// MIT License

// Copyright (c) 2023 João Chrisóstomo

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

//!HOOK CHROMA
//!BIND LUMA
//!BIND HOOKED
//!SAVE LUMA_LOWRES
//!WIDTH CHROMA.w
//!HEIGHT LUMA.h
//!WHEN CHROMA.w LUMA.w <
//!DESC Joint Bilateral (Downscaling Luma 1st Step)

vec4 hook() {
    float factor = ceil(LUMA_size.x / HOOKED_size.x);
    int start = int(ceil(-factor / 2.0 - 0.5));
    int end = int(floor(factor / 2.0 - 0.5));

    float output_luma = 0.0;
    int wt = 0;
    for (int dx = start; dx <= end; dx++) {
        output_luma += LUMA_texOff(vec2(dx + 0.5, 0.0)).x;
        wt++;
    }
    vec4 output_pix = vec4(output_luma / float(wt), 0.0, 0.0, 1.0);
    return output_pix;
}

//!HOOK CHROMA
//!BIND LUMA_LOWRES
//!BIND HOOKED
//!SAVE LUMA_LOWRES
//!WIDTH CHROMA.w
//!HEIGHT CHROMA.h
//!WHEN CHROMA.w LUMA.w <
//!DESC Joint Bilateral (Downscaling Luma 2nd Step)

vec4 hook() {
    float factor = ceil(LUMA_LOWRES_size.y / HOOKED_size.y);
    int start = int(ceil(-factor / 2.0 - 0.5));
    int end = int(floor(factor / 2.0 - 0.5));

    float output_luma = 0.0;
    int wt = 0;
    for (int dy = start; dy <= end; dy++) {
        output_luma += LUMA_LOWRES_texOff(vec2(0.0, dy + 0.5)).x;
        wt++;
    }
    vec4 output_pix = vec4(output_luma / float(wt), 0.0, 0.0, 1.0);
    return output_pix;
}

//!PARAM distance_coeff
//!TYPE float
//!MINIMUM 0.0
0.5

//!PARAM intensity_coeff
//!TYPE float
//!MINIMUM 0.0
512.0

//!HOOK CHROMA
//!BIND LUMA
//!BIND LUMA_LOWRES
//!BIND HOOKED
//!WIDTH LUMA.w
//!HEIGHT LUMA.h
//!WHEN CHROMA.w LUMA.w <
//!OFFSET ALIGN
//!DESC Joint Bilateral (Upscaling Chroma)

#define USE_SHARP_SPATIAL_FILTER 1

float comp_wd1(vec2 distance) {
    float d2 = min(pow(length(distance), 2.0), 4.0);
    return (25.0 / 16.0 * pow(2.0 / 5.0 * d2 - 1.0, 2.0) - (25.0 / 16.0 - 1.0)) * pow(1.0 / 4.0 * d2 - 1.0, 2.0);
}

float comp_wd2(vec2 distance) {
    return exp(-distance_coeff * pow(length(distance), 2.0));
}

float comp_wi(float distance) {
    return exp(-intensity_coeff * pow(distance, 2.0));
}

vec4 hook() {
#if (USE_SHARP_SPATIAL_FILTER == 1)
    float ar_strength = 0.5;
    float division_limit = 1e-4;
#endif
    float luma_zero = LUMA_texOff(0.0).x;
    vec4 output_pix = vec4(0.0, 0.0, 0.0, 1.0);

    vec2 pp = HOOKED_pos * HOOKED_size - vec2(0.5);
    vec2 fp = floor(pp);
    pp -= fp;

