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

public class ArcPrediction : MonoBehaviour
{
    LineRenderer lr;
    const int MAX_RENDER_LENGHT = 1000;

    private void Awake()
    {
        lr = GetComponent<LineRenderer>();
    }

    //initialization
    public void RenderArc(float velocity, int resolution, Vector3 rotation)
    {
        var prediction = CalculateArcArray(velocity, resolution, rotation);
        lr.startWidth = 0.005f;
        lr.endWidth = lr.startWidth *  Mathf.Sqrt(Vector3.Distance(prediction[0], prediction[prediction.Length-1]));// valeurs exp�rimental
        lr.positionCount = prediction.Length;
        lr.SetPositions(prediction);
    }

    public void HideArc()
    {
        lr.startWidth = lr.endWidth = 0;
    }

    //Create an array of Vector 3 positions for the arc
    Vector3[] CalculateArcArray(float velocity, int resolution, Vector3 rotation)
    {
        Vector3[] arcArray = new Vector3[MAX_RENDER_LENGHT];
        Vector3 velocityVector = rotation * velocity;
        arcArray[0] = transform.parent.position;
        int validSegments = 0;
        for (int i = 1; i < MAX_RENDER_LENGHT; i++)
        {
            //Figure out next position
            float t = (float)i / (float)resolution;
            Vector3 horizontalMovement = new Vector3(velocityVector.x, 0, velocityVector.z) * t;
            Vector3 verticalDirection = new Vector3(0, t * velocityVector.y + 0.5f * Physics.gravity.y * Mathf.Pow(t, 2), 0);
            var result = horizontalMovement + verticalDirection + transform.parent.position;
            arcArray[i] = result;

            //Figure out if the prediction should stop based on hitting an object
            RaycastHit hit;
            validSegments++;
            if (Physics.Linecast(arcArray[i - 1], arcArray[i], out hit))
            {
                arcArray[i] = hit.point;
                break;
            }
        }
        //IDK why this version of unity doesn't have a sub-array creation function, or at least why VisualStudio wasn't suggesting it
        Vector3[] output = new Vector3[validSegments+1];
        for(int i = 0; i <= validSegments; i++)
        {
            output[i] = arcArray[i];
        }
        return output;
    }
}