using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;

public class ShapeEditor
{
    public enum TangentMode { Linear, Continuous, Broken }

    private class Styles
    {
        public readonly GUIStyle pointNormalStyle;
        public readonly GUIStyle pointHoveredStyle;
        public readonly GUIStyle pointSelectedStyle;
        public readonly GUIStyle pointPreviewStyle;
        public readonly GUIStyle tangentNormalStyle;
        public readonly GUIStyle tangentHoveredStyle;

        public Styles()
        {
            Texture2D pointNormal = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/Editor/UI/ShapeEditor/Icon/ss_pointNormal.png");
            Texture2D pointHovered = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/Editor/UI/ShapeEditor/Icon/ss_pointHovered.png");
            Texture2D pointSelected = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/Editor/UI/ShapeEditor/Icon/ss_pointSelected.png");
            Texture2D pointPreview = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/Editor/UI/ShapeEditor/Icon/ss_pointPreview.png");
            Texture2D tangentNormal = AssetDatabase.LoadAssetAtPath<Texture2D>("Assets/Editor/UI/ShapeEditor/Icon/ss_tangentNormal.png");

            pointNormalStyle = new GUIStyle();
            pointNormalStyle.normal.background = pointNormal;
            pointNormalStyle.fixedWidth = 12f;
            pointNormalStyle.fixedHeight = 12f;

            pointHoveredStyle = new GUIStyle();
            pointHoveredStyle.normal.background = pointHovered;
            pointHoveredStyle.fixedWidth = 12f;
            pointHoveredStyle.fixedHeight = 12f;

            pointSelectedStyle = new GUIStyle();
            pointSelectedStyle.normal.background = pointSelected;
            pointSelectedStyle.fixedWidth = 12f;
            pointSelectedStyle.fixedHeight = 12f;

            pointPreviewStyle = new GUIStyle();
            pointPreviewStyle.normal.background = pointPreview;
            pointPreviewStyle.fixedWidth = 12f;
            pointPreviewStyle.fixedHeight = 12f;

            tangentNormalStyle = new GUIStyle();
            tangentNormalStyle.normal.background = tangentNormal;
            tangentNormalStyle.fixedWidth = 8f;
            tangentNormalStyle.fixedHeight = 8f;

            tangentHoveredStyle = new GUIStyle();
            tangentHoveredStyle.normal.background = pointHovered;
            tangentHoveredStyle.fixedWidth = 10f;
            tangentHoveredStyle.fixedHeight = 10f;
        }
    }

    private Styles m_Styles;
    private Styles styles
    {
        get
        {
            if (m_Styles == null)
                m_Styles = new Styles();

            return m_Styles;
        }
    }

    public Func<int, Vector3> GetPosition = i => Vector3.zero;
    public Action<int, Vector3> SetPosition = (i, p) => {};
    public Func<int, Vector3> GetLeftTangent = i => Vector3.zero;
    public Action<int, Vector3> SetLeftTangent = (i, p) => {};
    public Func<int, Vector3> GetRightTangent = i => Vector3.zero;
    public Action<int, Vector3> SetRightTangent = (i, p) => {};
    public Func<int, TangentMode> GetTangentMode = i => TangentMode.Linear;
    public Action<int, TangentMode> SetTangentMode = (i, m) => {};
    public Action<int, Vector3> InsertPointAt = (i, p) => {};
    public Action<int> RemovePointAt = i => {};
    public Func<int> GetPointCount = () => 0;
    // --- Transforms
    public Func<Vector2, Vector3> ScreenToWorld = i => i;
    public Func<Vector3, Vector2> WorldToScreen = i => i;
    public Func<Matrix4x4> LocalToWorldMatrix = () => Matrix4x4.identity;
    public Func<Vector3> GetForwardVector = () => Vector3.forward;
    public Func<Vector3> GetUpVector = () => Vector3.up;
    public Func<Vector3> GetRightVector = () => Vector3.right;
    // --- Other
    public Action Repaint = () => {};
    public Action RecordUndo = () => {};
    public Func<Vector3, Vector3> Snap = i => i;
    public Action<Bounds> Frame = b => {};
    public Func<bool> OpenEnded = () => false;
    public Func<Vector3, float> GetHandleSize;
    public Handles.CapFunction GetPointCapNormal;
    public Handles.CapFunction GetPointCapHovered;
    public Handles.CapFunction GetPointCapSelected;
    public Handles.CapFunction GetPointCapActive;
    public Handles.CapFunction GetPointCapPreview;
    public Handles.CapFunction GetTangentCapNormal;
    public Handles.CapFunction GetTangentCapHovered;
    public Handles.CapFunction GetTangentCapActive;
    // --- END

