#include "fb.h"

#include <linux/fb.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>

Framebuffer newFramebuffer(const char* device) {
	Framebuffer fb;
	
	// Open the framebuffer file descriptor
	fb.fd = open(device, O_RDWR);
	assert(fb.fd >= 0 && "Invalid framebuffer device, please ensure your user is in the 'video' group.");

	// Get information about framebuffer
	ioctl(fb.fd, FBIOGET_VSCREENINFO, &fb.vinfo);

	// Get size of screen for writing pixels in bounds
	fb.screensize = fb.vinfo.xres * fb.vinfo.yres * fb.vinfo.bits_per_pixel / 8;

	fb.data = mmap(0, fb.screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fb.fd, 0);

	return fb;
} 

void writeColourToFramebuffer(Framebuffer* fb, Pixel pixel, Colour colour) {
	int offset = (pixel.y * fb->vinfo.xres + pixel.x) * (fb->vinfo.bits_per_pixel / 8);

	fb->data[offset + 0] = colour.red;
	fb->data[offset + 1] = colour.green;
	fb->data[offset + 2] = colour.blue;
	fb->data[offset + 3] = colour.alpha;

	
	munmap(fb->data, fb->screensize);
}

void destroyFramebuffer(Framebuffer* fb) {
	close(fb->fd);

	// NOTE: Do not free fb->data, this is not memory owned by us.
	// Will cause a segfault
}