lite-xl/src/api/system.c

#include <SDL.h>
#include <string.h>
#include <stdbool.h>
#include <ctype.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "api.h"
#include "../rencache.h"
#ifdef _WIN32
  #include <direct.h>
  #include <windows.h>
  #include <fileapi.h>
  #include "../utfconv.h"
#else

#include <dirent.h>
#include <unistd.h>

#ifdef __linux__
  #include <sys/vfs.h>
#endif
#endif

extern SDL_Window *window;


static const char* button_name(int button) {
  switch (button) {
    case SDL_BUTTON_LEFT   : return "left";
    case SDL_BUTTON_MIDDLE : return "middle";
    case SDL_BUTTON_RIGHT  : return "right";
    case SDL_BUTTON_X1     : return "x";
    case SDL_BUTTON_X2     : return "y";
    default : return "?";
  }
}


static void str_tolower(char *p) {
  while (*p) {
    *p = tolower(*p);
    p++;
  }
}

struct HitTestInfo {
  int title_height;
  int controls_width;
  int resize_border;
};
typedef struct HitTestInfo HitTestInfo;

static HitTestInfo window_hit_info[1] = {{0, 0, 0}};

#define RESIZE_FROM_TOP 0
#define RESIZE_FROM_RIGHT 0

static SDL_HitTestResult SDLCALL hit_test(SDL_Window *window, const SDL_Point *pt, void *data) {
  const HitTestInfo *hit_info = (HitTestInfo *) data;
  const int resize_border = hit_info->resize_border;
  const int controls_width = hit_info->controls_width;
  int w, h;

  SDL_GetWindowSize(window, &w, &h);

  if (pt->y < hit_info->title_height &&
    #if RESIZE_FROM_TOP
    pt->y > hit_info->resize_border &&
    #endif
    pt->x > resize_border && pt->x < w - controls_width) {
    return SDL_HITTEST_DRAGGABLE;
  }

  #define REPORT_RESIZE_HIT(name) { \
    return SDL_HITTEST_RESIZE_##name; \
  }

  if (pt->x < resize_border && pt->y < resize_border) {
    REPORT_RESIZE_HIT(TOPLEFT);
  #if RESIZE_FROM_TOP
  } else if (pt->x > resize_border && pt->x < w - controls_width && pt->y < resize_border) {
    REPORT_RESIZE_HIT(TOP);
  #endif
  } else if (pt->x > w - resize_border && pt->y < resize_border) {
    REPORT_RESIZE_HIT(TOPRIGHT);
  #if RESIZE_FROM_RIGHT
  } else if (pt->x > w - resize_border && pt->y > resize_border && pt->y < h - resize_border) {
    REPORT_RESIZE_HIT(RIGHT);
  #endif
  } else if (pt->x > w - resize_border && pt->y > h - resize_border) {
    REPORT_RESIZE_HIT(BOTTOMRIGHT);
  } else if (pt->x < w - resize_border && pt->x > resize_border && pt->y > h - resize_border) {
    REPORT_RESIZE_HIT(BOTTOM);
  } else if (pt->x < resize_border && pt->y > h - resize_border) {
    REPORT_RESIZE_HIT(BOTTOMLEFT);
  } else if (pt->x < resize_border && pt->y < h - resize_border && pt->y > resize_border) {
    REPORT_RESIZE_HIT(LEFT);
  }

  return SDL_HITTEST_NORMAL;
}

static const char *numpad[] = { "end", "down", "pagedown", "left", "", "right", "home", "up", "pageup", "ins", "delete" };

static const char *get_key_name(const SDL_Event *e, char *buf) {
  SDL_Scancode scancode = e->key.keysym.scancode;
  /* Is the scancode from the keypad and the number-lock off?
  ** We assume that SDL_SCANCODE_KP_1 up to SDL_SCANCODE_KP_9 and SDL_SCANCODE_KP_0
  ** and SDL_SCANCODE_KP_PERIOD are declared in SDL2 in that order. */
  if (scancode >= SDL_SCANCODE_KP_1 && scancode <= SDL_SCANCODE_KP_1 + 10 &&
    !(e->key.keysym.mod & KMOD_NUM)) {
    return numpad[scancode - SDL_SCANCODE_KP_1];
  } else {
    /* We need to correctly handle non-standard layouts such as dvorak.
       Therefore, if a Latin letter(code<128) is pressed in the current layout,
       then we transmit it as it is. But we also need to support shortcuts in
       other languages, so for non-Latin characters(code>128) we pass the
       scancode based name that matches the letter in the QWERTY layout.

