViewModel.KLineState):
                    IsKLineSessionOpen   = Root.KLineState == KLineConnectionState.Connected;
                    IsKLineSessionFailed = Root.KLineState == KLineConnectionState.Failed;
                    break;

                case nameof(MainViewModel.CurrentUnlockVm):
                    OnPropertyChanged(nameof(UnlockVm));
                    break;
            }
        }

        private void RefreshDerivedFlags()
        {
            IsPumpSelected        = Root.CurrentPump != null;
            IsKLineSessionOpen    = Root.KLineState == KLineConnectionState.Connected;
            IsKLineSessionFailed  = Root.KLineState == KLineConnectionState.Failed;
            IsUnlockApplicable    = Root.CurrentPump != null && Root.CurrentPump.UnlockType != 0;
            OnPropertyChanged(nameof(UnlockVm));

            // Drop any stale DTCs from the previous pump.
            DtcList.Reset();
        }
    }
}