#version 420 core

#include <constants.glsl>

#define LIGHTING_TYPE (LIGHTING_TYPE_TRANSMISSION | LIGHTING_TYPE_REFLECTION)

#define LIGHTING_REFLECTION_KIND LIGHTING_REFLECTION_KIND_SPECULAR

#if (FLUID_MODE == FLUID_MODE_CHEAP)
#define LIGHTING_TRANSPORT_MODE LIGHTING_TRANSPORT_MODE_IMPORTANCE
#elif (FLUID_MODE >= FLUID_MODE_MEDIUM)
#define LIGHTING_TRANSPORT_MODE LIGHTING_TRANSPORT_MODE_RADIANCE
#endif

#define LIGHTING_DISTRIBUTION_SCHEME LIGHTING_DISTRIBUTION_SCHEME_MICROFACET

#define LIGHTING_DISTRIBUTION LIGHTING_DISTRIBUTION_BECKMANN

#define HAS_SHADOW_MAPS

#include <globals.glsl>
#include <random.glsl>

layout(location = 0) in vec3 f_pos;
layout(location = 1) flat in uint f_pos_norm;
layout(location = 2) in vec2 f_vel;
// in vec3 f_col;
// in float f_light;
// in vec3 light_pos[2];

// struct ShadowLocals {
//     mat4 shadowMatrices;
//     mat4 texture_mat;
// };
//
// layout (std140)
// uniform u_light_shadows {
//     ShadowLocals shadowMats[/*MAX_LAYER_FACES*/192];
// };

layout(std140, set = 2, binding = 0)
uniform u_locals {
    vec3 model_offs;
    float load_time;
    ivec4 atlas_offs;
};

layout(location = 0) out vec4 tgt_color;

#include <sky.glsl>
#include <light.glsl>
#include <lod.glsl>

void main() {
    #ifdef EXPERIMENTAL_BAREMINIMUM
        tgt_color = vec4(simple_lighting(f_pos.xyz, MU_SCATTER, 1.0), 0.5);
        return;
    #endif

    // tgt_color = vec4(1.0 - MU_WATER, 1.0);
    // return;
    // First 3 normals are negative, next 3 are positive
    vec3 normals[6] = vec3[](vec3(-1,0,0), vec3(1,0,0), vec3(0,-1,0), vec3(0,1,0), vec3(0,0,-1), vec3(0,0,1));

    // TODO: last 3 bits in v_pos_norm should be a number between 0 and 5, rather than 0-2 and a direction.
    uint norm_axis = (f_pos_norm >> 30) & 0x3u;
    // Increase array access by 3 to access positive values
    uint norm_dir = ((f_pos_norm >> 29) & 0x1u) * 3u;
    // Use an array to avoid conditional branching
    vec3 f_norm = normals[norm_axis + norm_dir];

    // vec4 light_pos[2];
// #if (SHADOW_MODE == SHADOW_MODE_MAP)
//     // for (uint i = 0u; i < light_shadow_count.z; ++i) {
//     //     light_pos[i] = /*vec3(*/shadowMats[i].texture_mat * vec4(f_pos, 1.0)/*)*/;
//     // }
//     vec4 sun_pos = /*vec3(*/shadowMats[0].texture_mat * vec4(f_pos, 1.0)/*)*/;
// #elif (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_NONE)
//     vec4 sun_pos = vec4(0.0);
// #endif

    vec3 cam_to_frag = normalize(f_pos - cam_pos.xyz);
    // vec4 vert_pos4 = view_mat * vec4(f_pos, 1.0);
    // vec3 view_dir = normalize(-vec3(vert_pos4)/* / vert_pos4.w*/);
    vec3 view_dir = -cam_to_frag;
    // vec3 surf_color = /*srgb_to_linear*/(vec3(0.4, 0.7, 2.0));
    /*const */vec3 water_color = (1.0 - MU_WATER) * MU_SCATTER;//srgb_to_linear(vec3(0.2, 0.5, 1.0));
    // /*const */vec3 water_color = srgb_to_linear(vec3(0.0, 0.25, 0.5));

