// Copyright (c) 2024 Nico de Poel
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using UnityEngine;

namespace FidelityFX.FrameGen
{
    /// <summary>
    /// Scriptable object containing all shader resources required by FidelityFX Optical Flow.
    /// These can be stored in an asset file and referenced from a scene or prefab, avoiding the need to load the shaders from a Resources folder.
    /// </summary>
    [CreateAssetMenu(fileName = "Optical Flow Assets", menuName = "FidelityFX/Optical Flow Assets", order = 1111)]
    public class OpticalFlowAssets : ScriptableObject
    {
        public OpticalFlowShaders shaders;
        
#if UNITY_EDITOR
        private void Reset()
        {
            shaders = new OpticalFlowShaders
            {
                generateOpticalFlowInputPyramid = FindComputeShader("ffx_opticalflow_compute_luminance_pyramid_pass"),
                prepareLuma = FindComputeShader("ffx_opticalflow_prepare_luma_pass"),
                generateScdHistogram = FindComputeShader("ffx_opticalflow_generate_scd_histogram_pass"),
                computeScdDivergence = FindComputeShader("ffx_opticalflow_compute_scd_divergence_pass"),
                computeOpticalFlow = FindComputeShader("ffx_opticalflow_compute_optical_flow_advanced_pass_v5"),
                filterOpticalFlow = FindComputeShader("ffx_opticalflow_filter_optical_flow_pass_v5"),
                scaleOpticalFlow = FindComputeShader("ffx_opticalflow_scale_optical_flow_advanced_pass_v5"),
            };
        }

        private static ComputeShader FindComputeShader(string name)
        {
            string[] assetGuids = UnityEditor.AssetDatabase.FindAssets($"t:ComputeShader {name}");
            if (assetGuids == null || assetGuids.Length == 0)
                return null;

            string assetPath = UnityEditor.AssetDatabase.GUIDToAssetPath(assetGuids[0]);
            return UnityEditor.AssetDatabase.LoadAssetAtPath<ComputeShader>(assetPath);
        }
#endif
    }
    
    /// <summary>
    /// All the compute shaders used by Optical Flow.
    /// </summary>
    [System.Serializable]
    public class OpticalFlowShaders
    {
        /// <summary>
        /// The compute shader used by the generate optical flow input pass.
        /// </summary>
        public ComputeShader generateOpticalFlowInputPyramid;

        /// <summary>
        /// The compute shader used by the prepare luma pass.
        /// </summary>
        public ComputeShader prepareLuma;

        /// <summary>
        /// The compute shader used by the generate scene change detection histogram pass.
        /// </summary>
        public ComputeShader generateScdHistogram;

        /// <summary>
        /// The compute shader used by the compute scene change detection divergence pass.
        /// </summary>
        public ComputeShader computeScdDivergence;

        /// <summary>
        /// The compute shader used by the compute optical flow pass.
        /// </summary>
        public ComputeShader computeOpticalFlow;

        /// <summary>
        /// The compute shader used by the filter optical flow pass.
        /// </summary>
        public ComputeShader filterOpticalFlow;

        /// <summary>
        /// The compute shader used by the scale optical flow mask.
        /// </summary>
        public ComputeShader scaleOpticalFlow;
        
        /// <summary>
        /// Returns a copy of this class and its contents.
        /// </summary>
        public OpticalFlowShaders Clone()
        {
            return (OpticalFlowShaders)MemberwiseClone();
        }

        /// <summary>
        /// Returns a copy of this class with clones of all its shaders.
        /// This can be useful if you're running multiple Optical Flow instances with different shader configurations.
        /// Be sure to clean up these clones through Dispose once you're done with them.
        /// </summary>
        public OpticalFlowShaders DeepCopy()
        {
            return new OpticalFlowShaders
            {
                generateOpticalFlowInputPyramid = Object.Instantiate(generateOpticalFlowInputPyramid),
                prepareLuma = Object.Instantiate(prepareLuma),
                generateScdHistogram = Object.Instantiate(generateScdHistogram),
                computeScdDivergence = Object.Instantiate(computeScdDivergence),
                computeOpticalFlow = Object.Instantiate(computeOpticalFlow),
                filterOpticalFlow = Object.Instantiate(filterOpticalFlow),
                scaleOpticalFlow = Object.Instantiate(scaleOpticalFlow),
            };
        }

        /// <summary>
        /// Destroy all the shaders within this instance.
        /// Use this only on clones created through DeepCopy.
        /// </summary>
        public void Dispose()
        {
            Object.Destroy(scaleOpticalFlow);
            Object.Destroy(filterOpticalFlow);
            Object.Destroy(computeOpticalFlow);
            Object.Destroy(computeScdDivergence);
            Object.Destroy(generateScdHistogram);
            Object.Destroy(prepareLuma);
            Object.Destroy(generateOpticalFlowInputPyramid);
        }
    }
}