using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

using CodeImp.DoomBuilder.Editing;
using CodeImp.DoomBuilder.Rendering;
using CodeImp.DoomBuilder.Geometry;
using CodeImp.DoomBuilder.Actions;
using CodeImp.DoomBuilder.Windows;
using CodeImp.DoomBuilder.Map;
using CodeImp.DoomBuilder.Plugins;

using CodeImp.DoomBuilder.BuilderModes.Interface;

namespace CodeImp.DoomBuilder.BuilderModes.ClassicModes {
    [EditMode(DisplayName = "Bridge Mode",
              SwitchAction = "bridgemode",
              ButtonImage = "BridgeMode.png",
              ButtonOrder = 51,
              ButtonGroup = "002_tools",
              AllowCopyPaste = false,
              Volatile = true,
              Optional = false)]

    public class BridgeMode : BaseClassicMode {
        private const float GRIP_SIZE = 9.0f;
        private const float LINE_THICKNESS = 0.8f;
        
        internal static int MAX_SUBDIVISIONS = 32;
        internal static int MIN_SUBDIVISIONS = 0;

        protected string undoName = "Bridge draw";
        protected string shapeName = "mesh";

        private Vector2D[] pointGroup1;
        private Vector2D[] pointGroup2;

        private SectorProperties[] sectorProps1;
        private SectorProperties[] sectorProps2;

        private float[] relLenGroup1;
        private float[] relLenGroup2;

        private ControlHandle[] controlHandles;
        private int curControlHandle = -1;

        private PixelColor handleColor;

        private List<Vector2D[]> curves;
        private int segmentsCount;

        // Options
        protected bool snaptogrid; // SHIFT to toggle

        //tools form
        private BridgeModeForm form;

        public BridgeMode() {
            // We have no destructor
            GC.SuppressFinalize(this);
        }

        // Engaging
        public override void OnEngage() {
            base.OnEngage();

            renderer.SetPresentation(Presentation.Standard);
            
            //check selection
            ICollection<Linedef> selection = General.Map.Map.GetSelectedLinedefs(true);

            List<Line> lines = new List<Line>();
            foreach (Linedef ld in selection) {
                Line l = new Line(ld);
                lines.Add(l);
            }

            //do we have valid selection?
            if (!setup(lines)) {
                FinishDraw();
                return;
            }

            //show form
            form = new BridgeModeForm();
            form.OnCancelClick += new EventHandler(form_OnCancelClick);
            form.OnOkClick += new EventHandler(form_OnOkClick);
            form.OnFlipClick += new EventHandler(form_OnFlipClick);
            form.OnSubdivisionChanged += new EventHandler(form_OnSubdivisionChanged);
            form.Show(Form.ActiveForm);
            General.Interface.FocusDisplay();

            handleColor = General.Colors.BrightColors[new Random().Next(General.Colors.BrightColors.Length - 1)];
            update();
        }

        // When select button is pressed
        protected override void OnSelectBegin() {
            base.OnSelectBegin();

            //check if control handle is selected
            for (int i = 0; i < 4; i++) {
                if (mousemappos.x <= controlHandles[i].Position.x + GRIP_SIZE && mousemappos.x >= controlHandles[i].Position.x - GRIP_SIZE && mousemappos.y <= controlHandles[i].Position.y + GRIP_SIZE && mousemappos.y >= controlHandles[i].Position.y - GRIP_SIZE) {
                    curControlHandle = i;
                    General.Interface.SetCursor(Cursors.Cross);
                    return;
                }
            }
            curControlHandle = -1;
        }

        // When select button is released
        protected override void OnSelectEnd() {
            base.OnSelectEnd();
            General.Interface.SetCursor(Cursors.Default);
            curControlHandle = -1;
        }