    public Texture2D lineTexture { get; set; }

    int m_ActiveEdgeIndex = -1;
    Vector3 m_SliderPosition;
    Vector3 m_ClosestPoint;
    float m_ClosestPointT;
    int m_DragPointControlId = -1;
    int m_DragEdgeControlId = -1;
    int m_DragTangentControlId = -1;
    int m_ActiveTangentPointIndex = -1;
    bool m_DragLeftTangent = false;
    int m_ActivePointIndex = -1;
    int m_HoveredPointIndex = -1;
    int m_HoveredEdgeIndex = -1;
    int m_HoveredTangentPoint = -1;
    bool m_HoveredLeftTangent = false;
    bool m_EdgePointsDirty = true;

    private List<Vector3[]> m_EdgePoints = new List<Vector3[]>();

    private static readonly Color kTangentColor = Handles.selectedColor;
    private static readonly Color kTangentColorAlternative = Handles.selectedColor;
    private const float kEdgeWidth = 2f;
    private const float kActiveEdgeWidth = 6f;
    private const int kBezierPatch = 40;

    Event currentEvent {get; set; }

    public ShapeEditor()
    {
        GetHandleSize = GetDefaultHandleSizeForPoint;
        GetPointCapNormal = PointCapNormal;
        GetPointCapHovered = PointCapHovered;
        GetPointCapSelected = PointCapSelected;
        GetPointCapActive = PointCapHovered;
        GetPointCapPreview = PointCapPreview;
        GetTangentCapNormal = TangentCapNormal;
        GetTangentCapHovered = TangentCapHovered;
        GetTangentCapActive = TangentCapHovered;
    }

    public void SetDirty()
    {
        m_EdgePointsDirty = true;
    }

    public void OnGUI()
    {
        Color currentColor = Handles.color;
        Matrix4x4 currentMatrix = Handles.matrix;
        Handles.matrix = LocalToWorldMatrix();

        currentEvent = Event.current;

        if (currentEvent.type == EventType.Layout)
        {
            if (m_DragPointControlId == -1)
                m_DragPointControlId = GUIUtility.GetControlID("DragPoint".GetHashCode(), FocusType.Passive);

            if (m_DragEdgeControlId == -1)
                m_DragEdgeControlId = GUIUtility.GetControlID("DragPoint".GetHashCode(), FocusType.Passive);

            if (m_DragTangentControlId == -1)
                m_DragTangentControlId = GUIUtility.GetControlID("DragTangent".GetHashCode(), FocusType.Passive);

            m_HoveredPointIndex = -1;
            m_HoveredEdgeIndex = -1;
            m_HoveredTangentPoint = -1;
        }

        LayoutPoints();
        LayoutTangents();
        LayoutEdges();

        DrawEdges();
        DrawPoints();
        DrawCreatePointPreview();
        DrawTangents();

        HandleDragEdge();

        HandleDragTangent();
        HandleInsertPointToEdge();
        HandleSelectPoint();
        HandleDragPoints();
        HandleDeletePoints();
        HandleUnselect();
        Framing();

        Handles.color = currentColor;
        Handles.matrix = currentMatrix;
    }

    private void PrepareEdgePoints()
    {
        int pointCount = GetPointCount();
        int edgeCount = OpenEnded() ? pointCount - 1 : pointCount;

        if (m_EdgePoints.Count != edgeCount)
            m_EdgePointsDirty = true;

        if (!m_EdgePointsDirty)
            return;

        m_EdgePoints.Clear();

        for (int index = 0; index < edgeCount; ++index)
        {
            int nextIndex = SplineUtility.NextIndex(index, pointCount);

