using System.Collections.Generic;
using System.Collections.ObjectModel;
using CommunityToolkit.Mvvm.ComponentModel;
using HC_APTBS.Models;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// Dashboard-side alarm aggregator.
    ///
    /// <para>Keeps an <see cref="ActiveAlarms"/> collection in sync with the
    /// bench <c>Alarms</c> CAN bitmask, resolving each set bit against the
    /// alarm definitions loaded from <c>alarms.xml</c>. The consumer (MainViewModel's
    /// refresh tick) calls <see cref="Update"/> every refresh interval.</para>
    /// </summary>
    public sealed partial class DashboardAlarmsViewModel : ObservableObject
    {
        private readonly IReadOnlyList<Alarm> _definitions;
        private int _lastMask = -1;

        /// <summary>List of currently asserted alarms.</summary>
        public ObservableCollection<Alarm> ActiveAlarms { get; } = new();

        /// <summary>True when no alarms are active — used to show the "System OK" banner.</summary>
        [ObservableProperty] private bool _isClear = true;

        /// <summary>True when at least one active alarm is flagged critical.</summary>
        [ObservableProperty] private bool _hasCritical;

        public DashboardAlarmsViewModel(IReadOnlyList<Alarm> definitions)
        {
            _definitions = definitions;
        }

        /// <summary>
        /// Rebuilds <see cref="ActiveAlarms"/> from the current bench alarm bitmask.
        /// Cheap no-op when the mask has not changed since the last call.
        /// Must be invoked on the UI thread.
        /// </summary>
        public void Update(int mask)
        {
            if (mask == _lastMask) return;
            _lastMask = mask;

            ActiveAlarms.Clear();
            bool anyCritical = false;

            foreach (var def in _definitions)
            {
                bool bitSet = (mask & (1 << def.Bit)) != 0;
                def.IsActive = bitSet;
                if (!bitSet) continue;

                ActiveAlarms.Add(def);
                if (def.IsCritical) anyCritical = true;
            }

            IsClear     = ActiveAlarms.Count == 0;
            HasCritical = anyCritical;
        }
    }
}