using System;
using UnityEngine;
using UnityEditor;
using Object = UnityEngine.Object;
using System.Reflection;

namespace BezierSolution.Extras
{
	public static class BezierUtils
	{
		private const string PRECEDING_CONTROL_POINT_LABEL = "  <--";
		private const string FOLLOWING_CONTROL_POINT_LABEL = "  -->";

		private static readonly Color AUTO_CONSTRUCT_SPLINE_BUTTON_COLOR = new Color( 0.65f, 1f, 0.65f );

		private static readonly GUIContent LOOP_TEXT = new GUIContent( "Loop", "Connects the first end point and the last end point of the spline" );
		private static readonly GUIContent DRAW_RUNTIME_GIZMOS_TEXT = new GUIContent( "Draw Runtime Gizmos", "Draws the spline during gameplay" );
		private static readonly GUIContent SHOW_CONTROL_POINTS_TEXT = new GUIContent( "Show Control Points", "Shows control points of the end points in Scene window" );
		private static readonly GUIContent SHOW_DIRECTIONS_TEXT = new GUIContent( "Show Directions", "Shows control points' directions in Scene window" );
		private static readonly GUIContent SHOW_POINT_INDICES_TEXT = new GUIContent( "Show Point Indices", "Shows end points' indices in Scene window" );
		private static readonly GUIContent SHOW_NORMALS_TEXT = new GUIContent( "Show Normals", "Shows end points' normal vectors in Scene window" );
		private static readonly GUIContent DISPLAYED_INTERMEDIATE_NORMALS_COUNT_TEXT = new GUIContent( "Displayed Intermediate Normals", "The number of normal vectors to display in-between each end point pair" );
		private static readonly GUIContent AUTO_CALCULATED_NORMALS_ANGLE_TEXT = new GUIContent( "Auto Calculated Normals Angle", "When 'Auto Calculate Normals' button is clicked, all normals will be rotated around their Z axis by the specified amount (each end point's rotation angle can further be customized from the end point's Inspector)" );
		private static readonly GUIContent AUTO_CALCULATED_INTERMEDIATE_NORMALS_TEXT = new GUIContent( "Auto Calculated Intermediate Normals", "When 'Auto Calculate Normals' button is clicked, this many intermediate normal vectors will be calculated and stored for each end point pair. If no intermediate normal vectors are calculated (0), normals of end point pairs will be lerped to estimate the intermediate values" );
		private static readonly GUIContent EVENLY_SPACED_POINTS_RESOLUTION_TEXT = new GUIContent( "Evenly Spaced Points Resolution", "Determines approximately how many points will be calculated per each segment of the spline while generating 'evenlySpacedPoints'. Evenly spaced points are used by numerous utility components when their 'High Quality' option is enabled" );
		private static readonly GUIContent EVENLY_SPACED_POINTS_ACCURACY_TEXT = new GUIContent( "Evenly Spaced Points Accuracy", "Determines how accurate the uniform spacing of 'evenlySpacedPoints' will be" );
		private static readonly GUIContent POINT_CACHE_RESOLUTION_TEXT = new GUIContent( "Point Cache Resolution", "Determines how many uniformly distributed points 'pointCache' will have" );
		private static readonly GUIContent CONSTRUCT_LINEAR_PATH_TEXT = new GUIContent( "Construct Linear Path", "Constructs a completely linear path (end points' Handle Mode will be set to Free)" );
		private static readonly GUIContent AUTO_CONSTRUCT_SPLINE_TEXT = new GUIContent( "Auto Construct Spline", "Constructs a smooth path" );
		private static readonly GUIContent AUTO_CONSTRUCT_SPLINE_2_TEXT = new GUIContent( "Auto Construct Spline 2", "Constructs a smooth path (another algorithm)" );
		private static readonly GUIContent AUTO_CALCULATE_NORMALS_TEXT = new GUIContent( "Auto Calculate Normals", "Attempts to automatically calculate the end points' normal vectors" );
		private static readonly GUIContent AUTO_CONSTRUCT_ALWAYS_TEXT = new GUIContent( "Always", "Applies this method automatically as spline's points change" );
		private static readonly GUIContent QUICK_EDIT_MODE_TEXT = new GUIContent( "Quick Edit Mode", "Quickly add new points to the spline or snap existing points to the scene geometry" );
		private static readonly GUIContent QUICK_EDIT_MODIFY_NORMALS_TEXT = new GUIContent( "Use Raycast Normals", "While dragging a point or adding a new point, the point's Normal vector will be set to the normal of the scene geometry under the cursor" );
		private static readonly GUIContent QUICK_EDIT_PRESERVE_SPLINE_SHAPE_TEXT = new GUIContent( "Preserve Spline Shape", "While inserting new points along the spline, the spline's shape will be preserved but the neighboring end points' 'Handle Mode' will no longer be 'Mirrored'" );

		public static readonly GUILayoutOption GL_WIDTH_45 = GUILayout.Width( 45f );
		public static readonly GUILayoutOption GL_WIDTH_60 = GUILayout.Width( 60f );
		public static readonly GUILayoutOption GL_WIDTH_100 = GUILayout.Width( 100f );
		public static readonly GUILayoutOption GL_WIDTH_155 = GUILayout.Width( 155f );

		private static readonly MethodInfo intersectRayMeshMethod = typeof( HandleUtility ).GetMethod( "IntersectRayMesh", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static );

		public static bool QuickEditSplineMode { get; private set; }

		[MenuItem( "GameObject/Bezier Spline", priority = 35 )]
		private static void NewSpline( MenuCommand command )
		{
			GameObject spline = new GameObject( "BezierSpline", typeof( BezierSpline ) );
			Undo.RegisterCreatedObjectUndo( spline, "Create Spline" );
			if( command.context )
				Undo.SetTransformParent( spline.transform, ( (GameObject) command.context ).transform, "Create Spline" );

			spline.transform.localPosition = new Vector3( 0f, 0f, 0f );
			spline.transform.localRotation = Quaternion.identity;
			spline.transform.localScale = new Vector3( 1f, 1f, 1f );

