using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Windows.Forms;
using OpenNest.Bending;
using OpenNest.Geometry;
using OpenNest.Math;

namespace OpenNest.Controls
{
    public class EntityView : DrawControl
    {
        public List<Entity> Entities;
        public List<Bend> Bends = new List<Bend>();
        public int SelectedBendIndex = -1;

        private HashSet<Entity> simplifierHighlightSet;

        public List<Entity> SimplifierHighlight
        {
            get => simplifierHighlightSet?.ToList();
            set => simplifierHighlightSet = value != null ? new HashSet<Entity>(value) : null;
        }

        public Arc SimplifierPreview { get; set; }
        public List<Entity> SimplifierToleranceLeft { get; set; }
        public List<Entity> SimplifierToleranceRight { get; set; }
        public List<Entity> OriginalEntities { get; set; }
        public bool ShowEntityLabels { get; set; }
        public List<CadText> Texts { get; set; } = new List<CadText>();

        private readonly Pen gridPen = new Pen(Color.FromArgb(70, 70, 70));
        private readonly Dictionary<int, Pen> penCache = new Dictionary<int, Pen>();
        private readonly Font labelFont = new Font("Segoe UI", 7f);
        private readonly SolidBrush labelBrush = new SolidBrush(Color.FromArgb(220, 255, 255, 200));
        private readonly SolidBrush labelBackBrush = new SolidBrush(Color.FromArgb(33, 40, 48));
        private readonly SolidBrush textBrush = new SolidBrush(Color.FromArgb(180, 200, 200, 200));

        public event EventHandler<Line> LinePicked;
        public event EventHandler PickCancelled;
        public event EventHandler<CadText> TextConvertRequested;

        private bool isPickingBendLine;
        public bool IsPickingBendLine
        {
            get => isPickingBendLine;
            set
            {
                isPickingBendLine = value;
                Cursor = value ? Cursors.Hand : Cursors.Cross;
            }
        }

        public EntityView()
        {
            Entities = new List<Entity>();

            this.BackColor = Color.FromArgb(33, 40, 48);
            this.Cursor = Cursors.Cross;

            SetStyle(
                ControlStyles.AllPaintingInWmPaint
                    | ControlStyles.OptimizedDoubleBuffer
                    | ControlStyles.UserPaint,
                true
            );
        }

        protected override void OnMouseClick(MouseEventArgs e)
        {
            base.OnMouseClick(e);
            if (!Focused)
                Focus();

            if (IsPickingBendLine && e.Button == MouseButtons.Left)
            {
                var line = HitTestLine(e.Location);
                if (line != null)
                    LinePicked?.Invoke(this, line);
            }

            if (e.Button == MouseButtons.Right)
            {
                var text = HitTestText(e.Location);
                if (text != null)
                    ShowTextContextMenu(text, e.Location);
            }
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            e.Graphics.SmoothingMode = SmoothingMode.HighSpeed;
            e.Graphics.DrawLine(gridPen, origin.X, 0, origin.X, Height);
            e.Graphics.DrawLine(gridPen, 0, origin.Y, Width, origin.Y);

            e.Graphics.TranslateTransform(origin.X, origin.Y);

            // Draw original geometry overlay (faded, behind current)
            if (OriginalEntities != null)
            {
                using var origPen = new Pen(Color.FromArgb(50, 255, 140, 40));
                foreach (var entity in OriginalEntities)
                {
                    if (!IsEtchLayer(entity.Layer))
                        DrawEntity(e.Graphics, entity, origPen);
                }
            }

            foreach (var entity in Entities)
            {
                if (IsEtchLayer(entity.Layer))
                    continue;
                var isHighlighted =
                    simplifierHighlightSet != null && simplifierHighlightSet.Contains(entity);
                var pen = isHighlighted
                    ? GetEntityPen(Color.FromArgb(60, entity.Color))
                    : GetEntityPen(entity.Color);
                DrawEntity(e.Graphics, entity, pen);
            }

            DrawBendLines(e.Graphics);

            foreach (var entity in Entities)
            {
                if (!IsEtchLayer(entity.Layer))
                    continue;
                var pen = GetEntityPen(entity.Color);
                DrawEntity(e.Graphics, entity, pen);
            }

            DrawTexts(e.Graphics);

            if (ShowEntityLabels)
                DrawEntityLabels(e.Graphics);

            if (SimplifierPreview != null)
            {
                // Draw tolerance zone (offset lines each side of original geometry)
                if (SimplifierToleranceLeft != null)
                {
                    using var zonePen = new Pen(Color.FromArgb(40, 100, 200, 100));
                    foreach (var entity in SimplifierToleranceLeft)
                        DrawEntity(e.Graphics, entity, zonePen);
                    foreach (var entity in SimplifierToleranceRight)
                        DrawEntity(e.Graphics, entity, zonePen);
                }