            Vector3 position0 = GetPosition(index);
            Vector3 position1 = GetPosition(nextIndex);

            if (GetTangentMode(index) == TangentMode.Linear && GetTangentMode(nextIndex) == TangentMode.Linear)
            {
                m_EdgePoints.Add(new Vector3[] { position0, position1 });
            }
            else
            {
                var tangent0 = GetRightTangent(index) + position0;
                var tangent1 = GetLeftTangent(nextIndex) + position1;
                m_EdgePoints.Add(Handles.MakeBezierPoints(position0, position1, tangent0, tangent1, kBezierPatch));
            }
        }

        m_EdgePointsDirty = false;
    }

    private void LayoutPoints()
    {
        for (int index = 0; index < GetPointCount(); index++)
        {
            int id = GUIUtility.GetControlID("Point".GetHashCode(), FocusType.Passive);

            if (currentEvent.type == EventType.Layout)
            {
                Vector3 position = GetPosition(index);
                GetPointCapNormal(id, position, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(position), EventType.Layout);

                if (m_HoveredEdgeIndex == -1)
                {
                    if (HandleUtility.nearestControl == id)
                    {
                        m_HoveredPointIndex = index;
                    }
                }
            }
        }
    }

    private void DrawPoints()
    {
        if (currentEvent.type != EventType.Repaint)
            return;

        for (int index = 0; index < GetPointCount(); index++)
        {
            var position = GetPosition(index);

            if (m_ActivePointIndex == index)
                GetPointCapActive(0, position, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(position), currentEvent.type);
            else if (m_HoveredPointIndex == index && GUIUtility.hotControl == 0)
                GetPointCapHovered(0, position, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(position), currentEvent.type);
            else if (ShapeEditorCache.GetSelection().IsSelected(index))
                GetPointCapSelected(0, position, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(position), currentEvent.type);
            else
                GetPointCapNormal(0, position, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(position), currentEvent.type);
        }
    }

    private void DrawCreatePointPreview()
    {
        if (GUIUtility.hotControl == 0 && m_HoveredTangentPoint == -1 && m_HoveredPointIndex == -1 && !currentEvent.shift && !EdgeDragModifiersActive())
        {
            if (m_HoveredEdgeIndex != -1)
                GetPointCapHovered(0, m_ClosestPoint, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(m_ClosestPoint), currentEvent.type);
            else
                GetPointCapPreview(0, m_ClosestPoint, Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(m_ClosestPoint), currentEvent.type);
        }
    }

    private void HandleSelectPoint()
    {
        EventType eventType = currentEvent.GetTypeForControl(m_DragPointControlId);

        if (GUIUtility.hotControl == 0 && m_HoveredPointIndex != -1 && eventType == EventType.MouseDown && currentEvent.button == 0)
        {
            SelectPoint(m_HoveredPointIndex);
        }
    }

    private void HandleDeletePoints()
    {
        bool wantsDelete = GUIUtility.hotControl == 0 &&
            (currentEvent.type == EventType.ExecuteCommand || currentEvent.type == EventType.ValidateCommand)
            && (currentEvent.commandName == "SoftDelete" || currentEvent.commandName == "Delete");

        if (wantsDelete)
        {
            if (currentEvent.type == EventType.ValidateCommand)
            {
                currentEvent.Use();
            }
            else if (currentEvent.type == EventType.ExecuteCommand)
            {
                DeleteSelected();
                currentEvent.Use();
            }
        }
    }

    private void HandleDragPoints()
    {
        EventType eventType = currentEvent.GetTypeForControl(m_DragPointControlId);

        if ((!currentEvent.alt && GUIUtility.hotControl == 0 && m_HoveredPointIndex != -1 && !EditorGUI.actionKey) ||
            GUIUtility.hotControl == m_DragPointControlId)
        {
            if (eventType == EventType.Layout && GUIUtility.hotControl == 0)
                GetPointCapNormal(m_DragPointControlId, GetPosition(m_HoveredPointIndex), Quaternion.LookRotation(GetForwardVector(), GetUpVector()), GetHandleSize(GetPosition(m_HoveredPointIndex)), EventType.Layout);

            if (eventType == EventType.MouseDown && currentEvent.button == 0)
            {
                m_ActivePointIndex = m_HoveredPointIndex;
                m_SliderPosition = GetPosition(m_HoveredPointIndex);
            }

            if (eventType == EventType.MouseUp && currentEvent.button == 0)
                m_ActivePointIndex = -1;