    vec2 chroma_pixels[12];
    chroma_pixels[0]  = HOOKED_tex(vec2((fp + vec2(0.5, -0.5)) * HOOKED_pt)).xy;
    chroma_pixels[1]  = HOOKED_tex(vec2((fp + vec2(1.5, -0.5)) * HOOKED_pt)).xy;
    chroma_pixels[2]  = HOOKED_tex(vec2((fp + vec2(-0.5, 0.5)) * HOOKED_pt)).xy;
    chroma_pixels[3]  = HOOKED_tex(vec2((fp + vec2( 0.5, 0.5)) * HOOKED_pt)).xy;
    chroma_pixels[4]  = HOOKED_tex(vec2((fp + vec2( 1.5, 0.5)) * HOOKED_pt)).xy;
    chroma_pixels[5]  = HOOKED_tex(vec2((fp + vec2( 2.5, 0.5)) * HOOKED_pt)).xy;
    chroma_pixels[6]  = HOOKED_tex(vec2((fp + vec2(-0.5, 1.5)) * HOOKED_pt)).xy;
    chroma_pixels[7]  = HOOKED_tex(vec2((fp + vec2( 0.5, 1.5)) * HOOKED_pt)).xy;
    chroma_pixels[8]  = HOOKED_tex(vec2((fp + vec2( 1.5, 1.5)) * HOOKED_pt)).xy;
    chroma_pixels[9]  = HOOKED_tex(vec2((fp + vec2( 2.5, 1.5)) * HOOKED_pt)).xy;
    chroma_pixels[10] = HOOKED_tex(vec2((fp + vec2( 0.5, 2.5)) * HOOKED_pt)).xy;
    chroma_pixels[11] = HOOKED_tex(vec2((fp + vec2( 1.5, 2.5)) * HOOKED_pt)).xy;

    float luma_pixels[12];
    luma_pixels[0]  = LUMA_LOWRES_tex(vec2((fp + vec2(0.5, -0.5)) * HOOKED_pt)).x;
    luma_pixels[1]  = LUMA_LOWRES_tex(vec2((fp + vec2(1.5, -0.5)) * HOOKED_pt)).x;
    luma_pixels[2]  = LUMA_LOWRES_tex(vec2((fp + vec2(-0.5, 0.5)) * HOOKED_pt)).x;
    luma_pixels[3]  = LUMA_LOWRES_tex(vec2((fp + vec2( 0.5, 0.5)) * HOOKED_pt)).x;
    luma_pixels[4]  = LUMA_LOWRES_tex(vec2((fp + vec2( 1.5, 0.5)) * HOOKED_pt)).x;
    luma_pixels[5]  = LUMA_LOWRES_tex(vec2((fp + vec2( 2.5, 0.5)) * HOOKED_pt)).x;
    luma_pixels[6]  = LUMA_LOWRES_tex(vec2((fp + vec2(-0.5, 1.5)) * HOOKED_pt)).x;
    luma_pixels[7]  = LUMA_LOWRES_tex(vec2((fp + vec2( 0.5, 1.5)) * HOOKED_pt)).x;
    luma_pixels[8]  = LUMA_LOWRES_tex(vec2((fp + vec2( 1.5, 1.5)) * HOOKED_pt)).x;
    luma_pixels[9]  = LUMA_LOWRES_tex(vec2((fp + vec2( 2.5, 1.5)) * HOOKED_pt)).x;
    luma_pixels[10] = LUMA_LOWRES_tex(vec2((fp + vec2( 0.5, 2.5)) * HOOKED_pt)).x;
    luma_pixels[11] = LUMA_LOWRES_tex(vec2((fp + vec2( 1.5, 2.5)) * HOOKED_pt)).x;

    vec2 chroma_min = vec2(1e8);
    chroma_min = min(chroma_min, chroma_pixels[3]);
    chroma_min = min(chroma_min, chroma_pixels[4]);
    chroma_min = min(chroma_min, chroma_pixels[7]);
    chroma_min = min(chroma_min, chroma_pixels[8]);

    vec2 chroma_max = vec2(1e-8);
    chroma_max = max(chroma_max, chroma_pixels[3]);
    chroma_max = max(chroma_max, chroma_pixels[4]);
    chroma_max = max(chroma_max, chroma_pixels[7]);
    chroma_max = max(chroma_max, chroma_pixels[8]);

