#include "imesh.h"

#include "glassert.h"

#define BUFFER_OFFSET(i) ((char *)NULL + (i))

IMesh::~IMesh()
{
    destroyGL();
}

void IMesh::addVertex(float x, float y, float z)
{
    addVertex((glm::vec3(x, y, z));
}

void IMesh::addVertex(glm::vec3 &position)
{
    positions.push_back(position);
}

void IMesh::addVertex(glm::vec3 &position, glm::vec3 &normal)
{
    addVertex(position);
    normals.push_back(normal);
}

void IMesh::addVertex(glm::vec3 &position, glm::vec2 &texCoord)
{
    addVertex(position);
    texCoords.push_back(texCoord);
}

void IMesh::addVertex(glm::vec3 &position, glm::vec3 &normal, glm::vec2 &texCoord)
{
    addVertex(position, normal);
    texCoords.push_back(texCoord);
}


void IMesh::addFace(int i1, int i2, int i3)
{
    if(!locked)
    {
        indices.push_back(i1);
        indices.push_back(i2);
        indices.push_back(i3);
    }
}

void IMesh::computeFaceNormals()
{

}

void IMesh::computeVertexNormals()
{

}

void IMesh::computeTangents()
{

}

bool IMesh::hasNormals()
{
    return normals.size() != 0;
}

bool IMesh::hasTexCoords()
{
    return texCoords.size() != 0;
}

bool IMesh::hasTangents()
{
    return tangents.size() != 0;
}

void IMesh::initGL(bool isDynamic)
{
    if(locked)
        destroyGL();

    GLenum buffer_type = isDynamic ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW;

    // create VAO
    glAssert(glGenVertexArrays(1, &vao));
    glAssert(glBindVertexArray(vao));

    // create VBOs
    glAssert(glGenBuffers(NB_BUFFERS, vbo));

    // init positions vbo
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo[POSITION_BUFFER]));
    glAssert(glBufferData(GL_ARRAY_BUFFER, positions.size() * sizeof(glm::vec3), positions.data(), buffer_type));

    // init normals vbo
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo[NORMAL_BUFFER]));
    glAssert(glBufferData(GL_ARRAY_BUFFER, normals.size() * sizeof(glm::vec3), normals.data(), buffer_type));

    // init texCoords vbo
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo[TEXCOORD_BUFFER]));
    glAssert(glBufferData(GL_ARRAY_BUFFER, texCoords.size() * sizeof(glm::vec2), texCoords.data(), buffer_type));

    // init tangents vbo
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo[TANGENT_BUFFER]));
    glAssert(glBufferData(GL_ARRAY_BUFFER, tangents.size() * sizeof(glm::vec3)*2, tangents.data(), buffer_type));

    // init indices vbo
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo[INDICES_BUFFER]));
    glAssert(glBufferData(GL_ARRAY_BUFFER, indices.size() * sizeof(GLuint), indices.data(), buffer_type));

    // unbind vao
    glAssert(glBindVertexArray(0));

    locked = true;
}

void IMesh::destroyGL()
{
    if(locked)
    {
        locked = false;
        glAssert(glDeleteVertexArrays(1, &vao));
        glAssert(glDeleteBuffers(2, vbo));
    }
}

void IMesh::draw()
{
    if(locked)
    {
        glAssert(glBindVertexArray(vao));
        glAssert(glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_INT, indices.data()));
    }
}