using System;
using UnityEngine;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering;

namespace UnityEngine.Perception.GroundTruth
{
    abstract class GroundTruthCrossPipelinePass : IGroundTruthGenerator
    {
        public Camera targetCamera;

        bool m_IsActivated;

        protected GroundTruthCrossPipelinePass(Camera targetCamera)
        {
            this.targetCamera = targetCamera;
        }

        public virtual void Setup()
        {
            if (targetCamera == null)
                throw new InvalidOperationException("targetCamera may not be null");

            // If we are forced to activate here we will get zeroes in the first frame.
            EnsureActivated();
        }

        public void Execute(
            ScriptableRenderContext renderContext, CommandBuffer cmd, Camera camera, CullingResults cullingResult)
        {
            // CustomPasses are executed for each camera. We only want to run for the target camera
            if (camera != targetCamera)
                return;

            ExecutePass(renderContext, cmd, camera, cullingResult);
        }

        protected abstract void ExecutePass(
            ScriptableRenderContext renderContext, CommandBuffer cmd, Camera camera, CullingResults cullingResult);

        public void EnsureActivated()
        {
            if (!m_IsActivated)
            {
                LabelManager.singleton.Activate(this);
                m_IsActivated = true;
            }
        }

        public void Cleanup()
        {
            LabelManager.singleton.Deactivate(this);
        }

        protected RendererListDesc CreateRendererListDesc(
            Camera camera,
            CullingResults cullingResult,
            string overrideMaterialPassName,
            int overrideMaterialPassIndex,
            Material overrideMaterial,
            LayerMask layerMask)
        {
            var shaderPasses = new[]
            {
                new ShaderTagId("Forward"), // HD Lit shader
                new ShaderTagId("ForwardOnly"), // HD Unlit shader
                new ShaderTagId("SRPDefaultUnlit"), // Cross SRP Unlit shader
                new ShaderTagId("UniversalForward"), // URP Forward
                new ShaderTagId("LightweightForward"), // LWRP Forward
                new ShaderTagId(overrideMaterialPassName), // The override material shader
            };

            var stateBlock = new RenderStateBlock(0)
            {
                depthState = new DepthState(true, CompareFunction.LessEqual),
            };

            var result = new RendererListDesc(shaderPasses, cullingResult, camera)
            {
                rendererConfiguration = PerObjectData.None,
                renderQueueRange = new RenderQueueRange { lowerBound = 0, upperBound = 5000 },
                sortingCriteria = SortingCriteria.CommonOpaque,
                excludeObjectMotionVectors = false,
                overrideMaterial = overrideMaterial,
                overrideMaterialPassIndex = overrideMaterialPassIndex,
                stateBlock = stateBlock,
                layerMask = layerMask,
            };
            return result;
        }

        protected static void DrawRendererList(
            ScriptableRenderContext renderContext, CommandBuffer cmd, RendererList rendererList)
        {
            if (!rendererList.isValid)
                throw new ArgumentException("Invalid renderer list provided to DrawRendererList");

            // This is done here because DrawRenderers API lives outside command buffers so we need to call this before
            // doing any DrawRenders or things will be executed out of order
            renderContext.ExecuteCommandBuffer(cmd);
            cmd.Clear();

            if (rendererList.stateBlock == null)
                renderContext.DrawRenderers(
                    rendererList.cullingResult, ref rendererList.drawSettings, ref rendererList.filteringSettings);
            else
            {
                var renderStateBlock = rendererList.stateBlock.Value;
                renderContext.DrawRenderers(
                    rendererList.cullingResult,
                    ref rendererList.drawSettings,
                    ref rendererList.filteringSettings,
                    ref renderStateBlock);
            }
        }

        public abstract void SetupMaterialProperties(
            MaterialPropertyBlock mpb, Renderer meshRenderer, Labeling labeling, uint instanceId);
    }
}