#include "lighting.h"

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

#include "shared/types.h"
#include "color.h"
#include "euclid.h"
#include "renderer.h"
#include "scenery.h"
#include "sky.h"
#include "terrain.h"
#include "tools.h"
#include "water.h"

static LightDefinition _LIGHT_NULL;

void lightingInit()
{
    _LIGHT_NULL.direction.x = 0.0;
    _LIGHT_NULL.direction.y = 1.0;
    _LIGHT_NULL.direction.z = 0.0;
    _LIGHT_NULL.color = COLOR_BLACK;
    _LIGHT_NULL.reflection = 0.0;
    _LIGHT_NULL.filtered = 0;
    _LIGHT_NULL.masked = 0;
    _LIGHT_NULL.amplitude = 0.0;
}

void lightingQuit()
{
}

void lightingSave(PackStream* stream, LightingDefinition* definition)
{
    int i;

    packWriteInt(stream, &definition->autosetfromsky);
    packWriteInt(stream, &definition->nblights);
    for (i = 0; i < definition->nblights; i++)
    {
        v3Save(stream, &definition->lights[i].direction);
        colorSave(stream, &definition->lights[i].color);
        packWriteDouble(stream, &definition->lights[i].reflection);
        packWriteInt(stream, &definition->lights[i].filtered);
        packWriteInt(stream, &definition->lights[i].masked);
        packWriteDouble(stream, &definition->lights[i].amplitude);
    }
}

void lightingLoad(PackStream* stream, LightingDefinition* definition)
{
    int i;

    packReadInt(stream, &definition->autosetfromsky);
    packReadInt(stream, &definition->nblights);
    for (i = 0; i < definition->nblights; i++)
    {
        v3Load(stream, &definition->lights[i].direction);
        colorLoad(stream, &definition->lights[i].color);
        packReadDouble(stream, &definition->lights[i].reflection);
        packReadInt(stream, &definition->lights[i].filtered);
        packReadInt(stream, &definition->lights[i].masked);
        packReadDouble(stream, &definition->lights[i].amplitude);
    }

    lightingValidateDefinition(definition);
}

LightingDefinition lightingCreateDefinition()
{
    LightingDefinition definition;

    definition.autosetfromsky = 0;
    definition.nblights = 0;
    definition._nbautolights = 0;

    return definition;
}

void lightingDeleteDefinition(LightingDefinition* definition)
{
}

void lightingCopyDefinition(LightingDefinition* source, LightingDefinition* destination)
{
    *destination = *source;
}

void lightingValidateDefinition(LightingDefinition* definition)
{
    if (definition->autosetfromsky)
    {
        SkyDefinition sky;

        sky = skyCreateDefinition();
        sceneryGetSky(&sky);
        definition->_nbautolights = skyGetLights(&sky, definition->_autolights, LIGHTING_MAX_LIGHTS);
        skyDeleteDefinition(&sky);
    }
    else
    {
        definition->_nbautolights = 0;
    }
}

int lightingGetLightCount(LightingDefinition* definition)
{
    return definition->nblights;
}

LightDefinition lightingGetLight(LightingDefinition* definition, int light)
{
    if (light >= 0 && light < definition->nblights)
    {
        return definition->lights[light];
    }
    else
    {
        return _LIGHT_NULL;
    }
}

int lightingAddLight(LightingDefinition* definition, LightDefinition light)
{
    if (definition->nblights < LIGHTING_MAX_LIGHTS)
    {
        definition->lights[definition->nblights] = light;
        return definition->nblights++;
    }
    else
    {
        return -1;
    }
}

void lightingDeleteLight(LightingDefinition* definition, int light)
{
    if (light >= 0 && light < definition->nblights)
    {
        if (definition->nblights > 1 && light < definition->nblights - 1)
        {
            memmove(definition->lights + light, definition->lights + light + 1, sizeof(LightDefinition) * definition->nblights - light - 1);
        }
        definition->nblights--;
    }
}

static int _getLightStatus(LightDefinition* definition, Renderer* renderer, Vector3 location, LightDefinition* result)
{
    *result = *definition;
    
    if (definition->masked || definition->filtered)
    {
        renderer->alterLight(renderer, result, location);
    }
    
    if (result->color.r > 0.0 || result->color.g > 0.0 || result->color.b > 0.0)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}

