#include "forwardmodule.h"
#include "scene.h"
#include "phongentity.h"
#include "mesh.h"
#include "shader.h"
#include "light.h"
#include "glassert.h"
#include <glm/ext.hpp>

const char* const ForwardModule::flagStr[] =
{
    "NORMAL_MAP",
    "AMBIENT_TEXTURE",
    "DIFFUSE_TEXTURE",
    "SPECULAR_TEXTURE",
    "ALPHA_MASK"
};

const char* const ForwardModule::lightStr[] =
{
    "AMBIENT_LIGHT",
    "DIRECTIONNAL_LIGHT",
    "POINT_LIGHT"
};

void ForwardModule::renderGL(Camera* myCamera, Scene* scene)
{
    // render ambient lighting
    glAssert(glClearColor(0, 0.1f, 0.05f, 1.)); // add attribute, and setter for clear color
    glAssert(glClearDepth(1.0));
    glAssert(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT));
    glAssert(glDepthFunc(GL_LESS));
    glAssert(glDisable(GL_BLEND));

    lightPass(myCamera, scene, NULL, AMBIENT_LIGHT);

    // render directionnal lighting and point lighting
    glAssert(glDepthFunc(GL_LEQUAL));
    glAssert(glEnable(GL_BLEND));
    glAssert(glBlendFunc(GL_ONE, GL_ONE));
    glAssert(glDepthMask(GL_FALSE));

    for(SceneIterator<Light*>* lightIt = scene->getLights();
        lightIt->isValid(); lightIt->next())
    {
        Light* l = lightIt->getItem();
        unsigned int type = l->isDirectionnal() ? DIRECTIONNAL_LIGHT : POINT_LIGHT;
        lightPass(myCamera, scene, l, type);
    }

    glAssert(glDisable(GL_BLEND));
    glAssert(glDepthFunc(GL_LESS));
    glAssert(glDepthMask(GL_TRUE));
}

void ForwardModule::lightPass(Camera* myCamera, Scene* scene, Light* light, unsigned int type)
{
    // loop over all types of geometry
    for(int i=0; i<flags.size(); ++i)
    {
        // bind shader
        Shader* shader = shaders[i*NB_LIGHT_FLAGS + type];
        shader->bind();
        // bind light attributes
        if(type == DIRECTIONNAL_LIGHT)
            shader->bindVec3(shader->getLocation("dirLight"), light->getDir());
        if(type == POINT_LIGHT)
            shader->bindVec3(shader->getLocation("pointLight"), light->getPos());
        glm::vec3 color;
        if(type == AMBIENT_LIGHT)
            color = glm::vec3(0.1f); // add attribute, and setter for ambient lighting
        else
            color = light->getColor();
        shader->bindVec3(shader->getLocation("lightColor"), color);
        for(SceneIterator<PhongEntity*>* entityIt = scene->getGeometry();
            entityIt->isValid(); entityIt->next())
        {
            // compute matrix attributes
            PhongEntity* entity = entityIt->getItem();
            glm::mat4 modelViewMatrix = myCamera->getViewMatrix() * entity->modelMatrix;
            glm::mat4 mvp = myCamera->getProjectionMatrix() * modelViewMatrix;
            glm::mat4 normalMatrix = glm::transpose(glm::inverse(modelViewMatrix));
            // loop over material groups
            for(int j=0; j<entity->getMesh()->indiceGroups.size(); ++j)
            {
                Material* mat = entity->getMesh()->indiceGroups[j].material;
                if(mat->getFlags() == flags[i])
                {
                    // bind material attributes
                    mat->bindAttributes(shader);
                    shader->bindMat4(shader->getLocation("viewMatrix"), myCamera->getViewMatrix());
                    shader->bindMat4(shader->getLocation("modelViewMatrix"), modelViewMatrix);
                    shader->bindMat3(shader->getLocation("normalMatrix"), glm::mat3(normalMatrix));
                    shader->bindMat4(shader->getLocation("MVP"), mvp);
                    // draw geometry
                    entity->drawGroup(j);
                }
            }
        }
    }
}

// modern opengl methods

void ForwardModule::setShaderSource(ShaderSource* source)
{
    if(shaderSources != NULL)
        delete(shaderSources);
    shaderSources = source;
}

void ForwardModule::compileShaders(Scene* scene)
{
    flags.clear();
    for(Shader* s : shaders)
        delete(s);
    shaders.clear();

    int size = 1 << NB_FLAGS;
    bool geometryFlags[size];
    for(int i=0; i<size; ++i)
        geometryFlags[i] = false;

    // get material flags
    for(SceneIterator<PhongEntity*>* entityIt = scene->getGeometry();
        entityIt->isValid(); entityIt->next())
    {
        Mesh* m = entityIt->getItem()->getMesh();
        for(Mesh::Group &g : m->indiceGroups)
            geometryFlags[g.material->getFlags()] = true;
    }

    // shader compilation
    for(int i=0; i<size; ++i)
    {
        if(geometryFlags[i])
        {
            std::vector<const char*> defines;
            defines.push_back(lightStr[AMBIENT_LIGHT]);

            // set defines
            if(i & NORMAL_MAP_FLAG)
                defines.push_back(flagStr[NORMAL_MAP]);
            if(i & AMBIENT_TEXTURE_FLAG)
                defines.push_back(flagStr[AMBIENT_TEXTURE]);
            if(i & DIFFUSE_TEXTURE_FLAG)
                defines.push_back(flagStr[DIFFUSE_TEXTURE]);
            if(i & SPECULAR_TEXTURE_FLAG)
                defines.push_back(flagStr[SPECULAR_TEXTURE]);

            // for each geometry flag, 3 shaders are compiled, one for each kind of lighting
            flags.push_back(i);
            // ambient
            shaders.push_back(shaderSources->compile(defines.size(), defines.data()));
            // directionnal
            defines[0] = lightStr[DIRECTIONNAL_LIGHT];
            shaders.push_back(shaderSources->compile(defines.size(), defines.data()));
            // point
            defines[0] = lightStr[POINT_LIGHT];
            shaders.push_back(shaderSources->compile(defines.size(), defines.data()));
        }
    }
}