       In SDL, the codes of all special buttons such as control, shift, arrows
       and others, are masked with SDLK_SCANCODE_MASK, which moves them outside
       the unicode range (>0x10FFFF). Users can remap these buttons, so we need
       to return the correct name, not scancode based. */
    if ((e->key.keysym.sym < 128) || (e->key.keysym.sym & SDLK_SCANCODE_MASK))
      strcpy(buf, SDL_GetKeyName(e->key.keysym.sym));
    else
      strcpy(buf, SDL_GetScancodeName(scancode));
    str_tolower(buf);
    return buf;
  }
}

#ifdef _WIN32
static char *win32_error(DWORD rc) {
  LPSTR message;
  FormatMessage(
    FORMAT_MESSAGE_ALLOCATE_BUFFER |
    FORMAT_MESSAGE_FROM_SYSTEM |
    FORMAT_MESSAGE_IGNORE_INSERTS,
    NULL,
    rc,
    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
    (LPTSTR) &message,
    0,
    NULL
  );

  return message;
}

static void push_win32_error(lua_State *L, DWORD rc) {
  LPSTR message = win32_error(rc);
  lua_pushstring(L, message);
  LocalFree(message);
}
#endif

static int f_poll_event(lua_State *L) {
  char buf[16];
  int mx, my;
  SDL_Event e;

top:
  if ( !SDL_PollEvent(&e) ) {
    return 0;
  }

  switch (e.type) {
    case SDL_QUIT:
      lua_pushstring(L, "quit");
      return 1;

    case SDL_WINDOWEVENT:
      if (e.window.event == SDL_WINDOWEVENT_RESIZED) {
        ren_resize_window();
        lua_pushstring(L, "resized");
        /* The size below will be in points. */
        lua_pushinteger(L, e.window.data1);
        lua_pushinteger(L, e.window.data2);
        return 3;
      } else if (e.window.event == SDL_WINDOWEVENT_EXPOSED) {
        rencache_invalidate();
        lua_pushstring(L, "exposed");
        return 1;
      } else if (e.window.event == SDL_WINDOWEVENT_MINIMIZED) {
        lua_pushstring(L, "minimized");
        return 1;
      } else if (e.window.event == SDL_WINDOWEVENT_MAXIMIZED) {
        lua_pushstring(L, "maximized");
        return 1;
      } else if (e.window.event == SDL_WINDOWEVENT_RESTORED) {
        lua_pushstring(L, "restored");
        return 1;
      } else if (e.window.event == SDL_WINDOWEVENT_LEAVE) {
        lua_pushstring(L, "mouseleft");
        return 1;
      }
      if (e.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
        lua_pushstring(L, "focuslost");
        return 1;
      }
      /* on some systems, when alt-tabbing to the window SDL will queue up
      ** several KEYDOWN events for the `tab` key; we flush all keydown
      ** events on focus so these are discarded */
      if (e.window.event == SDL_WINDOWEVENT_FOCUS_GAINED) {
        SDL_FlushEvent(SDL_KEYDOWN);
      }
      goto top;

    case SDL_DROPFILE:
      SDL_GetMouseState(&mx, &my);
      lua_pushstring(L, "filedropped");
      lua_pushstring(L, e.drop.file);
      lua_pushinteger(L, mx);
      lua_pushinteger(L, my);
      SDL_free(e.drop.file);
      return 4;

    case SDL_KEYDOWN:
#ifdef __APPLE__
      /* on macos 11.2.3 with sdl 2.0.14 the keyup handler for cmd+w below
      ** was not enough. Maybe the quit event started to be triggered from the
      ** keydown handler? In any case, flushing the quit event here too helped. */
      if ((e.key.keysym.sym == SDLK_w) && (e.key.keysym.mod & KMOD_GUI)) {
        SDL_FlushEvent(SDL_QUIT);
      }
#endif
      lua_pushstring(L, "keypressed");
      lua_pushstring(L, get_key_name(&e, buf));
      return 2;

    case SDL_KEYUP:
#ifdef __APPLE__
      /* on macos command+w will close the current window
      ** we want to flush this event and let the keymapper
      ** handle this key combination.
      ** Thanks to mathewmariani, taken from his lite-macos github repository. */
      if ((e.key.keysym.sym == SDLK_w) && (e.key.keysym.mod & KMOD_GUI)) {
        SDL_FlushEvent(SDL_QUIT);
      }
#endif
      lua_pushstring(L, "keyreleased");
      lua_pushstring(L, get_key_name(&e, buf));
      return 2;

