using System;
using System.Globalization;
using System.Windows;
using System.Windows.Media;

namespace HC_APTBS.Views.Controls
{
    /// <summary>
    /// Geometry-rendered circular angle gauge for the bench advance-monitoring display.
    /// Shows a 360° dial with 5° tick steps, major labels every 45°, and up to three
    /// directional thumb markers: a primary thumb (manual wheel or PSG), an optional
    /// target thumb (lock-angle target, colour-coded for tolerance), and an optional
    /// ghost thumb (secondary / de-emphasised context indicator).
    /// </summary>
    public sealed class RadialAngleGauge : FrameworkElement
    {
        // ── Dependency properties ─────────────────────────────────────────────────

        public static readonly DependencyProperty PrimaryAngleProperty =
            DependencyProperty.Register(nameof(PrimaryAngle), typeof(double), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(0.0, FrameworkPropertyMetadataOptions.AffectsRender));

        public static readonly DependencyProperty TargetAngleProperty =
            DependencyProperty.Register(nameof(TargetAngle), typeof(double?), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));

        public static readonly DependencyProperty SecondaryAngleProperty =
            DependencyProperty.Register(nameof(SecondaryAngle), typeof(double?), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));

        public static readonly DependencyProperty PrimaryBrushProperty =
            DependencyProperty.Register(nameof(PrimaryBrush), typeof(Brush), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));

        public static readonly DependencyProperty TargetBrushProperty =
            DependencyProperty.Register(nameof(TargetBrush), typeof(Brush), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender));

        public static readonly DependencyProperty IsRunningModeProperty =
            DependencyProperty.Register(nameof(IsRunningMode), typeof(bool), typeof(RadialAngleGauge),
                new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.AffectsRender));

        // ── Property accessors ────────────────────────────────────────────────────

        /// <summary>Primary thumb angle in degrees (0 = top, clockwise positive).</summary>
        public double PrimaryAngle
        {
            get => (double)GetValue(PrimaryAngleProperty);
            set => SetValue(PrimaryAngleProperty, value);
        }

        /// <summary>Target thumb angle in degrees, or null to hide it.</summary>
        public double? TargetAngle
        {
            get => (double?)GetValue(TargetAngleProperty);
            set => SetValue(TargetAngleProperty, value);
        }

        /// <summary>Ghost secondary thumb angle in degrees, or null to hide it.</summary>
        public double? SecondaryAngle
        {
            get => (double?)GetValue(SecondaryAngleProperty);
            set => SetValue(SecondaryAngleProperty, value);
        }

        /// <summary>Fill brush for the primary thumb. Falls back to the accent brush when null.</summary>
        public Brush? PrimaryBrush
        {
            get => (Brush?)GetValue(PrimaryBrushProperty);
            set => SetValue(PrimaryBrushProperty, value);
        }

        /// <summary>Fill brush for the target thumb (green = within tolerance, red = off-target).</summary>
        public Brush? TargetBrush
        {
            get => (Brush?)GetValue(TargetBrushProperty);
            set => SetValue(TargetBrushProperty, value);
        }

        /// <summary>When true the mode label switches to PSG context; adjusts visual emphasis.</summary>
        public bool IsRunningMode
        {
            get => (bool)GetValue(IsRunningModeProperty);
            set => SetValue(IsRunningModeProperty, value);
        }

        // ── Layout ────────────────────────────────────────────────────────────────

        protected override Size MeasureOverride(Size availableSize)
        {
            double side = double.IsInfinity(availableSize.Width) ? 240.0 : availableSize.Width;
            if (!double.IsInfinity(availableSize.Height))
                side = Math.Min(side, availableSize.Height);
            side = Math.Max(side, 120.0);
            return new Size(side, side);
        }

        // ── Render ────────────────────────────────────────────────────────────────

        protected override void OnRender(DrawingContext dc)
        {
            double w = ActualWidth;
            double h = ActualHeight;
            double side = Math.Min(w, h);
            double cx = w / 2.0;
            double cy = h / 2.0;

            // Radii as fractions of half-side
            double halfS     = side / 2.0;
            double rOuter    = halfS * 0.88;
            double rInner    = halfS * 0.82;
            double rTickOut  = halfS * 0.86;
            double rMinorIn  = halfS * 0.80;
            double rMajorIn  = halfS * 0.74;
            double rLabel    = halfS * 0.68;
            double rThumbTip = halfS * 0.88;
            double rThumbBase= halfS * 0.72;
            double thumbHalf = halfS * 0.06; // half-width of triangle base