            EditorGUI.BeginChangeCheck();

            Vector3 newPosition = DoSlider(m_DragPointControlId, m_SliderPosition, GetUpVector(), GetRightVector(), GetHandleSize(m_SliderPosition), (int cid, Vector3 p, Quaternion q, float s, EventType et) => {});

            if (EditorGUI.EndChangeCheck())
            {
                newPosition = Snap(newPosition);
                MoveSelectedPoints(newPosition - m_SliderPosition);
            }

            m_SliderPosition = newPosition;
        }
    }

    private void LayoutEdges()
    {
        if (currentEvent.type != EventType.Layout)
            return;

        PrepareEdgePoints();

        int pointCount = GetPointCount();
        int edgeCount = OpenEnded() ? pointCount - 1 : pointCount;

        float minDistance = float.MaxValue;

        for (int index = 0; index < edgeCount; ++index)
        {
            int id = GUIUtility.GetControlID("Edge".GetHashCode(), FocusType.Passive);

            if (currentEvent.type == EventType.Layout)
            {
                int nextIndex = SplineUtility.NextIndex(index, pointCount);

                Vector3 position0 = GetPosition(index);
                Vector3 position1 = GetPosition(nextIndex);
                Vector3 tangent0 = GetRightTangent(index) + position0;
                Vector3 tangent1 = GetLeftTangent(nextIndex) + position1;

                float t;
                Vector3 closestPoint = BezierUtility.ClosestPointOnCurve(ScreenToWorld(currentEvent.mousePosition), position0, position1, tangent0, tangent1, out t);

                Vector2 guiPosition = HandleUtility.WorldToGUIPoint(closestPoint);

                float distance = (currentEvent.mousePosition - guiPosition).magnitude;

                if (m_HoveredPointIndex == -1)
                {
                    HandleUtility.AddControl(id, distance);

                    if (HandleUtility.nearestControl == id)
                    {
                        m_HoveredEdgeIndex = index;
                        m_HoveredPointIndex = -1;
                        m_HoveredTangentPoint = -1;
                    }
                }

                if (distance < minDistance)
                {
                    m_ClosestPoint = closestPoint;
                    m_ClosestPointT = t;
                    minDistance = distance;
                }
            }
        }
    }

    private void DrawEdges()
    {
        PrepareEdgePoints();

        if (currentEvent.type != EventType.Repaint)
            return;

        Color handlesOldColor = Handles.color;

        var pointCount = GetPointCount();
        int edgeCount = OpenEnded() ? pointCount - 1 : pointCount;

        for (int index = 0; index < edgeCount; index++)
        {
            Color edgeColor = Color.white;

            if ((m_HoveredEdgeIndex == index && HandleUtility.nearestControl == m_DragEdgeControlId) ||
                (m_ActiveEdgeIndex == index && GUIUtility.hotControl == m_DragEdgeControlId))
                edgeColor = Handles.selectedColor;

            float edgeWidth = kEdgeWidth;

            if ((m_ActiveEdgeIndex == index && GUIUtility.hotControl == m_DragEdgeControlId) ||
                (GUIUtility.hotControl == 0 && m_HoveredEdgeIndex == index))
                edgeWidth = kActiveEdgeWidth;

            Handles.color = edgeColor;
            Handles.DrawAAPolyLine(lineTexture, edgeWidth, m_EdgePoints[index]);
        }
        Handles.color = handlesOldColor;
    }

    private void HandleUnselect()
    {
        EventType eventType = currentEvent.type;

        if (GUIUtility.hotControl == 0 && eventType == EventType.MouseDown && currentEvent.button == 1)
        {
            ClearSelection();
        }
    }

    private void HandleInsertPointToEdge()
    {
        EventType eventType = currentEvent.GetTypeForControl(m_DragPointControlId);

        if (m_HoveredPointIndex == -1 && m_HoveredEdgeIndex != -1 && GUIUtility.hotControl == 0 && eventType == EventType.MouseDown && currentEvent.button == 0 && !currentEvent.shift)
        {
            RecordUndo();
            ClearSelection();

            int nextIndex = SplineUtility.NextIndex(m_HoveredEdgeIndex, GetPointCount());