    case SDL_TEXTINPUT:
      lua_pushstring(L, "textinput");
      lua_pushstring(L, e.text.text);
      return 2;

    case SDL_MOUSEBUTTONDOWN:
      if (e.button.button == 1) { SDL_CaptureMouse(1); }
      lua_pushstring(L, "mousepressed");
      lua_pushstring(L, button_name(e.button.button));
      lua_pushinteger(L, e.button.x);
      lua_pushinteger(L, e.button.y);
      lua_pushinteger(L, e.button.clicks);
      return 5;

    case SDL_MOUSEBUTTONUP:
      if (e.button.button == 1) { SDL_CaptureMouse(0); }
      lua_pushstring(L, "mousereleased");
      lua_pushstring(L, button_name(e.button.button));
      lua_pushinteger(L, e.button.x);
      lua_pushinteger(L, e.button.y);
      return 4;

    case SDL_MOUSEMOTION:
      SDL_PumpEvents();
      SDL_Event event_plus;
      while (SDL_PeepEvents(&event_plus, 1, SDL_GETEVENT, SDL_MOUSEMOTION, SDL_MOUSEMOTION) > 0) {
        e.motion.x = event_plus.motion.x;
        e.motion.y = event_plus.motion.y;
        e.motion.xrel += event_plus.motion.xrel;
        e.motion.yrel += event_plus.motion.yrel;
      }
      lua_pushstring(L, "mousemoved");
      lua_pushinteger(L, e.motion.x);
      lua_pushinteger(L, e.motion.y);
      lua_pushinteger(L, e.motion.xrel);
      lua_pushinteger(L, e.motion.yrel);
      return 5;

    case SDL_MOUSEWHEEL:
      lua_pushstring(L, "mousewheel");
      lua_pushinteger(L, e.wheel.y);
      return 2;

    default:
      goto top;
  }

  return 0;
}


static int f_wait_event(lua_State *L) {
  int nargs = lua_gettop(L);
  if (nargs >= 1) {
    double n = luaL_checknumber(L, 1);
    lua_pushboolean(L, SDL_WaitEventTimeout(NULL, n * 1000));
  } else {
    lua_pushboolean(L, SDL_WaitEvent(NULL));
  }
  return 1;
}


static SDL_Cursor* cursor_cache[SDL_SYSTEM_CURSOR_HAND + 1];

static const char *cursor_opts[] = {
  "arrow",
  "ibeam",
  "sizeh",
  "sizev",
  "hand",
  NULL
};

static const int cursor_enums[] = {
  SDL_SYSTEM_CURSOR_ARROW,
  SDL_SYSTEM_CURSOR_IBEAM,
  SDL_SYSTEM_CURSOR_SIZEWE,
  SDL_SYSTEM_CURSOR_SIZENS,
  SDL_SYSTEM_CURSOR_HAND
};

static int f_set_cursor(lua_State *L) {
  int opt = luaL_checkoption(L, 1, "arrow", cursor_opts);
  int n = cursor_enums[opt];
  SDL_Cursor *cursor = cursor_cache[n];
  if (!cursor) {
    cursor = SDL_CreateSystemCursor(n);
    cursor_cache[n] = cursor;
  }
  SDL_SetCursor(cursor);
  return 0;
}


static int f_set_window_title(lua_State *L) {
  const char *title = luaL_checkstring(L, 1);
  SDL_SetWindowTitle(window, title);
  return 0;
}


static const char *window_opts[] = { "normal", "minimized", "maximized", "fullscreen", 0 };
enum { WIN_NORMAL, WIN_MINIMIZED, WIN_MAXIMIZED, WIN_FULLSCREEN };

static int f_set_window_mode(lua_State *L) {
  int n = luaL_checkoption(L, 1, "normal", window_opts);
  SDL_SetWindowFullscreen(window,
    n == WIN_FULLSCREEN ? SDL_WINDOW_FULLSCREEN_DESKTOP : 0);
  if (n == WIN_NORMAL) { SDL_RestoreWindow(window); }
  if (n == WIN_MAXIMIZED) { SDL_MaximizeWindow(window); }
  if (n == WIN_MINIMIZED) { SDL_MinimizeWindow(window); }
  return 0;
}


static int f_set_window_bordered(lua_State *L) {
  int bordered = lua_toboolean(L, 1);
  SDL_SetWindowBordered(window, bordered);
  return 0;
}


