// Crest Water System
// Copyright © 2024 Wave Harmonic. All rights reserved.

using UnityEngine;
using UnityEngine.Rendering;

namespace WaveHarmonic.Crest
{
    static class RenderPipelineCompatibilityHelper
    {
        // Taken from:
        // https://github.com/Unity-Technologies/Graphics/blob/19ec161f3f752db865597374b3ad1b3eaf110097/Packages/com.unity.render-pipelines.universal/Runtime/RenderingUtils.cs#L588-L634

        /// <summary>
        /// Return true if handle does not match descriptor
        /// </summary>
        /// <param name="handle">RTHandle to check (can be null)</param>
        /// <param name="descriptor">Descriptor for the RTHandle to match</param>
        /// <param name="filterMode">Filtering mode of the RTHandle.</param>
        /// <param name="wrapMode">Addressing mode of the RTHandle.</param>
        /// <param name="isShadowMap">Set to true if the depth buffer should be used as a shadow map.</param>
        /// <param name="anisoLevel">Anisotropic filtering level.</param>
        /// <param name="mipMapBias">Bias applied to mipmaps during filtering.</param>
        /// <param name="name">Name of the RTHandle.</param>
        /// <param name="scaled">Check if the RTHandle has auto scaling enabled if not, check the widths and heights</param>
        /// <returns></returns>
        internal static bool RTHandleNeedsReAlloc(
            RTHandle handle,
            in RenderTextureDescriptor descriptor,
            FilterMode filterMode,
            TextureWrapMode wrapMode,
            bool isShadowMap,
            int anisoLevel,
            float mipMapBias,
            string name,
            bool scaled)
        {
            if (handle == null || handle.rt == null)
                return true;
            if (handle.useScaling != scaled)
                return true;
            if (!scaled && (handle.rt.width != descriptor.width || handle.rt.height != descriptor.height))
                return true;
            return
                handle.rt.descriptor.depthBufferBits != descriptor.depthBufferBits ||
                (handle.rt.descriptor.depthBufferBits == (int)DepthBits.None && !isShadowMap && handle.rt.descriptor.graphicsFormat != descriptor.graphicsFormat) ||
                handle.rt.descriptor.dimension != descriptor.dimension ||
                handle.rt.descriptor.enableRandomWrite != descriptor.enableRandomWrite ||
                handle.rt.descriptor.useMipMap != descriptor.useMipMap ||
                handle.rt.descriptor.autoGenerateMips != descriptor.autoGenerateMips ||
                handle.rt.descriptor.msaaSamples != descriptor.msaaSamples ||
                handle.rt.descriptor.bindMS != descriptor.bindMS ||
                handle.rt.descriptor.useDynamicScale != descriptor.useDynamicScale ||
                handle.rt.descriptor.memoryless != descriptor.memoryless ||
                handle.rt.filterMode != filterMode ||
                handle.rt.wrapMode != wrapMode ||
                handle.rt.anisoLevel != anisoLevel ||
                handle.rt.mipMapBias != mipMapBias ||
                handle.name != name;
        }


        // https://github.com/Unity-Technologies/Graphics/blob/19ec161f3f752db865597374b3ad1b3eaf110097/Packages/com.unity.render-pipelines.universal/Runtime/RenderingUtils.cs#L666-L695

        /// <summary>
        /// Re-allocate fixed-size RTHandle if it is not allocated or doesn't match the descriptor
        /// </summary>
        /// <param name="handle">RTHandle to check (can be null)</param>
        /// <param name="descriptor">Descriptor for the RTHandle to match</param>
        /// <param name="filterMode">Filtering mode of the RTHandle.</param>
        /// <param name="wrapMode">Addressing mode of the RTHandle.</param>
        /// <param name="isShadowMap">Set to true if the depth buffer should be used as a shadow map.</param>
        /// <param name="anisoLevel">Anisotropic filtering level.</param>
        /// <param name="mipMapBias">Bias applied to mipmaps during filtering.</param>
        /// <param name="name">Name of the RTHandle.</param>
        /// <returns></returns>
        public static bool ReAllocateIfNeeded(
            ref RTHandle handle,
            in RenderTextureDescriptor descriptor,
            FilterMode filterMode = FilterMode.Point,
            TextureWrapMode wrapMode = TextureWrapMode.Repeat,
            bool isShadowMap = false,
            int anisoLevel = 1,
            float mipMapBias = 0,
            string name = "")
        {
            if (RTHandleNeedsReAlloc(handle, descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name, false))
            {
                handle?.Release();
                handle = RTHandles.Alloc(descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name);
                return true;
            }
            return false;
        }