			Selection.activeTransform = spline.transform;
		}

		[DrawGizmo( GizmoType.NonSelected | GizmoType.Pickable )]
		private static void DrawSplineGizmo( BezierSpline spline, GizmoType gizmoType )
		{
			if( spline.Count < 2 )
				return;

			// Make sure that none of the points of the spline are selected
			if( BezierPointEditor.ActiveEditor && Array.IndexOf( BezierPointEditor.ActiveEditor.allSplines, spline ) >= 0 )
				return;

			Gizmos.color = BezierSettings.NormalSplineColor;

			Vector3 lastPos = spline[0].position;
			float increaseAmount = 1f / ( spline.Count * BezierSettings.SplineSmoothness );

			for( float i = increaseAmount; i < 1f; i += increaseAmount )
			{
				Vector3 pos = spline.GetPoint( i );
				Gizmos.DrawLine( lastPos, pos );
				lastPos = pos;
			}

			Gizmos.DrawLine( lastPos, spline.GetPoint( 1f ) );
		}

		[DrawGizmo( GizmoType.Selected | GizmoType.NonSelected )]
		private static void DrawPointExtraDataFrustumGizmo( BezierPoint point, GizmoType gizmoType )
		{
			if( !BezierSettings.VisualizeExtraDataAsFrustum )
				return;

			// If the either the point or its spline isn't selected, don't show frustum of the point
			if( ( !BezierSplineEditor.ActiveEditor || Array.IndexOf( BezierSplineEditor.ActiveEditor.allSplines, point.spline ) < 0 ) &&
				( !BezierPointEditor.ActiveEditor || Array.IndexOf( BezierPointEditor.ActiveEditor.allSplines, point.spline ) < 0 ) )
				return;

			Quaternion rotation = point.extraData;
			if( Mathf.Approximately( rotation.x * rotation.x + rotation.y * rotation.y + rotation.z * rotation.z + rotation.w * rotation.w, 1f ) )
			{
				Matrix4x4 temp = Gizmos.matrix;
				Gizmos.matrix = Matrix4x4.TRS( point.position, rotation, Vector3.one * ( BezierSettings.ExtraDataAsFrustumSize * HandleUtility.GetHandleSize( point.position ) ) );
				Gizmos.DrawFrustum( new Vector3( 0f, 0f, 0f ), 60f, 0.18f, 0.01f, 1.5f );
				Gizmos.matrix = temp;
			}
		}

		public static void DrawSplineDetailed( BezierSpline spline )
		{
			if( spline.Count < 2 )
				return;

			BezierPoint endPoint0 = null, endPoint1 = null;
			for( int i = 0; i < spline.Count - 1; i++ )
			{
				endPoint0 = spline[i];
				endPoint1 = spline[i + 1];

				DrawBezier( endPoint0, endPoint1 );
			}

			if( spline.loop && endPoint1 != null )
				DrawBezier( endPoint1, spline[0] );

			// Draw tangent lines on scene view
			//Color _tmp = Handles.color;
			//Handles.color = Color.cyan;
			//for( float i = 0f; i < 1f; i += 0.05f )
			//{
			//	Handles.DrawLine( spline.GetPoint( i ), spline.GetPoint( i ) + spline.GetTangent( i ) );
			//}
			//Handles.color = _tmp;
		}

		public static void DrawSplineEvenlySpacedPoints( BezierSpline spline )
		{
			if( Event.current.type == EventType.Repaint )
			{
				Color c = Handles.color;
				Handles.color = BezierSettings.EvenlySpacedPointsColor;

				float[] evenlySpacedNormalizedTs = spline.evenlySpacedPoints.uniformNormalizedTs;
				for( int i = 0; i < evenlySpacedNormalizedTs.Length; i++ )
				{
					Vector3 evenlySpacedPoint = spline.GetPoint( evenlySpacedNormalizedTs[i] );
					Handles.SphereHandleCap( 0, evenlySpacedPoint, Quaternion.identity, HandleUtility.GetHandleSize( evenlySpacedPoint ) * BezierSettings.EvenlySpacedPointsSize, EventType.Repaint );
				}

				Handles.color = c;
			}
		}

		public static void DrawSplineInspectorGUI( BezierSpline[] splines )
		{
			if( splines.Length == 0 )
				return;

			for( int i = 0; i < splines.Length; i++ )
			{
				if( splines[i].Count < 2 )
				{
					if( GUILayout.Button( "Initialize Spline" ) )
					{
						Object[] selection = Selection.objects;
						for( int j = 0; j < splines.Length; j++ )
						{
							BezierSpline spline = splines[j];
							if( spline.Count < 2 )
							{
								bool isSplineSelected = false;
								for( int k = 0; k < selection.Length; k++ )
								{
									if( selection[k] == spline || selection[k] == spline.transform || selection[k] == spline.gameObject )
									{
										isSplineSelected = true;
										break;
									}
								}

								spline.Reset();

