Shader "Unlit/SolarFlare"
{
    Properties
    {
        _Speed("Flow Speed", Range(0.01, 5.0)) = 1.0
        _Scale("Pattern Scale", Range(0.5, 20.0)) = 3.0
        _FlareColor("Flare Color", Color) = (1.0, 0.3, 0.05, 1.0)
        _HotColor("Hot Color", Color) = (1.0, 0.8, 0.3, 1.0)
        _Intensity("Intensity", Range(0.1, 10.0)) = 3.0
        _FlowDir("Flow Direction", Range(-1, 1)) = 1.0
        _FadeEdge("Edge Fade Power", Range(0.5, 5.0)) = 2.0
        _FadeEnds("End Fade", Range(0.0, 0.5)) = 0.15
        _Wisps("Wisp Count", Range(1.0, 8.0)) = 4.0
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" "Queue"="Transparent" }
        LOD 100
        Blend One One
        ZWrite Off
        Cull Off

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

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

            float _Speed;
            float _Scale;
            float4 _FlareColor;
            float4 _HotColor;
            float _Intensity;
            float _FlowDir;
            float _FadeEdge;
            float _FadeEnds;
            float _Wisps;

            // 3D simplex noise (same as LiquidStar)
            float3 mod289(float3 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
            float4 mod289(float4 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
            float4 permute(float4 x) { return mod289(((x * 34.0) + 10.0) * x); }
            float4 taylorInvSqrt(float4 r) { return 1.79284291400159 - 0.85373472095314 * r; }

            float snoise(float3 v)
            {
                const float2 C = float2(1.0 / 6.0, 1.0 / 3.0);
                const float4 D = float4(0.0, 0.5, 1.0, 2.0);

                float3 i = floor(v + dot(v, C.yyy));
                float3 x0 = v - i + dot(i, C.xxx);

                float3 g = step(x0.yzx, x0.xyz);
                float3 l = 1.0 - g;
                float3 i1 = min(g.xyz, l.zxy);
                float3 i2 = max(g.xyz, l.zxy);

                float3 x1 = x0 - i1 + C.xxx;
                float3 x2 = x0 - i2 + C.yyy;
                float3 x3 = x0 - D.yyy;

                i = mod289(i);
                float4 p = permute(permute(permute(
                    i.z + float4(0.0, i1.z, i2.z, 1.0))
                    + i.y + float4(0.0, i1.y, i2.y, 1.0))
                    + i.x + float4(0.0, i1.x, i2.x, 1.0));

                float n_ = 0.142857142857;
                float3 ns = n_ * D.wyz - D.xzx;

                float4 j = p - 49.0 * floor(p * ns.z * ns.z);

                float4 x_ = floor(j * ns.z);
                float4 y_ = floor(j - 7.0 * x_);

                float4 x = x_ * ns.x + ns.yyyy;
                float4 y = y_ * ns.x + ns.yyyy;
                float4 h = 1.0 - abs(x) - abs(y);

                float4 b0 = float4(x.xy, y.xy);
                float4 b1 = float4(x.zw, y.zw);

                float4 s0 = floor(b0) * 2.0 + 1.0;
                float4 s1 = floor(b1) * 2.0 + 1.0;
                float4 sh = -step(h, float4(0, 0, 0, 0));

                float4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
                float4 a1 = b1.xzyw + s1.xzyw * sh.zzww;

                float3 p0 = float3(a0.xy, h.x);
                float3 p1 = float3(a0.zw, h.y);
                float3 p2 = float3(a1.xy, h.z);
                float3 p3 = float3(a1.zw, h.w);

                float4 norm = taylorInvSqrt(float4(dot(p0,p0), dot(p1,p1), dot(p2,p2), dot(p3,p3)));
                p0 *= norm.x;
                p1 *= norm.y;
                p2 *= norm.z;
                p3 *= norm.w;

                float4 m = max(0.6 - float4(dot(x0,x0), dot(x1,x1), dot(x2,x2), dot(x3,x3)), 0.0);
                m = m * m;
                return 42.0 * dot(m * m, float4(dot(p0,x0), dot(p1,x1), dot(p2,x2), dot(p3,x3)));
            }

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            float4 frag(v2f i) : SV_Target
            {
                float time = _Time.y * _Speed;

                // UV: x wraps around cylinder, y goes along length
                float2 uv = i.uv;

                // Flow along the cylinder length
                float flow = uv.y + time * _FlowDir * 0.2;

                // Wispy tendrils flowing along the cylinder
                float3 p = float3(uv.x * _Scale, flow * _Scale, time * 0.1);

                float n1 = snoise(p);                                    // 1
                float n2 = snoise(p * 1.7 + float3(5.2, time * 0.15, 1.3)); // 2
                float n3 = snoise(p * 0.5 + float3(time * 0.1, 3.1, 7.4)); // 3

                // Wisp pattern - creates streaky tendrils
                float wispAngle = uv.x * _Wisps * 6.2831;
                float wisp = sin(wispAngle + n1 * 3.0 + flow * 4.0) * 0.5 + 0.5;
                wisp = pow(wisp, 3.0);

                // Combine noise layers
                float pattern = wisp * (n2 * 0.5 + 0.5);
                pattern += pow(max(0, n3 * 0.5 + 0.5), 2.0) * 0.3;

                // Pulsing hotspots that travel along the cylinder
                float pulse = snoise(float3(uv.x * 2.0, flow * 2.0, time * 0.3)); // 4
                float hotspot = pow(saturate(pulse), 4.0);

                // Radial fade - fade out at edges of cylinder (using X as wrap-around)
                float radialDist = abs(uv.x - 0.5) * 2.0;
                float radialFade = pow(1.0 - saturate(radialDist), _FadeEdge);

                // End caps fade - fade near top and bottom of cylinder
                float endFade = smoothstep(0.0, _FadeEnds, uv.y) * smoothstep(1.0, 1.0 - _FadeEnds, uv.y);

                // Color
                float3 col = lerp(_FlareColor.rgb, _HotColor.rgb, hotspot + pattern * 0.3);
                col *= _Intensity;

                float alpha = pattern * radialFade * endFade + hotspot * radialFade * endFade * 2.0;
                alpha = saturate(alpha);

                return float4(col * alpha, 1.0);
            }
            ENDCG
        }
    }
}