#include <glm/mat4x4.hpp>
#include <glm/mat3x3.hpp>
#include "skyboxmodule.h"
#include "phongentity.h"
#include "shader.h"
#include "texture.h"
#include "camera.h"
#include "glassert.h"

SkyboxModule::SkyboxModule(Texture* myCubeMap)
{
    if(isAvailable())
    {
        shader = new Shader(vertSource, fragSource);
        cubeMap = myCubeMap;

        // set up vao
        glAssert(glGenVertexArrays(1, &vao));
        glAssert(glBindVertexArray(vao));
        glAssert(glGenBuffers(1, &vbo));
        glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo));
        glAssert(glBufferData(GL_ARRAY_BUFFER, 108 * sizeof(GLfloat), skyboxVertices, GL_STATIC_DRAW));
        glAssert(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float)*3, NULL));
        glAssert(glEnableVertexAttribArray(0));
        glAssert(glBindVertexArray(0));

        mvpLocation = shader->getLocation("MVP");
    }
}

SkyboxModule::~SkyboxModule()
{
    glAssert(glDeleteVertexArrays(1, &vao));
    glAssert(glDeleteBuffers(1, &vbo));
}

void SkyboxModule::renderGL(Camera* myCamera)
{
    shader->bind();
    glm::mat4 mvp = myCamera->getProjectionMatrix() * glm::mat4(glm::mat3(myCamera->getViewMatrix()));
    glAssert(glDepthMask(GL_FALSE));
    cubeMap->bind(0);
    shader->bindMatrix(mvpLocation, mvp);
    glAssert(glBindVertexArray(vao));
    glAssert(glDrawArrays(GL_TRIANGLES, 0, 36));
    glAssert(glDepthMask(GL_TRUE));
}

const GLfloat SkyboxModule::skyboxVertices[] = {
    -1.0f,  1.0f, -1.0f,
    -1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,

    -1.0f, -1.0f,  1.0f,
    -1.0f, -1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f,  1.0f,
    -1.0f, -1.0f,  1.0f,

     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,

    -1.0f, -1.0f,  1.0f,
    -1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f, -1.0f,  1.0f,
    -1.0f, -1.0f,  1.0f,

    -1.0f,  1.0f, -1.0f,
     1.0f,  1.0f, -1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
    -1.0f,  1.0f,  1.0f,
    -1.0f,  1.0f, -1.0f,

    -1.0f, -1.0f, -1.0f,
    -1.0f, -1.0f,  1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
    -1.0f, -1.0f,  1.0f,
     1.0f, -1.0f,  1.0f
};

const std::string SkyboxModule::vertSource =
        "#version 330 core\n\
        layout(location = 0)in vec3 inPosition;\n\
        out vec3 varTexCoord;\n\
        uniform mat4 MVP;\n\
        void main()\n\
        {\n\
            gl_Position = MVP * vec4(inPosition, 1.0);\n\
            varTexCoord = inPosition;\n\
        }\n";

const std::string SkyboxModule::fragSource =
        "#version 330 core\n\
        in vec3 varTexCoord;\n\
        out vec4 outColor;\n\
        uniform samplerCube skybox;\n\
        void main()\n\
        {\n\
            outColor = texture(skybox, varTexCoord);\n\
        }\n";