using ScottPlot;
using SSPCTester.Devices.Interfaces;
using SSPCTester.Logic.Calculation;

namespace SSPCTester.Logic.Report;

public static class CurveImageRenderer
{
    public static byte[] RenderChannel(
        int channel,
        CurveData rising,
        CurveData falling,
        double? viewStartMs = null,
        double? viewEndMs = null,
        int width = 900,
        int height = 360)
    {
        var plot = new Plot();
        double start = viewStartMs ?? 0;
        double end = viewEndMs ?? 0;
        bool hasWindow = IsValidWindow(viewStartMs, viewEndMs);
        plot.Title(hasWindow
            ? $"CH{channel:00} ON / OFF Curve ({start:F3}-{end:F3} ms)"
            : $"CH{channel:00} ON / OFF Curve");
        plot.XLabel("t (ms)");
        plot.YLabel("V");
        plot.FigureBackground.Color = Color.FromHex("#FBFCFD");
        plot.DataBackground.Color = Color.FromHex("#FBFCFD");
        plot.Grid.MajorLineColor = Color.FromHex("#DFE4EA");

        AddCurve(plot, rising, Color.FromHex("#1A73C4"), "ON", viewStartMs, viewEndMs);
        AddCurve(plot, falling, Color.FromHex("#D23B3B"), "OFF", viewStartMs, viewEndMs);

        double vMax = CurveMetrics.EstimateVMax(rising.Voltage);
        AddThreshold(plot, vMax * 0.9, "90%");
        AddThreshold(plot, vMax * 0.1, "10%");

        if (!hasWindow || (start <= 0 && end >= 0))
        {
            var trigger = plot.Add.VerticalLine(0);
            trigger.Color = Color.FromHex("#98A1AD");
            trigger.LinePattern = LinePattern.Dotted;
            trigger.LineWidth = 1;
        }

        plot.ShowLegend();
        plot.Axes.AutoScale();
        return plot.GetImageBytes(width, height, ImageFormat.Png);
    }

    private static void AddCurve(Plot plot, CurveData curve, Color color, string label, double? viewStartMs, double? viewEndMs)
    {
        if (curve.Voltage.Length == 0) return;

        var points = BuildViewPoints(curve, viewStartMs, viewEndMs);
        if (points.Count == 0) return;

        var xs = new double[points.Count];
        var ys = new double[points.Count];
        for (int i = 0; i < points.Count; i++)
        {
            xs[i] = points[i].TimeMs;
            ys[i] = points[i].Voltage;
        }

        var signal = plot.Add.ScatterLine(xs, ys, color);
        signal.LineWidth = 2;
        signal.MarkerSize = 0;
        signal.LegendText = label;
    }

    private static List<(double TimeMs, double Voltage)> BuildViewPoints(CurveData curve, double? viewStartMs, double? viewEndMs)
    {
        var points = new List<(double TimeMs, double Voltage)>(curve.Voltage.Length);
        double start = viewStartMs ?? 0;
        double end = viewEndMs ?? 0;
        bool hasWindow = IsValidWindow(viewStartMs, viewEndMs);

        for (int i = 0; i < curve.Voltage.Length; i++)
        {
            double timeMs = (curve.TimeAt(i) - curve.TriggerTimeSec) * 1000.0;
            if (!hasWindow || (timeMs >= start && timeMs <= end))
                points.Add((timeMs, curve.Voltage[i]));
        }

        return points;
    }

    private static bool IsValidWindow(double? viewStartMs, double? viewEndMs) =>
        viewStartMs is double start && viewEndMs is double end
        && double.IsFinite(start) && double.IsFinite(end) && end > start;

    private static void AddThreshold(Plot plot, double volts, string label)
    {
        if (!double.IsFinite(volts)) return;

        var line = plot.Add.HorizontalLine(volts);
        line.Color = Color.FromHex("#98A1AD");
        line.LinePattern = LinePattern.Dashed;
        line.LineWidth = 1;
        line.LegendText = label;
    }
}