using System;
using System.Reflection;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

namespace BadDog.Rendering.AreaLight
{
    public class ShadowAtlasResolutionAttribute : PropertyAttribute
    {
    }

    [Serializable]
    public class AreaLightSettings
    {
        [Tooltip("Maximum number of area lights processed per frame")]
        [Range(0, 8)]
        public int maxAreaLights = 8;
        
        [Tooltip("Pre-integrated FGD shader for GGX and Disney Diffuse")]
        public Shader preIntegratedFGD_GGXDisneyDiffuse;
        
        [Tooltip("Pre-integrated FGD shader for Charlie and Fabric Lambert")]
        public Shader preIntegratedFGD_CharlieFabricLambert;
        
        [Tooltip("Pre-integrated FGD shader for Marschner")]
        public Shader preIntegratedFGD_Marschner;
    }

    [Serializable]
    public class AreaLightShadowSettings
    {
        public enum BGAreaLightShadowMode
        {
            Off = 0,
            PCF2x2 = 1,
            Tent5x5 = 2,
            Tent7x7 = 3,
            PCSS = 4,
        }
        
        [Tooltip("Resolution of the area light shadow atlas (e.g., 512, 1024, 2048, 4096, 8192).)")]
        [ShadowAtlasResolution]
        public int shadowAtlasResolution = 1024;
        
        [Tooltip("Maximum number of area lights that can cast shadows simultaneously")]
        [Range(0, 8)]
        public int maxShadowCastingLights = 8;

        [Tooltip("Shadow filtering mode")] 
        public BGAreaLightShadowMode shadowFilter = BGAreaLightShadowMode.Tent5x5;

        [Tooltip("Softness radius in world units for PCSS")]
        [Range(0.0f, 32.0f)]
        public float pcssShadowSoftness = 2f;
        [Tooltip("Number of samples used to search blockers in PCSS.")]
        [Range(4, 32)]
        public int pcssBlockerSampleCount = 16;

        [Tooltip("Number of samples used for PCSS filtering.")] [Range(4, 32)]
        public int pcssFilterSampleCount = 16;
        
        public string GetShadowKeyword()
        {
            switch (shadowFilter)
            {
                case BGAreaLightShadowMode.Off:
                    return null;  // No keyword = off
                case BGAreaLightShadowMode.PCF2x2:
                    return "_BG_AREALIGHT_SHADOWS_PCF2X2";
                case BGAreaLightShadowMode.Tent5x5:
                    return "_BG_AREALIGHT_SHADOWS_TENT5X5";
                case BGAreaLightShadowMode.Tent7x7:
                    return "_BG_AREALIGHT_SHADOWS_TENT7X7";
                case BGAreaLightShadowMode.PCSS:
                    return "_BG_AREALIGHT_SHADOWS_PCSS";
                default:
                    return null;
            }
        }
    }
    
    public class AreaLighting : ScriptableRendererFeature
    {
        [SerializeField]
        private AreaLightSettings m_LightSettings = new AreaLightSettings();
        
        [SerializeField]
        private AreaLightShadowSettings m_ShadowSettings = new AreaLightShadowSettings();
        
        private AreaLightingPass m_AreaLightingPass;

        public override void Create()
        {
            if (m_AreaLightingPass == null)
            {
                m_AreaLightingPass = new AreaLightingPass();
            }
        }

        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            GraphicsSettings.realtimeDirectRectangularAreaLights = true;
            m_AreaLightingPass.Setup(m_LightSettings, m_ShadowSettings, renderingData);
            renderer.EnqueuePass(m_AreaLightingPass);
        }

        protected override void Dispose(bool disposing)
        {
            m_AreaLightingPass?.Dispose();
            m_AreaLightingPass = null;
        }
    }
}