            TangentMode leftTangentMode = GetTangentMode(m_HoveredEdgeIndex);
            TangentMode rightTangentMode = GetTangentMode(nextIndex);

            Vector3 leftStartPosition;
            Vector3 leftEndPosition;
            Vector3 leftStartTangent;
            Vector3 leftEndTangent;

            Vector3 rightStartPosition;
            Vector3 rightEndPosition;
            Vector3 rightStartTangent;
            Vector3 rightEndTangent;

            Vector3 position0 = GetPosition(m_HoveredEdgeIndex);
            Vector3 position1 = GetPosition(nextIndex);
            Vector3 tangent0 = GetRightTangent(m_HoveredEdgeIndex) + position0;
            Vector3 tangent1 = GetLeftTangent(nextIndex) + position1;

            BezierUtility.SplitBezier(m_ClosestPointT, position0, position1, tangent0, tangent1,
                out leftStartPosition, out leftEndPosition, out leftStartTangent, out leftEndTangent,
                out rightStartPosition, out rightEndPosition, out rightStartTangent, out rightEndTangent);

            if (leftTangentMode != TangentMode.Linear)
            {
                SetTangentMode(m_HoveredEdgeIndex, TangentMode.Broken);
                SetRightTangent(m_HoveredEdgeIndex, leftStartTangent - leftStartPosition);
            }

            if (rightTangentMode != TangentMode.Linear)
            {
                SetTangentMode(nextIndex, TangentMode.Broken);
                SetLeftTangent(nextIndex, rightEndTangent - rightEndPosition);
            }

            InsertPointAt(nextIndex, m_ClosestPoint);

            if (leftTangentMode != TangentMode.Linear || rightTangentMode != TangentMode.Linear)
            {
                SetTangentMode(nextIndex, TangentMode.Broken);

                if (m_ClosestPointT == 0.5f)
                    SetTangentMode(nextIndex, TangentMode.Continuous);

                SetLeftTangent(nextIndex, leftEndTangent - leftEndPosition);
                SetRightTangent(nextIndex, rightStartTangent - rightStartPosition);
            }

            m_HoveredPointIndex = nextIndex;
            m_HoveredEdgeIndex = -1;

            HandleUtility.nearestControl = m_DragPointControlId;
        }
    }

    private void HandleDragEdge()
    {
        EventType eventType = currentEvent.GetTypeForControl(m_DragEdgeControlId);

        if ((m_HoveredEdgeIndex != -1 && GUIUtility.hotControl == 0 && EdgeDragModifiersActive()) ||
            GUIUtility.hotControl == m_DragEdgeControlId)
        {
            if (eventType == EventType.MouseDown && currentEvent.button == 0)
            {
                m_ActiveEdgeIndex = m_HoveredEdgeIndex;
                m_SliderPosition = GetPosition(m_HoveredEdgeIndex);
            }

            if (eventType == EventType.MouseUp && currentEvent.button == 0)
            {
                m_ActiveEdgeIndex = -1;
            }

            if (eventType == EventType.Layout && GUIUtility.hotControl == 0)
                HandleUtility.AddControl(m_DragEdgeControlId, 0f);

            EditorGUI.BeginChangeCheck();

            Vector3 newPosition = DoSlider(m_DragEdgeControlId, m_SliderPosition, GetUpVector(), GetRightVector(), GetHandleSize(m_SliderPosition), (int cid, Vector3 p, Quaternion q, float s, EventType et) => {});

            if (EditorGUI.EndChangeCheck())
            {
                Vector3 snappedDelta = Snap(newPosition) - m_SliderPosition;
                int nextIndex = SplineUtility.NextIndex(m_ActiveEdgeIndex, GetPointCount());

                RecordUndo();
                SetPosition(m_ActiveEdgeIndex, GetPosition(m_ActiveEdgeIndex) + snappedDelta);
                SetPosition(nextIndex, GetPosition(nextIndex) + snappedDelta);

                m_EdgePointsDirty = true;
            }

            m_SliderPosition = newPosition;
        }
    }

    private void LayoutTangents()
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        int selectedPoint = selection.single;

        if (selectedPoint == -1 || GetTangentMode(selectedPoint) == TangentMode.Linear)
            return;

        int tangentId = GUIUtility.GetControlID("Tangent".GetHashCode(), FocusType.Passive);