                // Draw old geometry (highlighted lines) in orange dashed
                if (simplifierHighlightSet != null)
                {
                    using var oldPen = new Pen(Color.FromArgb(180, 255, 160, 50), 1f / ViewScale)
                    {
                        DashPattern = new float[] { 6, 3 },
                    };
                    foreach (var entity in simplifierHighlightSet)
                        DrawEntity(e.Graphics, entity, oldPen);
                }

                // Draw the new arc in bright green
                using var previewPen = new Pen(Color.FromArgb(0, 200, 80), 2f / ViewScale);
                DrawArc(e.Graphics, SimplifierPreview, previewPen);
            }

            PaintOverlay?.Invoke(e.Graphics);
        }

        public Action<Graphics> PaintOverlay { get; set; }

        protected override void OnMouseWheel(MouseEventArgs e)
        {
            base.OnMouseWheel(e);

            float multiplier = System.Math.Abs(e.Delta / 120.0f);

            if (e.Delta > 0)
                ZoomToControlPoint(e.Location, (float)System.Math.Pow(ZoomInFactor, multiplier));
            else
                ZoomToControlPoint(e.Location, (float)System.Math.Pow(ZoomOutFactor, multiplier));

            Invalidate();
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Middle)
            {
                var diffx = e.X - lastPoint.X;
                var diffy = e.Y - lastPoint.Y;

                origin.X += diffx;
                origin.Y += diffy;

                Invalidate();
            }
            else
            {
                LastPoint = CurrentPoint;
                CurrentPoint = PointControlToWorld(e.Location);
            }

            lastPoint = e.Location;

            base.OnMouseMove(e);
        }

        protected override void OnMouseDoubleClick(MouseEventArgs e)
        {
            base.OnMouseDoubleClick(e);

            if (e.Button == MouseButtons.Middle)
                ZoomToFit();
        }

        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);

            if (e.KeyCode == Keys.F)
                ZoomToFit();

            if (IsPickingBendLine && e.KeyCode == Keys.Escape)
            {
                IsPickingBendLine = false;
                PickCancelled?.Invoke(this, EventArgs.Empty);
            }
        }

        private Pen GetEntityPen(Color color)
        {
            if (color.IsEmpty || color.A == 0)
                color = Color.White;

            // Clamp dark colors to ensure visibility on dark background
            var brightness = (color.R * 299 + color.G * 587 + color.B * 114) / 1000;
            if (brightness < 80)
                color = Color.FromArgb(
                    color.A,
                    System.Math.Max(color.R, (byte)80),
                    System.Math.Max(color.G, (byte)80),
                    System.Math.Max(color.B, (byte)80)
                );

            var argb = color.ToArgb();
            if (!penCache.TryGetValue(argb, out var pen))
            {
                pen = new Pen(color);
                penCache[argb] = pen;
            }
            return pen;
        }

        public void ClearPenCache()
        {
            foreach (var pen in penCache.Values)
                pen.Dispose();
            penCache.Clear();
        }

        private static bool IsEtchLayer(Layer layer) =>
            string.Equals(layer?.Name, "ETCH", System.StringComparison.OrdinalIgnoreCase);

        private void DrawBendLines(Graphics g)
        {
            if (Bends == null || Bends.Count == 0)
                return;

            using var bendPen = new Pen(Color.Yellow, 1.5f) { DashPattern = new float[] { 8, 6 } };
            using var glowPen = new Pen(Color.OrangeRed, 2.0f)
            {
                DashPattern = new float[] { 6, 4 },
            };
            using var noteFont = new Font("Segoe UI", 9f);
            using var noteBrush = new SolidBrush(Color.FromArgb(220, 255, 255, 200));
            using var selectedNoteBrush = new SolidBrush(Color.FromArgb(220, 255, 180, 100));

            for (var i = 0; i < Bends.Count; i++)
            {
                var bend = Bends[i];
                var pt1 = PointWorldToGraph(bend.StartPoint);
                var pt2 = PointWorldToGraph(bend.EndPoint);
                var isSelected = i == SelectedBendIndex;

                if (isSelected)
                    g.DrawLine(glowPen, pt1, pt2);
                else
                    g.DrawLine(bendPen, pt1, pt2);

                if (!string.IsNullOrEmpty(bend.NoteText))
                {
                    var mid = new PointF((pt1.X + pt2.X) / 2f, (pt1.Y + pt2.Y) / 2f);
                    var angle = (float)(
                        System.Math.Atan2(pt2.Y - pt1.Y, pt2.X - pt1.X) * 180.0 / System.Math.PI
                    );