        // Mouse moves
        public override void OnMouseMove(MouseEventArgs e) {
            base.OnMouseMove(e);

            if (curControlHandle != -1) {
                ControlHandle handle = controlHandles[curControlHandle];
                
                if (snaptogrid) {
                    handle.Position = DrawGeometryMode.GetCurrentPosition(mousemappos, false, true, renderer, new List<DrawnVertex>()).pos;
                } else {
                    handle.Position = mousemappos;
                }

                if (form.MirrorMode) {
                    Vector2D pos = handle.RelativePosition;
                    //handle angle
                    float angle = (float)Math.Atan2(-pos.y, -pos.x) + (float)Math.PI / 2f;
                    //angle of line, connecting handles ControlledPoints
                    float dirAngle = -(float)Math.Atan2(handle.Pair.ControlledPoint.y - handle.ControlledPoint.y, handle.Pair.ControlledPoint.x - handle.ControlledPoint.x); 
                    float length = (float)Math.Sqrt(Math.Pow(Math.Abs(pos.x), 2.0) + Math.Pow(Math.Abs(pos.y), 2.0));
                    float mirroredAngle = angle + dirAngle * 2.0f;

                    handle.Pair.RelativePosition = new Vector2D((float)Math.Sin(mirroredAngle) * length, (float)Math.Cos(mirroredAngle) * length);
                } else if (form.CopyMode) {
                    handle.Pair.RelativePosition = handle.RelativePosition;
                }    
                update();
            }
        }

        // Accepted
        public override void OnAccept() {
            Cursor.Current = Cursors.AppStarting;

            General.Settings.FindDefaultDrawSettings();

            //get vertices
            List<List<Vector2D[]>> shapes = getShapes();
            List<List<List<DrawnVertex>>> drawShapes = new List<List<List<DrawnVertex>>>();
            List<List<DrawnVertex>> shapesRow;
            List<DrawnVertex> points;

            //set stitch range
            float stitchrange = BuilderPlug.Me.StitchRange;
            BuilderPlug.Me.StitchRange = 0.1f;

            for (int i = 0; i < shapes.Count; i++) {
                shapesRow = new List<List<DrawnVertex>>();
                for (int c = 0; c < shapes[i].Count; c++) {
                    points = new List<DrawnVertex>();
                    for (int p = 0; p < shapes[i][c].Length; p++)
                        points.Add(DrawGeometryMode.GetCurrentPosition(shapes[i][c][p], true, false, renderer, points));
                    shapesRow.Add(points);
                }
                drawShapes.Add(shapesRow);
            }

            //restore stitch range
            BuilderPlug.Me.StitchRange = stitchrange;

            //draw lines
            if (drawShapes.Count > 0) {
                // Make undo for the draw
                General.Map.UndoRedo.CreateUndo("Bridge ("+form.Subdivisions+" subdivisions)");

                List<List<SectorProperties>> sectorProps = new List<List<SectorProperties>>();
                List<List<List<Sector>>> newSectors = new List<List<List<Sector>>>();
                
                //create sector properties collection
                //sector row
                for (int i = 0; i < drawShapes.Count; i++) {
                    sectorProps.Add(new List<SectorProperties>());
                    
                    //sector in row
                    for (int c = 0; c < drawShapes[i].Count; c++)
                        sectorProps[i].Add(getSectorProperties(i, c));
                }

                // Make the drawing
                //sector row
                for (int i = 0; i < drawShapes.Count; i++) {
                    newSectors.Add(new List<List<Sector>>());

                    //sector in row
                    for (int c = 0; c < drawShapes[i].Count; c++) {
                        if (!Tools.DrawLines(drawShapes[i][c])) {
                            // Drawing failed
                            // NOTE: I have to call this twice, because the first time only cancels this volatile mode
                            General.Interface.DisplayStatus(StatusType.Warning, "Failed to create a Bezier Path...");
                            General.Map.UndoRedo.WithdrawUndo();
                            General.Map.UndoRedo.WithdrawUndo();
                            return;
                        }

                        List<Sector> newsectors = General.Map.Map.GetMarkedSectors(true);
                        newSectors[i].Add(newsectors);

                        //set floor/ceiling heights and brightness
                        foreach (Sector s in newsectors) {
                            SectorProperties sp = sectorProps[i][c];
                            s.Brightness = sp.Brightness;
                            s.FloorHeight = sp.FloorHeight;
                            s.CeilHeight = (sp.CeilingHeight < sp.FloorHeight ? sp.FloorHeight + 8 : sp.CeilingHeight);
                        }
                    }
                }

