using System;
using UnityEngine;

public class RainExposure : MonoBehaviour
{
    [Serializable]
    public class Settings
    {
        public float RipplesSpeed = 2f;
        public float WetSpeed = .5f;
        public float RaycastDistance = 50f;
    }

    [Serializable]
    public class References
    {
        public Shader Shader;
        public Renderer[] Renderers;
    }

    [Serializable]
    public class State
    {
        [Range(0f, 1f)] public float Ripples;
        [Range(0f, 1f)] public float Wet;
    }

    [SerializeField] private Settings _settings;
    [SerializeField] private References _references;
    [SerializeField] private State _state;

    private bool covered;
    private float coverDistance;

    private static readonly int RipplesId = Shader.PropertyToID("_Ripples");
    private static readonly int WetId = Shader.PropertyToID("_Wet");

    private readonly RaycastHit[] _hits = new RaycastHit[32];

    void OnDrawGizmosSelected()
    {
        Color col = Color.white;
        if (Application.isPlaying)
            col = covered ? Color.green : Color.red;

        Gizmos.color = col;
        Gizmos.DrawLine(transform.position, transform.position + Vector3.up * (covered ? coverDistance : _settings.RaycastDistance));
    }

    void Update()
    {
        float t = Time.deltaTime;

        covered = IsCovered();
        float target = covered ? 0f : 1f;

        _state.Ripples = Mathf.MoveTowards(_state.Ripples, target, _settings.RipplesSpeed * t);
        _state.Wet = Mathf.MoveTowards(_state.Wet, target, _settings.WetSpeed * t);

        SetMaterials();
    }

    private bool IsCovered()
    {
        int hitCount = Physics.RaycastNonAlloc(transform.position, Vector3.up, _hits, _settings.RaycastDistance);

        for (int i = 0; i < hitCount; i++)
        {
            Collider col = _hits[i].collider;

            if (!col)
                continue;

            if (col.transform == transform || col.transform.IsChildOf(transform))
                continue;

            coverDistance = _hits[i].distance;
            return true;
        }

        return false;
    }

    private void SetMaterials()
    {
        if (!_references.Shader || _references.Renderers == null)
            return;

        for (int i = 0; i < _references.Renderers.Length; i++)
        {
            Renderer rend = _references.Renderers[i];

            if (rend == null)
                continue;

            Material[] mats = rend.materials;

            for (int j = 0; j < mats.Length; j++)
            {
                Material mat = mats[j];

                if (mat == null || mat.shader != _references.Shader)
                    continue;

                mat.SetFloat(RipplesId, _state.Ripples);
                mat.SetFloat(WetId, _state.Wet);
            }
        }
    }
}