static int f_set_window_hit_test(lua_State *L) {
  if (lua_gettop(L) == 0) {
    SDL_SetWindowHitTest(window, NULL, NULL);
    return 0;
  }
  window_hit_info->title_height = luaL_checknumber(L, 1);
  window_hit_info->controls_width = luaL_checknumber(L, 2);
  window_hit_info->resize_border = luaL_checknumber(L, 3);
  SDL_SetWindowHitTest(window, hit_test, window_hit_info);
  return 0;
}


static int f_get_window_size(lua_State *L) {
  int x, y, w, h;
  SDL_GetWindowSize(window, &w, &h);
  SDL_GetWindowPosition(window, &x, &y);
  lua_pushinteger(L, w);
  lua_pushinteger(L, h);
  lua_pushinteger(L, x);
  lua_pushinteger(L, y);
  return 4;
}


static int f_set_window_size(lua_State *L) {
  double w = luaL_checknumber(L, 1);
  double h = luaL_checknumber(L, 2);
  double x = luaL_checknumber(L, 3);
  double y = luaL_checknumber(L, 4);
  SDL_SetWindowSize(window, w, h);
  SDL_SetWindowPosition(window, x, y);
  ren_resize_window();
  return 0;
}


static int f_window_has_focus(lua_State *L) {
  unsigned flags = SDL_GetWindowFlags(window);
  lua_pushboolean(L, flags & SDL_WINDOW_INPUT_FOCUS);
  return 1;
}


static int f_get_window_mode(lua_State *L) {
  unsigned flags = SDL_GetWindowFlags(window);
  if (flags & SDL_WINDOW_FULLSCREEN_DESKTOP) {
    lua_pushstring(L, "fullscreen");
  } else if (flags & SDL_WINDOW_MINIMIZED) {
    lua_pushstring(L, "minimized");
  } else if (flags & SDL_WINDOW_MAXIMIZED) {
    lua_pushstring(L, "maximized");
  } else {
    lua_pushstring(L, "normal");
  }
  return 1;
}


static int f_raise_window(lua_State *L) {
  /*
    SDL_RaiseWindow should be enough but on some window managers like the
    one used on Gnome the window needs to first have input focus in order
    to allow the window to be focused. Also on wayland the raise window event
    may not always be obeyed.
  */
  SDL_SetWindowInputFocus(window);
  SDL_RaiseWindow(window);
  return 0;
}


static int f_show_fatal_error(lua_State *L) {
  const char *title = luaL_checkstring(L, 1);
  const char *msg = luaL_checkstring(L, 2);

#ifdef _WIN32
  MessageBox(0, msg, title, MB_OK | MB_ICONERROR);

#else
  SDL_MessageBoxButtonData buttons[] = {
    { SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT, 0, "Ok" },
  };
  SDL_MessageBoxData data = {
    .title = title,
    .message = msg,
    .numbuttons = 1,
    .buttons = buttons,
  };
  int buttonid;
  SDL_ShowMessageBox(&data, &buttonid);
#endif
  return 0;
}


// removes an empty directory
static int f_rmdir(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);

#ifdef _WIN32
  LPWSTR wpath = utfconv_utf8towc(path);
  int deleted = RemoveDirectoryW(wpath);
  free(wpath);
  if (deleted > 0) {
    lua_pushboolean(L, 1);
  } else {
    lua_pushboolean(L, 0);
    push_win32_error(L, GetLastError());
    return 2;
  }
#else
  int deleted = remove(path);
  if(deleted < 0) {
    lua_pushboolean(L, 0);
    lua_pushstring(L, strerror(errno));

    return 2;
  } else {
    lua_pushboolean(L, 1);
  }
#endif

  return 1;
}


static int f_chdir(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);
#ifdef _WIN32
  LPWSTR wpath = utfconv_utf8towc(path);
  if (wpath == NULL) { return luaL_error(L, UTFCONV_ERROR_INVALID_CONVERSION ); }
  int err = _wchdir(wpath);
  free(wpath);
#else
  int err = chdir(path);
#endif
  if (err) { luaL_error(L, "chdir() failed: %s", strerror(errno)); }
  return 0;
}


static int f_list_dir(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);

#ifdef _WIN32
  lua_settop(L, 1);
  if (path[0] == 0 || strchr("\\/", path[strlen(path) - 1]) != NULL)
    lua_pushstring(L, "*");
  else
    lua_pushstring(L, "/*");

  lua_concat(L, 2);
  path = lua_tostring(L, -1);

