using System;
using System.Globalization;
using System.Windows.Media;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using HC_APTBS.Services;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// ViewModel for the advance monitoring display showing PSG, Injector, and Manual
    /// encoder angles with zero-reference tracking and lock angle calculation.
    /// </summary>
    public sealed partial class AngleDisplayViewModel : ObservableObject
    {
        private const string NaN = "- -";
        private const double LockAngleTolerance = 0.1;

        private readonly int _encoderResolution;

        // ── Internal state ────────────────────────────────────────────────────────

        private double _psgRaw;
        private bool   _psgWorking;
        private double _injRaw;
        private bool   _injWorking;
        private double _manualRaw;
        private double _currentRpm;
        private bool   _isDirectionRight;

        private double _zeroPsgEncoder;
        private double _zeroInjDegrees;
        private double _injEncoderDegrees;
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(PrimaryGaugeAngle))]
        [NotifyPropertyChangedFor(nameof(SecondaryGaugeAngle))]
        private double _currentManualDegrees;
        private double _lockAngleValue;
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(TargetAngleForGauge))]
        private bool _isLockSet;
        private bool _isManualVisible;

        // ── Observable properties (bound by View) ─────────────────────────────────

        /// <summary>Formatted relative PSG angle or "- -" when sensor offline.</summary>
        [ObservableProperty] private string _psgRelativeAngle = NaN;

        /// <summary>Formatted raw PSG encoder degrees or "- -" when sensor offline.</summary>
        [ObservableProperty] private string _psgEncoderAngle = NaN;

        /// <summary>Foreground brush for PSG angle text (White = OK, Red = offline).</summary>
        [ObservableProperty] private Brush _psgAngleForeground = Brushes.White;

        /// <summary>Formatted relative INJ angle or "- -" when sensor offline.</summary>
        [ObservableProperty] private string _injRelativeAngle = NaN;

        /// <summary>Formatted raw INJ encoder degrees or "- -" when sensor offline.</summary>
        [ObservableProperty] private string _injEncoderAngle = NaN;

        /// <summary>Foreground brush for INJ angle text (White = OK, Red = offline).</summary>
        [ObservableProperty] private Brush _injAngleForeground = Brushes.White;

        /// <summary>Manual encoder angle in degrees, or "-" when RPM >= 30.</summary>
        [ObservableProperty] private string _manualAngleText = "-";

        /// <summary>Delta offset input for lock angle calculation (two-way bound to TextBox).</summary>
        [ObservableProperty] private string _lockAngleDeltaInput = "0";

        /// <summary>Computed lock angle result display.</summary>
        [ObservableProperty] private string _lockAngleDisplay = "00.0";

        /// <summary>Foreground brush for the lock angle display (Green/Red/White).</summary>
        [ObservableProperty] private Brush _lockAngleForeground = Brushes.White;

        // ── Numeric doubles for radial advance-monitor control ────────────────────

        /// <summary>PSG relative angle as a double for gauge binding.</summary>
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(PrimaryGaugeAngle))]
        private double _psgRelativeDegrees;

        /// <summary>INJ encoder absolute degrees (0–360) as a double.</summary>
        [ObservableProperty] private double _injEncoderDegreesValue;

        /// <summary>Lock angle target (0–360 degrees) as a double for gauge binding.</summary>
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(TargetAngleForGauge))]
        private double _targetLockAngle;

        /// <summary>True when bench RPM ≥ 31, hysteresis-cleared below 29.</summary>
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(PrimaryGaugeAngle))]
        [NotifyPropertyChangedFor(nameof(SecondaryGaugeAngle))]
        private bool _isRunningMode;

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

        /// <summary>
        /// Creates the angle display ViewModel, reading encoder resolution from configuration.
        /// </summary>
        public AngleDisplayViewModel(IConfigurationService configService)
        {
            _encoderResolution = configService.Settings.EncoderResolution;
        }

        // ── Computed for radial gauge ─────────────────────────────────────────────

        /// <summary>Primary thumb angle: manual-wheel angle in hand-mode, PSG relative angle when running.</summary>
        public double PrimaryGaugeAngle => IsRunningMode ? PsgRelativeDegrees : CurrentManualDegrees;

        /// <summary>Target thumb angle for the radial gauge, or null when no lock has been set yet.</summary>
        public double? TargetAngleForGauge => IsLockSet ? TargetLockAngle : (double?)null;

        /// <summary>Ghost secondary thumb angle: manual-wheel position shown when running, null in hand-mode (primary already shows it).</summary>
        public double? SecondaryGaugeAngle => IsRunningMode ? CurrentManualDegrees : (double?)null;

        // ── Public update (called from MainViewModel.OnRefreshTick) ───────────────

        /// <summary>
        /// Feeds all encoder channel values and recalculates display properties.
        /// Must be called on the UI thread.
        /// </summary>
        public void Update(
            double psgRaw, bool psgWorking,
            double injRaw, bool injWorking,
            double manualRaw, double rpm,
            bool isDirectionRight)
        {
            _psgRaw          = psgRaw;
            _psgWorking      = psgWorking;
            _injRaw          = injRaw;
            _injWorking      = injWorking;
            _manualRaw       = manualRaw;
            _currentRpm      = rpm;
            _isDirectionRight = isDirectionRight;

            if (!IsRunningMode && rpm >= 31.0)
                IsRunningMode = true;
            else if (IsRunningMode && rpm < 29.0)
                IsRunningMode = false;

