#include "forwardmodule.h"
#include "scene.h"
#include "mesh.h"
#include "shader.h"
#include "light.h"
#include "pbrmaterial.h"
#include "texture.h"
#include "camera.h"
#include <glm/ext.hpp>

void ForwardModule::renderGL(Camera* myCamera, Scene* scene)
{
    // bind target
    glViewport(0, 0, width, height);
    
    for(const Pass &p : passes)
    {
        for(Light *light : p.lights)
        {
            if(light->getFlags() & (1 << Light::AMBIENT_FLAG))
            {
                // render ambient lighting (opaque)
                glEnable(GL_DEPTH_TEST);
                glDepthFunc(GL_LESS);
                glDisable(GL_BLEND);
            }
            else
            {
                // render directionnal lighting and point lighting (additive light)
                glDepthFunc(GL_LEQUAL);
                glEnable(GL_BLEND);
                glBlendFunc(GL_ONE, GL_ONE);
                glDepthMask(GL_FALSE);
            }
            Shader *shader = p.shader;
            shader->bind();
            light->bindAttributes(shader, myCamera);
            unsigned int id = 2;
            for(GeometryNode *node : p.geometry)
            {
                shader->bindUnsignedInteger(shader->getLocation("object_identifier"), id);
                if(node->mesh->m_instances_offsets.empty())
                    ++id;
                else
                    id += node->mesh->m_instances_offsets.size();
                // compute matrix attributes
                glm::mat4 modelViewMatrix = myCamera->getViewMatrix() * node->modelMatrix;
                glm::mat4 mvp = myCamera->getProjectionMatrix() * modelViewMatrix;
                glm::mat4 normalMatrix = glm::transpose(glm::inverse(modelViewMatrix));
                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);
                node->mesh->draw(shader);
            }
        }
    }
    
    glDisable(GL_BLEND);
    glDepthFunc(GL_LESS);
    glDepthMask(GL_TRUE);
}

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

void ForwardModule::compileShaders(Scene* scene)
{
    for(Pass &p : passes)
        delete(p.shader);
    passes.clear();
    // list all geometry types
    geometry.clear();
    for(SceneIterator<GeometryNode*>* geometryIt = scene->getGeometry();
        geometryIt->isValid(); geometryIt->next())
    {
        GeometryNode* n = geometryIt->getItem();
        geometry[n->mesh->getFlags()].push_back(n);
    }
    // list all light types
    lights.clear();
    lights[ambientLight.getFlags()].push_back(&ambientLight);
    for(SceneIterator<Light*>* lightIt = scene->getLights();
        lightIt->isValid(); lightIt->next())
    {
        Light* l = lightIt->getItem();
        lights[l->getFlags()].push_back(l);
    }
    // compile shaders and add the pass for the ambient light first
    unsigned int ambientFlags = ambientLight.getFlags();
    for(const auto &geomIt : geometry)
    {
        unsigned int geomFlags = geomIt.first;
        passes.push_back(Pass(shaderSources->compile(geomFlags, ambientFlags), geomIt.second, lights[ambientFlags]));
    }
    // compile a shader for each combination of a geometry flag and a light flag
    for(const auto &lightIt : lights)
    {
        unsigned int lightFlags = lightIt.first;
        if(lightFlags != ambientFlags) // ambient shaders are already ready
        {
            for(const auto &geomIt : geometry)
            {
                unsigned int geomFlags = geomIt.first;
                passes.push_back(Pass(shaderSources->compile(geomFlags, lightFlags), geomIt.second, lightIt.second));
            }
        }
    }
}