// Modified version of stencil render pass by Alexander Ameye.
// https://alexanderameye.github.io/
// https://twitter.com/alexanderameye/status/1332286868222775298

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

public class JumpFloodOutlineStencilPass : ScriptableRenderPass
{
  private const string k_ProfilerTag = "JumpFlood Outline Stencil Pass";
  private const string k_ShaderName = "Hidden/shader_jumpflood_outline";

  public static class ShaderIDs
  {
    private static readonly ShaderTagId SRPDefaultUnlit = new ShaderTagId("SRPDefaultUnlit");
    private static readonly ShaderTagId UniversalForward = new ShaderTagId("UniversalForward");
    private static readonly ShaderTagId LightweightForward = new ShaderTagId("LightweightForward");

    public static readonly List<ShaderTagId> ShaderTags = new List<ShaderTagId>
    {
        SRPDefaultUnlit, UniversalForward, LightweightForward,
    };
  }

  private readonly JumpFloodOutlineFeature.Settings m_settings;

  private readonly Material m_stencilMaterial;
  private FilteringSettings m_filteringSettings;

  public bool IsValid => m_stencilMaterial != null;

  public JumpFloodOutlineStencilPass(JumpFloodOutlineFeature.Settings settings)
  {
    profilingSampler = new ProfilingSampler(k_ProfilerTag);
    m_settings = settings;
    renderPassEvent = settings.renderPassEvent;

    // TODO: Try this again when render layers are working with hybrid renderer.
    // uint renderingLayerMask = 1u << settings.RenderLayer - 1;
    // _filteringSettings = new FilteringSettings(RenderQueueRange.all, settings.LayerMask.value, renderingLayerMask);
    m_filteringSettings = new FilteringSettings(RenderQueueRange.all, settings.layerMask.value);

    int flags = (int)ScriptableRenderPassInput.Depth; // require depth
    this.ConfigureInput((ScriptableRenderPassInput)flags);

    if (!m_stencilMaterial)
    {
      Shader shader = Shader.Find(k_ShaderName);
      shader = shader == null ? settings.outlineShader : shader;

      if (shader != null)
      {
        m_stencilMaterial = CoreUtils.CreateEngineMaterial(shader);
      }
      else
      {
        Debug.LogError($"Failed to Load shader: \"{k_ShaderName}\"");
      }
    }
  }

  public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
  {
    if (IsValid)
    {
      DrawingSettings drawingSettings = CreateDrawingSettings(
          ShaderIDs.ShaderTags,
          ref renderingData,
          m_settings.sortingCriteria
      );
      drawingSettings.overrideMaterial = m_stencilMaterial;
      drawingSettings.overrideMaterialPassIndex = 0;

      // TODO: Switch to this once mismatched markers bug is fixed.
      // CommandBuffer cmd = CommandBufferPool.Get(ProfilerTag);
      CommandBuffer cmd = CommandBufferPool.Get();
      using (new ProfilingScope(cmd, profilingSampler))
      {
        context.ExecuteCommandBuffer(cmd);
        cmd.Clear();
        context.DrawRenderers(renderingData.cullResults, ref drawingSettings, ref m_filteringSettings);
      }

      context.ExecuteCommandBuffer(cmd);
      CommandBufferPool.Release(cmd);
    }
  }
}