#include "texture.h"

#include <stdexcept>

#include "stb_image.h"

Texture::Texture(const char* filename) : path(filename)
{
    int nrComponents;
    stbi_set_flip_vertically_on_load(true);
    unsigned char* bytes = stbi_load(filename, &width, &height, &nrComponents, 4);
    if (not bytes)
        throw std::runtime_error("Failed to load texture: " + path);

    pixels.assign(bytes, bytes + (size_t)width * height * 4);
    stbi_image_free(bytes);

    CreateGLTexture();
}

Texture::Texture(const unsigned char* encoded, int size, const std::string& name) : path(name)
{
    int nrComponents;
    stbi_set_flip_vertically_on_load(true);
    unsigned char* bytes = stbi_load_from_memory(encoded, size, &width, &height, &nrComponents, 4);
    if (not bytes)
        throw std::runtime_error("Failed to load texture: " + path);

    pixels.assign(bytes, bytes + (size_t)width * height * 4);
    stbi_image_free(bytes);

    CreateGLTexture();
}

Texture::Texture(int newWidth, int newHeight) : width(newWidth), height(newHeight)
{
    pixels.assign((size_t)width * height * 4, 255);
    CreateGLTexture();
}

Texture::Texture(const Texture& source)
    : path(source.path), width(source.width), height(source.height), pixels(source.pixels)
{
    CreateGLTexture();
}

void Texture::CreateGLTexture()
{
    glGenTextures(1, &ID);
    glBindTexture(GL_TEXTURE_2D, ID);

    // Mipmaps when shrunk, otherwise tiled textures shimmer in the distance
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels.data());
    glGenerateMipmap(GL_TEXTURE_2D);

    glBindTexture(GL_TEXTURE_2D, 0);
}

void Texture::Upload()
{
    glBindTexture(GL_TEXTURE_2D, ID);
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels.data());
    glGenerateMipmap(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, 0);
}

void Texture::Delete() {
    glDeleteTextures(1, &ID);
}