                //apply textures
                //sector row
                for (int i = 0; i < newSectors.Count; i++) {
                    //sector in row
                    for (int c = 0; c < newSectors[i].Count; c++) {
                        foreach (Sector s in newSectors[i][c]) {
                            foreach(Sidedef sd in s.Sidedefs){
                                if (sd.LowRequired())
                                    sd.SetTextureLow(sectorProps[i][c].LowTexture);
                                if (sd.HighRequired())
                                    sd.SetTextureHigh(sectorProps[i][c].HighTexture);    
                            }
                        }
                    }
                }

                //apply textures to front/back sides of shape
                //sector row
                for (int i = 0; i < newSectors.Count; i++) {
                    //first/last sector in row
                    for (int c = 0; c < newSectors[i].Count; c += newSectors[i].Count-1) {
                        foreach (Sector s in newSectors[i][c]) {
                            foreach (Sidedef sd in s.Sidedefs) {
                                if (sd.Other != null) {
                                    if (sd.Other.LowRequired() && sd.Other.LowTexture == "-")
                                        sd.Other.SetTextureLow(sectorProps[i][c].LowTexture);
                                    if (sd.Other.HighRequired() && sd.Other.HighTexture == "-")
                                        sd.Other.SetTextureHigh(sectorProps[i][c].HighTexture);
                                }
                            }
                        }
                    }
                }

                General.Interface.DisplayStatus(StatusType.Action, "Created a Bridge with " + form.Subdivisions + " subdivisions.");

                // Snap to map format accuracy
                General.Map.Map.SnapAllToAccuracy();

                // Clear selection
                General.Map.Map.ClearAllSelected();

                // Update cached values
                General.Map.Map.Update();

                // Update the used textures
                General.Map.Data.UpdateUsedTextures();

                // Map is changed
                General.Map.IsChanged = true;
            }

            //close form
            if (form != null)
                form.Close();

            // Done
            Cursor.Current = Cursors.Default;

            // Return to original mode
            General.Editing.ChangeMode(General.Editing.PreviousStableMode.Name);
        }

        // Cancelled
        public override void OnCancel() {
            // Cancel base class
            base.OnCancel();

            //close form
            if (form != null)
                form.Dispose();

            // Return to original mode
            General.Editing.ChangeMode(General.Editing.PreviousStableMode.Name);
        }

        // When a key is released
        public override void OnKeyUp(KeyEventArgs e) {
            base.OnKeyUp(e);
            if (snaptogrid != (General.Interface.ShiftState ^ General.Interface.SnapToGrid)) update();
        }

        // When a key is pressed
        public override void OnKeyDown(KeyEventArgs e) {
            base.OnKeyDown(e);
            if (snaptogrid != (General.Interface.ShiftState ^ General.Interface.SnapToGrid)) update();
        }

        // This redraws the display
        public override void OnRedrawDisplay() {
            renderer.RedrawSurface();

            // Render lines
            if (renderer.StartPlotter(true)) {
                renderer.PlotLinedefSet(General.Map.Map.Linedefs);
                renderer.PlotVerticesSet(General.Map.Map.Vertices);
                renderer.Finish();
            }

            // Render things
            if (renderer.StartThings(true)) {
                renderer.RenderThingSet(General.Map.Map.Things, 1.0f);
                renderer.Finish();
            }

            // Normal update
            update();
        }

        //this checks if initial data is valid
        private bool setup(List<Line> lines) {
            if (!setupPointGroups(lines))
                return false;

            //setup control handles
            Vector2D center1 = getPointOnLine(pointGroup1[0], pointGroup1[segmentsCount - 1], 0.5f);
            Vector2D center2 = getPointOnLine(pointGroup2[0], pointGroup2[segmentsCount - 1], 0.5f);

            Vector2D loc1 = getHandleLocation(pointGroup1[0], pointGroup1[segmentsCount - 1], center2);
            Vector2D loc2 = getHandleLocation(pointGroup2[0], pointGroup2[segmentsCount - 1], center1);

