// Display images inside a terminal
// Copyright (C) 2023  JustKidding
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#include "shm.hpp"
#include "util.hpp"
#include "util/ptr.hpp"

#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

#include <fmt/format.h>

#include <cerrno>
#include <system_error>

WaylandShm::WaylandShm(int width, int height, int scale_factor, struct wl_shm *shm)
    : shm(shm),
      width(width),
      height(height),
      stride(width * 4),
      pool_size(height * stride * scale_factor)
{
    const int path_size = 32;
    shm_path = fmt::format("/{}", util::generate_random_string(path_size));
    create_shm_file();
    allocate_pool_buffers();
}

void WaylandShm::create_shm_file()
{
    fd = memfd_create("ueberzugpp-shm", 0);
    if (fd == -1) {
        throw std::system_error(errno, std::system_category());
    }
    int res = ftruncate(fd, pool_size);
    if (res == -1) {
        throw std::system_error(errno, std::system_category());
    }
    auto *pool_ptr = mmap(nullptr, pool_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if (pool_ptr == MAP_FAILED) {
        throw std::system_error(errno, std::system_category());
    }
    pool_data = static_cast<uint8_t *>(pool_ptr);
}

void WaylandShm::allocate_pool_buffers()
{
    const auto pool = c_unique_ptr<struct wl_shm_pool, wl_shm_pool_destroy>{wl_shm_create_pool(shm, fd, pool_size)};
    buffer = wl_shm_pool_create_buffer(pool.get(), 0, width, height, stride, WL_SHM_FORMAT_ARGB8888);
}

WaylandShm::~WaylandShm()
{
    shm_unlink(shm_path.c_str());
    close(fd);
    munmap(pool_data, pool_size);
    if (buffer != nullptr) {
        wl_buffer_destroy(buffer);
    }
}