        Vector3 position = GetPosition(selectedPoint);

        if (currentEvent.type == EventType.Layout)
        {
            Vector3 leftTangentPosition = GetLeftTangent(selectedPoint);
            GetTangentCapNormal(tangentId, leftTangentPosition + position, Quaternion.identity, GetHandleSize(leftTangentPosition + position), EventType.Layout);

            if (HandleUtility.nearestControl == tangentId)
            {
                m_HoveredTangentPoint = selectedPoint;
                m_HoveredLeftTangent = true;
                m_HoveredPointIndex = -1;
            }
        }

        tangentId = GUIUtility.GetControlID("Tangent".GetHashCode(), FocusType.Passive);

        if (currentEvent.type == EventType.Layout)
        {
            Vector3 rightTangentPosition = GetRightTangent(selection.single);
            GetTangentCapNormal(tangentId, rightTangentPosition + position, Quaternion.identity, GetHandleSize(rightTangentPosition + position), EventType.Layout);

            if (HandleUtility.nearestControl == tangentId)
            {
                m_HoveredTangentPoint = selectedPoint;
                m_HoveredLeftTangent = false;
                m_HoveredPointIndex = -1;
            }
        }
    }

    private void DrawTangentLine(Vector3 position, Vector3 tangent, Color color)
    {
        if (currentEvent.type != EventType.Repaint)
            return;

        Handles.color = color;
        Handles.DrawAAPolyLine(lineTexture, 3f, new Vector3[] { position, position + tangent });
    }

    private void DrawTangents()
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        int selectedPoint = selection.single;

        if (selectedPoint == -1 || GetTangentMode(selectedPoint) == TangentMode.Linear || currentEvent.type != EventType.Repaint)
            return;

        Vector3 position = GetPosition(selectedPoint);
        Vector3 leftTangent = GetLeftTangent(selectedPoint);
        Vector3 rightTangent = GetRightTangent(selection.single);

        Color color = kTangentColor;

        DrawTangentLine(position, leftTangent, color);

        if (GetTangentMode(selectedPoint) == TangentMode.Broken)
            color = kTangentColorAlternative;

        DrawTangentLine(position, rightTangent, color);

        if (m_ActiveTangentPointIndex != -1)
        {
            if (m_DragLeftTangent)
            {
                GetTangentCapActive(0, leftTangent + position, Quaternion.identity, GetHandleSize(leftTangent + position), EventType.Repaint);
                GetTangentCapNormal(0, rightTangent + position, Quaternion.identity, GetHandleSize(rightTangent + position), EventType.Repaint);
            }
            else
            {
                GetTangentCapNormal(0, leftTangent + position, Quaternion.identity, GetHandleSize(leftTangent + position), EventType.Repaint);
                GetTangentCapActive(0, rightTangent + position, Quaternion.identity, GetHandleSize(rightTangent + position), EventType.Repaint);
            }
        }
        else if (GUIUtility.hotControl == 0 && m_HoveredTangentPoint != -1)
        {
            if (m_HoveredLeftTangent)
            {
                GetTangentCapHovered(0, leftTangent + position, Quaternion.identity, GetHandleSize(leftTangent + position), EventType.Repaint);
                GetTangentCapNormal(0, rightTangent + position, Quaternion.identity, GetHandleSize(rightTangent + position), EventType.Repaint);
            }
            else
            {
                GetTangentCapNormal(0, leftTangent + position, Quaternion.identity, GetHandleSize(leftTangent + position), EventType.Repaint);
                GetTangentCapHovered(0, rightTangent + position, Quaternion.identity, GetHandleSize(rightTangent + position), EventType.Repaint);
            }
        }
        else
        {
            GetTangentCapNormal(0, leftTangent + position, Quaternion.identity, GetHandleSize(leftTangent + position), EventType.Repaint);
            GetTangentCapNormal(0, rightTangent + position, Quaternion.identity, GetHandleSize(rightTangent + position), EventType.Repaint);
        }
    }

    private void HandleDragTangent()
    {
        EventType eventType = currentEvent.GetTypeForControl(m_DragTangentControlId);

