#include "gfx/gl_loader.h"
#include "gfx/gl_framebuffer.h"

namespace fn::gfx {

static void create_tex(Framebuffer& f) {
    glGenTextures(1, &f.tex);
    glBindTexture(GL_TEXTURE_2D, f.tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, f.width, f.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glBindTexture(GL_TEXTURE_2D, 0);
}

void fb_init(Framebuffer& f) {
    f.width = 1;
    f.height = 1;
    create_tex(f);
    glGenFramebuffers(1, &f.fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, f.fbo);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, f.tex, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void fb_resize(Framebuffer& f, int w, int h) {
    if (w == f.width && h == f.height) return;
    f.width = w;
    f.height = h;
    if (f.tex) glDeleteTextures(1, &f.tex);
    f.tex = 0;
    create_tex(f);
    glBindFramebuffer(GL_FRAMEBUFFER, f.fbo);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, f.tex, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void fb_destroy(Framebuffer& f) {
    if (f.fbo) { glDeleteFramebuffers(1, &f.fbo); f.fbo = 0; }
    if (f.tex) { glDeleteTextures(1, &f.tex); f.tex = 0; }
    f.width = 0;
    f.height = 0;
}

} // namespace fn::gfx