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

public class WaterShapeController : MonoBehaviour
{
    [SerializeField]
    private GameObject wavePointPref;
    [SerializeField]
    private float _springStiffness = 0.1f;
    [SerializeField]
    private float _dampening = 0.3f;
    [SerializeField]
    private List<WaterSpring> _springs = new List<WaterSpring>();
    [SerializeField]
    private SpriteShapeController _spriteShapeController;
    [SerializeField]
    private int _wavesCount = 6;
    [SerializeField]
    private GameObject _wavePoints;
    private int _cornersCount = 2;
    
    private float _spread = 0.006f;

    private void SetWaves()
    {
        Spline waterSpline = _spriteShapeController.spline;
        var waterPointsCount = waterSpline.GetPointCount();

        for (int count = _cornersCount; count < waterPointsCount - _cornersCount; count++)
        {
            waterSpline.RemovePointAt(_cornersCount);
        }

        Vector3 waterTopLeftCorner = waterSpline.GetPosition(1);
        Vector3 waterTopRightCorner = waterSpline.GetPosition(2);
        float waterWidth = waterTopRightCorner.x - waterTopLeftCorner.x;
        float spacingPerWawe = waterWidth / (_wavesCount + 1);

        for (int count = _wavesCount; count > 0; count--)
        {
            int index = _cornersCount;
            float xPosition=waterTopLeftCorner.x+(spacingPerWawe * count);
            Vector3 wavePoint=new Vector3(xPosition,waterTopLeftCorner.y,waterTopLeftCorner.z);
            waterSpline.InsertPointAt(index, wavePoint );
            waterSpline.SetHeight(index, 0f);
            waterSpline.SetCorner(index, false);
        }
        CreateSprings(waterSpline);
        Splash(2, 0.1f);
    }

    private void CreateSprings(Spline waterSpline)
    {
        _springs = new List<WaterSpring>();
        for(int idx=0;idx<_wavesCount+1; idx++)
        {
            int index = idx + 1;

            Smoothen(waterSpline, index);

            GameObject wavePoint = Instantiate(wavePointPref, _wavePoints.transform, false);
            
            wavePoint.transform.position = waterSpline.GetPosition(index);
            WaterSpring waterSpring=wavePoint.GetComponent<WaterSpring>();
            waterSpring.Init(_spriteShapeController);
            _springs.Add( waterSpring );
                
        }
    }

    private void Smoothen(Spline waterSpline, int index)
    {
        Vector3 position = waterSpline.GetPosition(index);
        Vector3 positionPrev = position;
        Vector3 positionNext = position;
        if (index > 1)
        {
            positionPrev = waterSpline.GetPosition(index - 1);
        }
        if (index - 1 <= _wavesCount)
        {
            positionNext = waterSpline.GetPosition(index + 1);
        }

        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;

        SplineUtility.CalculateTangents(position, positionPrev, positionNext, forward, scale, out rightTangent, out leftTangent);

        waterSpline.SetLeftTangent(index, leftTangent);
        waterSpline.SetRightTangent(index, rightTangent);
    }

    private void UpdateSprings()
    {
        int springsCount = _springs.Count;
        float[] left_deltas = new float[springsCount];
        float[] right_deltas = new float[springsCount];
        for (int index = 0; index < springsCount; index++)
        {
            if (index > 0)
            {
                left_deltas[index] = _spread * (_springs[index].Height - _springs[index - 1].Height);
                _springs[index - 1].Velocity += left_deltas[index];
            }
            if (index <springsCount-1)
            {
                right_deltas[index] = _spread * (_springs[index].Height - _springs[index + 1].Height);
                _springs[index + 1].Velocity += right_deltas[index];
            }
        }
    }

    private void Splash(int index,float speed)
    {
        if(index>=0 && index<_springs.Count) {
            _springs[index].Velocity += speed;
        }
    }

    //On Enable for example purposes
    void OnEnable()
    {
        StartCoroutine(CreateWaves());
        foreach (WaterSpring waterSpringComponent in _springs)
        {
            waterSpringComponent.Init(_spriteShapeController);
        }
    }
    IEnumerator CreateWaves()
    {
        foreach (Transform child in _wavePoints.transform)
        {
            StartCoroutine(Destroy(child.gameObject));
        }
        yield return null;
        SetWaves();
        yield return null;
    }
    IEnumerator Destroy(GameObject go)
    {
        yield return null;
        DestroyImmediate(go);
    }

    private void FixedUpdate()
    {
        foreach (WaterSpring spring in _springs)
        {
            spring.WaveSpringUpdate(_springStiffness, _dampening);
            spring.WavePointUpdate();
        }
        UpdateSprings();
    }
}