static Color _applyDirectLight(LightDefinition* definition, Renderer* renderer, Vector3 location, Vector3 normal, SurfaceMaterial material)
{
    Color result, light;
    double diffuse, specular, normal_norm;
    Vector3 view, reflect, direction_inv;

    light = definition->color;
    direction_inv = v3Scale(definition->direction, -1.0);

    if (definition->amplitude > 0.0)
    {
        /* TODO Sampling around light direction */
        int xsamples, ysamples, samples, x, y;
        double xstep, ystep, factor;
        LightDefinition sublight;
        
        ysamples = renderer->render_quality / 4 + 1;
        xsamples = renderer->render_quality / 2 + 1;
        samples = xsamples * ysamples + 1;
        factor = 1.0 / (double)samples;
        
        xstep = M_PI * 2.0 / (double)xsamples;
        ystep = M_PI * 0.5 / (double)(ysamples - 1);
        
        sublight = *definition;
        sublight.amplitude = 0.0;
        sublight.color.r *= factor;
        sublight.color.g *= factor;
        sublight.color.b *= factor;

        result = _applyDirectLight(&sublight, renderer, location, normal, material);
        for (x = 0; x < xsamples; x++)
        {
            for (y = 0; y < ysamples; y++)
            {
                sublight.direction.x = cos(x * xstep) * cos(y * ystep);
                sublight.direction.y = -sin(y * ystep);
                sublight.direction.z = sin(x * xstep) * cos(y * ystep);
                light = _applyDirectLight(&sublight, renderer, location, normal, material);
                result.r += light.r;
                result.g += light.g;
                result.b += light.b;
            }
        }
        return result;
    }
    
    normal_norm = v3Norm(normal);
    if (normal_norm > 1.0)
    {
        normal_norm = 1.0;
    }
    normal = v3Normalize(normal);

    diffuse = v3Dot(direction_inv, normal);
    /*diffuse = pow(diffuse * 0.5 + 0.5, 2.0);*/
    diffuse = diffuse * 0.5 + 0.5;
    if (diffuse > 0.0)
    {
        if (material.shininess > 0.0 && definition->reflection > 0.0)
        {
            view = v3Normalize(v3Sub(location, renderer->camera_location));
            reflect = v3Sub(direction_inv, v3Scale(normal, 2.0 * v3Dot(direction_inv, normal)));

            specular = v3Dot(reflect, view);
            if (specular > 0.0)
            {
                specular = pow(specular, material.shininess);
            }
            else
            {
                specular = 0.0;
            }
            specular *= material.reflection;
        }
        else
        {
            specular = 0.0;
        }
    }
    else
    {
        diffuse = 0.0;
        specular = 0.0;
    }

    specular *= normal_norm * definition->reflection;
    diffuse = 1.0 - normal_norm + diffuse * normal_norm;

    result.r = material.base.r * diffuse * light.r + specular * light.r;
    result.g = material.base.g * diffuse * light.g + specular * light.g;
    result.b = material.base.b * diffuse * light.b + specular * light.b;
    result.a = material.base.a;

    return result;
}

void lightingGetStatus(LightingDefinition* definition, Renderer* renderer, Vector3 location, LightStatus* result)
{
    int i;
    
    result->nblights = 0;
    
    for (i = 0; i < definition->nblights; i++)
    {
        if (_getLightStatus(definition->lights + i, renderer, location, result->lights + result->nblights))
        {
            result->nblights++;
        }
    }
    for (i = 0; i < definition->_nbautolights; i++)
    {
        if (_getLightStatus(definition->_autolights + i, renderer, location, result->lights + result->nblights))
        {
            result->nblights++;
        }
    }
}

Color lightingApplyStatusToSurface(Renderer* renderer, LightStatus* status, Vector3 location, Vector3 normal, SurfaceMaterial material)
{
    Color result, lighted;
    int i;

    result = COLOR_BLACK;
    result.a = material.base.a;
    
    for (i = 0; i < status->nblights; i++)
    {
        lighted = _applyDirectLight(status->lights + i, renderer, location, normal, material);
        result.r += lighted.r;
        result.g += lighted.g;
        result.b += lighted.b;
    }
    
    return result;
}

Color lightingApplyToSurface(LightingDefinition* definition, Renderer* renderer, Vector3 location, Vector3 normal, SurfaceMaterial material)
{
    LightStatus status;
    
    lightingGetStatus(definition, renderer, location, &status);
    return lightingApplyStatusToSurface(renderer, &status, location, normal, material);
}