#if (USE_SHARP_SPATIAL_FILTER == 1)
    float wd1[12];
    wd1[0]  = comp_wd1(vec2( 0.0,-1.0) - pp);
    wd1[1]  = comp_wd1(vec2( 1.0,-1.0) - pp);
    wd1[2]  = comp_wd1(vec2(-1.0, 0.0) - pp);
    wd1[3]  = comp_wd1(vec2( 0.0, 0.0) - pp);
    wd1[4]  = comp_wd1(vec2( 1.0, 0.0) - pp);
    wd1[5]  = comp_wd1(vec2( 2.0, 0.0) - pp);
    wd1[6]  = comp_wd1(vec2(-1.0, 1.0) - pp);
    wd1[7]  = comp_wd1(vec2( 0.0, 1.0) - pp);
    wd1[8]  = comp_wd1(vec2( 1.0, 1.0) - pp);
    wd1[9]  = comp_wd1(vec2( 2.0, 1.0) - pp);
    wd1[10] = comp_wd1(vec2( 0.0, 2.0) - pp);
    wd1[11] = comp_wd1(vec2( 1.0, 2.0) - pp);

    float wt1 = 0.0;
    for (int i = 0; i < 12; i++) {
        wt1 += wd1[i];
    }

    vec2 ct1 = vec2(0.0);
    for (int i = 0; i < 12; i++) {
        ct1 += wd1[i] * chroma_pixels[i];
    }

    vec2 chroma_spatial = clamp(ct1 / wt1, 0.0, 1.0);
    chroma_spatial = mix(chroma_spatial, clamp(chroma_spatial, chroma_min, chroma_max), ar_strength);
#endif
    float wd2[12];
    wd2[0]   = comp_wd2(vec2( 0.0,-1.0) - pp);
    wd2[1]   = comp_wd2(vec2( 1.0,-1.0) - pp);
    wd2[2]   = comp_wd2(vec2(-1.0, 0.0) - pp);
    wd2[3]   = comp_wd2(vec2( 0.0, 0.0) - pp);
    wd2[4]   = comp_wd2(vec2( 1.0, 0.0) - pp);
    wd2[5]   = comp_wd2(vec2( 2.0, 0.0) - pp);
    wd2[6]   = comp_wd2(vec2(-1.0, 1.0) - pp);
    wd2[7]   = comp_wd2(vec2( 0.0, 1.0) - pp);
    wd2[8]   = comp_wd2(vec2( 1.0, 1.0) - pp);
    wd2[9]   = comp_wd2(vec2( 2.0, 1.0) - pp);
    wd2[10]  = comp_wd2(vec2( 0.0, 2.0) - pp);
    wd2[11]  = comp_wd2(vec2( 1.0, 2.0) - pp);

    float wi[12];
    for (int i = 0; i < 12; i++) {
        wi[i] = comp_wi(luma_zero - luma_pixels[i]);
    }

    float w[12];
    for (int i = 0; i < 12; i++) {
        w[i] = wd2[i] * wi[i];
    }

    float wt2 = 0.0;
    for (int i = 0; i < 12; i++) {
        wt2 += w[i];
    }

    vec2 ct2 = vec2(0.0);
    for (int i = 0; i < 12; i++) {
        ct2 += w[i] * chroma_pixels[i];
    }

    vec2 chroma_bilat = clamp(ct2 / wt2, 0.0, 1.0);

#if (USE_SHARP_SPATIAL_FILTER == 1)
    float luma_avg = 0.0;
    for(int i = 0; i < 12; i++) {
        luma_avg += luma_pixels[i];
    }
    luma_avg /= 12.0;

    float luma_var = 0.0;
    for(int i = 0; i < 12; i++) {
        luma_var += pow(luma_pixels[i] - luma_avg, 2.0);
    }

    vec2 chroma_avg = vec2(0.0);
    for(int i = 0; i < 12; i++) {
        chroma_avg += chroma_pixels[i];
    }
    chroma_avg /= 12.0;

    vec2 chroma_var = vec2(0.0);
    for(int i = 0; i < 12; i++) {
        chroma_var += pow(chroma_pixels[i] - chroma_avg, vec2(2.0));
    }

    vec2 luma_chroma_cov = vec2(0.0);
    for(int i = 0; i < 12; i++) {
        luma_chroma_cov += (luma_pixels[i] - luma_avg) * (chroma_pixels[i] - chroma_avg);
    }

    vec2 corr = abs(luma_chroma_cov / max(sqrt(luma_var * chroma_var), division_limit));
    corr = clamp(corr, 0.0, 1.0);

    output_pix.xy = mix(chroma_spatial, chroma_bilat, pow(corr, vec2(2.0)) / 2.0);
    output_pix.xy = clamp(output_pix.xy, 0.0, 1.0);
#else
    output_pix.xy = chroma_bilat;
#endif
    return output_pix;
}