        if ((!currentEvent.alt && GUIUtility.hotControl == 0 && m_HoveredTangentPoint != -1 && !EditorGUI.actionKey) ||
            GUIUtility.hotControl == m_DragTangentControlId)
        {
            if (eventType == EventType.MouseDown && currentEvent.button == 0)
            {
                m_ActiveTangentPointIndex = m_HoveredTangentPoint;
                m_DragLeftTangent = m_HoveredLeftTangent;

                if (m_DragLeftTangent)
                    m_SliderPosition = GetLeftTangent(m_HoveredTangentPoint) + GetPosition(m_HoveredTangentPoint);
                else
                    m_SliderPosition = GetRightTangent(m_HoveredTangentPoint) + GetPosition(m_HoveredTangentPoint);
            }

            if (eventType == EventType.MouseUp && currentEvent.button == 0)
            {
                Vector3 leftTangent = GetLeftTangent(m_ActiveTangentPointIndex);
                Vector3 rightTangent = GetRightTangent(m_ActiveTangentPointIndex);

                if (leftTangent.sqrMagnitude == 0f && rightTangent.sqrMagnitude == 0f)
                    SetTangentMode(m_ActiveTangentPointIndex, TangentMode.Linear);

                m_ActiveTangentPointIndex = -1;
            }

            if (eventType == EventType.Layout && GUIUtility.hotControl == 0)
                HandleUtility.AddControl(m_DragTangentControlId, 0f);

            EditorGUI.BeginChangeCheck();

            Vector3 newPosition = DoSlider(m_DragTangentControlId, m_SliderPosition, GetUpVector(), GetRightVector(), GetHandleSize(m_SliderPosition), (int cid, Vector3 p, Quaternion q, float s, EventType et) => {});

            if (EditorGUI.EndChangeCheck())
            {
                RecordUndo();

                Vector3 tangent = newPosition - GetPosition(m_ActiveTangentPointIndex);

                if (tangent.magnitude < GetHandleSize(GetPosition(m_ActiveTangentPointIndex)))
                    tangent = Vector3.zero;

                if (m_DragLeftTangent)
                    SetLeftTangent(m_ActiveTangentPointIndex, tangent);
                else
                    SetRightTangent(m_ActiveTangentPointIndex, tangent);

                ValidateTangents(!m_DragLeftTangent);
            }
        }
    }

    private void Framing()
    {
        if (GetPointCount() == 0)
            return;

        ISelection selection = ShapeEditorCache.GetSelection();

        if (currentEvent.commandName == "FrameSelected" && selection.Count > 0)
        {
            switch (currentEvent.type)
            {
                case EventType.ExecuteCommand:
                    Bounds bounds = default(Bounds);

                    if (selection.Count == 0)
                    {
                        bounds = new Bounds(GetPosition(0), Vector3.zero);

                        for (int index = 1; index < GetPointCount(); ++index)
                        {
                            bounds.Encapsulate(GetPosition(index));
                        }
                    }
                    else
                    {
                        bounds = new Bounds(GetPosition(selection.any), Vector3.zero);

                        foreach (int index in selection)
                            bounds.Encapsulate(GetPosition(index));
                    }

                    Frame(bounds);

                    currentEvent.Use();
                    break;

                case EventType.ValidateCommand:
                    currentEvent.Use();
                    break;
            }
        }
    }

    private float GetDefaultHandleSizeForPoint(Vector3 position)
    {
        return Camera.current != null ? HandleUtility.GetHandleSize(position) * 0.09f : 5f;
    }

    private float GetTangentSizeForPoint(int index)
    {
        return GetHandleSize(GetPosition(index)) * 0.7f;
    }

    private void ValidateTangents(bool rightTangentChanged)
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        TangentMode mode = GetTangentMode(selection.single);
        Vector3 leftTangent = GetLeftTangent(selection.single);
        Vector3 rightTangent = GetRightTangent(selection.single);

        if (mode == TangentMode.Continuous)
        {
            if (rightTangentChanged)
                leftTangent = -rightTangent;
            else
                rightTangent = -leftTangent;
        }

        SetLeftTangent(selection.single, leftTangent);
        SetRightTangent(selection.single, rightTangent);