								// Try to continue showing spline's scene gizmos after initialization by keeping
								// either the spline or a point of it selected
								if( !isSplineSelected )
								{
									Array.Resize( ref selection, selection.Length + 1 );
									selection[selection.Length - 1] = spline[0].gameObject;
								}
							}
						}

						Selection.objects = selection;
						GUIUtility.ExitGUI();
					}

					return;
				}
			}

			Color c = GUI.backgroundColor;

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.loop == s2.loop );
			EditorGUI.BeginChangeCheck();
			bool loop = EditorGUILayout.Toggle( LOOP_TEXT, splines[0].loop );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierSpline spline = splines[i];
					Undo.RecordObject( spline, "Toggle Loop" );
					spline.loop = loop;
					SetSplineDirtyWithUndo( spline, "Toggle Loop", InternalDirtyFlags.EndPointTransformChange | InternalDirtyFlags.ControlPointPositionChange );
				}

				SceneView.RepaintAll();
			}

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.drawGizmos == s2.drawGizmos );
			EditorGUI.BeginChangeCheck();
			bool drawGizmos = EditorGUILayout.Toggle( DRAW_RUNTIME_GIZMOS_TEXT, splines[0].drawGizmos );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Toggle Draw Gizmos" );
					splines[i].drawGizmos = drawGizmos;
				}

				SceneView.RepaintAll();
			}

			if( drawGizmos )
			{
				EditorGUI.indentLevel++;

				EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.gizmoColor == s2.gizmoColor );
				EditorGUI.BeginChangeCheck();
				Color gizmoColor = EditorGUILayout.ColorField( "Gizmo Color", splines[0].gizmoColor );
				if( EditorGUI.EndChangeCheck() )
				{
					for( int i = 0; i < splines.Length; i++ )
					{
						Undo.RecordObject( splines[i], "Change Gizmo Color" );
						splines[i].gizmoColor = gizmoColor;
					}

					SceneView.RepaintAll();
				}

				EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.gizmoSmoothness == s2.gizmoSmoothness );
				EditorGUI.BeginChangeCheck();
				int gizmoSmoothness = EditorGUILayout.IntSlider( "Gizmo Smoothness", splines[0].gizmoSmoothness, 1, 30 );
				if( EditorGUI.EndChangeCheck() )
				{
					for( int i = 0; i < splines.Length; i++ )
					{
						Undo.RecordObject( splines[i], "Change Gizmo Smoothness" );
						splines[i].gizmoSmoothness = gizmoSmoothness;
					}

					SceneView.RepaintAll();
				}

				EditorGUI.indentLevel--;
			}

			EditorGUI.showMixedValue = false;

			EditorGUI.BeginChangeCheck();
			bool showControlPoints = EditorGUILayout.Toggle( SHOW_CONTROL_POINTS_TEXT, BezierSettings.ShowControlPoints );
			if( EditorGUI.EndChangeCheck() )
			{
				BezierSettings.ShowControlPoints = showControlPoints;
				SceneView.RepaintAll();
			}

			if( showControlPoints )
			{
				EditorGUI.indentLevel++;
				EditorGUI.BeginChangeCheck();
				bool showControlPointDirections = EditorGUILayout.Toggle( SHOW_DIRECTIONS_TEXT, BezierSettings.ShowControlPointDirections );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.ShowControlPointDirections = showControlPointDirections;
					SceneView.RepaintAll();
				}
				EditorGUI.indentLevel--;
			}

			EditorGUI.BeginChangeCheck();
			bool showEndPointLabels = EditorGUILayout.Toggle( SHOW_POINT_INDICES_TEXT, BezierSettings.ShowEndPointLabels );
			if( EditorGUI.EndChangeCheck() )
			{
				BezierSettings.ShowEndPointLabels = showEndPointLabels;
				SceneView.RepaintAll();
			}

			EditorGUI.BeginChangeCheck();
			bool showNormals = EditorGUILayout.Toggle( SHOW_NORMALS_TEXT, BezierSettings.ShowNormals );
			if( EditorGUI.EndChangeCheck() )
			{
				BezierSettings.ShowNormals = showNormals;
				SceneView.RepaintAll();
			}

			if( showNormals )
			{
				EditorGUI.indentLevel++;

				EditorGUI.BeginChangeCheck();
				Color normalsPreviewColor = EditorGUILayout.ColorField( "Color", BezierSettings.NormalsPreviewColor );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.NormalsPreviewColor = normalsPreviewColor;
					SceneView.RepaintAll();
				}

				EditorGUI.BeginChangeCheck();
				float normalsPreviewLength = EditorGUILayout.FloatField( "Length", BezierSettings.NormalsPreviewLength );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.NormalsPreviewLength = normalsPreviewLength;
					SceneView.RepaintAll();
				}

				EditorGUI.BeginChangeCheck();
				int displayedIntermediateNormalsCount = EditorGUILayout.IntField( DISPLAYED_INTERMEDIATE_NORMALS_COUNT_TEXT, BezierSettings.DisplayedIntermediateNormalsCount );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.DisplayedIntermediateNormalsCount = displayedIntermediateNormalsCount;
					SceneView.RepaintAll();
				}

				EditorGUI.indentLevel--;
			}

			EditorGUILayout.Space();

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.autoCalculatedNormalsAngle == s2.autoCalculatedNormalsAngle );
			EditorGUI.BeginChangeCheck();
			float autoCalculatedNormalsAngle = EditorGUILayout.FloatField( AUTO_CALCULATED_NORMALS_ANGLE_TEXT, splines[0].autoCalculatedNormalsAngle );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Change Normals Angle" );
					splines[i].autoCalculatedNormalsAngle = autoCalculatedNormalsAngle;
					SetSplineDirtyWithUndo( splines[i], "Change Normals Angle", InternalDirtyFlags.NormalOffsetChange );
				}

