#include "framebuffer.hpp"
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/fb.h>
#include <cstring>

FrameBuffer::FrameBuffer() : _fd(-1), _buffer(nullptr), _width(0), _height(0), _screensize(0) {}

FrameBuffer::~FrameBuffer() { release(); }

bool FrameBuffer::init(const char* device)
{
    _fd = open(device, O_RDWR);
    if (_fd < 0) return false;

    fb_var_screeninfo vinfo;
    if (ioctl(_fd, FBIOGET_VSCREENINFO, &vinfo) < 0) return false;

    _width  = vinfo.xres;
    _height = vinfo.yres;
    _screensize = _width * _height * 2;  // RGB565 = 2 bytes/pixel

    _buffer = (uint16*)mmap(nullptr, _screensize, PROT_READ | PROT_WRITE,
                             MAP_SHARED, _fd, 0);
    return (_buffer != MAP_FAILED);
}

void FrameBuffer::release()
{
    if (_buffer && _buffer != MAP_FAILED)
        munmap(_buffer, _screensize);
    if (_fd >= 0) { close(_fd); _fd = -1; }
    _buffer = nullptr;
}

void FrameBuffer::_rgb888_to_rgb565(const uint8* src, uint16* dst, int pixels)
{
    for (int i = 0; i < pixels; ++i)
    {
        uint8 r = src[i * 3];
        uint8 g = src[i * 3 + 1];
        uint8 b = src[i * 3 + 2];
        dst[i] = ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3);
    }
}

bool FrameBuffer::write(const uint8* rgb888_data, int w, int h)
{
    if (!_buffer || _buffer == MAP_FAILED) return false;

    int copy_w = (w < _width) ? w : _width;
    int copy_h = (h < _height) ? h : _height;

    for (int y = 0; y < copy_h; ++y)
        _rgb888_to_rgb565(rgb888_data + y * w * 3, _buffer + y * _width, copy_w);

    return true;
}