            ControlHandle ch1 = new ControlHandle();
            ch1.ControlledPoint = pointGroup1[0];
            ch1.RelativePosition = loc1;

            ControlHandle ch2 = new ControlHandle();
            ch2.ControlledPoint = pointGroup2[0];
            ch2.RelativePosition = loc2;

            ControlHandle ch3 = new ControlHandle();
            ch3.ControlledPoint = pointGroup1[segmentsCount - 1];
            ch3.RelativePosition = loc1;

            ControlHandle ch4 = new ControlHandle();
            ch4.ControlledPoint = pointGroup2[segmentsCount - 1];
            ch4.RelativePosition = loc2;

            ch1.Pair = ch3;
            ch2.Pair = ch4;
            ch3.Pair = ch1;
            ch4.Pair = ch2;

            controlHandles = new ControlHandle[] {ch1, ch2, ch3, ch4};

            //setup relative segments lengths
            relLenGroup1 = getRelativeLengths(pointGroup1);
            relLenGroup2 = getRelativeLengths(pointGroup2);

            return true;
        }

        private void update() {
            if (renderer.StartOverlay(true)) {
                snaptogrid = General.Interface.ShiftState ^ General.Interface.SnapToGrid;
                
                PixelColor linesColor = snaptogrid ? General.Colors.Selection : General.Colors.Highlight;
                
                //draw curves
                Vector2D cp1, cp2;
                curves = new List<Vector2D[]>();

                for (int i = 0; i < segmentsCount; i++) {
                    cp1 = getPointOnLine(controlHandles[0].Position, controlHandles[2].Position, relLenGroup1[i]);
                    cp2 = getPointOnLine(controlHandles[1].Position, controlHandles[3].Position, relLenGroup2[i]);
                    curves.Add(getBezierCurve(pointGroup1[i], pointGroup2[i], cp1, cp2, form.Subdivisions));

                    for (int c = 1; c < curves[i].Length; c++ )
                        renderer.RenderLine(curves[i][c - 1], curves[i][c], LINE_THICKNESS, linesColor, true);
                }

                //draw connecting lines
                if (form.Subdivisions > 1) {
                    for (int i = 1; i < segmentsCount; i++) {
                        for (int c = 1; c < form.Subdivisions; c++) {
                            renderer.RenderLine(curves[i-1][c], curves[i][c], LINE_THICKNESS, linesColor, true);
                        }
                    }
                }

                //draw vertices
                float vsize = ((float)renderer.VertexSize + 1.0f) / renderer.Scale;

                foreach(Vector2D[] points in curves){
                    for (int i = 1; i < points.Length - 1; i++ ) {
                        renderer.RenderRectangleFilled(new RectangleF(points[i].x - vsize, points[i].y - vsize, vsize * 2.0f, vsize * 2.0f), linesColor, true);
                    }
                }

                //draw handle lines
                renderer.RenderLine(pointGroup1[0], controlHandles[0].Position, LINE_THICKNESS, handleColor, true);
                renderer.RenderLine(pointGroup2[0], controlHandles[1].Position, LINE_THICKNESS, handleColor, true);
                renderer.RenderLine(pointGroup1[segmentsCount - 1], controlHandles[2].Position, LINE_THICKNESS, handleColor, true);
                renderer.RenderLine(pointGroup2[segmentsCount - 1], controlHandles[3].Position, LINE_THICKNESS, handleColor, true);

                //draw handles
                float gripsize = GRIP_SIZE / renderer.Scale;

                for (int i = 0; i < 4; i++) {
                    RectangleF handleRect = new RectangleF(controlHandles[i].Position.x - gripsize * 0.5f, controlHandles[i].Position.y - gripsize * 0.5f, gripsize, gripsize);
                    renderer.RenderRectangleFilled(handleRect, General.Colors.Background, true);
                    renderer.RenderRectangle(handleRect, 2, General.Colors.Highlight, true);
                }
                renderer.Finish();
            }
            renderer.Present();
        }