				SceneView.RepaintAll();
			}

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.autoCalculatedIntermediateNormalsCount == s2.autoCalculatedIntermediateNormalsCount );
			EditorGUI.BeginChangeCheck();
			int autoCalculatedIntermediateNormalsCount = EditorGUILayout.IntField( AUTO_CALCULATED_INTERMEDIATE_NORMALS_TEXT, splines[0].autoCalculatedIntermediateNormalsCount );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Change Intermediate Normals Count" );
					splines[i].autoCalculatedIntermediateNormalsCount = autoCalculatedIntermediateNormalsCount;
					SetSplineDirtyWithUndo( splines[i], "Change Intermediate Normals Count", InternalDirtyFlags.NormalOffsetChange );
				}

				SceneView.RepaintAll();
			}

			EditorGUILayout.Space();

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.evenlySpacedPointsResolution == s2.evenlySpacedPointsResolution );
			EditorGUI.BeginChangeCheck();
			float evenlySpacedPointsResolution = EditorGUILayout.FloatField( EVENLY_SPACED_POINTS_RESOLUTION_TEXT, splines[0].evenlySpacedPointsResolution );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Change Evenly Spaced Points Resolution" );
					splines[i].evenlySpacedPointsResolution = evenlySpacedPointsResolution;
					SetSplineDirtyWithUndo( splines[i], "Change Evenly Spaced Points Resolution", InternalDirtyFlags.All );
				}

				SceneView.RepaintAll();
			}

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.evenlySpacedPointsAccuracy == s2.evenlySpacedPointsAccuracy );
			EditorGUI.BeginChangeCheck();
			float evenlySpacedPointsAccuracy = EditorGUILayout.FloatField( EVENLY_SPACED_POINTS_ACCURACY_TEXT, splines[0].evenlySpacedPointsAccuracy );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Change Evenly Spaced Points Accuracy" );
					splines[i].evenlySpacedPointsAccuracy = evenlySpacedPointsAccuracy;
					SetSplineDirtyWithUndo( splines[i], "Change Evenly Spaced Points Accuracy", InternalDirtyFlags.All );
				}

				SceneView.RepaintAll();
			}

			EditorGUI.showMixedValue = HasMultipleDifferentValues( splines, ( s1, s2 ) => s1.pointCacheResolution == s2.pointCacheResolution );
			EditorGUI.BeginChangeCheck();
			int pointCacheResolution = EditorGUILayout.IntField( POINT_CACHE_RESOLUTION_TEXT, splines[0].pointCacheResolution );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					Undo.RecordObject( splines[i], "Change Point Cache Resolution" );
					splines[i].pointCacheResolution = pointCacheResolution;
					SetSplineDirtyWithUndo( splines[i], "Change Point Cache Resolution", InternalDirtyFlags.All );
				}

				SceneView.RepaintAll();
			}

			EditorGUI.showMixedValue = false;

			EditorGUI.BeginChangeCheck();
			bool showEvenlySpacedPoints = EditorGUILayout.Toggle( "Visualize Evenly Spaced Points", BezierSettings.ShowEvenlySpacedPoints );
			if( EditorGUI.EndChangeCheck() )
			{
				BezierSettings.ShowEvenlySpacedPoints = showEvenlySpacedPoints;
				SceneView.RepaintAll();
			}

			if( showEvenlySpacedPoints )
			{
				EditorGUI.indentLevel++;

				EditorGUI.BeginChangeCheck();
				Color evenlySpacedPointsColor = EditorGUILayout.ColorField( "Color", BezierSettings.EvenlySpacedPointsColor );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.EvenlySpacedPointsColor = evenlySpacedPointsColor;
					SceneView.RepaintAll();
				}

				EditorGUI.BeginChangeCheck();
				float evenlySpacedPointsSize = EditorGUILayout.FloatField( "Size", BezierSettings.EvenlySpacedPointsSize );
				if( EditorGUI.EndChangeCheck() )
				{
					BezierSettings.EvenlySpacedPointsSize = evenlySpacedPointsSize;
					SceneView.RepaintAll();
				}

				EditorGUI.indentLevel--;
			}

			EditorGUILayout.Space();

			GUI.backgroundColor = AUTO_CONSTRUCT_SPLINE_BUTTON_COLOR;
			ShowAutoConstructButton( splines, CONSTRUCT_LINEAR_PATH_TEXT, SplineAutoConstructMode.Linear );
			ShowAutoConstructButton( splines, AUTO_CONSTRUCT_SPLINE_TEXT, SplineAutoConstructMode.Smooth1 );
			ShowAutoConstructButton( splines, AUTO_CONSTRUCT_SPLINE_2_TEXT, SplineAutoConstructMode.Smooth2 );

			GUILayout.BeginHorizontal();
			if( GUILayout.Button( AUTO_CALCULATE_NORMALS_TEXT ) )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierSpline spline = splines[i];
					Undo.RecordObject( spline, "Auto Calculate Normals" );

					try
					{
						spline.autoCalculateNormals = true;
						SetSplineDirtyWithUndo( spline, "Auto Calculate Normals", InternalDirtyFlags.NormalOffsetChange );
					}
					finally
					{
						spline.autoCalculateNormals = false;
					}
				}

