using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Media;
using DesktopBot.ViewModels;

namespace DesktopBot.Controls
{
    /// <summary>
    /// Line chart WPF nativo (nessuna dipendenza esterna).
    /// Legge una <see cref="System.Collections.ObjectModel.ObservableCollection{PricePoint}"/>
    /// e ridisegna automaticamente ad ogni variazione.
    /// </summary>
    public class PriceLineChart : FrameworkElement
    {
        // ── Dependency Properties ────────────────────────────────────────────

        public static readonly DependencyProperty PriceDataProperty =
            DependencyProperty.Register(
                nameof(PriceData),
                typeof(IEnumerable<PricePoint>),
                typeof(PriceLineChart),
                new FrameworkPropertyMetadata(null,
                    FrameworkPropertyMetadataOptions.AffectsRender,
                    OnPriceDataChanged));

        public IEnumerable<PricePoint> PriceData
        {
            get => (IEnumerable<PricePoint>)GetValue(PriceDataProperty);
            set => SetValue(PriceDataProperty, value);
        }

        public static readonly DependencyProperty LineColorProperty =
            DependencyProperty.Register(
                nameof(LineColor), typeof(Color), typeof(PriceLineChart),
                new FrameworkPropertyMetadata(Colors.LimeGreen,
                    FrameworkPropertyMetadataOptions.AffectsRender));

        public Color LineColor
        {
            get => (Color)GetValue(LineColorProperty);
            set => SetValue(LineColorProperty, value);
        }

        // ── Osserva notifiche della collection ──────────────────────────────

        private static void OnPriceDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var chart = (PriceLineChart)d;

            if (e.OldValue is INotifyCollectionChanged oldCol)
                oldCol.CollectionChanged -= chart.OnCollectionChanged;

            if (e.NewValue is INotifyCollectionChanged newCol)
                newCol.CollectionChanged += chart.OnCollectionChanged;

            chart.InvalidateVisual();
        }

        private void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
            => InvalidateVisual();

        // ── Rendering ───────────────────────────────────────────────────────

        protected override void OnRender(DrawingContext dc)
        {
            double w = ActualWidth;
            double h = ActualHeight;
            if (w < 10 || h < 10) return;

            // Sfondo
            dc.DrawRectangle(new SolidColorBrush(Color.FromRgb(0x0E, 0x0E, 0x14)),
                             null, new Rect(0, 0, w, h));

            var points = PriceData?.OfType<PricePoint>().ToList();
            if (points == null || points.Count < 2)
            {
                DrawNoData(dc, w, h);
                return;
            }

            const double padLeft   = 72;
            const double padRight  = 76;   // spazio per la label del prezzo corrente
            const double padTop    = 16;
            const double padBottom = 32;

            double chartW = w - padLeft - padRight;
            double chartH = h - padTop  - padBottom;

            decimal minP = points.Min(p => p.Price);
            decimal maxP = points.Max(p => p.Price);
            decimal range = maxP - minP;
            if (range == 0) range = maxP * 0.01m;

            // Griglia orizzontale (5 linee)
            var gridPen = new Pen(new SolidColorBrush(Color.FromArgb(40, 255, 255, 255)), 1);
            gridPen.Freeze();
            for (int i = 0; i <= 4; i++)
            {
                double y = padTop + chartH * i / 4.0;
                dc.DrawLine(gridPen,
                    new Point(padLeft, y),
                    new Point(padLeft + chartW, y));

                decimal price = maxP - range * (decimal)(i / 4.0);
                DrawLabel(dc, price.ToString("N0"), padLeft - 6, y,
                    Color.FromRgb(0x88, 0x88, 0x99), 9, TextAlignment.Right);
            }

            // Curva prezzi con fill gradiente
            var geometry = new StreamGeometry();
            using (var ctx = geometry.Open())
            {
                for (int i = 0; i < points.Count; i++)
                {
                    double x = padLeft + chartW * i / (double)(points.Count - 1);
                    double y = padTop  + chartH * (double)((maxP - points[i].Price) / range);
                    if (i == 0) ctx.BeginFigure(new Point(x, y), isFilled: false, isClosed: false);
                    else        ctx.LineTo(new Point(x, y), isStroked: true, isSmoothJoin: true);
                }
            }
            geometry.Freeze();