        private SectorProperties getSectorProperties(int lineIndex, int sectorIndex) {
            float delta = (float)sectorIndex / (float)form.Subdivisions;
            delta += (1.0f - delta) / (float)form.Subdivisions;
            SectorProperties sp = new SectorProperties();

            sp.Brightness = intepolateValue(sectorProps1[lineIndex].Brightness, sectorProps2[lineIndex].Brightness, delta, form.BrightnessMode);
            sp.FloorHeight = intepolateValue(sectorProps1[lineIndex].FloorHeight, sectorProps2[lineIndex].FloorHeight, delta, form.FloorAlignMode);
            sp.CeilingHeight = intepolateValue(sectorProps1[lineIndex].CeilingHeight, sectorProps2[lineIndex].CeilingHeight, delta, form.CeilingAlignMode);

            //textures
            sp.LowTexture = sectorProps1[lineIndex].LowTexture != "-" ? sectorProps1[lineIndex].LowTexture : sectorProps2[lineIndex].LowTexture;
            sp.HighTexture = sectorProps1[lineIndex].HighTexture != "-" ? sectorProps1[lineIndex].HighTexture : sectorProps2[lineIndex].HighTexture;

            return sp;
        }

        //this returns a list of shapes to draw
        private List<List<Vector2D[]>> getShapes() {
            List<List<Vector2D[]>> shapes = new List<List<Vector2D[]>>();

            for (int i = 1; i < segmentsCount; i++) {
                List<Vector2D[]> segShapes = new List<Vector2D[]>();

                for (int c = 1; c <= form.Subdivisions; c++) {
                    Vector2D p0 = curves[i - 1][c - 1];
                    Vector2D p1 = curves[i - 1][c];
                    Vector2D p2 = curves[i][c];
                    Vector2D p3 = curves[i][c - 1];
                    segShapes.Add(new Vector2D[] { p0, p1, p2, p3, p0 });
                }
                shapes.Add(segShapes);
            }

            return shapes;
        }

//POINT OPS
        //this returns an array of linedef lengths relative to total segment length
        private float[] getRelativeLengths(Vector2D[] pointGroup) {
            float[] relLenGroup = new float[pointGroup.Length];
            relLenGroup[0] = 0.0f;

            //get length and angle of line, which defines the shape
            float length = getLineLength(pointGroup[0], pointGroup[segmentsCount - 1]);
            float angle = (float)Math.Atan2(pointGroup[0].y - pointGroup[segmentsCount - 1].y, pointGroup[0].x - pointGroup[segmentsCount - 1].x);

            float curAngle, diff, segLen;
            Vector2D p0, p1;

            //get relative length of every line
            for (int i = 1; i < pointGroup.Length - 1; i++) {
                p0 = pointGroup[i - 1];
                p1 = pointGroup[i];
                curAngle = (float)Math.Atan2(p0.y - p1.y, p0.x - p1.x);
                diff = (angle + (float)Math.PI) - (curAngle + (float)Math.PI);
                segLen = (int)(getLineLength(p0, p1) * Math.Cos(diff));
                relLenGroup[i] = relLenGroup[i - 1] + segLen / length;
            }

            relLenGroup[pointGroup.Length - 1] = 1.0f;

            return relLenGroup;
        }

        private float getLineLength(Vector2D p0, Vector2D p1) {
            float vx = Math.Abs(p0.x - p1.x);
            float vy = Math.Abs(p0.y - p1.y);
            return (float)Math.Sqrt(vx * vx + vy * vy);
        }

        //this returns relative handle location
        private Vector2D getHandleLocation(Vector2D start, Vector2D end, Vector2D direction) {
            float angle = -(float)Math.Atan2(start.y - end.y, start.x - end.x);
            float dirAngle = -(float)Math.Atan2(direction.y - start.y, direction.x - start.x);
            float length = (float)Math.Sqrt(Math.Pow(Math.Abs(start.x - end.x), 2.0) + Math.Pow(Math.Abs(start.y - end.y), 2.0)) * 0.3f;
            float diff = (angle + (float)Math.PI) - (dirAngle + (float)Math.PI);

            if (diff > Math.PI || (diff < 0 && diff > -Math.PI))
                angle += (float)Math.PI;

            return new Vector2D((float)(Math.Sin(angle) * length), (float)(Math.Cos(angle) * length));
        }

