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#ifndef SAMPLE_PROBE_GLSLLIB
#define SAMPLE_PROBE_GLSLLIB 1

#include "sampleProbePre.glsllib"

#define USE_RGBE

uniform sampler2D light_probe;
uniform vec4 light_probe_props;
uniform vec4 light_probe_rotation;
uniform vec4 light_probe_offset;    // light_probe_offset.w = number of mipmaps

#if QT3DS_ENABLE_LIGHT_PROBE_2
uniform sampler2D light_probe2;
uniform vec4 light_probe2_props;
#endif

#if QT3DS_ENABLE_IBL_FOV
uniform vec4 light_probe_opts;
#endif

float noise1d(vec2 n)
{
    return 0.5 + 0.5 * fract(sin(dot(n.xy, vec2(12.9898, 78.233))) * 43758.5453);
}

mat3 orthoNormalize(in mat3 tanFrame)
{
   mat3 outMat;
   outMat[0] = normalize(cross(tanFrame[1], tanFrame[2]));
   outMat[1] = normalize(cross(tanFrame[2], outMat[0]));
   outMat[2] = tanFrame[2];

   return outMat;
}

mat3 tangentFrame(vec3 N, vec3 p)
{
    // get edge vectors of the pixel triangle
    vec3 dp1 = dFdx(p);
    vec3 dp2 = dFdy(p);
    // solve the linear system
    vec3 dp2perp = cross(dp2, N);
    vec3 dp1perp = cross(N, dp1);
    vec3 T = normalize(dp1perp);
    vec3 B = normalize(dp2perp);
    return mat3(T, B, N);
}

vec2 transformSample(vec2 origUV, vec4 probeRot, vec2 probeOfs)
{
    vec2 retUV;
    retUV.x = dot(vec3(origUV, 1.0), vec3(probeRot.xy, probeOfs.x));
    retUV.y = dot(vec3(origUV, 1.0), vec3(probeRot.zw, probeOfs.y));
    return retUV;
}

vec3 textureProbe(sampler2D lightProbe, vec2 coord, float lod)
{
#ifdef USE_RGBE
    vec4 ret = textureLod(lightProbe, coord, lod);
    return ret.rgb * pow(2.0, ret.a * 255.0 - 128.0);
#else
    return textureLod(lightProbe, coord, lod).rgb;
#endif
}

// This is broken out into its own routine so that if we get some other
// format image than a lat-long, then we can account for that by changing
// the code here alone.
vec2 getProbeSampleUV(vec3 smpDir, vec4 probeRot, vec2 probeOfs)
{
    vec2 smpUV;

#if QT3DS_ENABLE_IBL_FOV
    smpUV = vec2(atan(smpDir.x, smpDir.z), asin(smpDir.y));
    // assume equirectangular HDR spherical map (instead of cube map) and warp sample
    // UV coordinates accordingly
    smpUV *= 2.0 * vec2(0.1591596371160, 0.318319274232054);
    // Default FOV is 180 deg = pi rad. Narrow the FOV
    // by scaling texture coordinates by the ratio of
    // incoming FOV to 180 degrees default
    smpUV *= 3.14159265358 / light_probe_opts.x;
#else
    smpUV.x = atan( smpDir.x, smpDir.z) / 3.14159265359;
    smpUV.y = 1.0 - (acos(smpDir.y) / 1.57079632679);
#endif
    smpUV = transformSample( smpUV.xy * 0.5, probeRot, probeOfs ) + vec2(0.5, 0.5);

    return smpUV;
}

vec4 getTopLayerSample(vec3 inDir, float lodShift, vec3 lodOffsets)
{
#if QT3DS_ENABLE_LIGHT_PROBE_2
    if (light_probe2_props.w < 0.5)
        return vec4(0.0, 0.0, 0.0, 0.0);

    vec2 smpUV = getProbeSampleUV(inDir, vec4(1.0, 0.0, 0.0, 1.0), light_probe_props.xy);
    smpUV.x -= 0.5;
    smpUV.x *= light_probe2_props.x;
    smpUV.x += light_probe2_props.y;

    vec4 retVal = 0.4 * textureLod(light_probe2, smpUV , lodShift);
    retVal += 0.2 * textureLod(light_probe2, smpUV, lodShift+lodOffsets.x);
    retVal += 0.3 * textureLod(light_probe2, smpUV, lodShift+lodOffsets.y);
    retVal += 0.1 * textureLod(light_probe2, smpUV, lodShift+lodOffsets.z);
    return retVal;
#else
    return vec4(0.0, 0.0, 0.0, 0.0);
#endif
}

vec3 getProbeSample(vec3 smpDir, float lodShift, vec3 normal)
{
    vec2 smpUV = getProbeSampleUV(smpDir, light_probe_rotation, light_probe_offset.xy);
    return textureProbe(light_probe, smpUV , lodShift);
}

vec3 getProbeWeightedSample(vec3 smpDir, float lodShift, float roughness, vec3 normal)
{
    // This gives us a weighted sum that approximates the total filter support
    // of the full-blown convolution.
    vec2 smpUV = getProbeSampleUV(smpDir, light_probe_rotation, light_probe_offset.xy);
    float wt = 1.0;

