#include <stdlib.h>
#include <math.h>

#include "shared/types.h"
#include "shared/functions.h"
#include "shared/globals.h"
#include "shared/constants.h"
#include "clouds.h"
#include "sky.h"

#define SPHERE_SIZE 1000.0

SkyDefinition _definition;
SkyQuality _quality;
SkyEnvironment _environment;

void skyInit()
{
    skySetDefinition(skyCreateDefinition());
}

void skySave(FILE* f)
{
    toolsSaveDouble(f, _definition.daytime);
    colorGradationSave(f, _definition.sun_color);
    toolsSaveDouble(f, _definition.sun_radius);
    colorGradationSave(f, _definition.zenith_color);
    colorGradationSave(f, _definition.haze_color);
    toolsSaveDouble(f, _definition.haze_height);
    toolsSaveDouble(f, _definition.haze_smoothing);
}

void skyLoad(FILE* f)
{

    SkyDefinition def;

    def.daytime = toolsLoadDouble(f);
    def.sun_color = colorGradationLoad(f);
    def.sun_radius = toolsLoadDouble(f);
    def.zenith_color = colorGradationLoad(f);
    def.haze_color = colorGradationLoad(f);
    def.haze_height = toolsLoadDouble(f);
    def.haze_smoothing = toolsLoadDouble(f);

    skySetDefinition(def);
}

SkyDefinition skyCreateDefinition()
{
    SkyDefinition def;

    def.daytime = 0.0;
    def.sun_color = colorGradationCreate();
    def.sun_radius = 1.0;
    def.zenith_color = colorGradationCreate();
    def.haze_color = colorGradationCreate();
    def.haze_height = 0.0;
    def.haze_smoothing = 0.0;

    skyValidateDefinition(&def);

    return def;
}

void skyDeleteDefinition(SkyDefinition definition)
{
}

void skyCopyDefinition(SkyDefinition source, SkyDefinition* destination)
{
    *destination = source;
}

void skyValidateDefinition(SkyDefinition* definition)
{
    Color zenith, haze;

    zenith = colorGradationGet(&definition->zenith_color, definition->daytime);
    haze = colorGradationGet(&definition->haze_color, definition->daytime);

    definition->_sky_gradation = colorGradationCreate();
    colorGradationAdd(&definition->_sky_gradation, 0.0, &haze);
    colorGradationAdd(&definition->_sky_gradation, definition->haze_height - definition->haze_smoothing, &haze);
    colorGradationAdd(&definition->_sky_gradation, definition->haze_height, &zenith);
    colorGradationAdd(&definition->_sky_gradation, 1.0, &zenith);
}

void skySetDefinition(SkyDefinition definition)
{
    skyValidateDefinition(&definition);
    _definition = definition;
}

SkyDefinition skyGetDefinition()
{
    return _definition;
}

Color skyGetColorCustom(Vector3 eye, Vector3 look, SkyDefinition* definition, SkyQuality* quality, SkyEnvironment* environment)
{
    double sun_angle, dist;
    Vector3 sun_position;
    Color sun_color, sky_color;

    if (definition == NULL)
    {
        definition = &_definition;
    }
    if (quality == NULL)
    {
        quality = &_quality;
    }
    if (environment == NULL)
    {
        environment = &_environment;
    }

    sun_angle = (definition->daytime + 0.75) * M_PI * 2.0;
    sun_position.x = cos(sun_angle);
    sun_position.y = sin(sun_angle);
    sun_position.z = 0.0;

    look = v3Normalize(look);
    dist = v3Norm(v3Sub(look, sun_position));

    sky_color = colorGradationGet(&definition->_sky_gradation, look.y * 0.5 + 0.5);
    if (dist < definition->sun_radius)
    {
        dist = dist / definition->sun_radius;
        sun_color = colorGradationGet(&definition->sun_color, definition->daytime);
        if (dist < 0.9)
        {
            return sun_color;
        }
        else
        {
            sun_color.a = (1.0 - dist) / 0.1;
            colorMask(&sky_color, &sun_color);
            return sky_color;
        }
    }
    else
    {
        return sky_color;
    }
}