  LPWSTR wpath = utfconv_utf8towc(path);
  if (wpath == NULL) {
    lua_pushnil(L);
    lua_pushstring(L, UTFCONV_ERROR_INVALID_CONVERSION);
    return 2;
  }

  WIN32_FIND_DATAW fd;
  HANDLE find_handle = FindFirstFileExW(wpath, FindExInfoBasic, &fd, FindExSearchNameMatch, NULL, 0);
  free(wpath);
  if (find_handle == INVALID_HANDLE_VALUE) {
    lua_pushnil(L);
    push_win32_error(L, GetLastError());
    return 2;
  }

  char mbpath[MAX_PATH * 4]; // utf-8 spans 4 bytes at most
  int len, i = 1;
  lua_newtable(L);

  do
  {
    if (wcscmp(fd.cFileName, L".") == 0) { continue; }
    if (wcscmp(fd.cFileName, L"..") == 0) { continue; }

    len = WideCharToMultiByte(CP_UTF8, 0, fd.cFileName, -1, mbpath, MAX_PATH * 4, NULL, NULL);
    if (len == 0) { break; }
    lua_pushlstring(L, mbpath, len - 1); // len includes \0
    lua_rawseti(L, -2, i++);
  } while (FindNextFileW(find_handle, &fd));

  if (GetLastError() != ERROR_NO_MORE_FILES) {
    lua_pushnil(L);
    push_win32_error(L, GetLastError());
    FindClose(find_handle);
    return 2;
  }

  FindClose(find_handle);
  return 1;
#else
  DIR *dir = opendir(path);
  if (!dir) {
    lua_pushnil(L);
    lua_pushstring(L, strerror(errno));
    return 2;
  }

  lua_newtable(L);
  int i = 1;
  struct dirent *entry;
  while ( (entry = readdir(dir)) ) {
    if (strcmp(entry->d_name, "." ) == 0) { continue; }
    if (strcmp(entry->d_name, "..") == 0) { continue; }
    lua_pushstring(L, entry->d_name);
    lua_rawseti(L, -2, i);
    i++;
  }

  closedir(dir);
  return 1;
#endif
}


#ifdef _WIN32
  #define realpath(x, y) _wfullpath(y, x, MAX_PATH)
#endif

static int f_absolute_path(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);
#ifdef _WIN32
  LPWSTR wpath = utfconv_utf8towc(path);
  if (!wpath) { return 0; }

  LPWSTR wfullpath = realpath(wpath, NULL);
  free(wpath);
  if (!wfullpath) { return 0; }

  char *res = utfconv_wctoutf8(wfullpath);
  free(wfullpath);
#else
  char *res = realpath(path, NULL);
#endif
  if (!res) { return 0; }
  lua_pushstring(L, res);
  free(res);
  return 1;
}


static int f_get_file_info(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);

#ifdef _WIN32
  struct _stat s;
  LPWSTR wpath = utfconv_utf8towc(path);
  if (wpath == NULL) {
    lua_pushnil(L);
    lua_pushstring(L, UTFCONV_ERROR_INVALID_CONVERSION);
    return 2;
  }
  int err = _wstat(wpath, &s);
  free(wpath);
#else
  struct stat s;
  int err = stat(path, &s);
#endif
  if (err < 0) {
    lua_pushnil(L);
    lua_pushstring(L, strerror(errno));
    return 2;
  }

  lua_newtable(L);
  lua_pushinteger(L, s.st_mtime);
  lua_setfield(L, -2, "modified");

  lua_pushinteger(L, s.st_size);
  lua_setfield(L, -2, "size");

  if (S_ISREG(s.st_mode)) {
    lua_pushstring(L, "file");
  } else if (S_ISDIR(s.st_mode)) {
    lua_pushstring(L, "dir");
  } else {
    lua_pushnil(L);
  }
  lua_setfield(L, -2, "type");

#if __linux__
  if (S_ISDIR(s.st_mode)) {
    if (lstat(path, &s) == 0) {
      lua_pushboolean(L, S_ISLNK(s.st_mode));
      lua_setfield(L, -2, "symlink");
    }
  }
#endif
  return 1;
}