				SceneView.RepaintAll();
			}

			EditorGUI.BeginChangeCheck();
			bool autoCalculateNormalsEnabled = GUILayout.Toggle( Array.Find( splines, ( s ) => s.autoCalculateNormals ), AUTO_CONSTRUCT_ALWAYS_TEXT, GUI.skin.button, EditorGUIUtility.wideMode ? GL_WIDTH_100 : GL_WIDTH_60 );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierSpline spline = splines[i];
					Undo.RecordObject( spline, "Change Auto Calculate Normals" );
					spline.autoCalculateNormals = autoCalculateNormalsEnabled;

					if( autoCalculateNormalsEnabled )
						SetSplineDirtyWithUndo( spline, "Change Auto Calculate Normals", InternalDirtyFlags.NormalOffsetChange );
				}

				SceneView.RepaintAll();
			}
			GUILayout.EndHorizontal();

			GUI.backgroundColor = c;

			EditorGUILayout.Space();

			EditorGUI.BeginChangeCheck();
			QuickEditSplineMode = GUILayout.Toggle( QuickEditSplineMode, QUICK_EDIT_MODE_TEXT, GUI.skin.button );
			if( EditorGUI.EndChangeCheck() )
			{
				EditorApplication.update -= SceneView.RepaintAll;

				if( QuickEditSplineMode )
				{
					Tools.hidden = true;
					EditorApplication.update += SceneView.RepaintAll;
				}
				else if( BezierSplineEditor.ActiveEditor )
					Tools.hidden = false;

				SceneView.RepaintAll();
			}

			if( QuickEditSplineMode )
			{
				EditorGUILayout.HelpBox( "- Dragging a point: snaps the dragged point to the scene geometry under the cursor\n- CTRL+Left Click: adds a new point to the end of the spline\n- CTRL+Shift+Left Click: inserts a new point along the spline\n- Shift+Left Click: deletes clicked point", MessageType.Info );

				if( Array.Find( splines, ( s ) => !s.autoCalculateNormals ) )
				{
					EditorGUI.indentLevel++;
					BezierSettings.QuickEditSplineModifyNormals = EditorGUILayout.Toggle( QUICK_EDIT_MODIFY_NORMALS_TEXT, BezierSettings.QuickEditSplineModifyNormals );
					EditorGUI.indentLevel--;
				}

				if( Array.Find( splines, ( s ) => s.autoConstructMode == SplineAutoConstructMode.None ) )
				{
					EditorGUI.indentLevel++;
					BezierSettings.QuickEditSplinePreserveShape = EditorGUILayout.Toggle( QUICK_EDIT_PRESERVE_SPLINE_SHAPE_TEXT, BezierSettings.QuickEditSplinePreserveShape );
					EditorGUI.indentLevel--;
				}
			}
		}

		public static void DrawBezierPoint( BezierPoint point, int pointIndex, bool isSelected )
		{
			Color c = Handles.color;
			Event e = Event.current;

			if( QuickEditSplineMode )
				isSelected = false;

			Handles.color = isSelected ? BezierSettings.SelectedEndPointColor : BezierSettings.NormalEndPointColor;
			float size = isSelected ? BezierSettings.SelectedEndPointSize : BezierSettings.EndPointSize;

			if( QuickEditSplineMode )
			{
				if( e.alt || e.control )
					Handles.DotHandleCap( 0, point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size, EventType.Repaint );
				else if( !e.shift )
				{
					// Shift isn't held: move dragged points

					// Draw a ScaleValueHandle for the sole purpose of detecting drag input
					EditorGUI.BeginChangeCheck();
					Handles.ScaleValueHandle( 1f, point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size * 6.5f, Handles.DotHandleCap, 1f );
					if( EditorGUI.EndChangeCheck() )
					{
						// Point is dragged, snap it to the scene geometry
						Vector3 sceneHitPoint, sceneHitNormal;
						RaycastAgainstScene( point.spline[point.spline.Count - 1], out sceneHitPoint, out sceneHitNormal );

						Undo.RecordObject( point.transform, "Move point" );
						point.transform.position = sceneHitPoint;

						if( BezierSettings.QuickEditSplineModifyNormals && !point.spline.autoCalculateNormals )
							point.SetNormalAndResetIntermediateNormals( sceneHitNormal, "Move point" );
					}
				}
				else
				{
					// Shift is held: delete clicked points

					// Disallow deleting points from splines with only 2 or less points
					if( point.spline.Count <= 2 )
						Handles.DotHandleCap( 0, point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size, EventType.Repaint );
					else
					{
						Handles.color = BezierSettings.QuickEditModeDeleteEndPointColor;

						if( Handles.Button( point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size, size, Handles.DotHandleCap ) )
						{
							// When the selected point is deleted, automatically select the next point so that there is still an active BezierPointEditor
							// to continue editing this spline
							Object[] selection = Selection.objects;
							int pointIndexInSelection = Array.IndexOf( selection, point.gameObject );
							if( pointIndexInSelection >= 0 )
								selection[pointIndexInSelection] = point.spline[( point.index + 1 ) % point.spline.Count].gameObject;

