#version 330 core

layout(location = 0) out vec4 fragColor;

in vec2 texcoord;

uniform sampler2D hdr_tex;
uniform sampler2D bloom_tex;

uniform vec2 fg_BufferSize;

uniform float bloom_strength;
uniform bool debug_ev100;

const float NOISE_GRANULARITY = 0.5 / 255.0;

// color.glsl
vec3 eotf_sRGB(vec3 linear_srgb);
// aces.glsl
vec3 aces_fitted(vec3 color);
// redout.glsl
vec2 redout_distort(vec2 uv);
vec3 redout_apply(vec3 color, vec2 uv);
// noise.glsl
float rand_2d(vec2 co);

vec3 get_debug_color(float value)
{
    float level = value * 3.14159265 * 0.5;
    vec3 col;
    col.r = sin(level);
    col.g = sin(level * 2.0);
    col.b = cos(level);
    return col;
}

vec3 get_ev100_color(vec3 hdr)
{
    float level;
    if (texcoord.y < 0.05) {
        const float w = 0.001;
        if (texcoord.x >= (0.5 - w) && texcoord.x <= (0.5 + w))
            return vec3(1.0);
        return get_debug_color(texcoord.x);
    }
    float lum = max(dot(hdr, vec3(0.299, 0.587, 0.114)), 0.0001);
    float ev100 = log2(lum * 8.0);
    float norm = ev100 / 12.0 + 0.5;
    return get_debug_color(norm);
}

void main()
{
    if (debug_ev100) {
        fragColor = vec4(get_ev100_color(texture(hdr_tex, texcoord).rgb), 1.0);
        return;
    }

    // Blackout/redout applies a small distortion effect
    vec2 uv = redout_distort(texcoord);

    vec3 hdr_color = texture(hdr_tex, uv).rgb;
    // Apply bloom
    vec3 bloom = texture(bloom_tex, uv).rgb;
    hdr_color = mix(hdr_color, bloom, bloom_strength);
    // Tonemap
    vec3 color = aces_fitted(hdr_color);
    // Apply blackout/redout
    color = redout_apply(color, uv);
    // Gamma correction
    color = eotf_sRGB(color);
    // Dithering
    color += mix(-NOISE_GRANULARITY, NOISE_GRANULARITY, rand_2d(texcoord));

    fragColor = vec4(color, 1.0);
}