#if __linux__
// https://man7.org/linux/man-pages/man2/statfs.2.html

struct f_type_names {
  uint32_t magic;
  const char *name;
};

static struct f_type_names fs_names[] = {
  { 0xef53,     "ext2/ext3" },
  { 0x6969,     "nfs"       },
  { 0x65735546, "fuse"      },
  { 0x517b,     "smb"       },
  { 0xfe534d42, "smb2"      },
  { 0x52654973, "reiserfs"  },
  { 0x01021994, "tmpfs"     },
  { 0x858458f6, "ramfs"     },
  { 0x5346544e, "ntfs"      },
  { 0x0,        NULL        },
};

#endif

static int f_get_fs_type(lua_State *L) {
  #if __linux__
    const char *path = luaL_checkstring(L, 1);
    struct statfs buf;
    int status = statfs(path, &buf);
    if (status != 0) {
      return luaL_error(L, "error calling statfs on %s", path);
    }
    for (int i = 0; fs_names[i].magic; i++) {
      if (fs_names[i].magic == buf.f_type) {
        lua_pushstring(L, fs_names[i].name);
        return 1;
      }
    }
  #endif
  lua_pushstring(L, "unknown");
  return 1;
}


static int f_mkdir(lua_State *L) {
  const char *path = luaL_checkstring(L, 1);

#ifdef _WIN32
  LPWSTR wpath = utfconv_utf8towc(path);
  if (wpath == NULL) {
    lua_pushboolean(L, 0);
    lua_pushstring(L, UTFCONV_ERROR_INVALID_CONVERSION);
    return 2;
  }

  int err = _wmkdir(wpath);
  free(wpath);
#else
  int err = mkdir(path, S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
#endif
  if (err < 0) {
    lua_pushboolean(L, 0);
    lua_pushstring(L, strerror(errno));
    return 2;
  }

  lua_pushboolean(L, 1);
  return 1;
}


static int f_get_clipboard(lua_State *L) {
  char *text = SDL_GetClipboardText();
  if (!text) { return 0; }
  lua_pushstring(L, text);
  SDL_free(text);
  return 1;
}


static int f_set_clipboard(lua_State *L) {
  const char *text = luaL_checkstring(L, 1);
  SDL_SetClipboardText(text);
  return 0;
}


static int f_get_process_id(lua_State *L) {
#ifdef _WIN32
  lua_pushinteger(L, GetCurrentProcessId());
#else
  lua_pushinteger(L, getpid());
#endif
  return 1;
}


static int f_get_time(lua_State *L) {
  double n = SDL_GetPerformanceCounter() / (double) SDL_GetPerformanceFrequency();
  lua_pushnumber(L, n);
  return 1;
}


static int f_sleep(lua_State *L) {
  double n = luaL_checknumber(L, 1);
  SDL_Delay(n * 1000);
  return 0;
}


static int f_exec(lua_State *L) {
  size_t len;
  const char *cmd = luaL_checklstring(L, 1, &len);
  char *buf = malloc(len + 32);
  if (!buf) { luaL_error(L, "buffer allocation failed"); }
#if _WIN32
  sprintf(buf, "cmd /c \"%s\"", cmd);
  WinExec(buf, SW_HIDE);
#else
  sprintf(buf, "%s &", cmd);
  int res = system(buf);
  (void) res;
#endif
  free(buf);
  return 0;
}

static int f_fuzzy_match(lua_State *L) {
  size_t strLen, ptnLen;
  const char *str = luaL_checklstring(L, 1, &strLen);
  const char *ptn = luaL_checklstring(L, 2, &ptnLen);
  // If true match things *backwards*. This allows for better matching on filenames than the above
  // function. For example, in the lite project, opening "renderer" has lib/font_render/build.sh
  // as the first result, rather than src/renderer.c. Clearly that's wrong.
  bool files = lua_gettop(L) > 2 && lua_isboolean(L,3) && lua_toboolean(L, 3);
  int score = 0, run = 0, increment = files ? -1 : 1;
  const char* strTarget = files ? str + strLen - 1 : str;
  const char* ptnTarget = files ? ptn + ptnLen - 1 : ptn;
  while (strTarget >= str && ptnTarget >= ptn && *strTarget && *ptnTarget) {
    while (strTarget >= str && *strTarget == ' ') { strTarget += increment; }
    while (ptnTarget >= ptn && *ptnTarget == ' ') { ptnTarget += increment; }
    if (tolower(*strTarget) == tolower(*ptnTarget)) {
      score += run * 10 - (*strTarget != *ptnTarget);
      run++;
      ptnTarget += increment;
    } else {
      score -= 10;
      run = 0;
    }
    strTarget += increment;
  }
  if (ptnTarget >= ptn && *ptnTarget) { return 0; }
  lua_pushinteger(L, score - (int)strLen * 10);
  return 1;
}

static int f_set_window_opacity(lua_State *L) {
  double n = luaL_checknumber(L, 1);
  int r = SDL_SetWindowOpacity(window, n);
  lua_pushboolean(L, r > -1);
  return 1;
}

typedef void (*fptr)(void);

typedef struct lua_function_node {
  const char *symbol;
  fptr address;
} lua_function_node;