//LINE DRAWING
        //this returns array of Vector2D to draw 4-point bezier curve
        private Vector2D[] getBezierCurve(Vector2D p1, Vector2D p2, Vector2D cp1, Vector2D cp2, int steps) {
            if (steps < 0) return null;

            int totalSteps = steps + 1;
            Vector2D[] points = new Vector2D[totalSteps];
            float step = 1f / (float)steps;
            float curStep = 0f;
            float curStepInv, m1, m2, m3, m4;

            for (int i = 0; i < totalSteps; i++) {
                curStepInv = 1f - curStep;

                m1 = curStepInv * curStepInv * curStepInv;
                m2 = 3 * curStep * curStepInv * curStepInv;
                m3 = 3 * curStep * curStep * curStepInv;
                m4 = curStep * curStep * curStep;

                int px = (int)(m1 * p1.x + m2 * cp1.x + m3 * cp2.x + m4 * p2.x);
                int py = (int)(m1 * p1.y + m2 * cp1.y + m3 * cp2.y + m4 * p2.y);

                points[i] = new Vector2D(px, py);

                curStep += step;
            }
            return points;
        }

        //returns true if 2 lines intersect
        private bool linesIntersect(Line line1, Line line2) {
            float zn = (line2.End.y - line2.Start.y) * (line1.End.x - line1.Start.x) - (line2.End.x - line2.Start.x) * (line1.End.y - line1.Start.y);
            float ch1 = (line2.End.x - line2.Start.x) * (line1.Start.y - line2.Start.y) - (line2.End.y - line2.Start.y) * (line1.Start.x - line2.Start.x);
            float ch2 = (line1.End.x - line1.Start.x) * (line1.Start.y - line2.Start.y) - (line1.End.y - line1.Start.y) * (line1.Start.x - line2.Start.x);

            if (zn == 0) return false;

            if ((ch1 / zn <= 1 && ch1 / zn >= 0) && (ch2 / zn <= 1 && ch2 / zn >= 0))
                return true;
            return false;
        }

        //it's basically 2-point bezier curve
        private Vector2D getPointOnLine(Vector2D p1, Vector2D p2, float delta) {
            return new Vector2D((int)((1f - delta) * p1.x + delta * p2.x), (int)((1f - delta) * p1.y + delta * p2.y));
        }

//LINE SORTING
        //this gets two arrays of connected points from given lines. Returns true if all went well.
        private bool setupPointGroups(List<Line> linesList) {
            //find prev/next lines for each line
            for (int i = 0; i < linesList.Count; i++) {
                Line curLine = linesList[i];

                for (int c = 0; c < linesList.Count; c++) {
                    if (c != i) {//don't wanna play with ourselves :)
                        Line line = linesList[c];

                        //check start and end points
                        if (curLine.Start == line.Start) {
                            line.Invert();
                            curLine.Previous = line;
                        } else if (curLine.Start == line.End) {
                            curLine.Previous = line;
                        } else if (curLine.End == line.End) {
                            line.Invert();
                            curLine.Next = line;
                        } else if (curLine.End == line.Start) {
                            curLine.Next = line;
                        }
                    }
                }
            }

            List<List<Vector2D>> pointGroups = new List<List<Vector2D>>();
            List<List<Line>> sortedLines = new List<List<Line>>();

            //now find start lines
            for (int i = 0; i < linesList.Count; i++) {
                Line curLine = linesList[i];

                if (curLine.Previous == null) { //found start
                    //collect points
                    Line l = curLine;
                    List<Vector2D> points = new List<Vector2D>();
                    List<Line> lines = new List<Line>();
                    points.Add(l.Start);

                    do {
                        points.Add(l.End);
                        lines.Add(l);
                    } while ((l = l.Next) != null);

                    pointGroups.Add(points);
                    sortedLines.Add(lines);
                }
            }

            if (pointGroups.Count != 2) {
                General.Interface.DisplayStatus(StatusType.Warning, "Incorrect number of linedef groups! Expected 2, but got " + pointGroups.Count);
                return false;
            }

            if (pointGroups[0].Count != pointGroups[1].Count) {
                General.Interface.DisplayStatus(StatusType.Warning, "Linedefs groups must have equal length! Got " + pointGroups[0].Count + " in first group and " + pointGroups[1].Count + " in second.");
                return false;
            }