    /* vec3 sun_dir = get_sun_dir(time_of_day.x);
    vec3 moon_dir = get_moon_dir(time_of_day.x); */
#if (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_MAP || FLUID_MODE >= FLUID_MODE_MEDIUM)
    float f_alt = alt_at(f_pos.xy);
#elif (SHADOW_MODE == SHADOW_MODE_NONE || FLUID_MODE == FLUID_MODE_CHEAP)
    float f_alt = f_pos.z;
#endif

#if (SHADOW_MODE == SHADOW_MODE_CHEAP || SHADOW_MODE == SHADOW_MODE_MAP)
    vec4 f_shadow = textureBicubic(t_horizon, s_horizon, pos_to_tex(f_pos.xy));
    float sun_shade_frac = horizon_at2(f_shadow, f_alt, f_pos, sun_dir);
#elif (SHADOW_MODE == SHADOW_MODE_NONE)
    float sun_shade_frac = 1.0;//horizon_at2(f_shadow, f_alt, f_pos, sun_dir);
#endif
    float moon_shade_frac = 1.0;//horizon_at2(f_shadow, f_alt, f_pos, moon_dir);
    // float sun_shade_frac = horizon_at(/*f_shadow, f_pos.z, */f_pos, sun_dir);
    // float moon_shade_frac = horizon_at(/*f_shadow, f_pos.z, */f_pos, moon_dir);
    // float shade_frac = /*1.0;*/sun_shade_frac + moon_shade_frac;

    // DirectionalLight sun_info = get_sun_info(sun_dir, sun_shade_frac, light_pos);
    float point_shadow = shadow_at(f_pos, f_norm);
    DirectionalLight sun_info = get_sun_info(sun_dir, point_shadow * sun_shade_frac, /*sun_pos*/f_pos);
    DirectionalLight moon_info = get_moon_info(moon_dir, point_shadow * moon_shade_frac/*, light_pos*/);

    float fluid_alt = f_pos.z;//max(ceil(f_pos.z), floor(f_alt));// f_alt;//max(f_alt - f_pos.z, 0.0);

    const float alpha = 0.255/* / 4.0 / sqrt(2.0)*/;
    const float n2 = 1.3325;
    const float R_s2s0 = pow((1.0 - n2) / (1.0 + n2), 2);
    const float R_s1s0 = pow((1.3325 - n2) / (1.3325 + n2), 2);
    const float R_s2s1 = pow((1.0 - 1.3325) / (1.0 + 1.3325), 2);
    const float R_s1s2 = pow((1.3325 - 1.0) / (1.3325 + 1.0), 2);
    float R_s = (f_pos.z < fluid_alt) ? mix(R_s2s1 * R_s1s0, R_s1s0, medium.x) : mix(R_s2s0, R_s1s2 * R_s2s0, medium.x);

    // Water is transparent so both normals are valid.
    vec3 cam_norm = faceforward(f_norm, f_norm, cam_to_frag);

    vec3 mu = MU_WATER;
    // NOTE: Default intersection point is camera position, meaning if we fail to intersect we assume the whole camera is in water.
    vec3 cam_attenuation = vec3(1.0);//compute_attenuation_point(f_pos, -view_dir, mu, fluid_alt, cam_pos.xyz);

    // NOTE: Assumes normal is vertical.
    vec3 sun_view_dir = cam_pos.z <= fluid_alt ? /*refract(view_dir, -f_norm, 1.0 / n2)*//*reflect(view_dir, -f_norm)*/-view_dir : view_dir;//vec3(view_dir.xy, -view_dir.z) : view_dir;

    vec3 k_a = vec3(1.0);
    vec3 k_d = vec3(1.0);
    vec3 k_s = vec3(R_s);

    vec3 emitted_light, reflected_light;

    // Prevent the sky affecting light when underground
    float not_underground = clamp((f_pos.z - f_alt) / 128.0 + 1.0, 0.0, 1.0);

    // float point_shadow = shadow_at(f_pos, f_norm);
    // vec3 cam_to_frag = normalize(f_pos - cam_pos.xyz);
    // vec3 emitted_light, reflected_light;
    // vec3 light, diffuse_light, ambient_light;
    // Squared to account for prior saturation.
    // float f_light = 1.0;// pow(f_light, 1.5);
    // float vert_light = f_light;
    // vec3 light_frac = /*vec3(1.0);*/light_reflection_factor(f_norm/*vec3(0, 0, 1.0)*/, view_dir, vec3(0, 0, -1.0), vec3(1.0), vec3(R_s), alpha);