							Undo.DestroyObjectImmediate( point.gameObject );

							if( pointIndexInSelection >= 0 )
								Selection.objects = selection;
						}
					}
				}
			}
			else if( e.alt || e.button > 0 || ( isSelected && !e.control ) )
				Handles.DotHandleCap( 0, point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size, EventType.Repaint );
			else if( Handles.Button( point.position, Quaternion.identity, HandleUtility.GetHandleSize( point.position ) * size, size, Handles.DotHandleCap ) )
			{
				if( !e.shift && !e.control )
					Selection.activeTransform = point.transform;
				else
				{
					Object[] selection = Selection.objects;
					if( !isSelected )
					{
						// If point's spline is included in current selection, remove the spline
						// from selection since its Scene handles interfere with points' scene handles
						bool splineIncludedInSelection = false;
						if( point.spline )
						{
							for( int i = 0; i < selection.Length; i++ )
							{
								if( selection[i] == point.spline || selection[i] == point.spline.transform || selection[i] == point.spline.gameObject )
								{
									selection[i] = point.gameObject;
									splineIncludedInSelection = true;
									break;
								}
							}
						}

						if( !splineIncludedInSelection )
						{
							Array.Resize( ref selection, selection.Length + 1 );
							selection[selection.Length - 1] = point.gameObject;
						}
					}
					else
					{
						for( int i = 0; i < selection.Length; i++ )
						{
							if( selection[i] == point || selection[i] == point.transform || selection[i] == point.gameObject )
							{
								if( selection.Length == 1 )
								{
									// When all points are deselected, select the spline automatically
									if( point.spline )
									{
										selection[0] = point.spline.gameObject;
										break;
									}
								}

								for( int j = i + 1; j < selection.Length; j++ )
									selection[j - 1] = selection[j];

								Array.Resize( ref selection, selection.Length - 1 );
								break;
							}
						}
					}

					Selection.objects = selection;
				}
			}

			Handles.color = c;

			if( BezierSettings.ShowControlPoints )
			{
				Handles.DrawLine( point.position, point.precedingControlPointPosition );
				Handles.DrawLine( point.position, point.followingControlPointPosition );

				Handles.color = isSelected ? BezierSettings.SelectedControlPointColor : BezierSettings.NormalControlPointColor;

				Handles.RectangleHandleCap( 0, point.precedingControlPointPosition, SceneView.lastActiveSceneView.rotation, HandleUtility.GetHandleSize( point.precedingControlPointPosition ) * BezierSettings.ControlPointSize, EventType.Repaint );
				Handles.RectangleHandleCap( 0, point.followingControlPointPosition, SceneView.lastActiveSceneView.rotation, HandleUtility.GetHandleSize( point.followingControlPointPosition ) * BezierSettings.ControlPointSize, EventType.Repaint );

				Handles.color = c;
			}

			if( BezierSettings.ShowEndPointLabels )
				Handles.Label( point.position, "Point" + pointIndex );

			if( BezierSettings.ShowControlPoints && BezierSettings.ShowControlPointDirections )
			{
				Handles.Label( point.precedingControlPointPosition, PRECEDING_CONTROL_POINT_LABEL );
				Handles.Label( point.followingControlPointPosition, FOLLOWING_CONTROL_POINT_LABEL );
			}

			if( BezierSettings.ShowNormals )
			{
				Handles.color = BezierSettings.NormalsPreviewColor;
				Handles.DrawLine( point.position, point.position + point.normal * HandleUtility.GetHandleSize( point.position ) * BezierSettings.NormalsPreviewLength );

				if( BezierSettings.DisplayedIntermediateNormalsCount > 0 && point.spline && point.nextPoint )
				{
					BezierSpline.Segment segment = new BezierSpline.Segment( point, point.nextPoint, 0f );
					float localTMultiplier = 1f / ( BezierSettings.DisplayedIntermediateNormalsCount + 1 );
					for( int i = BezierSettings.DisplayedIntermediateNormalsCount; i > 0; i-- )
					{
						float localT = i * localTMultiplier;
						Vector3 segmentPosition = segment.GetPoint( localT );
						Handles.DrawLine( segmentPosition, segmentPosition + segment.GetNormal( localT ) * HandleUtility.GetHandleSize( segmentPosition ) * BezierSettings.NormalsPreviewLength * 0.75f );
					}
				}

				Handles.color = c;
			}
		}

		public static void QuickEditModeSceneGUI( BezierSpline[] splines )
		{
			Event e = Event.current;
			GUIContent QUICK_EDIT_MODE_TEXT = new GUIContent( "QUICK EDIT SPLINE MODE" );

			GUIStyle style = "PreOverlayLabel"; // Taken from: https://github.com/Unity-Technologies/UnityCsReference/blob/f78f4093c8a2b45949a847cdc704cf209dcf2f36/Editor/Mono/EditorGUI.cs#L629
			Rect multiEditTipRect = new Rect( new Vector2( 0f, 5f ), style.CalcSize( QUICK_EDIT_MODE_TEXT ) );
			multiEditTipRect.x = ( EditorGUIUtility.currentViewWidth - multiEditTipRect.width ) * 0.5f; // Center the text

			Handles.BeginGUI();
			EditorGUI.DropShadowLabel( multiEditTipRect, QUICK_EDIT_MODE_TEXT, style );
			Handles.EndGUI();

			if( splines.Length == 0 || e.alt || !e.control || GUIUtility.hotControl != 0 )
				return;

			if( !e.shift )
			{
				// Shift isn't held: add new point to the closest spline when LMB is pressed

				// Get a line that starts from Scene camera's position and goes at cursor's direction
				Ray ray = HandleUtility.GUIPointToWorldRay( e.mousePosition );
				Vector3 lineStart = ray.origin;
				Vector3 lineEnd = lineStart + ray.direction * 2500f;