#define P(FUNC) { "lua_" #FUNC, (fptr)(lua_##FUNC) }
#define U(FUNC) { "luaL_" #FUNC, (fptr)(luaL_##FUNC) }
static void* api_require(const char* symbol) {
  static lua_function_node nodes[] = {
    P(atpanic), P(checkstack),
    P(close), P(concat), P(copy), P(createtable), P(dump),
    P(error),  P(gc), P(getallocf),  P(getfield),
    P(gethook), P(gethookcount), P(gethookmask), P(getinfo), P(getlocal),
    P(getmetatable), P(getstack), P(gettable), P(gettop), P(getupvalue),
    P(isnumber), P(isstring), P(isuserdata),
    P(load), P(newstate), P(newthread), P(next),
    P(pushboolean), P(pushcclosure), P(pushfstring), P(pushinteger),
    P(pushlightuserdata), P(pushlstring), P(pushnil), P(pushnumber),
    P(pushstring), P(pushthread),  P(pushvalue),
    P(pushvfstring), P(rawequal), P(rawget), P(rawgeti),
    P(rawset), P(rawseti), P(resume),
    P(setallocf), P(setfield), P(sethook), P(setlocal),
    P(setmetatable), P(settable), P(settop), P(setupvalue),
    P(status), P(tocfunction), P(tointegerx), P(tolstring), P(toboolean),
    P(tonumberx), P(topointer), P(tothread),  P(touserdata),
    P(type), P(typename), P(upvalueid), P(upvaluejoin), P(version), P(xmove),
    U(getmetafield), U(callmeta), U(argerror), U(checknumber), U(optnumber),
    U(checkinteger), U(checkstack), U(checktype), U(checkany),
    U(newmetatable), U(setmetatable), U(testudata), U(checkudata), U(where),
    U(error), U(fileresult), U(execresult), U(ref), U(unref), U(loadstring),
    U(newstate), U(setfuncs), U(buffinit), U(addlstring), U(addstring),
    U(addvalue), U(pushresult), {"api_load_libs", (void*)(api_load_libs)},
    #if LUA_VERSION_NUM >= 502
    P(absindex), P(arith), P(callk), P(compare), P(getglobal),
    P(len), P(pcallk), P(rawgetp), P(rawlen), P(rawsetp), P(setglobal),
    P(iscfunction), P(yieldk),
    U(checkversion_), U(tolstring), U(len), U(getsubtable), U(prepbuffsize),
    U(pushresultsize), U(buffinitsize), U(checklstring), U(checkoption), U(gsub), U(loadbufferx),
    U(loadfilex), U(optinteger), U(optlstring), U(requiref), U(traceback)
    #else
    P(objlen)
    #endif

  };
  for (size_t i = 0; i < sizeof(nodes) / sizeof(lua_function_node); ++i) {
    if (strcmp(nodes[i].symbol, symbol) == 0)
      return *(void**)(&nodes[i].address);
  }
  return NULL;
}

static int f_load_native_plugin(lua_State *L) {
  char entrypoint_name[512]; entrypoint_name[sizeof(entrypoint_name) - 1] = '\0';
  int result;

  const char *name = luaL_checkstring(L, 1);
  const char *path = luaL_checkstring(L, 2);
  void *library = SDL_LoadObject(path);
  if (!library)
    return (lua_pushstring(L, SDL_GetError()), lua_error(L));

  lua_getglobal(L, "package");
  lua_getfield(L, -1, "native_plugins");
  lua_pushlightuserdata(L, library);
  lua_setfield(L, -2, name);
  lua_pop(L, 1);

