#include "../../include/mgl/graphics/texture.h"
#include "../../include/mgl/mgl.h"

#define STBI_NO_PSD
#define STBI_NO_TGA
#define STBI_NO_HDR
#define STBI_NO_PIC
#define STBI_NO_PNM
#define STB_IMAGE_IMPLEMENTATION
#include "../../external/stb_image.h"

static int mgl_texture_format_to_opengl_format(mgl_texture_format format) {
    switch(format) {
        case MGL_TEXTURE_GRAY:       return GL_LUMINANCE8;
        case MGL_TEXTURE_GRAY_ALPHA: return GL_LUMINANCE8_ALPHA8;
        case MGL_TEXTURE_RGB:        return GL_RGB8;
        case MGL_TEXTURE_RGB_ALPHA:  return GL_RGBA8;
    }
    return 0;
}

static int mgl_texture_format_to_source_opengl_format(mgl_texture_format format) {
    switch(format) {
        case MGL_TEXTURE_GRAY:       return GL_LUMINANCE8_ALPHA8;
        case MGL_TEXTURE_GRAY_ALPHA: return GL_LUMINANCE8_ALPHA8;
        case MGL_TEXTURE_RGB:        return GL_RGB;
        case MGL_TEXTURE_RGB_ALPHA:  return GL_RGBA;
    }
    return 0;
}

/* TODO: Ensure texture is power of 2 if the hardware doesn't support non power of two textures */
int mgl_texture_load_from_file(mgl_texture *self, const char *filepath) {
    self->id = 0;
    
    int format;
    stbi_uc *image_data = stbi_load(filepath, &self->width, &self->height, &format, 0);
    if(!image_data) {
        fprintf(stderr, "Error: failed to load image %s, error: %s\n", filepath, stbi_failure_reason());
        return -1;
    }
    self->format = format;

    mgl_context *context = mgl_get_context();
    context->gl.glGenTextures(1, &self->id);
    if(self->id == 0) {
        stbi_image_free(image_data);
        return -1;
    }

    const int opengl_texture_format = mgl_texture_format_to_opengl_format(self->format);

    context->gl.glBindTexture(GL_TEXTURE_2D, self->id);
    context->gl.glTexImage2D(GL_TEXTURE_2D, 0, opengl_texture_format, self->width, self->height, 0, mgl_texture_format_to_source_opengl_format(self->format), GL_UNSIGNED_BYTE, image_data);
    context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    context->gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    context->gl.glBindTexture(GL_TEXTURE_2D, 0);

    stbi_image_free(image_data);
    return 0;
}

void mgl_texture_unload(mgl_texture *self) {
    mgl_context *context = mgl_get_context();
    if(self->id) {
        context->gl.glDeleteTextures(1, &self->id);
        self->id = 0;
    }
}