				// Find the spline end point closest to this line
				BezierPoint closestEndPoint = null;
				float closestEndPointDistance = float.PositiveInfinity;
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierPoint point = splines[i][splines[i].Count - 1];
					float pointDistance = HandleUtility.DistancePointLine( point.position, lineStart, lineEnd );
					if( pointDistance <= closestEndPointDistance )
					{
						closestEndPoint = point;
						closestEndPointDistance = pointDistance;
					}
				}

				if( closestEndPoint )
				{
					Vector3 sceneHitPoint, sceneHitNormal;
					RaycastAgainstScene( closestEndPoint, out sceneHitPoint, out sceneHitNormal );

					// Draw a line from the closest end point to the raycast hit point
					Color c = Handles.color;
					Handles.color = BezierSettings.QuickEditModeNewEndPointColor;
					Handles.DotHandleCap( 0, sceneHitPoint, Quaternion.identity, HandleUtility.GetHandleSize( sceneHitPoint ) * BezierSettings.QuickEditModeNewEndPointSize, EventType.Repaint );
					Handles.DrawLine( sceneHitPoint, closestEndPoint.position );
					Handles.color = c;

					// When left clicked, insert a point at the highlighted position
					if( e.type == EventType.MouseDown && e.button == 0 )
					{
						BezierPoint newPoint = closestEndPoint.spline.InsertNewPointAt( closestEndPoint.spline.Count );
						newPoint.position = sceneHitPoint;
						if( BezierSettings.QuickEditSplineModifyNormals && !closestEndPoint.spline.autoCalculateNormals )
							newPoint.SetNormalAndResetIntermediateNormals( sceneHitNormal, null );

						// Rotate the previous point's followingControlPointPosition in the direction of the new point and assign the resulting vector
						// to the new point's followingControlPointPosition
						Vector3 directionToNewPoint = sceneHitPoint - closestEndPoint.position;
						Quaternion controlPointDeltaRotation = Quaternion.FromToRotation( closestEndPoint.followingControlPointPosition - closestEndPoint.position, directionToNewPoint );
						newPoint.followingControlPointPosition = sceneHitPoint + controlPointDeltaRotation * ( directionToNewPoint * 0.35f );

						Undo.RegisterCreatedObjectUndo( newPoint.gameObject, "Insert Point" );
						if( newPoint.transform.parent )
							Undo.RegisterCompleteObjectUndo( newPoint.transform.parent, "Insert Point" );

						e.Use();
					}
				}
			}
			else
			{
				// Shift is held: insert point to closest spline when LMB is pressed

				// Get a line that starts from Scene camera's position and goes at cursor's direction
				Ray ray = HandleUtility.GUIPointToWorldRay( e.mousePosition );
				Vector3 lineStart = ray.origin;
				Vector3 lineEnd = lineStart + ray.direction * 2500f;

				// Find the spline point closest to this line
				BezierSpline closestSpline = null;
				Vector3 closestPointOnSpline = Vector3.zero;
				float closestPointDistance = float.PositiveInfinity;
				float closestPointNormalizedT = 0f;
				for( int i = 0; i < splines.Length; i++ )
				{
					Vector3 pointOnLine;
					Vector3 pointOnSpline = splines[i].FindNearestPointToLine( lineStart, lineEnd, out pointOnLine, out closestPointNormalizedT );
					float pointDistance = ( pointOnLine - pointOnSpline ).sqrMagnitude;
					if( pointDistance <= closestPointDistance )
					{
						closestSpline = splines[i];
						closestPointOnSpline = pointOnSpline;
						closestPointDistance = pointDistance;
					}
				}

				if( closestSpline )
				{
					Color c = Handles.color;
					Handles.color = BezierSettings.QuickEditModeNewEndPointColor;
					Handles.DotHandleCap( 0, closestPointOnSpline, Quaternion.identity, HandleUtility.GetHandleSize( closestPointOnSpline ) * BezierSettings.QuickEditModeNewEndPointSize, EventType.Repaint );
					Handles.color = c;

					// When left clicked, insert a point at the highlighted position
					if( e.type == EventType.MouseDown && e.button == 0 )
					{
						BezierSpline.Segment segment = closestSpline.GetSegmentAt( closestPointNormalizedT );
						bool preserveSplineShape = BezierSettings.QuickEditSplinePreserveShape && closestSpline.autoConstructMode == SplineAutoConstructMode.None;

						Vector3 position, precedingControlPointPosition, followingControlPointPosition;
						BezierPointEditor.CalculateInsertedPointPosition( segment.point1, segment.point2, segment.localT, preserveSplineShape, out position, out precedingControlPointPosition, out followingControlPointPosition );

						BezierPoint newPoint = closestSpline.InsertNewPointAt( segment.point2.index );
						newPoint.position = position;
						if( preserveSplineShape )
						{
							newPoint.handleMode = BezierPoint.HandleMode.Aligned;
							newPoint.precedingControlPointPosition = precedingControlPointPosition;
							newPoint.followingControlPointPosition = followingControlPointPosition;
						}
						else
						{
							Vector3 precedingDirection = precedingControlPointPosition - position;
							Vector3 followingDirection = followingControlPointPosition - position;
							newPoint.followingControlPointPosition = position + followingDirection.normalized * Mathf.Min( precedingDirection.magnitude, followingDirection.magnitude );
						}

						Undo.RegisterCreatedObjectUndo( newPoint.gameObject, "Insert Point" );
						if( newPoint.transform.parent )
							Undo.RegisterCompleteObjectUndo( newPoint.transform.parent, "Insert Point" );

						e.Use();
					}
				}
			}
		}

		private static void ShowAutoConstructButton( BezierSpline[] splines, GUIContent label, SplineAutoConstructMode mode )
		{
			GUILayout.BeginHorizontal();
			if( GUILayout.Button( label ) )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierSpline spline = splines[i];
					Undo.RecordObject( spline, label.text );

					try
					{
						spline.autoConstructMode = mode;
						SetSplineDirtyWithUndo( spline, label.text, InternalDirtyFlags.EndPointTransformChange | InternalDirtyFlags.ControlPointPositionChange );
					}
					finally
					{
						spline.autoConstructMode = SplineAutoConstructMode.None;
					}
				}