                    // Keep text readable (not upside-down)
                    if (angle > 90f)
                        angle -= 180f;
                    else if (angle < -90f)
                        angle += 180f;

                    var textSize = g.MeasureString(bend.NoteText, noteFont);
                    var state = g.Save();
                    g.TranslateTransform(mid.X, mid.Y);
                    g.RotateTransform(angle);
                    g.DrawString(
                        bend.NoteText,
                        noteFont,
                        isSelected ? selectedNoteBrush : noteBrush,
                        -textSize.Width / 2f,
                        -textSize.Height
                    );
                    g.Restore(state);
                }
            }
        }

        private Line HitTestLine(Point controlPoint)
        {
            var worldPoint = PointControlToWorld(controlPoint);
            var tolerance = LengthGuiToWorld(6);
            Line bestLine = null;
            var bestDistance = double.MaxValue;

            foreach (var entity in Entities)
            {
                if (entity.Type != EntityType.Line || !entity.IsVisible)
                    continue;

                var line = (Line)entity;
                var closest = line.ClosestPointTo(worldPoint);
                var distance = worldPoint.DistanceTo(closest);

                if (distance < tolerance && distance < bestDistance)
                {
                    bestLine = line;
                    bestDistance = distance;
                }
            }

            return bestLine;
        }

        private CadText HitTestText(Point controlPoint)
        {
            if (Texts == null || Texts.Count == 0)
                return null;

            var worldPoint = PointControlToWorld(controlPoint);
            var tolerance = LengthGuiToWorld(8);

            foreach (var text in Texts)
            {
                if (string.IsNullOrEmpty(text.Value) || text.IsReplacedByBendNote(Bends))
                    continue;

                var estimatedWidth = text.Height * text.Value.Length * 0.6;
                var minX = text.Position.X - tolerance;
                var maxX = text.Position.X + estimatedWidth + tolerance;
                var minY = text.Position.Y - tolerance;
                var maxY = text.Position.Y + text.Height + tolerance;

                if (
                    worldPoint.X >= minX
                    && worldPoint.X <= maxX
                    && worldPoint.Y >= minY
                    && worldPoint.Y <= maxY
                )
                    return text;
            }

            return null;
        }

        private void ShowTextContextMenu(CadText text, Point location)
        {
            var menu = new ContextMenuStrip();
            var item = menu.Items.Add($"Convert \"{text.Value}\" to Geometry");
            item.Click += (s, e) => TextConvertRequested?.Invoke(this, text);
            menu.Show(this, location);
        }

        private void DrawEntityLabels(Graphics g)
        {
            for (var i = 0; i < Entities.Count; i++)
            {
                var entity = Entities[i];
                if (!entity.Layer.IsVisible || !entity.IsVisible)
                    continue;

                var mid = GetEntityMidPoint(entity, i);
                if (!mid.HasValue)
                    continue;

                var screenExtent = GetEntityScreenExtent(entity);
                var text = i.ToString();
                var size = g.MeasureString(text, labelFont);
                var radius = System.Math.Max(size.Width, size.Height) / 2f + 2f;

                // Hide label when the entity is too small on screen to fit it
                if (screenExtent < radius * 2f)
                    continue;

                var pt = PointWorldToGraph(mid.Value);
                var cx = pt.X - size.Width / 2f;
                var cy = pt.Y - size.Height / 2f;
                g.FillEllipse(
                    labelBackBrush,
                    pt.X - radius,
                    pt.Y - radius,
                    radius * 2f,
                    radius * 2f
                );
                g.DrawString(text, labelFont, labelBrush, cx, cy);
            }
        }

        private float GetEntityScreenExtent(Entity entity)
        {
            switch (entity)
            {
                case Line line:
                    var dx = line.EndPoint.X - line.StartPoint.X;
                    var dy = line.EndPoint.Y - line.StartPoint.Y;
                    return LengthWorldToGui(System.Math.Sqrt(dx * dx + dy * dy));

                case Arc arc:
                    return LengthWorldToGui(arc.Radius * 2.0);

                case Circle circle:
                    return LengthWorldToGui(circle.Radius * 2.0);

                default:
                    return 0f;
            }
        }

        private static Vector? GetEntityMidPoint(Entity entity, int index)
        {
            switch (entity)
            {
                case Line line:
                    return line.MidPoint;

                case Arc arc:
                    var midAngle = arc.IsReversed
                        ? arc.StartAngle - arc.SweepAngle() / 2.0
                        : arc.StartAngle + arc.SweepAngle() / 2.0;
                    return new Vector(
                        arc.Center.X + arc.Radius * System.Math.Cos(midAngle),
                        arc.Center.Y + arc.Radius * System.Math.Sin(midAngle)
                    );

                case Circle circle:
                    // Use golden angle (~137.5°) per index so concentric circles spread labels apart
                    var circleAngle = index * 2.399;
                    return new Vector(
                        circle.Center.X + circle.Radius * System.Math.Cos(circleAngle),
                        circle.Center.Y + circle.Radius * System.Math.Sin(circleAngle)
                    );

