using System;
using System.Runtime.InteropServices;
using UnityEngine;
using UnityEngine.Experimental.Rendering;

namespace FidelityFX
{
    internal abstract class FfxResourcesBase
    {
        protected static ComputeBuffer CreateBuffer<TElem>(string name, int count)
        {
            return new ComputeBuffer(count, Marshal.SizeOf<TElem>());
        }

        protected static Texture2D CreateLookup(string name, GraphicsFormat format, Color data)
        {
            var tex = new Texture2D(1, 1, format, TextureCreationFlags.None) { name = name };
            tex.SetPixel(0, 0, data);
            tex.Apply();
            return tex;
        }
        
        protected static Texture2D CreateLookup<T>(string name, in Vector2Int size, GraphicsFormat format, T[] data)
        {
            var tex = new Texture2D(size.x, size.y, format, TextureCreationFlags.None) { name = name };
            tex.SetPixelData(data, 0);
            tex.Apply();
            return tex;
        }
        
        protected static RenderTexture CreateResource(string name, in Vector2Int size, GraphicsFormat format)
        {
            var rt = new RenderTexture(size.x, size.y, 0, format) { name = name, enableRandomWrite = true };
            rt.Create();
            return rt;
        }
        
        protected static RenderTexture CreateResourceMips(string name, in Vector2Int size, GraphicsFormat format)
        {
            int mipCount = 1 + Mathf.FloorToInt(Mathf.Log(Math.Max(size.x, size.y), 2.0f));
            var rt = new RenderTexture(size.x, size.y, 0, format, mipCount) { name = name, enableRandomWrite = true, useMipMap = true, autoGenerateMips = false };
            rt.Create();
            return rt;
        }
        
        protected static void CreateDoubleBufferedResource(RenderTexture[] resource, string name, in Vector2Int size, GraphicsFormat format, int numElements = 2)
        {
            numElements = Math.Min(resource.Length, numElements);
            for (int i = 0; i < numElements; ++i)
            {
                resource[i] = new RenderTexture(size.x, size.y, 0, format) { name = name + (i + 1), enableRandomWrite = true };
                resource[i].Create();
            }
        }
        
        protected static void DestroyResource(ref Texture2D resource)
        {
            if (resource == null)
                return;
            
#if UNITY_EDITOR
            if (Application.isPlaying && !UnityEditor.EditorApplication.isPaused)
                UnityEngine.Object.Destroy(resource);
            else
                UnityEngine.Object.DestroyImmediate(resource);
#else
            UnityEngine.Object.Destroy(resource);
#endif
            resource = null;
        }

        protected static void DestroyResource(ref RenderTexture resource)
        {
            if (resource == null)
                return;
            
            resource.Release();
            resource = null;
        }
        
        protected static void DestroyResource(ref ComputeBuffer resource)
        {
            if (resource == null)
                return;
            
            resource.Release();
            resource = null;
        }

        protected static void DestroyResource(RenderTexture[] resource)
        {
            for (int i = 0; i < resource.Length; ++i)
                DestroyResource(ref resource[i]);
        }
    }
}