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

struct DifferentialEquationData
{
    public float water;
    public float vegetation;
}
public class GrassController : MonoBehaviour
{
    int _structSize()
    {
        return sizeof(float) + sizeof(float);
    }
    private GameObject cube;

    public float updateInterval;
    float timePassed;
    Terrain terrain;
    public ComputeShader computeShader;

    [Header("equation coeffs")]
    public float DWater = 1.0f;
    public float DVegetation = 0.5f;
    public float feedRate = 0.055f;
    public float killRate = 0.0462f;
    public float dT = 0.10f;
    public int stepsNumber = 1;


    int sizeX;
    int sizeY;

    ComputeBuffer vegetation;
    ComputeBuffer oldVegetation;
    // Start is called before the first frame update
    void Start()
    {
        terrain = gameObject.GetComponent<Terrain>();

        sizeX = terrain.terrainData.detailWidth;
        sizeY = terrain.terrainData.detailHeight;

        initComputeShader();
    }


    bool doUpdate()
    {
        timePassed += Time.deltaTime;
        if (timePassed < updateInterval)
        {
            return false;
        }
        else
        {
            timePassed = 0;
            return true;
        }

    }

    void initKillFeedBuffers()
    {
        //tutaj stworz
    }
    public void initBufferValues()
    {

        // tutaj uzupelnij wartosci buforow
        float[] initValues = new float[sizeX * sizeY];

        for (int i = 0; i < sizeX * sizeY; i++)
        {
            initValues[i] = Random.Range(0.0f, 1.0f);
        }
        vegetation.SetData(initValues);
        oldVegetation.SetData(initValues);
    }

    public void resetGrass()
    {
        initBufferValues();

        //var detail = new int[sizeX, sizeY];

        //for (int i = 0; i < sizeX; i++) {
        //    detail[i, i] = 16;
        //}
        //terrain.terrainData.SetDetailLayer(0, 0, 1, detail);




    }
    void initParameters()
    {
        //tutaj zainicjalizuj parametry
        computeShader.SetInt("sizeX", sizeX);
        computeShader.SetInt("sizeY", sizeY);

    }
    void initComputeShader()
    {
        //tutaj zainicjalizuj compute shader
        vegetation = new ComputeBuffer(sizeX * sizeY, sizeof(float));
        oldVegetation = new ComputeBuffer(sizeX * sizeY, sizeof(float));

        computeShader.SetBuffer(0, "vegetation", vegetation);
        computeShader.SetBuffer(0, "oldVegetation", oldVegetation);

        initKillFeedBuffers();
        initBufferValues();
        initParameters();
    }


    void swapBuffers()
    {
        //tutaj zamien bufory ze soba
        var temp = vegetation;
        vegetation = oldVegetation;
        oldVegetation = temp;

        computeShader.SetBuffer(0, "vegetation", vegetation);
        computeShader.SetBuffer(0, "oldVegetation", oldVegetation);
    }
    void doSimulationSteps(int steps)
    {
        //tutaj wykonaj kroki symulacji
        for (int i = 0; i < steps; i++)
        {
            computeShader.Dispatch(0, sizeX, sizeY, 1);
        }
    }

    void recoverData()
    {
        //tutaj odczytaj bufor i przeslij wynik jako mapa detali
        var result = new float[sizeX * sizeY];
        vegetation.GetData(result);
        int[,] detailLayer = new int[sizeX, sizeY];

        for (int i = 0; i < sizeX; i++)
        {
            for (int j = 0; j < sizeX; j++)
            {
                detailLayer[i, j] = Mathf.FloorToInt(result[i + j * sizeX] * 10);
            }
        }

        terrain.terrainData.SetDetailLayer(0, 0, 1, detailLayer);
    }
    // Update is called once per frame
    void Update()
    {
        if (doUpdate())
        {
            terrain = gameObject.GetComponent<Terrain>();
            initParameters();
            doSimulationSteps(stepsNumber);
            recoverData();
        }
    }
}