                default:
                    return null;
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                ClearPenCache();
                gridPen.Dispose();
                labelFont.Dispose();
                labelBrush.Dispose();
                labelBackBrush.Dispose();
                textBrush.Dispose();
            }
            base.Dispose(disposing);
        }

        private void DrawEntity(Graphics g, Entity e, Pen pen)
        {
            if (!e.Layer.IsVisible || !e.IsVisible)
                return;

            switch (e.Type)
            {
                case EntityType.Arc:
                    DrawArc(g, (Arc)e, pen);
                    break;

                case EntityType.Circle:
                    DrawCircle(g, (Circle)e, pen);
                    break;

                case EntityType.Line:
                    DrawLine(g, (Line)e, pen);
                    break;
            }
        }

        private void DrawLine(Graphics g, Line line, Pen pen)
        {
            var pt1 = PointWorldToGraph(line.StartPoint);
            var pt2 = PointWorldToGraph(line.EndPoint);

            g.DrawLine(pen, pt1, pt2);
        }

        private void DrawArc(Graphics g, Arc arc, Pen pen)
        {
            var center = PointWorldToGraph(arc.Center);
            var radius = LengthWorldToGui(arc.Radius);
            var diameter = radius * 2.0f;

            var startAngle = arc.IsReversed
                ? -(float)Angle.ToDegrees(arc.EndAngle)
                : -(float)Angle.ToDegrees(arc.StartAngle);

            g.DrawArc(
                pen,
                center.X - radius,
                center.Y - radius,
                diameter,
                diameter,
                startAngle,
                -(float)Angle.ToDegrees(arc.SweepAngle())
            );
        }

        private void DrawCircle(Graphics g, Circle circle, Pen pen)
        {
            var center = PointWorldToGraph(circle.Center);
            var radius = LengthWorldToGui(circle.Radius);
            var diameter = radius * 2.0f;

            g.DrawEllipse(pen, center.X - radius, center.Y - radius, diameter, diameter);
        }

        private void DrawTexts(Graphics g)
        {
            if (Texts == null || Texts.Count == 0)
                return;

            using var sf = new StringFormat();

            foreach (var text in Texts)
            {
                // The bend overlay already renders this source annotation.
                if (text.IsReplacedByBendNote(Bends))
                    continue;

                var pos = PointWorldToGraph(text.Position);
                var fontSize = LengthWorldToGui(text.Height);
                if (fontSize < 2f)
                    continue;

                var state = g.Save();
                g.TranslateTransform(pos.X, pos.Y);

                if (text.Rotation != 0)
                    g.RotateTransform((float)OpenNest.Math.Angle.ToDegrees(text.Rotation));

                sf.Alignment = text.HAlign;
                sf.LineAlignment = text.VAlign;

                using var font = new Font("Segoe UI", fontSize, GraphicsUnit.Pixel);
                g.DrawString(text.Value, font, textBrush, 0, 0, sf);
                g.Restore(state);
            }
        }

        private void DrawPoint(Graphics g, Vector pt, Pen pen)
        {
            var pt1 = PointWorldToGraph(pt);

            g.DrawLine(pen, pt1.X - 3, pt1.Y, pt1.X + 3, pt1.Y);
            g.DrawLine(pen, pt1.X, pt1.Y - 3, pt1.X, pt1.Y + 3);
        }

        private void DrawPoint(Graphics g, Vector pt, Pen pen, Brush fillBrush)
        {
            var pt1 = PointWorldToGraph(pt);
            var rect = new RectangleF(pt1.X - 3, pt1.Y - 3, 6, 6);

            g.FillEllipse(fillBrush, rect);
            g.DrawEllipse(pen, rect);
        }

        private void DrawIntersections(Graphics g)
        {
            for (int i = 0; i < Entities.Count; ++i)
            {
                var entity1 = Entities[i];

                if (entity1.Type != EntityType.Line)
                    continue;

                for (int j = i + 1; j < Entities.Count; ++j)
                {
                    var entity2 = Entities[j];

                    if (entity2.Type != EntityType.Line)
                        continue;

                    var line1 = (Line)entity1;
                    var line2 = (Line)entity2;

                    Vector pt;

                    if (line1.Intersects(line2, out pt))
                        DrawPoint(g, pt, Pens.Yellow, Brushes.Red);
                }
            }
        }

        public void ClearSimplifierPreview()
        {
            SimplifierHighlight = null;
            SimplifierPreview = null;
            SimplifierToleranceLeft = null;
            SimplifierToleranceRight = null;
            Invalidate();
        }

        public void ZoomToFit(bool redraw = true)
        {
            ZoomToArea(Entities.GetBoundingBox(), redraw);
        }
    }
}