            //check if lines from first group intersect with lines from second group
            foreach (Line l1 in sortedLines[0]) {
                foreach (Line l2 in sortedLines[1]) {
                    if (linesIntersect(l1, l2)) {
                        General.Interface.DisplayStatus(StatusType.Warning, "One or more lines from first group intersect with one or more lines from second group!");
                        return false;
                    }
                }
            }

            //both groups count should match at this point
            segmentsCount = pointGroups[0].Count;

            //collect sector properties
            sectorProps1 = new SectorProperties[sortedLines[0].Count];
            for (int i = 0; i < sortedLines[0].Count; i++ ) {
                sectorProps1[i] = sortedLines[0][i].SectorProperties;
            }
            sectorProps2 = new SectorProperties[sortedLines[1].Count];
            for (int i = 0; i < sortedLines[1].Count; i++) {
                sectorProps2[i] = sortedLines[1][i].SectorProperties;
            }

            //check if we need to reverse one of point groups
            Line line1 = new Line(pointGroups[0][0], pointGroups[1][0]);
            Line line2 = new Line(pointGroups[0][segmentsCount - 1], pointGroups[1][segmentsCount - 1]);

            if (linesIntersect(line1, line2)) {
                pointGroups[0].Reverse();
                Array.Reverse(sectorProps1);
            }

            //fill point groups
            pointGroup1 = new Vector2D[segmentsCount];
            pointGroup2 = new Vector2D[segmentsCount];

            pointGroups[0].CopyTo(pointGroup1);
            pointGroups[1].CopyTo(pointGroup2);

            return true;
        }

//Easing functions. Based on Robert Penner's original easing equations (http://www.robertpenner.com/easing/)
        /**
		 * Easing equation function for a sinusoidal (sin(t)) easing in: accelerating from zero velocity.
		 */
        private int easeInSine(int val1, int val2, float delta) {
            float f_val1 = (float)val1;
            float f_val2 = (float)val2 - f_val1;
            return (int)(-f_val2 * Math.Cos(delta * (Math.PI / 2.0f)) + f_val2 + f_val1);
        }

        /**
		 * Easing equation function for a sinusoidal (sin(t)) easing out: decelerating from zero velocity.
		 */
        private int easeOutSine(int val1, int val2, float delta) {
            float f_val1 = (float)val1;
            float f_val2 = (float)val2;
            return (int)((f_val2 - f_val1) * Math.Sin(delta * ((float)Math.PI / 2.0f)) + f_val1);
        }

        /**
		 * Easing equation function for a sinusoidal (sin(t)) easing in/out: acceleration until halfway, then deceleration.
		 */
        private int easeInOutSine(int val1, int val2, float delta) {
            float f_val1 = (float)val1;
            float f_val2 = (float)val2;
            return (int)(-f_val2 / 2.0f * (Math.Cos(Math.PI * delta) - 1.0f) + f_val1);
        }

        private int intepolateValue(int val1, int val2, float delta, string mode) {
            switch (mode) {
                case BridgeInterpolationMode.HIGHEST:
                case BridgeInterpolationMode.BRIGHTNESS_HIGHEST:
                    return Math.Max(val1, val2);
                    break;

                case BridgeInterpolationMode.LOWEST:
                case BridgeInterpolationMode.BRIGHTNESS_LOWEST:
                    return Math.Min(val1, val2);
                    break;
                
                case BridgeInterpolationMode.LINEAR:
                    return (int)(delta * (float)val2 + (1.0f - delta) * (float)val1);
                    break;

                case BridgeInterpolationMode.IN_SINE:
                    return easeInSine(val1, val2, delta);
                    break;

                case BridgeInterpolationMode.OUT_SINE:
                    return easeOutSine(val1, val2, delta);
                    break;

