using CommunityToolkit.Mvvm.ComponentModel;
using HC_APTBS.Models;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// ViewModel for the BenchParamConfig user control.
    ///
    /// <para>
    /// Exposes all editable fields for one <see cref="CanBusParameter"/>: CAN message ID,
    /// byte positions, IIR filter alpha, and the six calibration coefficients P1–P6.
    /// Call <see cref="LoadParameter"/> to populate from a model instance, then
    /// <see cref="ApplyToParameter"/> to write edited values back.
    /// </para>
    /// </summary>
    public sealed partial class BenchConfigViewModel : ObservableObject
    {
        // ── Display ───────────────────────────────────────────────────────────────

        /// <summary>Human-readable name of the parameter being edited.</summary>
        [ObservableProperty] private string _name = string.Empty;

        // ── CAN frame fields ──────────────────────────────────────────────────────

        /// <summary>CAN message ID as a hex string (e.g. "1A0").</summary>
        [ObservableProperty] private string _messageIdHex = string.Empty;

        /// <summary>High-byte index within the CAN payload (0-based).</summary>
        [ObservableProperty] private string _byteH = string.Empty;

        /// <summary>Low-byte index within the CAN payload (0-based).</summary>
        [ObservableProperty] private string _byteL = string.Empty;

        /// <summary>IIR smoothing factor α (0–1). 1 = no filtering.</summary>
        [ObservableProperty] private string _alpha = string.Empty;

        // ── Calibration formula ───────────────────────────────────────────────────

        /// <summary>True when the 6-parameter calibration formula is enabled.</summary>
        [ObservableProperty] private bool _formulaEnabled;

        /// <summary>Calibration coefficient P1.</summary>
        [ObservableProperty] private string _p1 = string.Empty;

        /// <summary>Calibration coefficient P2.</summary>
        [ObservableProperty] private string _p2 = string.Empty;

        /// <summary>Calibration coefficient P3.</summary>
        [ObservableProperty] private string _p3 = string.Empty;

        /// <summary>Calibration coefficient P4.</summary>
        [ObservableProperty] private string _p4 = string.Empty;

        /// <summary>Calibration coefficient P5.</summary>
        [ObservableProperty] private string _p5 = string.Empty;

        /// <summary>Calibration coefficient P6.</summary>
        [ObservableProperty] private string _p6 = string.Empty;

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

        /// <summary>Populates all editable fields from <paramref name="parameter"/>.</summary>
        public void LoadParameter(CanBusParameter parameter)
        {
            Name          = parameter.Name;
            MessageIdHex  = parameter.ID.ToString("X");
            ByteH         = parameter.ByteH.ToString();
            ByteL         = parameter.ByteL.ToString();
            Alpha         = parameter.Alpha.ToString();
            FormulaEnabled = !parameter.DisableCalibration;

            P1 = parameter.P1.ToString();
            P2 = parameter.P2.ToString();
            P3 = parameter.P3.ToString();
            P4 = parameter.P4.ToString();
            P5 = parameter.P5.ToString();
            P6 = parameter.P6.ToString();
        }

        /// <summary>
        /// Writes all edited values back to <paramref name="parameter"/>.
        /// Returns <see langword="false"/> if any field fails to parse.
        /// </summary>
        public bool ApplyToParameter(CanBusParameter parameter)
        {
            if (!uint.TryParse(MessageIdHex,
                    System.Globalization.NumberStyles.HexNumber,
                    null, out uint id)) return false;
            if (!ushort.TryParse(ByteH, out ushort byteH)) return false;
            if (!ushort.TryParse(ByteL, out ushort byteL)) return false;
            if (!double.TryParse(Alpha,
                    System.Globalization.NumberStyles.Any,
                    System.Globalization.CultureInfo.InvariantCulture,
                    out double alpha)) return false;

            parameter.ID    = id;
            parameter.ByteH = byteH;
            parameter.ByteL = byteL;
            parameter.Alpha = alpha;
            parameter.DisableCalibration = !FormulaEnabled;

            if (FormulaEnabled)
            {
                if (!TryParseInvariant(P1, out double p1)) return false;
                if (!TryParseInvariant(P2, out double p2)) return false;
                if (!TryParseInvariant(P3, out double p3)) return false;
                if (!TryParseInvariant(P4, out double p4)) return false;
                if (!TryParseInvariant(P5, out double p5)) return false;
                if (!TryParseInvariant(P6, out double p6)) return false;

                parameter.P1 = p1;
                parameter.P2 = p2;
                parameter.P3 = p3;
                parameter.P4 = p4;
                parameter.P5 = p5;
                parameter.P6 = p6;
            }

            return true;
        }

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

        private static bool TryParseInvariant(string text, out double result)
            => double.TryParse(text,
                System.Globalization.NumberStyles.Any,
                System.Globalization.CultureInfo.InvariantCulture,
                out result);
    }
}