Shader "Custom/UniversalLiquidSurface_URP"
{
    Properties
    {
        _MainColor ("Main Color", Color) = (0.0, 0.5, 1.0, 1.0)
        _EmissionColor ("Emission Color", Color) = (1.0, 0.4, 0.0, 1.0)
        _SurfaceType ("Surface Type", Range(0,3)) = 0 // 0: Water, 1: Lava, 2: Ice, 3: River

        _Speed ("Animation Speed", Float) = 1.0
        _DistortionStrength ("Distortion Strength", Float) = 0.1
        _ReflectionStrength ("Reflection Strength", Float) = 0.5

        _MainTex ("Main Texture", 2D) = "white" {}
        _NormalMap ("Normal Map", 2D) = "bump" {}

        _BubbleMask ("Bubble Mask (for Lava)", 2D) = "black" {}
        _BubbleSpeed ("Bubble Rising Speed", Float) = 0.2

        _FoamTex ("Foam Texture (for Water/River)", 2D) = "white" {}
        _FoamStrength ("Foam Strength", Float) = 0.5
    }

    SubShader
    {
        Tags { "RenderPipeline"="UniversalRenderPipeline" "RenderType"="Opaque" }
        LOD 300

        Pass
        {
            Name "ForwardLit"
            Tags { "LightMode"="UniversalForward" }

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile _ _MAIN_LIGHT_SHADOWS
            #pragma multi_compile _ _ADDITIONAL_LIGHTS
            #pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
            #pragma multi_compile _ _SHADOWS_SOFT
            #pragma multi_compile_fog

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"

            struct Attributes
            {
                float4 positionOS : POSITION;
                float2 uv : TEXCOORD0;
                float3 normalOS : NORMAL;
            };

            struct Varyings
            {
                float4 positionHCS : SV_POSITION;
                float2 uv : TEXCOORD0;
                float3 worldPos : TEXCOORD1;
                float3 normalWS : TEXCOORD2;
                float3 viewDirWS : TEXCOORD3;
            };

            sampler2D _MainTex;
            sampler2D _NormalMap;
            sampler2D _BubbleMask;
            sampler2D _FoamTex;

            float4 _MainColor;
            float4 _EmissionColor;
            float _SurfaceType;
            float _Speed;
            float _DistortionStrength;
            float _ReflectionStrength;
            float _BubbleSpeed;
            float _FoamStrength;

            Varyings vert (Attributes IN)
            {
                Varyings OUT;
                OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);
                OUT.uv = IN.uv;
                OUT.worldPos = TransformObjectToWorld(IN.positionOS.xyz);
                OUT.normalWS = TransformObjectToWorldNormal(IN.normalOS);
                OUT.viewDirWS = GetWorldSpaceViewDir(OUT.worldPos);
                return OUT;
            }

            half4 frag (Varyings IN) : SV_Target
            {
                // Animacja UV
                float2 animatedUV = IN.uv + float2(_Time.y * _Speed, _Time.y * _Speed);

                // Tekstury
                half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, animatedUV);
                half3 normalTS = UnpackNormal(SAMPLE_TEXTURE2D(_NormalMap, sampler_NormalMap, animatedUV));
                float2 distortedUV = animatedUV + normalTS.xy * _DistortionStrength;

                // Kolor bazowy
                half3 baseColor = lerp(tex.rgb, _MainColor.rgb, 0.5);

                // Fresnel
                float3 N = normalize(IN.normalWS);
                float3 V = normalize(IN.viewDirWS);
                float fresnel = pow(1.0 - saturate(dot(N, V)), 3.0);

                half3 finalColor = baseColor;
                half3 emission = 0;
                half smoothness = 0.5;

                // Typ powierzchni
                if (_SurfaceType == 0) // 🌊 Woda
                {
                    smoothness = 0.8;
                    emission += fresnel * _ReflectionStrength;

                    half4 foam = SAMPLE_TEXTURE2D(_FoamTex, sampler_FoamTex, IN.uv * 2.0 + float2(0, _Time.y * _Speed));
                    emission += foam.r * _FoamStrength;
                }
                else if (_SurfaceType == 1) // 🔥 Lawa
                {
                    finalColor = _MainColor.rgb;
                    smoothness = 0.3;
                    emission = _EmissionColor.rgb;

                    float2 bubbleUV = IN.uv + float2(0, _Time.y * _BubbleSpeed);
                    half4 bubbleTex = SAMPLE_TEXTURE2D(_BubbleMask, sampler_BubbleMask, bubbleUV);
                    emission += bubbleTex.r * _EmissionColor.rgb * 2.0;
                }
                else if (_SurfaceType == 2) // ❄️ Lód
                {
                    finalColor = _MainColor.rgb;
                    smoothness = 1.0;
                    emission = fresnel * _ReflectionStrength * 0.8;
                }
                else if (_SurfaceType == 3) // 🌿 Rzeka
                {
                    finalColor = tex.rgb * _MainColor.rgb;
                    smoothness = 0.6;

                    half4 foam = SAMPLE_TEXTURE2D(_FoamTex, sampler_FoamTex, IN.uv * 3.0 + float2(_Time.y * _Speed, 0));
                    emission = foam.r * _FoamStrength;
                }

                // Oświetlenie URP
                InputData lightingInput = (InputData)0;
                lightingInput.positionWS = IN.worldPos;
                lightingInput.normalWS = N;
                lightingInput.viewDirectionWS = V;
                lightingInput.shadowCoord = TransformWorldToShadowCoord(IN.worldPos);

                SurfaceData surfaceData;
                surfaceData.albedo = finalColor;
                surfaceData.alpha = 1;
                surfaceData.metallic = 0;
                surfaceData.specular = 0;
                surfaceData.smoothness = smoothness;
                surfaceData.normalTS = normalTS;
                surfaceData.emission = emission;

                return UniversalFragmentPBR(lightingInput, surfaceData);
            }
            ENDHLSL
        }
    }
}