            // Brushes — use WPF-UI resources when available, safe hard-coded fallbacks otherwise
            Brush ringBrush     = GetThemeBrush("ControlStrokeColorDefaultBrush",  new SolidColorBrush(Color.FromArgb(64, 200, 200, 200)));
            Brush tickBrush     = GetThemeBrush("TextFillColorSecondaryBrush",     new SolidColorBrush(Color.FromArgb(120, 180, 180, 180)));
            Brush majorBrush    = GetThemeBrush("TextFillColorPrimaryBrush",       Brushes.WhiteSmoke);
            Brush accentBrush   = GetThemeBrush("AccentFillColorPrimaryBrush",     Brushes.DodgerBlue);
            Brush primaryFill   = PrimaryBrush ?? accentBrush;
            Brush targetFill    = TargetBrush  ?? Brushes.White;
            Brush ghostFill     = new SolidColorBrush(Color.FromArgb(80, 200, 200, 200));

            var ringPen   = new Pen(ringBrush,  1.0);
            var minorPen  = new Pen(tickBrush,  1.0);
            var majorPen  = new Pen(majorBrush, 2.0);

            // Background ring (outer circle)
            dc.DrawEllipse(null, ringPen, new Point(cx, cy), rOuter, rOuter);
            dc.DrawEllipse(null, new Pen(ringBrush, 0.5), new Point(cx, cy), rInner, rInner);

            // Tick marks and labels
            var labelTypeface = new Typeface("Segoe UI");
            double dpi = VisualTreeHelper.GetDpi(this).PixelsPerDip;

            for (int deg = 0; deg < 360; deg += 5)
            {
                bool isMajor = (deg % 45 == 0);
                double rad = deg * Math.PI / 180.0;
                double sinA = Math.Sin(rad);
                double cosA = Math.Cos(rad);

                double oR = rTickOut;
                double iR = isMajor ? rMajorIn : rMinorIn;
                var p1 = new Point(cx + oR * sinA, cy - oR * cosA);
                var p2 = new Point(cx + iR * sinA, cy - iR * cosA);
                dc.DrawLine(isMajor ? majorPen : minorPen, p1, p2);

                if (isMajor)
                {
                    string label = deg.ToString(CultureInfo.InvariantCulture);
                    var ft = new FormattedText(label, CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
                        labelTypeface, 10, majorBrush, dpi);
                    var labelPt = new Point(
                        cx + rLabel * sinA - ft.Width / 2,
                        cy - rLabel * cosA - ft.Height / 2);
                    dc.DrawText(ft, labelPt);
                }
            }

            // Ghost / secondary thumb
            if (SecondaryAngle.HasValue)
                DrawThumb(dc, cx, cy, SecondaryAngle.Value, rThumbTip, rThumbBase, thumbHalf, ghostFill, null);

            // Target thumb (outline + thin fill)
            if (TargetAngle.HasValue)
            {
                var targetOutline = new Pen(targetFill, 1.5);
                DrawThumb(dc, cx, cy, TargetAngle.Value, rThumbTip + halfS * 0.03, rThumbBase - halfS * 0.03, thumbHalf * 1.3, null, targetOutline);
            }

            // Primary thumb (filled)
            DrawThumb(dc, cx, cy, PrimaryAngle, rThumbTip, rThumbBase, thumbHalf, primaryFill, null);

            // Centre readout
            string centre = $"{PrimaryAngle:F1}°";
            var cft = new FormattedText(centre, CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
                new Typeface("Consolas"), 14, primaryFill, dpi);
            dc.DrawText(cft, new Point(cx - cft.Width / 2, cy - cft.Height / 2));

            // Mode label (tiny)
            string modeLabel = IsRunningMode ? "PSG" : "MAN";
            var mft = new FormattedText(modeLabel, CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
                new Typeface("Segoe UI"), 9, tickBrush, dpi);
            dc.DrawText(mft, new Point(cx - mft.Width / 2, cy + 12));
        }

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

        /// <summary>Draws an inward-pointing triangle thumb at the given dial angle.</summary>
        private static void DrawThumb(
            DrawingContext dc, double cx, double cy,
            double angleDeg, double tipR, double baseR, double halfWidth,
            Brush? fill, Pen? outline)
        {
            double rad    = angleDeg * Math.PI / 180.0;
            double sinA   = Math.Sin(rad);
            double cosA   = Math.Cos(rad);
            double perpSin = Math.Sin(rad + Math.PI / 2.0);
            double perpCos = Math.Cos(rad + Math.PI / 2.0);

            var tip   = new Point(cx + tipR  * sinA, cy - tipR  * cosA);
            var left  = new Point(cx + baseR * sinA + halfWidth * perpSin,
                                  cy - baseR * cosA - halfWidth * perpCos);
            var right = new Point(cx + baseR * sinA - halfWidth * perpSin,
                                  cy - baseR * cosA + halfWidth * perpCos);

            var geo = new StreamGeometry();
            using (var ctx = geo.Open())
            {
                ctx.BeginFigure(tip, true, true);
                ctx.LineTo(left,  true, false);
                ctx.LineTo(right, true, false);
            }
            geo.Freeze();
            dc.DrawGeometry(fill, outline, geo);
        }

        /// <summary>Resolves a WPF-UI theme brush by key with a safe fallback.</summary>
        private Brush GetThemeBrush(string key, Brush fallback)
            => TryFindResource(key) as Brush ?? fallback;
    }
}