using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.U2D;

// Dynamic modification of spline to follow the path of mouse movement.
// This script is just a simplified demo to demonstrate the idea.
namespace SpriteShapeExtras
{

public class SimpleDraw : MonoBehaviour
{
    public float minimumDistance = 1.0f;
    private Vector3 lastPosition;

    // Use this for initialization
    void Start()
    {

    }

        private static int NextIndex(int index, int pointCount)
        {
            return Mod(index + 1, pointCount);
        }
    
        private static int PreviousIndex(int index, int pointCount)
        {
            return Mod(index - 1, pointCount);
        }
    
        private static int Mod(int x, int m)
        {
            int r = x % m;
            return r < 0 ? r + m : r;
        }
    
    private void Smoothen(SpriteShapeController sc, int pointIndex)
    {
        Vector3 position = sc.spline.GetPosition(pointIndex);
            Vector3 positionNext = sc.spline.GetPosition(NextIndex(pointIndex, sc.spline.GetPointCount()));
            Vector3 positionPrev = sc.spline.GetPosition(PreviousIndex(pointIndex, sc.spline.GetPointCount()));
        Vector3 forward = gameObject.transform.forward;

        float scale = Mathf.Min((positionNext - position).magnitude, (positionPrev - position).magnitude) * 0.33f;

        Vector3 leftTangent = (positionPrev - position).normalized * scale;
        Vector3 rightTangent = (positionNext - position).normalized * scale;

        sc.spline.SetTangentMode(pointIndex, ShapeTangentMode.Continuous);
        SplineUtility.CalculateTangents(position, positionPrev, positionNext, forward, scale, out rightTangent, out leftTangent);

        sc.spline.SetLeftTangent(pointIndex, leftTangent);
        sc.spline.SetRightTangent(pointIndex, rightTangent);
    }

    // Update is called once per frame
    void Update()
    {
        var mp = Input.mousePosition;
        mp.z = 10.0f;
        mp = Camera.main.ScreenToWorldPoint(mp);
        var dt = Mathf.Abs((mp - lastPosition).magnitude);
        var md = (minimumDistance > 1.0f) ? minimumDistance : 1.0f;
        if (Input.GetMouseButton(0) && dt > md)
        {
            var spriteShapeController = gameObject.GetComponent<SpriteShapeController>();
            var spline = spriteShapeController.spline;
            spline.InsertPointAt(spline.GetPointCount(), mp);
            var newPointIndex = spline.GetPointCount() - 1;
            Smoothen(spriteShapeController, newPointIndex - 1);

            spline.SetHeight(newPointIndex, UnityEngine.Random.Range(0.1f, 2.0f));
            lastPosition = mp;
        }
    }
}
}