#include "texture.h"
#include "debug.h"

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

Texture::Texture(std::string imagePath) :
    m_id(0), m_wrapS(GL_REPEAT), m_wrapT(GL_REPEAT), m_filterMin(GL_LINEAR_MIPMAP_LINEAR), m_filterMax(GL_LINEAR)
{
    unsigned char* imageData = stbi_load(imagePath.c_str(), (int*)&m_width, (int*)&m_height, (int*)&m_channelCount, 0);

    if (imageData)
    {
        createTexture((std::byte*)imageData);
        stbi_image_free(imageData);
    }
}

Texture::Texture(std::byte * imageData, size_t width, size_t height, size_t channelsCount) :
    m_id(0), m_wrapS(GL_REPEAT), m_wrapT(GL_REPEAT), m_filterMin(GL_LINEAR_MIPMAP_LINEAR), m_filterMax(GL_LINEAR), m_width(width), m_height(height), m_channelCount(channelsCount)
{
    createTexture(imageData);
}

Texture::~Texture()
{
    glDeleteTextures(1, &m_id);
}

GLuint Texture::getId() const
{
    return m_id;
}

size_t Texture::getWidth() const
{
    return m_width;
}

size_t Texture::getHeight() const
{
    return m_height;
}

void Texture::bind(GLenum activeTexture)
{
    glActiveTexture(activeTexture);
    glBindTexture(GL_TEXTURE_2D, m_id);
}

void Texture::createTexture(std::byte * imageData)
{
    // Texture construction shall not interfere with the current texture unit configuration
    // Retrieve current texture in texture unit 0 and restore it later.
    GLint currentTextureId = 0;
    glActiveTexture(GL_TEXTURE0);
    glGetIntegerv(GL_TEXTURE_BINDING_2D, &currentTextureId);


    glGenTextures(1, &m_id);
    glBindTexture(GL_TEXTURE_2D, m_id);

    GLenum format = GL_RGB;

    switch (m_channelCount)
    {
    case 3:
        format = GL_RGB;
        break;
    case 4:
        format = GL_RGBA;
        break;
    default:
        ASSERT(1 == 2);
        break;
    }

    glTexImage2D(GL_TEXTURE_2D, 0, format, m_width, m_height, 0, format, GL_UNSIGNED_BYTE, imageData);
    glGenerateMipmap(GL_TEXTURE_2D);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, m_wrapS);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, m_wrapT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, m_filterMin);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, m_filterMax);


    glBindTexture(GL_TEXTURE_2D, currentTextureId); // Restore previous config of texture unit 0
}