                case BridgeInterpolationMode.IN_OUT_SINE:
                    return easeInOutSine(val1, val2, delta);
                    break;

                default:
                    throw new Exception("DrawBezierPathMode.intepolateValue: got unknown mode: '" + mode + "'");
                    break;
            }

            return -1;
        }

//EVENTS
        private void form_OnSubdivisionChanged(object sender, EventArgs e) {
            update();
        }

        private void form_OnOkClick(object sender, EventArgs e) {
            FinishDraw();
        }

        private void form_OnCancelClick(object sender, EventArgs e) {
            OnCancel();
        }

        private void form_OnFlipClick(object sender, EventArgs e) {
            Array.Reverse(pointGroup1);
            Array.Reverse(sectorProps1);
            
            //swap handles position
            Vector2D p = controlHandles[0].Position;
            controlHandles[0].Position = controlHandles[2].Position;
            controlHandles[2].Position = p;

            update();
        }

//ACTIONS
        // Finish drawing
        [BeginAction("finishdraw")]
        public void FinishDraw() {
            // Accept the changes
            General.Editing.AcceptMode();
        }

        [BeginAction("increasesubdivlevel")]
        private void increaseSubdivLevel() {
            if (form != null && form.Subdivisions < MAX_SUBDIVISIONS)
                form.Subdivisions++;
        }

        [BeginAction("decreasesubdivlevel")]
        private void decreaseSubdivLevel() {
            if (form != null && form.Subdivisions > MIN_SUBDIVISIONS)
                form.Subdivisions--;
        }
    }

    internal struct SectorProperties {
        public int FloorHeight;
        public int CeilingHeight;
        public int Brightness;
        public float Angle;
        public string HighTexture;
        public string LowTexture;
    }

    internal class ControlHandle
    {
        public Vector2D Position;
        public Vector2D ControlledPoint; //point, to which this handle is assigned
        public Vector2D RelativePosition {
            get {
                return new Vector2D(Position.x - ControlledPoint.x, Position.y - ControlledPoint.y);
            }
            set {
                Position = new Vector2D(ControlledPoint.x + value.x, ControlledPoint.y + value.y);
            }
        }
        public ControlHandle Pair; //second handle, to which this handle is paired
    }

    internal class Line {
        public Vector2D Start { get { return start; } }
        private Vector2D start;

        public Vector2D End { get { return end; } }
        private Vector2D end;
        
        public SectorProperties SectorProperties;

        public Line Previous;
        public Line Next;

        public Line(Linedef ld) {
            start = new Vector2D((int)ld.Start.Position.x, (int)ld.Start.Position.y);
            end = new Vector2D((int)ld.End.Position.x, (int)ld.End.Position.y);

            SectorProperties = new SectorProperties();

            SectorProperties.Angle = ld.Angle;

            if (ld.Back != null) {
                SectorProperties.CeilingHeight = ld.Back.Sector.CeilHeight;
                SectorProperties.FloorHeight = ld.Back.Sector.FloorHeight;
                SectorProperties.Brightness = ld.Back.Sector.Brightness;
                SectorProperties.HighTexture = ld.Back.HighTexture;
                SectorProperties.LowTexture = ld.Back.LowTexture;
            }else if(ld.Front != null){
                SectorProperties.CeilingHeight = ld.Front.Sector.CeilHeight;
                SectorProperties.FloorHeight = ld.Front.Sector.FloorHeight;
                SectorProperties.Brightness = ld.Front.Sector.Brightness;
                SectorProperties.HighTexture = ld.Front.HighTexture;
                SectorProperties.LowTexture = ld.Front.LowTexture;
            }else{
                SectorProperties.CeilingHeight = 128;
                SectorProperties.FloorHeight = 0;
                SectorProperties.Brightness = 192;
                SectorProperties.HighTexture = "-";
                SectorProperties.LowTexture = "-";
            }
        }

        public Line(Vector2D start, Vector2D end) {
            this.start = start;
            this.end = end;
        }

        public void Invert() {
            Vector2D s = start;
            start = end;
            end = s;
            SectorProperties.Angle *= -1;
        }
    }
}