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

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// Represents the state of a single bit indicator in the 16-bit pump status word display.
    /// </summary>
    public sealed class BitIndicatorViewModel : ObservableObject
    {
        [System.Runtime.CompilerServices.CompilerGenerated]
        private string _color = "#26C200";

        /// <summary>HTML hex colour for the indicator background (e.g. "#26C200" = green, "#FF1E1E" = red).</summary>
        public string Color
        {
            get => _color;
            set => SetProperty(ref _color, value);
        }

        [System.Runtime.CompilerServices.CompilerGenerated]
        private string _description = string.Empty;

        /// <summary>Tooltip / label for this bit's current state.</summary>
        public string Description
        {
            get => _description;
            set => SetProperty(ref _description, value);
        }

        [System.Runtime.CompilerServices.CompilerGenerated]
        private bool _isActive;

        /// <summary>True when this bit is set in the status word.</summary>
        public bool IsActive
        {
            get => _isActive;
            set => SetProperty(ref _isActive, value);
        }

        /// <summary>Zero-based bit position (0–15) shown as a label beneath the indicator.</summary>
        public int Index { get; init; }
    }

    /// <summary>
    /// ViewModel for the StatusDisplay user control.
    ///
    /// <para>
    /// Maintains a 16-element collection of <see cref="BitIndicatorViewModel"/> objects,
    /// one per bit of the pump status word.  Call <see cref="UpdateStatusWord"/> whenever
    /// a new value arrives from the CAN bus.
    /// </para>
    /// </summary>
    public sealed partial class StatusDisplayViewModel : ObservableObject
    {
        // ── Properties ────────────────────────────────────────────────────────────

        /// <summary>Title shown above the bit display (e.g. "Table 2 – Status").</summary>
        [ObservableProperty] private string _title = "STATUS";

        /// <summary>16 bit indicators for bits 0–15 of the current status word.</summary>
        public ObservableCollection<BitIndicatorViewModel> Bits { get; } = new();

        /// <summary>
        /// Fired when a bit that is flagged as an error transitions to active.
        /// The argument is the bit position (0-based).
        /// </summary>
        public event Action<int>? ErrorBitDetected;

        // ── Constructor ───────────────────────────────────────────────────────────

        /// <summary>Initialises the collection with 16 green indicator placeholders.</summary>
        public StatusDisplayViewModel()
        {
            for (int i = 0; i < 16; i++)
                Bits.Add(new BitIndicatorViewModel { Color = "#26C200", Description = $"Bit {i}", Index = i });
        }

        // ── Public API ────────────────────────────────────────────────────────────

        /// <summary>
        /// Updates all 16 bit indicators from a <see cref="PumpStatusDefinition"/> and a live value.
        /// Must be called on the UI thread.
        /// </summary>
        /// <param name="statusDefinition">Definition describing what each bit means.</param>
        /// <param name="rawValue">Integer value from the pump CAN status parameter.</param>
        public void UpdateStatusWord(PumpStatusDefinition statusDefinition, int rawValue)
        {
            if (statusDefinition == null) return;

            Title = $"Table {statusDefinition.Id} – {statusDefinition.Name}";
            var bits = new BitArray(new[] { rawValue });

            foreach (var statusBit in statusDefinition.Bits)
            {
                int index = statusBit.Bit;
                if (index < 0 || index >= 16) continue;

                bool isSet = index < bits.Length && bits[index];
                var indicator = Bits[index];
                indicator.IsActive = isSet;

                // Find the matching state definition and apply its colour/description.
                foreach (var val in statusBit.Values)
                {
                    int expectedState = isSet ? 1 : 0;
                    if (val.State == expectedState)
                    {
                        indicator.Color       = "#" + val.Color;
                        indicator.Description = val.Description;
                        break;
                    }
                }

                // Notify the bench service / main VM of error bits.
                if (isSet && statusBit.Enabled)
                    ErrorBitDetected?.Invoke(index);
            }
        }

        /// <summary>Resets all indicators to the default green / inactive state.</summary>
        public void Reset()
        {
            for (int i = 0; i < Bits.Count; i++)
            {
                Bits[i].IsActive    = false;
                Bits[i].Color       = "#26C200";
                Bits[i].Description = $"Bit {i}";
            }
        }
    }
}