    // vec3 surf_color = /*srgb_to_linear*/(vec3(0.4, 0.7, 2.0));
    float max_light = 0.0;
    max_light += get_sun_diffuse2(sun_info, moon_info, f_norm, /*time_of_day.x*//*-cam_to_frag*/sun_view_dir/*view_dir*/, f_pos, mu, cam_attenuation, fluid_alt, k_a/* * (shade_frac * 0.5 + light_frac * 0.5)*/, /*vec3(0.0)*/k_d, k_s, alpha, f_norm, 1.0, emitted_light, reflected_light);

    emitted_light *= not_underground;
    reflected_light *= not_underground;

    // Global illumination when underground (silly)
    emitted_light += (1.0 - not_underground) * 0.05;
    // reflected_light *= f_light * point_shadow * shade_frac;
    // emitted_light *= f_light * point_shadow * max(shade_frac, MIN_SHADOW);
    // max_light *= f_light * point_shadow * shade_frac;
    // reflected_light *= f_light * point_shadow;
    // emitted_light *= f_light * point_shadow;
    // max_light *= f_light * point_shadow;
    // get_sun_diffuse(f_norm, time_of_day.x, light, diffuse_light, ambient_light, 0.0);
    // diffuse_light *= f_light * point_shadow;
    // ambient_light *= f_light, point_shadow;
    // vec3 point_light = light_at(f_pos, f_norm);
    // light += point_light;
    // diffuse_light += point_light;
    // reflected_light += point_light;
    // vec3 surf_color = srgb_to_linear(vec3(0.4, 0.7, 2.0)) * light * diffuse_light * ambient_light;

    // lights_at(f_pos, f_norm, cam_to_frag, k_a * f_light * point_shadow, k_d * f_light * point_shadow, k_s * f_light * point_shadow, alpha, emitted_light, reflected_light);
    /*vec3 point_light = light_at(f_pos, f_norm);
    emitted_light += point_light;
    reflected_light += point_light; */

    max_light += lights_at(f_pos, /*f_norm*/cam_norm, view_dir, mu, cam_attenuation, fluid_alt,  k_a, k_d, k_s, alpha, f_norm, 1.0, emitted_light, reflected_light);
    // vec3 diffuse_light_point = vec3(0.0);
    // max_light += lights_at(f_pos, f_norm, view_dir, k_a, vec3(1.0), k_s, alpha, emitted_light, diffuse_light_point);

    // float reflected_light_point = length(reflected_light);///*length*/(diffuse_light_point.r) + f_light * point_shadow;
    // float reflected_light_point = dot(reflected_light, reflected_light) * 0.5;///*length*/(diffuse_light_point.r) + f_light * point_shadow;
    // vec3 dump_light = vec3(0.0);
    // vec3 specular_light_point = vec3(0.0);
    // lights_at(f_pos, f_norm, view_dir, vec3(0.0), vec3(0.0), /*vec3(1.0)*/k_s, alpha, dump_light, specular_light_point);
    // diffuse_light_point -= specular_light_point;

    // float reflected_light_point = /*length*/(diffuse_light_point.r) + f_light * point_shadow;
    // reflected_light += k_d * (diffuse_light_point + f_light * point_shadow * shade_frac) + specular_light_point;

    float passthrough = max(dot(f_norm, -cam_to_frag), 0) * 0.75;
    float min_refl = 0.0;
    if (medium.x != MEDIUM_WATER) {
        min_refl = min(emitted_light.r, min(emitted_light.g, emitted_light.b));
    }

    vec3 surf_color = illuminate(max_light, view_dir, water_color * /* fog_color * */emitted_light, /*surf_color * */water_color * reflected_light);
    // vec4 color = vec4(surf_color, passthrough * 1.0 / (1.0 + min_refl));// * (1.0 - /*log(1.0 + cam_attenuation)*//*cam_attenuation*/1.0 / (2.0 - log_cam)));
    vec4 color = vec4(surf_color, (1.0 - passthrough) * 1.0 / (1.0 + min_refl));

    tgt_color = color;
}