#if QT3DS_ENABLE_IBL_FOV
    wt = min(wt, smoothstep(roughness * -0.25, roughness * 0.25, smpUV.x));
    wt = min(wt, smoothstep(roughness * -0.25, roughness * 0.25, smpUV.y));
    wt = min(wt, 1.0 - smoothstep(1.0 - roughness * 0.25, 1.0 + roughness * 0.25, smpUV.x));
    wt = min(wt, 1.0 - smoothstep(1.0 - roughness * 0.25, 1.0 + roughness * 0.25, smpUV.y));
#endif

    vec3 lodOffsets;
    lodOffsets.x = mix(-2.0, -0.70710678, roughness);
    lodOffsets.y = min(2.0 * smoothstep(0.0, 0.1, roughness), 2.0 - 1.29289 * smoothstep(0.1, 1.0, roughness));
    lodOffsets.z = min(6.0 * smoothstep(0.0, 0.1, roughness), 6.0 - 4.585786 * smoothstep(0.1, 1.0, roughness));

    ivec2 iSize = lightProbeSize(light_probe, 0);
    vec3 ddx = dFdx(smpDir) * float(iSize.x);
    vec3 ddy = dFdy(smpDir) * float(iSize.y);

    vec2 deriv;
    deriv.x = max(dot(ddx, ddx), dot(ddy, ddy));

    deriv = clamp(deriv, vec2(1.0), vec2(iSize.x * iSize.y));
    vec2 lodBound = 0.5 * log2(deriv) - vec2(1.0);

    float minLod = lodBound.x;
    float maxLod = log2(max(float(iSize.x), float(iSize.y)));
    minLod = clamp(minLod / maxLod, 0.0, 1.0);
    minLod *= minLod * maxLod;

    lodShift = max(lodShift, minLod);

    vec3 retVal = 0.4 * textureProbe(light_probe, smpUV , lodShift);
    retVal += 0.2 * textureProbe(light_probe, smpUV , max(minLod, lodShift+lodOffsets.x));
    retVal += 0.3 * textureProbe(light_probe, smpUV , lodShift+lodOffsets.y);
    retVal += 0.1 * textureProbe(light_probe, smpUV , lodShift+lodOffsets.z);

#if QT3DS_ENABLE_LIGHT_PROBE_2
    vec4 topSmp = getTopLayerSample(smpDir, lodShift, lodOffsets);
    vec3 tempVal = mix(retVal, topSmp.xyz, topSmp.w);
    retVal = mix(retVal, tempVal, light_probe2_props.z);
#endif

    if (light_probe_props.z > -1.0) {
        float ctr = 0.5 + 0.5 * light_probe_props.z;
        float vertWt = smoothstep(ctr-roughness * 0.25, ctr+roughness * 0.25, smpUV.y);
        float wtScaled = mix(1.0, vertWt, light_probe_props.z + 1.0);
        retVal *= wtScaled;
    }

    return retVal * wt;
}

vec4 sampleDiffuse(mat3 tanFrame)
{
    if (light_probe_props.w < 0.005)
        return vec4(0.0);

    return vec4(light_probe_props.w * getProbeWeightedSample(tanFrame[2], light_probe_offset.w - 2.65149613, 1.0, tanFrame[2]), 1.0 );
}

vec4 sampleDiffuseCustomMaterial(vec3 normal, vec3 worldPos, float aoFactor)
{
    mat3 tanFrame = tangentFrame(normal, worldPos);
    return sampleDiffuse(tanFrame);
}

vec4 sampleGlossy(mat3 tanFrame, vec3 viewDir, float roughness)
{
    if (light_probe_props.w < 0.005)
        return vec4(0.0);

    float sigma = smoothstep(0.0, 1.0, clamp(roughness, 0.0001, 1.0));
    vec3 ret = vec3(0, 0, 0);

    vec3 smpDir = reflect(-viewDir, tanFrame[2]);

    // Compute the Geometric occlusion/self-shadowing term
    float NdotL = clamp(dot(smpDir, tanFrame[2]), 0.0, 0.999995);
    float k = sigma * 0.31830988618;    // roughness / pi
    float Gl = clamp((NdotL / (NdotL*(1.0-k) + k) + (1.0 - k*k)) * 0.5, 0.0, 1.0 );

    vec3 outColor;

    outColor = getProbeSample(smpDir, sigma, tanFrame[2]);

    return vec4(light_probe_props.w * Gl * outColor, 1.0);
}

#endif