Shader "Custom/FrostedGlass"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        [Header(Blur)]
        _BlurRadius ("Blur Radius", Range(0, 20)) = 4.0
        _BlurSamples ("Blur Quality", Range(4, 32)) = 16

        [Header(Frost Noise)]
        _FrostIntensity ("Frost Distortion", Range(0, 0.03)) = 0.005
        _FrostScale ("Frost Scale", Range(10, 300)) = 100

        [Header(Glass Tint)]
        _GlassTint ("Glass Tint Color", Color) = (0.9, 0.95, 1.0, 1.0)
        _TintStrength ("Tint Strength", Range(0, 1)) = 0.15

        [Header(Adjust)]
        _Brightness ("Brightness", Range(0.5, 1.5)) = 1.0
        _Saturation ("Saturation", Range(0, 2)) = 0.85
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }
        Cull Off
        Lighting Off
        ZWrite Off
        Blend SrcAlpha OneMinusSrcAlpha

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 3.0

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float4 color  : COLOR;
                float2 uv     : TEXCOORD0;
            };

            struct v2f
            {
                float4 vertex : SV_POSITION;
                fixed4 color  : COLOR;
                float2 uv     : TEXCOORD0;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _MainTex_TexelSize;

            fixed4 _Color;
            float _BlurRadius;
            float _BlurSamples;
            float _FrostIntensity;
            float _FrostScale;
            fixed4 _GlassTint;
            float _TintStrength;
            float _Brightness;
            float _Saturation;

            float2 hash22(float2 p)
            {
                float3 p3 = frac(float3(p.xyx) * float3(0.1031, 0.1030, 0.0973));
                p3 += dot(p3, p3.yzx + 33.33);
                return frac((p3.xx + p3.yz) * p3.zy) * 2.0 - 1.0;
            }

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                o.color = v.color * _Color;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                float2 texelSize = _MainTex_TexelSize.xy;

                float2 frostNoise = hash22(i.uv * _FrostScale + _Time.y * 0.3);
                float2 frostOffset = frostNoise * _FrostIntensity;

                float samples = max(4.0, _BlurSamples);
                float3 blurColor = float3(0, 0, 0);
                float blurAlpha = 0;
                float totalWeight = 0.0;
                float goldenAngle = 2.39996323;

                for (float s = 0; s < samples; s++)
                {
                    float radius = sqrt((s + 0.5) / samples) * _BlurRadius;
                    float angle = s * goldenAngle;
                    float2 offset = float2(cos(angle), sin(angle)) * radius * texelSize + frostOffset;

                    float weight = 1.0 - (s / samples) * 0.3;
                    fixed4 sample = tex2D(_MainTex, i.uv + offset);
                    blurColor += sample.rgb * weight;
                    blurAlpha += sample.a * weight;
                    totalWeight += weight;
                }

                blurColor /= totalWeight;
                blurAlpha /= totalWeight;

                blurColor *= _Brightness;

                float gray = dot(blurColor, float3(0.299, 0.587, 0.114));
                blurColor = lerp(float3(gray, gray, gray), blurColor, _Saturation);

                blurColor = lerp(blurColor, blurColor * _GlassTint.rgb, _TintStrength);

                return fixed4(blurColor * i.color.rgb, blurAlpha * i.color.a);
            }
            ENDCG
        }
    }
    Fallback "Sprites/Default"
}