        ShapeEditorCache.RecordUndo();
        ShapeEditorCache.instance.rightTangentChanged = rightTangentChanged;
        if (rightTangentChanged)
            ShapeEditorCache.instance.rightTangent = rightTangent;
        else
            ShapeEditorCache.instance.leftTangent = leftTangent;
    }

    private bool EdgeDragModifiersActive()
    {
        return currentEvent.modifiers == EventModifiers.Control || currentEvent.modifiers == EventModifiers.Command;
    }

    private static Vector3 DoSlider(int id, Vector3 position, Vector3 slide1, Vector3 slide2, float s, Handles.CapFunction cap)
    {
        return Handles.Slider2D(id, position, Vector3.zero, Vector3.Cross(slide1, slide2), slide1, slide2, s, cap, Vector2.zero, false);
    }

    private void ClearSelection()
    {
        ShapeEditorCache.RecordUndo("Edit Selection");
        ShapeEditorCache.ClearSelection();

        GUI.changed = true;
    }

    private void DeleteSelected()
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        if (GetPointCount() <= 2)
            return;

        RecordUndo();

        List<int> indices = new List<int>(selection);
        indices.Sort();

        for (int i = indices.Count - 1; i >= 0; --i)
            RemovePointAt(indices[i]);

        ClearSelection();

        GUI.changed = true;
    }

    private void MoveSelectedPoints(Vector3 delta)
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        RecordUndo();

        if (delta.sqrMagnitude < float.Epsilon)
            return;

        foreach (int index in selection)
            SetPosition(index, GetPosition(index) + delta);
    }

    private void SelectPoint(int index)
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        bool additive = currentEvent.shift;
        bool subtractive = EditorGUI.actionKey;

        ShapeEditorCache.RecordUndo("Edit Selection");

        if (!additive && !subtractive)
            ShapeEditorCache.ClearSelection();

        selection.Select(index, (!selection.IsSelected(index) || additive) && !subtractive);

        HandleSinglePointSelection();

        GUI.changed = true;
    }

    public void HandleSinglePointSelection()
    {
        ISelection selection = ShapeEditorCache.GetSelection();

        if (selection.single != -1)
        {
            TangentMode mode = GetTangentMode(selection.single);

            SetTangentMode(selection.single, TangentMode.Broken);

            Vector3 leftTangent = GetLeftTangent(selection.single);
            Vector3 rightTangent = GetRightTangent(selection.single);

            ShapeEditorCache.instance.leftTangent = leftTangent;
            ShapeEditorCache.instance.rightTangent = rightTangent;
            ShapeEditorCache.instance.rightTangentChanged = true;

            if (rightTangent.magnitude == 0f)
                ShapeEditorCache.instance.rightTangentChanged = false;

            SetTangentMode(selection.single, mode);
        }
    }

    public void PointCapNormal(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.pointNormalStyle);
    }

    public void PointCapHovered(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.pointHoveredStyle);
    }

    public void PointCapSelected(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.pointSelectedStyle);
    }

    public void PointCapPreview(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.pointPreviewStyle);
    }

    public void DrawGUIStyleCap(int controlID, Vector3 position, Quaternion rotation, float size, GUIStyle guiStyle)
    {
        if (Camera.current && Vector3.Dot(position - Camera.current.transform.position, Camera.current.transform.forward) < 0f)
            return;

        Handles.BeginGUI();
        guiStyle.Draw(GetGUIStyleRect(guiStyle, position), GUIContent.none, controlID);
        Handles.EndGUI();
    }

    public void TangentCapNormal(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.tangentNormalStyle);
    }

    public void TangentCapHovered(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.tangentHoveredStyle);
    }

    public void TangentCapActive(int controlID, Vector3 position, Quaternion rotation, float size, EventType eventType)
    {
        if (eventType == EventType.Layout)
            HandleUtility.AddControl(controlID, HandleUtility.DistanceToCircle(position, size * 0.5f));
        else if (eventType == EventType.Repaint)
            DrawGUIStyleCap(controlID, position, rotation, size, styles.tangentHoveredStyle);
    }

    private Rect GetGUIStyleRect(GUIStyle style, Vector3 position)
    {
        Vector2 vector = HandleUtility.WorldToGUIPoint(position);

        float fixedWidth = style.fixedWidth;
        float fixedHeight = style.fixedHeight;

        return new Rect(vector.x - fixedWidth / 2f, vector.y - fixedHeight / 2f - 2f, fixedWidth, fixedHeight);
    }
}