  const char *basename = strrchr(name, '.');
  basename = !basename ? name : basename + 1;
  snprintf(entrypoint_name, sizeof(entrypoint_name), "luaopen_lite_xl_%s", basename);
  int (*ext_entrypoint) (lua_State *L, void* (*)(const char*));
  *(void**)(&ext_entrypoint) = SDL_LoadFunction(library, entrypoint_name);
  if (!ext_entrypoint) {
    snprintf(entrypoint_name, sizeof(entrypoint_name), "luaopen_%s", basename);
    int (*entrypoint)(lua_State *L);
    *(void**)(&entrypoint) = SDL_LoadFunction(library, entrypoint_name);
    if (!entrypoint)
      return luaL_error(L, "Unable to load %s: Can't find %s(lua_State *L, void *XL)", name, entrypoint_name);
    result = entrypoint(L);
  } else {
    result = ext_entrypoint(L, api_require);
  }

  if (!result)
    return luaL_error(L, "Unable to load %s: entrypoint must return a value", name);

  return result;
}

#ifdef _WIN32
#define PATHSEP '\\'
#else
#define PATHSEP '/'
#endif

/* Special purpose filepath compare function. Corresponds to the
   order used in the TreeView view of the project's files. Returns true iff
   path1 < path2 in the TreeView order. */
static int f_path_compare(lua_State *L) {
  const char *path1 = luaL_checkstring(L, 1);
  const char *type1_s = luaL_checkstring(L, 2);
  const char *path2 = luaL_checkstring(L, 3);
  const char *type2_s = luaL_checkstring(L, 4);
  const int len1 = strlen(path1), len2 = strlen(path2);
  int type1 = strcmp(type1_s, "dir") != 0;
  int type2 = strcmp(type2_s, "dir") != 0;
  /* Find the index of the common part of the path. */
  int offset = 0, i;
  for (i = 0; i < len1 && i < len2; i++) {
    if (path1[i] != path2[i]) break;
    if (path1[i] == PATHSEP) {
      offset = i + 1;
    }
  }
  /* If a path separator is present in the name after the common part we consider
     the entry like a directory. */
  if (strchr(path1 + offset, PATHSEP)) {
    type1 = 0;
  }
  if (strchr(path2 + offset, PATHSEP)) {
    type2 = 0;
  }
  /* If types are different "dir" types comes before "file" types. */
  if (type1 != type2) {
    lua_pushboolean(L, type1 < type2);
    return 1;
  }
  /* If types are the same compare the files' path alphabetically. */
  int cfr = 0;
  int len_min = (len1 < len2 ? len1 : len2);
  for (int j = offset; j <= len_min; j++) {
    if (path1[j] == path2[j]) continue;
    if (path1[j] == 0 || path2[j] == 0) {
      cfr = (path1[j] == 0);
    } else if (path1[j] == PATHSEP || path2[j] == PATHSEP) {
      /* For comparison we treat PATHSEP as if it was the string terminator. */
      cfr = (path1[j] == PATHSEP);
    } else {
      cfr = (path1[j] < path2[j]);
    }
    break;
  }
  lua_pushboolean(L, cfr);
  return 1;
}


static const luaL_Reg lib[] = {
  { "poll_event",          f_poll_event          },
  { "wait_event",          f_wait_event          },
  { "set_cursor",          f_set_cursor          },
  { "set_window_title",    f_set_window_title    },
  { "set_window_mode",     f_set_window_mode     },
  { "get_window_mode",     f_get_window_mode     },
  { "set_window_bordered", f_set_window_bordered },
  { "set_window_hit_test", f_set_window_hit_test },
  { "get_window_size",     f_get_window_size     },
  { "set_window_size",     f_set_window_size     },
  { "window_has_focus",    f_window_has_focus    },
  { "raise_window",        f_raise_window        },
  { "show_fatal_error",    f_show_fatal_error    },
  { "rmdir",               f_rmdir               },
  { "chdir",               f_chdir               },
  { "mkdir",               f_mkdir               },
  { "list_dir",            f_list_dir            },
  { "absolute_path",       f_absolute_path       },
  { "get_file_info",       f_get_file_info       },
  { "get_clipboard",       f_get_clipboard       },
  { "set_clipboard",       f_set_clipboard       },
  { "get_process_id",      f_get_process_id      },
  { "get_time",            f_get_time            },
  { "sleep",               f_sleep               },
  { "exec",                f_exec                },
  { "fuzzy_match",         f_fuzzy_match         },
  { "set_window_opacity",  f_set_window_opacity  },
  { "load_native_plugin",  f_load_native_plugin  },
  { "path_compare",        f_path_compare        },
  { "get_fs_type",         f_get_fs_type         },
  { NULL, NULL }
};


int luaopen_system(lua_State *L) {
  luaL_newlib(L, lib);
  return 1;
}