Color skyGetColor(Vector3 eye, Vector3 look)
{
    return skyGetColorCustom(eye, look, &_definition, &_quality, &_environment);
}

Color skyProjectRay(Vector3 start, Vector3 direction)
{
    Color color_sky, color_clouds;

    direction = v3Normalize(direction);

    color_sky = skyGetColor(start, direction);
    color_clouds = cloudsGetColor(start, v3Add(start, v3Scale(direction, SPHERE_SIZE)));

    colorMask(&color_sky, &color_clouds);

    return color_sky;
}

static int _postProcessFragment(RenderFragment* fragment)
{
    Vector3 location, direction;
    Color color_sky, color_clouds;

    location = fragment->vertex.location;
    direction = v3Sub(location, camera_location);

    color_sky = skyGetColor(camera_location, v3Normalize(direction));
    color_clouds = cloudsGetColor(camera_location, v3Add(camera_location, v3Scale(direction, 10.0)));

    colorMask(&color_sky, &color_clouds);
    fragment->vertex.color = color_sky;

    return 1;
}

void skyRender(RenderProgressCallback callback)
{
    int res_i, res_j;
    int i, j;
    double step_i, step_j;
    double current_i, current_j;
    Vertex vertex1, vertex2, vertex3, vertex4;
    Color col;
    Vector3 direction;

    res_i = render_quality * 40;
    res_j = render_quality * 20;
    step_i = M_PI * 2.0 / (double)res_i;
    step_j = M_PI / (double)res_j;

    col.r = 0.0;
    col.g = 0.0;
    col.a = 1.0;

    for (j = 0; j < res_j; j++)
    {
        if (!callback((double)j / (double)(res_j - 1)))
        {
            return;
        }

        current_j = (double)(j - res_j / 2) * step_j;

        for (i = 0; i < res_i; i++)
        {
            current_i = (double)i * step_i;

            direction.x = SPHERE_SIZE * cos(current_i) * cos(current_j);
            direction.y = SPHERE_SIZE * sin(current_j);
            direction.z = SPHERE_SIZE * sin(current_i) * cos(current_j);
            vertex1.location = v3Add(camera_location, direction);
            col.b = sin(direction.x) * sin(direction.x) * cos(direction.z) * cos(direction.z);
            vertex1.color = col;
            vertex1.callback = _postProcessFragment;

            direction.x = SPHERE_SIZE * cos(current_i + step_i) * cos(current_j);
            direction.y = SPHERE_SIZE * sin(current_j);
            direction.z = SPHERE_SIZE * sin(current_i + step_i) * cos(current_j);
            vertex2.location = v3Add(camera_location, direction);
            col.b = sin(direction.x) * sin(direction.x) * cos(direction.z) * cos(direction.z);
            vertex2.color = col;
            vertex2.callback = _postProcessFragment;

            direction.x = SPHERE_SIZE * cos(current_i + step_i) * cos(current_j + step_j);
            direction.y = SPHERE_SIZE * sin(current_j + step_j);
            direction.z = SPHERE_SIZE * sin(current_i + step_i) * cos(current_j + step_j);
            vertex3.location = v3Add(camera_location, direction);
            col.b = sin(direction.x) * sin(direction.x) * cos(direction.z) * cos(direction.z);
            vertex3.color = col;
            vertex3.callback = _postProcessFragment;

            direction.x = SPHERE_SIZE * cos(current_i) * cos(current_j + step_j);
            direction.y = SPHERE_SIZE * sin(current_j + step_j);
            direction.z = SPHERE_SIZE * sin(current_i) * cos(current_j + step_j);
            vertex4.location = v3Add(camera_location, direction);
            col.b = sin(direction.x) * sin(direction.x) * cos(direction.z) * cos(direction.z);
            vertex4.color = col;
            vertex4.callback = _postProcessFragment;

            /* TODO Triangles at poles */
            renderPushQuad(&vertex1, &vertex4, &vertex3, &vertex2);
        }
    }
}