				SceneView.RepaintAll();
			}

			EditorGUI.BeginChangeCheck();
			bool autoConstructEnabled = GUILayout.Toggle( Array.Find( splines, ( s ) => s.autoConstructMode == mode ), AUTO_CONSTRUCT_ALWAYS_TEXT, GUI.skin.button, EditorGUIUtility.wideMode ? GL_WIDTH_100 : GL_WIDTH_60 );
			if( EditorGUI.EndChangeCheck() )
			{
				for( int i = 0; i < splines.Length; i++ )
				{
					BezierSpline spline = splines[i];
					Undo.RecordObject( spline, "Change Autoconstruct Mode" );

					if( autoConstructEnabled )
					{
						spline.autoConstructMode = mode;
						SetSplineDirtyWithUndo( spline, "Change Autoconstruct Mode", InternalDirtyFlags.EndPointTransformChange | InternalDirtyFlags.ControlPointPositionChange );
					}
					else
						spline.autoConstructMode = SplineAutoConstructMode.None;
				}

				SceneView.RepaintAll();
			}
			GUILayout.EndHorizontal();
		}

		internal static void SetSplineDirtyWithUndo( BezierSpline spline, string undo, InternalDirtyFlags dirtyFlags )
		{
			if( spline.autoCalculateNormals || spline.autoConstructMode != SplineAutoConstructMode.None )
			{
				for( int i = 0; i < spline.Count; i++ )
				{
					Undo.RecordObject( spline[i], undo );
					Undo.RecordObject( spline[i].transform, undo );
				}
			}

			spline.dirtyFlags |= dirtyFlags;
			spline.CheckDirty();
		}

		private static void RaycastAgainstScene( BezierPoint referencePoint, out Vector3 position, out Vector3 normal )
		{
			EventType eventType = Event.current.type;
			Ray ray = HandleUtility.GUIPointToWorldRay( Event.current.mousePosition );

			// First, try raycasting against scene geometry with or without colliders (it doesn't matter)
			// Credit: https://forum.unity.com/threads/editor-raycast-against-scene-meshes-without-collider-editor-select-object-using-gui-coordinate.485502
			if( intersectRayMeshMethod != null && eventType != EventType.Layout && eventType != EventType.Repaint ) // HandleUtility.PickGameObject doesn't work with Layout and Repaint events in OnSceneGUI
			{
				GameObject gameObjectUnderCursor = HandleUtility.PickGameObject( Event.current.mousePosition, false );
				if( gameObjectUnderCursor )
				{
					Mesh meshUnderCursor = null;
					MeshFilter meshFilter = gameObjectUnderCursor.GetComponent<MeshFilter>();
					if( meshFilter )
						meshUnderCursor = meshFilter.sharedMesh;

					if( !meshUnderCursor )
					{
						SkinnedMeshRenderer skinnedMeshRenderer = gameObjectUnderCursor.GetComponent<SkinnedMeshRenderer>();
						if( skinnedMeshRenderer )
							meshUnderCursor = skinnedMeshRenderer.sharedMesh;
					}

					if( meshUnderCursor )
					{
						object[] rayMeshParameters = new object[] { ray, meshUnderCursor, gameObjectUnderCursor.transform.localToWorldMatrix, null };
						if( (bool) intersectRayMeshMethod.Invoke( null, rayMeshParameters ) )
						{
							RaycastHit hit = (RaycastHit) rayMeshParameters[3];
							position = hit.point;
							normal = hit.normal.normalized;

							return;
						}
					}
				}
			}

			// Raycast against scene geometry with colliders
			object raycastResult = HandleUtility.RaySnap( ray );
			if( raycastResult != null && raycastResult is RaycastHit )
			{
				position = ( (RaycastHit) raycastResult ).point;
				normal = ( (RaycastHit) raycastResult ).normal.normalized;

				return;
			}

			// Raycast against a plane that goes through referencePoint
			if( referencePoint )
			{
				Plane plane = new Plane( referencePoint.normal, referencePoint.position );
				float enter;
				if( plane.Raycast( ray, out enter ) )
				{
					position = ray.GetPoint( enter );
					normal = referencePoint.normal;

					return;
				}
			}

			position = ray.GetPoint( 5f );
			normal = Vector3.up;
		}

		public static void DrawSeparator()
		{
			GUILayout.Box( "", GUILayout.Height( 2f ), GUILayout.ExpandWidth( true ) );
		}

		private static void DrawBezier( BezierPoint endPoint0, BezierPoint endPoint1 )
		{
			Handles.DrawBezier( endPoint0.position, endPoint1.position,
								endPoint0.followingControlPointPosition,
								endPoint1.precedingControlPointPosition,
								BezierSettings.SelectedSplineColor, null, BezierSettings.SplineThickness );
		}

		private static bool HasMultipleDifferentValues( BezierSpline[] splines, Func<BezierSpline, BezierSpline, bool> comparer )
		{
			if( splines.Length <= 1 )
				return false;

			for( int i = 1; i < splines.Length; i++ )
			{
				if( !comparer( splines[0], splines[i] ) )
					return true;
			}

			return false;
		}
	}
}