using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

namespace HighlightPlus {

    public class HighlightPlusRenderPassFeature : ScriptableRendererFeature {
        class HighlightPass : ScriptableRenderPass {

            // far objects render first
            class DistanceComparer : IComparer<HighlightEffect> {

                public Vector3 camPos;

                public int Compare(HighlightEffect e1, HighlightEffect e2) {
                    Vector3 e1Pos = e1 == null ? Vector3.zero : e1.transform.position;
                    float dx1 = e1Pos.x - camPos.x;
                    float dy1 = e1Pos.y - camPos.y;
                    float dz1 = e1Pos.z - camPos.z;
                    float distE1 = dx1 * dx1 + dy1 * dy1 + dz1 * dz1;
                    Vector3 e2Pos = e2 == null ? Vector3.zero : e2.transform.position;
                    float dx2 = e2Pos.x - camPos.x;
                    float dy2 = e2Pos.y - camPos.y;
                    float dz2 = e2Pos.z - camPos.z;
                    float distE2 = dx2 * dx2 + dy2 * dy2 + dz2 * dz2;
                    if (distE1 > distE2) return -1;
                    if (distE1 < distE2) return 1;
                    return 0;
                }
            }


            public bool usesCameraOverlay = false;

            ScriptableRenderer renderer;
            RenderTextureDescriptor cameraTextureDescriptor;
            DistanceComparer effectDistanceComparer;
            static bool isVREnabled;
            bool clearStencil;
            FullScreenBlitMethod fullScreenBlitMethod = FullScreenBlit;

            public void Setup(HighlightPlusRenderPassFeature passFeature, ScriptableRenderer renderer) {
                this.renderPassEvent = passFeature.renderPassEvent;
                this.clearStencil = passFeature.clearStencil;
                this.renderer = renderer;
                if (effectDistanceComparer == null) {
                    effectDistanceComparer = new DistanceComparer();
                }
                isVREnabled = UnityEngine.XR.XRSettings.enabled && Application.isPlaying;
            }

            public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor) {
                this.cameraTextureDescriptor = cameraTextureDescriptor;
#if UNITY_2021_2_OR_NEWER
                ConfigureInput(ScriptableRenderPassInput.Depth);
#endif
            }

            public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData) {

                Camera cam = renderingData.cameraData.camera;
                int camLayer = 1 << cam.gameObject.layer;

                RenderTargetIdentifier cameraColorTarget = renderer.cameraColorTarget;
                RenderTargetIdentifier cameraDepthTarget = renderer.cameraDepthTarget;
#if !UNITY_2021_2_OR_NEWER
                // In Unity 2021.2, when MSAA > 1, cameraDepthTarget is no longer cameraColorTarget
                if (!usesCameraOverlay && (cameraTextureDescriptor.msaaSamples > 1 || cam.cameraType == CameraType.SceneView)) {
                    cameraDepthTarget = cameraColorTarget;
                }
#endif
                if (!HighlightEffect.customSorting && (Time.frameCount % 10 == 0 || !Application.isPlaying)) {
                    effectDistanceComparer.camPos = cam.transform.position;
                    HighlightEffect.effects.Sort(effectDistanceComparer);
                }

                int count = HighlightEffect.effects.Count;
                bool clearStencil = this.clearStencil;
                for (int k = 0; k < count; k++) {
                    HighlightEffect effect = HighlightEffect.effects[k];
                    if (effect.isActiveAndEnabled) {
                        if ((effect.camerasLayerMask & camLayer) == 0) continue;
                        CommandBuffer cb = effect.GetCommandBuffer(cam, cameraColorTarget, cameraDepthTarget, fullScreenBlitMethod, clearStencil);
                        if (cb != null) {
                            context.ExecuteCommandBuffer(cb);
                            clearStencil = false;
                        }
                    }
                }
            }

            static Matrix4x4 matrix4x4identity = Matrix4x4.identity;
            static void FullScreenBlit(CommandBuffer cmd, RenderTargetIdentifier source, RenderTargetIdentifier destination, Material material, int passIndex) {
                destination = new RenderTargetIdentifier(destination, 0, CubemapFace.Unknown, -1);
                cmd.SetRenderTarget(destination);
                cmd.SetGlobalTexture(ShaderParams.MainTex, source);
                cmd.SetGlobalFloat(ShaderParams.AspectRatio, isVREnabled ? 0.5f : 1);
                cmd.DrawMesh(RenderingUtils.fullscreenMesh, matrix4x4identity, material, 0, passIndex);
            }

            public override void FrameCleanup(CommandBuffer cmd) {
            }
        }

        HighlightPass renderPass;
        public RenderPassEvent renderPassEvent = RenderPassEvent.AfterRenderingTransparents;
        [Tooltip("Clears stencil buffer before rendering highlight effects. This option can solve compatibility issues with shaders that also use stencil buffers.")]
        public bool clearStencil;
        public static bool installed;


        void OnDisable() {
            installed = false;
        }

        public override void Create() {
            renderPass = new HighlightPass();
        }

        // This method is called when setting up the renderer once per-camera.
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData) {
#if UNITY_2019_4_OR_NEWER
            if (renderingData.cameraData.renderType == CameraRenderType.Base) {
                Camera cam = renderingData.cameraData.camera;
                renderPass.usesCameraOverlay = cam.GetUniversalAdditionalCameraData().cameraStack.Count > 0;
            }
#endif
            renderPass.Setup(this, renderer);
            renderer.EnqueuePass(renderPass);
            installed = true;
        }
    }

}