using System;
using System.Threading.Tasks;
using System.Windows;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using HC_APTBS.Services;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// ViewModel for the DFIManageDisplay user control.
    ///
    /// <para>
    /// Exposes the current DFI (injection timing offset) value, a slider for manual
    /// adjustment, KWP version selection, and commands to read and write DFI via K-Line.
    /// Auto-mode is respected by the bench service when executing a DFI test phase.
    /// </para>
    /// </summary>
    public sealed partial class DfiManageViewModel : ObservableObject
    {
        // ── Services ──────────────────────────────────────────────────────────────

        private readonly IKwpService _kwp;
        private readonly IConfigurationService _config;
        private readonly ILocalizationService _loc;
        private const string LogId = "DfiManageViewModel";

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

        /// <summary>Initialises the ViewModel with the required services.</summary>
        public DfiManageViewModel(IKwpService kwpService, IConfigurationService configService, ILocalizationService loc)
        {
            _kwp    = kwpService;
            _config = configService;
            _loc    = loc;

            // Update the slider and LCD display in real time when the DFI is
            // read during a full K-Line read (PumpIdentificationViewModel flow).
            _kwp.DfiRead += (dfi) => SetDfi(dfi);
        }

        // ── DFI display ───────────────────────────────────────────────────────────

        /// <summary>Current DFI value read from the ECU (displayed in the label).</summary>
        [ObservableProperty] private double _currentDfi;

        /// <summary>
        /// Slider position in integer hundredths of a DFI unit (range –300 to 300).
        /// Divide by 100 to get the actual DFI value.
        /// </summary>
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(SliderDfiValue))]
        private int _sliderRaw;

        /// <summary>The DFI value represented by the current slider position.</summary>
        public double SliderDfiValue => Math.Round(SliderRaw / 100.0, 2);

        // ── Options ───────────────────────────────────────────────────────────────

        /// <summary>
        /// KWP protocol version index (0, 1, or 2) used when writing DFI.
        /// Corresponds to the three known VP44 authentication variants.
        /// </summary>
        [ObservableProperty] private int _versionIndex = 1;

        /// <summary>
        /// When <see langword="true"/> the bench service may perform automatic DFI
        /// correction during test phases; when <see langword="false"/> it skips them.
        /// </summary>
        [ObservableProperty] private bool _isAutoMode = true;

        // ── Operation state ───────────────────────────────────────────────────────

        /// <summary>True while a read or write K-Line operation is in progress.</summary>
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ReadDfiCommand))]
        [NotifyCanExecuteChangedFor(nameof(WriteDfiCommand))]
        private bool _isBusy;

        /// <summary>Progress percentage (0–100) for the current K-Line operation.</summary>
        [ObservableProperty] private int _progressPercent;

        /// <summary>Verbose status message for the current K-Line operation.</summary>
        [ObservableProperty] private string _progressMessage = string.Empty;

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

        /// <summary>
        /// Sets the displayed DFI value and repositions the slider to match.
        /// Safe to call from any thread.
        /// </summary>
        public void SetDfi(double dfi)
        {
            double rounded = Math.Round(dfi, 2);
            Application.Current.Dispatcher.Invoke(() =>
            {
                CurrentDfi  = rounded;
                SliderRaw   = (int)(rounded * 100);
            });
        }

        /// <summary>
        /// Clears the DFI display and slider so the previous pump's value is not
        /// shown stale until a new K-Line read populates it. Called on pump change.
        /// </summary>
        public void Reset()
        {
            CurrentDfi = 0;
            SliderRaw  = 0;
        }

        // ── Commands ──────────────────────────────────────────────────────────────

        /// <summary>Reads the current DFI value from the ECU over K-Line.</summary>
        [RelayCommand(CanExecute = nameof(CanOperate))]
        private async Task ReadDfiAsync()
        {
            string? port = _kwp.DetectKLinePort();
            if (string.IsNullOrEmpty(port))
            {
                MessageBox.Show(_loc.GetString("Error.KLineNotFound"),
                    _loc.GetString("Error.KLineTitle"), MessageBoxButton.OK, MessageBoxImage.Warning);
                return;
            }

            IsBusy = true;
            _kwp.ProgressChanged += OnProgress;
            try
            {
                string dfiStr = await _kwp.ReadDfiAsync(port);
                if (double.TryParse(dfiStr,
                        System.Globalization.NumberStyles.Any,
                        System.Globalization.CultureInfo.InvariantCulture,
                        out double val))
                    SetDfi(val);
            }
            finally
            {
                _kwp.ProgressChanged -= OnProgress;
                IsBusy = false;
                ProgressPercent = 0;
                ProgressMessage = string.Empty;
            }
        }

        /// <summary>Writes the slider DFI value to the ECU and reads back the result.</summary>
        [RelayCommand(CanExecute = nameof(CanOperate))]
        private async Task WriteDfiAsync()
        {
            string? port = _kwp.DetectKLinePort();
            if (string.IsNullOrEmpty(port))
            {
                MessageBox.Show(_loc.GetString("Error.KLineNotFound"),
                    _loc.GetString("Error.KLineTitle"), MessageBoxButton.OK, MessageBoxImage.Warning);
                return;
            }

            float value   = (float)SliderDfiValue;
            int   version = VersionIndex;

            IsBusy = true;
            _kwp.ProgressChanged += OnProgress;
            try
            {
                string dfiStr = await _kwp.WriteDfiAsync(port, value, version);
                if (double.TryParse(dfiStr,
                        System.Globalization.NumberStyles.Any,
                        System.Globalization.CultureInfo.InvariantCulture,
                        out double val))
                    SetDfi(val);
            }
            finally
            {
                _kwp.ProgressChanged -= OnProgress;
                IsBusy = false;
                ProgressPercent = 0;
                ProgressMessage = string.Empty;
            }
        }

        private bool CanOperate() => !IsBusy;

        // ── Helpers ───────────────────────────────────────────────────────────────

        private void OnProgress(int pct, string msg)
        {
            Application.Current.Dispatcher.Invoke(() =>
            {
                ProgressPercent = pct;
                ProgressMessage = msg;
            });
        }
    }
}