using System;
using UnityEngine;

namespace BF
{
    /// <summary>
    /// bloom effect
    /// </summary>
    public class PostEffectBloom : AbsPostEffect
    {
        public static int BlurSizeID = Shader.PropertyToID("_BlurSize");
        public static int BloomID = Shader.PropertyToID("_Bloom");

        Material bloomMaterial;

        [Range(1, 8)]
        int iterations = 1;
        [Range(1, 16)]
        int downSample = 8;
        [Range(0.0f, 2.0f)]
        float luminanceThreshold = 0.6f;

        public int Iterations { get { return iterations; } }
        public int DownSample { get { return downSample; } }
        public float LuminanceThreshold { get { return luminanceThreshold; } }

        public void SetIteration(int iterations)
        {
            this.iterations = iterations;
        }

        public void SetDownSample(int downSample)
        {
            this.downSample = downSample;
        }

        public void SetLuminance(float luminanceThreshold)
        {
            this.luminanceThreshold = luminanceThreshold;
        }

        public PostEffectBloom()
        {
            bloomMaterial = BFMain.Instance.RenderMgr.BloomMat;
        }

        public override PostEffectContext OnRenderImage(PostEffectContext context)
        {
            var src = context.src;
            var dest = context.dest;

            bloomMaterial.SetFloat(LuminanceThresholdID, luminanceThreshold);
            var width = src.width / downSample;
            var height = src.height / downSample;
            var buffer0 = RenderTexture.GetTemporary(width, height, 0);
            buffer0.filterMode = FilterMode.Bilinear;
            Graphics.Blit(src, buffer0, bloomMaterial, 0);

            for (int i = 0; i < iterations; i++)
            {
                bloomMaterial.SetFloat(BlurSizeID, 1.0f + i);
                var buffer1 = RenderTexture.GetTemporary(width, height, 0);
                Graphics.Blit(buffer0, buffer1, bloomMaterial, 1);
                buffer0.DiscardContents();
                RenderTexture.ReleaseTemporary(buffer0);
                buffer0 = buffer1;
                buffer1 = RenderTexture.GetTemporary(width, height, 0);
                Graphics.Blit(buffer0, buffer1, bloomMaterial, 2);
                buffer0.DiscardContents();
                RenderTexture.ReleaseTemporary(buffer0);
                buffer0 = buffer1;
            }

            bloomMaterial.SetTexture(BloomID, buffer0);
            Graphics.Blit(src, dest, bloomMaterial, 3);
            buffer0.DiscardContents();
            RenderTexture.ReleaseTemporary(buffer0);

            return context;
        }
    }
}