        // https://github.com/Unity-Technologies/Graphics/blob/19ec161f3f752db865597374b3ad1b3eaf110097/Packages/com.unity.render-pipelines.universal/Runtime/RenderingUtils.cs#L697-L729

        /// <summary>
        /// Re-allocate dynamically resized RTHandle if it is not allocated or doesn't match the descriptor
        /// </summary>
        /// <param name="handle">RTHandle to check (can be null)</param>
        /// <param name="scaleFactor">Constant scale for the RTHandle size computation.</param>
        /// <param name="descriptor">Descriptor for the RTHandle to match</param>
        /// <param name="filterMode">Filtering mode of the RTHandle.</param>
        /// <param name="wrapMode">Addressing mode of the RTHandle.</param>
        /// <param name="isShadowMap">Set to true if the depth buffer should be used as a shadow map.</param>
        /// <param name="anisoLevel">Anisotropic filtering level.</param>
        /// <param name="mipMapBias">Bias applied to mipmaps during filtering.</param>
        /// <param name="name">Name of the RTHandle.</param>
        /// <returns>If the RTHandle should be re-allocated</returns>
        public static bool ReAllocateIfNeeded(
            ref RTHandle handle,
            Vector2 scaleFactor,
            in RenderTextureDescriptor descriptor,
            FilterMode filterMode = FilterMode.Point,
            TextureWrapMode wrapMode = TextureWrapMode.Repeat,
            bool isShadowMap = false,
            int anisoLevel = 1,
            float mipMapBias = 0,
            string name = "")
        {
            var usingConstantScale = handle != null && handle.useScaling && handle.scaleFactor == scaleFactor;
            if (!usingConstantScale || RTHandleNeedsReAlloc(handle, descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name, true))
            {
                handle?.Release();
                handle = RTHandles.Alloc(scaleFactor, descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name);
                return true;
            }
            return false;
        }

        // https://github.com/Unity-Technologies/Graphics/blob/19ec161f3f752db865597374b3ad1b3eaf110097/Packages/com.unity.render-pipelines.universal/Runtime/RenderingUtils.cs#L731-L764

        /// <summary>
        /// Re-allocate dynamically resized RTHandle if it is not allocated or doesn't match the descriptor
        /// </summary>
        /// <param name="handle">RTHandle to check (can be null)</param>
        /// <param name="scaleFunc">Function used for the RTHandle size computation.</param>
        /// <param name="descriptor">Descriptor for the RTHandle to match</param>
        /// <param name="filterMode">Filtering mode of the RTHandle.</param>
        /// <param name="wrapMode">Addressing mode of the RTHandle.</param>
        /// <param name="isShadowMap">Set to true if the depth buffer should be used as a shadow map.</param>
        /// <param name="anisoLevel">Anisotropic filtering level.</param>
        /// <param name="mipMapBias">Bias applied to mipmaps during filtering.</param>
        /// <param name="name">Name of the RTHandle.</param>
        /// <returns>If an allocation was done</returns>
        public static bool ReAllocateIfNeeded(
            ref RTHandle handle,
            ScaleFunc scaleFunc,
            in RenderTextureDescriptor descriptor,
            FilterMode filterMode = FilterMode.Point,
            TextureWrapMode wrapMode = TextureWrapMode.Repeat,
            bool isShadowMap = false,
            int anisoLevel = 1,
            float mipMapBias = 0,
            string name = "")
        {
            var usingScaleFunction = handle != null && handle.useScaling && handle.scaleFactor == Vector2.zero;
            if (!usingScaleFunction || RTHandleNeedsReAlloc(handle, descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name, true))
            {
                handle?.Release();
                handle = RTHandles.Alloc(scaleFunc, descriptor, filterMode, wrapMode, isShadowMap, anisoLevel, mipMapBias, name);
                return true;
            }

            return false;
        }
    }
}