//### Curve Drawing Helper
//Provides 
//
//License information: [ASSET STORE TERMS OF SERVICE AND EULA](https://unity3d.com/legal/as_terms)
//
//Developed by [MathArtCode](https://www.assetstore.unity3d.com/en/#!/search/page=1/sortby=popularity/query=publisher:8738) team, 2015

using Assets.Scripts.BezierCurvedParticlesFlow.Interfaces;
using UnityEditor;
using UnityEngine;

namespace Assets.Editor.BezierCurvedParticlesFlow.Utilities {
    public class CurveDrawingHelper {
        //### Provides events for handling interactions
        public delegate void ChangeCommit();
        public delegate void ChangeChangeStart( string label );

        public event ChangeChangeStart OnChangeInitiated;
        public event ChangeCommit OnChangeCommit;

        //### UI style settings
        private const float HandleSize = 0.04f;
        private const float PickSize = 0.06f;

        //### Main actors
        private readonly IBezierLogic _bezierLogic;

        private readonly UnityEditor.Editor _client;
        private readonly GameObject _splineControllerHost;

        //### Currently selected handle
        private Quaternion _handleRotation;
        private Transform _handleTransform;

        public int SelectedIndex = -1;

        //### Functions

        //Draws a dinamically movable UnityEditor point
        private Vector3 ShowPoint( int index ) {
            var point = _handleTransform.TransformPoint( _bezierLogic.GetControlPoint( index ) );
            var size = HandleUtility.GetHandleSize( point );
            if ( index == 0 ) {
                size *= 2f;
            }
            Handles.color = Color.cyan;

            if ( Handles.Button( point, _handleRotation, size * HandleSize, size * PickSize, Handles.DotHandleCap ) ) {
                SelectedIndex = index;
                _client.Repaint();
            }
            if ( SelectedIndex == index ) {
                EditorGUI.BeginChangeCheck();
                point = Handles.DoPositionHandle( point, _handleRotation );
                if ( EditorGUI.EndChangeCheck() ) {
                    if ( OnChangeInitiated != null ) {
                        OnChangeInitiated( "Move Point" );
                    }
                    _bezierLogic.SetControlPoint( index, _handleTransform.InverseTransformPoint( point ) );
                    if ( OnChangeCommit != null ) {
                        OnChangeCommit();
                    }
                }
            }
            return point;
        }

        // Draws a bezier curve in Scene space
        // ReSharper disable once InconsistentNaming
        public void OnSceneGUI() {
            if (_splineControllerHost == null) {
                Debug.LogError("_spline != null") ;
                return;
            }
            _handleTransform = _splineControllerHost.transform;
            _handleRotation = Tools.pivotRotation == PivotRotation.Local
                ? _handleTransform.rotation
                : Quaternion.identity;

            var p0 = ShowPoint( 0 );
            for ( var i = 1; i < _bezierLogic.ControlPointCount; i += 3 ) {
                var p1 = ShowPoint( i );
                var p2 = ShowPoint( i + 1 );
                var p3 = ShowPoint( i + 2 );

                Handles.color = Color.gray;
                Handles.DrawLine( p0, p1 );
                Handles.DrawLine( p2, p3 );

                Handles.color = Color.yellow;
                Handles.ArrowHandleCap( 0, p0, Quaternion.LookRotation( p3 - p0 ), 0.25f ,EventType.MouseDown);
#if !UNITY_3_5
                Handles.DrawBezier( p0, p3, p1, p2, Color.white, null, 1f );
#endif
                p0 = p3;
            }

#if UNITY_3_5
            var rasterize = 250;
            Handles.color = Color.gray;
            for (var i = 0; i < rasterize-1; i++) {
                var pn = _handleTransform.TransformPoint(  _bezierLogic.GetPoint( i / (float)rasterize ));
                var pk = _handleTransform.TransformPoint(  _bezierLogic.GetPoint( ( i + 1 ) / (float)rasterize ));
                Handles.DrawLine( pn, pk );
            }
#endif

            var e = Event.current;
            switch ( e.type ) {
                case EventType.KeyDown: {
                    if ( Event.current.keyCode == ( KeyCode.Delete ) || Event.current.keyCode == ( KeyCode.Backspace ) ) {
                        if ( SelectedIndex % 3 == 0 && SelectedIndex > 3 && SelectedIndex < _bezierLogic.ControlPointCount ) {
                            e.Use();
                            if ( OnChangeInitiated != null ) {
                                OnChangeInitiated( "Remove Point" );
                            }
                            _bezierLogic.RemovePoint( SelectedIndex );
                            if ( OnChangeCommit != null ) {
                                OnChangeCommit();
                            }
                        }
                    }

                    break;
                }
            }
        }

        public CurveDrawingHelper( UnityEditor.Editor uiClient, GameObject splineControllerHost, IBezierLogic splineSource ) {
            _client = uiClient;
            _splineControllerHost = splineControllerHost;
            _bezierLogic = splineSource;
        }
    }
}