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

namespace HC_APTBS.ViewModels.Dialogs
{
    /// <summary>
    /// ViewModel for the WKlineErrors dialog.
    ///
    /// <para>
    /// Displays the raw DTC (Diagnostic Trouble Code) text returned by the VP44 ECU
    /// over K-Line and provides commands to read or clear fault codes.
    /// </para>
    /// </summary>
    public sealed partial class KlineErrorsViewModel : ObservableObject
    {
        // ── Services ──────────────────────────────────────────────────────────────

        private readonly IKwpService _kwp;
        private readonly IConfigurationService _config;
        private readonly ILocalizationService _loc;

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

        /// <summary>Initialises the ViewModel and shows the initially known error text.</summary>
        public KlineErrorsViewModel(
            IKwpService kwpService,
            IConfigurationService configService,
            ILocalizationService loc,
            string initialErrors = "")
        {
            _kwp    = kwpService;
            _config = configService;
            _loc    = loc;
            ErrorText = initialErrors;

            _kwp.ProgressChanged += OnProgress;
        }

        // ── Properties ────────────────────────────────────────────────────────────

        /// <summary>Raw DTC string returned by the ECU, shown in the text box.</summary>
        [ObservableProperty] private string _errorText = string.Empty;

        /// <summary>True while a K-Line read or clear operation is in progress.</summary>
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(ReadErrorsCommand))]
        [NotifyCanExecuteChangedFor(nameof(ClearErrorsCommand))]
        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;

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

        /// <summary>Reads the current fault codes from the ECU.</summary>
        [RelayCommand(CanExecute = nameof(CanOperate))]
        private async Task ReadErrorsAsync()
        {
            string? port = GetPort();
            if (port == null) return;

            IsBusy = true;
            try
            {
                ErrorText = await _kwp.ReadFaultCodesAsync(port);
            }
            finally
            {
                IsBusy = false;
                ProgressPercent = 0;
                ProgressMessage = string.Empty;
            }
        }

        /// <summary>Clears fault codes on the ECU, then reads back the updated list.</summary>
        [RelayCommand(CanExecute = nameof(CanOperate))]
        private async Task ClearErrorsAsync()
        {
            string? port = GetPort();
            if (port == null) return;

            IsBusy = true;
            try
            {
                ErrorText = await _kwp.ClearFaultCodesAsync(port);
                // Re-read after clearing to confirm
                ErrorText = await _kwp.ReadFaultCodesAsync(port);
            }
            finally
            {
                IsBusy = false;
                ProgressPercent = 0;
                ProgressMessage = string.Empty;
            }
        }

        /// <summary>Closes the dialog.</summary>
        [RelayCommand]
        private void Close()
        {
            _kwp.ProgressChanged -= OnProgress;
            RequestClose?.Invoke();
        }

        // ── Events ────────────────────────────────────────────────────────────────

        /// <summary>Raised when the dialog should close itself.</summary>
        public event System.Action? RequestClose;

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

        private bool CanOperate() => !IsBusy;

        private string? GetPort()
        {
            string? port = _kwp.DetectKLinePort();
            if (!string.IsNullOrEmpty(port)) return port;

            MessageBox.Show(
                _loc.GetString("Error.KLineNotFound"),
                _loc.GetString("Error.KLineTitle"), MessageBoxButton.OK, MessageBoxImage.Warning);
            return null;
        }

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