            // Fill sotto la curva
            var fillGeometry = new StreamGeometry();
            using (var ctx = fillGeometry.Open())
            {
                double x0 = padLeft;
                double xN = padLeft + chartW;
                double yBase = padTop + chartH;

                ctx.BeginFigure(new Point(x0, yBase), isFilled: true, isClosed: true);
                for (int i = 0; i < points.Count; i++)
                {
                    double x = padLeft + chartW * i / (double)(points.Count - 1);
                    double y = padTop  + chartH * (double)((maxP - points[i].Price) / range);
                    ctx.LineTo(new Point(x, y), isStroked: false, isSmoothJoin: true);
                }
                ctx.LineTo(new Point(xN, yBase), isStroked: false, isSmoothJoin: false);
            }
            fillGeometry.Freeze();

            var fillBrush = new LinearGradientBrush(
                Color.FromArgb(80, LineColor.R, LineColor.G, LineColor.B),
                Color.FromArgb(0,  LineColor.R, LineColor.G, LineColor.B),
                new Point(0, 0), new Point(0, 1));
            fillBrush.Freeze();
            dc.DrawGeometry(fillBrush, null, fillGeometry);

            var linePen = new Pen(new SolidColorBrush(LineColor), 1.8);
            linePen.Freeze();
            dc.DrawGeometry(null, linePen, geometry);

            // Dot sul prezzo corrente (ultimo punto)
            var last = points.Last();
            double lx = padLeft + chartW;
            double ly = padTop + chartH * (double)((maxP - last.Price) / range);
            var dotBrush = new SolidColorBrush(LineColor);
            dotBrush.Freeze();
            dc.DrawEllipse(dotBrush, null, new Point(lx, ly), 4, 4);

            // Label prezzo corrente: disegnata a destra del dot, dentro padRight
            // Sfondo scuro per leggibilità sul gradiente
            var priceText = last.Price.ToString("N2");
            var priceTf = new FormattedText(
                priceText,
                System.Globalization.CultureInfo.CurrentCulture,
                FlowDirection.LeftToRight,
                new Typeface("Consolas"),
                10,
                new SolidColorBrush(LineColor),
                VisualTreeHelper.GetDpi(new DrawingVisual()).PixelsPerDip);
            double labelX = lx + 6;
            double labelY = ly - priceTf.Height / 2;
            // Sfondo pill
            var bgRect = new Rect(labelX - 2, labelY - 1, priceTf.Width + 4, priceTf.Height + 2);
            dc.DrawRectangle(new SolidColorBrush(Color.FromRgb(0x0E, 0x0E, 0x14)), null, bgRect);
            dc.DrawText(priceTf, new Point(labelX, labelY));

            // Etichette asse X (prime e ultime)
            if (points.Count >= 2)
            {
                DrawLabel(dc, points.First().Timestamp.ToString("HH:mm"),
                    padLeft, padTop + chartH + 6, Color.FromRgb(0x66, 0x66, 0x77), 9, TextAlignment.Left);
                DrawLabel(dc, points.Last().Timestamp.ToString("HH:mm"),
                    padLeft + chartW, padTop + chartH + 6, Color.FromRgb(0x66, 0x66, 0x77), 9, TextAlignment.Right);
            }
        }

        private static void DrawNoData(DrawingContext dc, double w, double h)
        {
            var tf = new FormattedText(
                "In attesa dei dati...",
                CultureInfo.CurrentCulture,
                FlowDirection.LeftToRight,
                new Typeface("Segoe UI"),
                13,
                new SolidColorBrush(Color.FromRgb(0x55, 0x55, 0x66)),
                VisualTreeHelper.GetDpi(new DrawingVisual()).PixelsPerDip);
            dc.DrawText(tf, new Point((w - tf.Width) / 2, (h - tf.Height) / 2));
        }

        private static void DrawLabel(DrawingContext dc, string text,
            double x, double y, Color color, double size, TextAlignment align)
        {
            var tf = new FormattedText(
                text,
                CultureInfo.CurrentCulture,
                FlowDirection.LeftToRight,
                new Typeface("Consolas"),
                size,
                new SolidColorBrush(color),
                VisualTreeHelper.GetDpi(new DrawingVisual()).PixelsPerDip);
            tf.TextAlignment = align;
            dc.DrawText(tf, new Point(x, y - tf.Height / 2));
        }
    }
}