            RecalculatePsg();
            RecalculateInj();
            RecalculateManual();
        }

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

        /// <summary>Sets the current PSG encoder value as the zero reference.</summary>
        [RelayCommand]
        private void SetPsgZero()
        {
            _zeroPsgEncoder = _psgRaw;
            RecalculatePsg();
        }

        /// <summary>Sets the current INJ encoder degrees as the zero reference.</summary>
        [RelayCommand]
        private void SetInjZero()
        {
            _zeroInjDegrees = _injEncoderDegrees;
            RecalculateInj();
        }

        // ── Public methods for test phase integration ─────────────────────────────

        /// <summary>
        /// Sets the lock angle delta from the pump definition and returns the computed
        /// lock angle result.  Called when the LockAngleFaseReady event fires.
        /// </summary>
        /// <param name="pumpLockAngle">Angle offset from <see cref="Models.PumpDefinition.LockAngle"/>.</param>
        /// <returns>Computed lock angle in degrees (0–360).</returns>
        public double SetLockAngle(double pumpLockAngle)
        {
            LockAngleDeltaInput = pumpLockAngle.ToString(CultureInfo.InvariantCulture);
            return _lockAngleValue;
        }

        /// <summary>
        /// Zeros the PSG encoder from a test phase (PsgModeFaseReady event).
        /// </summary>
        public void SetPsgZeroFromTest()
        {
            SetPsgZero();
        }

        // ── Lock angle delta change handler ───────────────────────────────────────

        partial void OnLockAngleDeltaInputChanged(string value)
        {
            if (double.TryParse(value, NumberStyles.Float, CultureInfo.InvariantCulture, out double delta))
            {
                _lockAngleValue = CalculateLockAngle(delta);
                TargetLockAngle = _lockAngleValue;
                IsLockSet = true;
                LockAngleDisplay = FormatAngle(_lockAngleValue);
            }

            RecalculateLockColor();
        }

        // ── Private recalculation methods ─────────────────────────────────────────

        private void RecalculatePsg()
        {
            if (!_psgWorking)
            {
                PsgRelativeAngle   = NaN;
                PsgEncoderAngle    = NaN;
                PsgAngleForeground = Brushes.Red;
                return;
            }

            PsgAngleForeground = Brushes.White;

            double sign = DirectionSign;

            // Raw encoder → degrees, normalized to ±180.
            double rawDeg = _psgRaw * (360.0 / _encoderResolution);
            if (rawDeg > 180) rawDeg = 360 - rawDeg;
            rawDeg *= sign;

            // Relative angle from zero reference.
            double relDeg = (_psgRaw - _zeroPsgEncoder) * (360.0 / _encoderResolution);
            if (relDeg > 180) relDeg = 360 - relDeg;
            relDeg *= sign;

            PsgRelativeDegrees = relDeg;
            PsgEncoderAngle    = FormatAngle(rawDeg);
            PsgRelativeAngle   = FormatAngle(relDeg);
        }

        private void RecalculateInj()
        {
            if (!_injWorking)
            {
                InjRelativeAngle   = NaN;
                InjEncoderAngle    = NaN;
                InjAngleForeground = Brushes.Red;
                return;
            }

            InjAngleForeground = Brushes.White;

            double sign = DirectionSign;

            // INJ encoder → degrees (full 0–360, NO 180 normalization).
            _injEncoderDegrees     = _injRaw * (360.0 / _encoderResolution);
            InjEncoderDegreesValue = _injEncoderDegrees;

            // Relative angle from zero reference.
            double relDeg = (_injEncoderDegrees - _zeroInjDegrees) * sign;

            InjEncoderAngle  = FormatAngle(_injEncoderDegrees);
            InjRelativeAngle = FormatAngle(relDeg);

            // Recompute lock angle if already set (INJ encoder changed).
            if (_isLockSet &&
                double.TryParse(LockAngleDeltaInput, NumberStyles.Float,
                                CultureInfo.InvariantCulture, out double delta))
            {
                _lockAngleValue = CalculateLockAngle(delta);
                TargetLockAngle = _lockAngleValue;
                LockAngleDisplay = FormatAngle(_lockAngleValue);
            }
        }

        private void RecalculateManual()
        {
            CurrentManualDegrees = _manualRaw * (360.0 / _encoderResolution);

            if (_currentRpm < 30)
            {
                ManualAngleText = FormatAngle(_currentManualDegrees);
                _isManualVisible = true;
            }
            else if (_isManualVisible)
            {
                ManualAngleText = "-";
                _isManualVisible = false;
            }

            RecalculateLockColor();
        }

        private void RecalculateLockColor()
        {
            if (!_isManualVisible)
            {
                LockAngleForeground = Brushes.White;
                return;
            }

            if (_isLockSet && Math.Abs(_lockAngleValue - _currentManualDegrees) <= LockAngleTolerance)
                LockAngleForeground = Brushes.Green;
            else if (_isLockSet)
                LockAngleForeground = Brushes.Red;
            else
                LockAngleForeground = Brushes.White;
        }

        private double CalculateLockAngle(double angleToAdd)
        {
            double result = (_injEncoderDegrees + angleToAdd) % 360;
            if (result < 0) result += 360;
            return result;
        }

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

        private double DirectionSign => _isDirectionRight ? -1.0 : 1.0;

        private static string FormatAngle(double degrees)
            => degrees.ToString("F1", CultureInfo.InvariantCulture);
    }
}