/*
** File system manipulation library.
** This library offers these functions:
**   luafilesystem.attributes (filepath [, attributename])
**   luafilesystem.chdir (path)
**   luafilesystem.currentdir ()
**   luafilesystem.dir (path)
**   luafilesystem.mkdir (path)
**   luafilesystem.lock (fh, mode)
**   luafilesystem.unlock (fh)
**
** $Id: luafilesystem.c,v 1.1.1.1 2004/07/27 14:15:24 tomas Exp $
*/

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

#ifdef WIN32
#include <direct.h>
#include <io.h>
#include <sys/locking.h>
#else
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#endif

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>

#include "luafilesystem.h"

/* Define 'strerror' for systems that do not implement it */
#ifdef NO_STRERROR
#define strerror(_)	"System unable to describe the error"
#endif

/* Define 'getcwd' for systems that do not implement it */
#ifdef NO_GETCWD
#define getcwd(p,s)	NULL
#define getcwd_error	"Function 'getcwd' not provided by system"
#else
#define getcwd_error	strerror(errno)
#endif

#define DIR_METATABLE "directory metatable"
#define MAX_DIR_LENGTH 1023
#ifdef _WIN32
typedef struct dir_data {
	long hFile;
	char pattern[MAX_DIR_LENGTH+1];
} dir_data;
#endif


/*
** This function changes the working (current) directory
*/
static int change_dir (lua_State *L) {
	const char *path = luaL_checkstring(L, 1);
	if (chdir(path)) 
		luaL_error(L,"Unable to change working directory to '%s'\n%s\n",
				path, chdir_error);
	return 0;
}

/*
** This function returns the current directory
** If unable to get the current directory, it returns nil
**  and a string describing the error
*/
static int get_dir (lua_State *L) {
	char path[255+2];
	if (getcwd(path, 255) == NULL) {
		lua_pushnil(L);
		lua_pushstring(L, getcwd_error);
		return 2;
	}
	else {
		lua_pushstring(L, path);
		return 1;
	}
}

/*
** Check if the given element on the stack is a file and returns it.
*/
static FILE *check_file (lua_State *L, int idx, const char *funcname) {
	FILE **fh = (FILE **)luaL_checkudata (L, idx, "FILE*");
	if (fh == NULL) {
		luaL_error (L, "%s: not a file", funcname);
		return 0;
	} else if (*fh == NULL) {
		luaL_error (L, "%s: closed file", funcname);
		return 0;
	} else
		return *fh;
}


/*
**
*/
static int _file_lock (lua_State *L, FILE *fh, const char *mode, const long start, long len, const char *funcname) {
	int code;
#ifdef WIN32
	/* lkmode valid values are:
	   _LK_LOCK    Locks the specified bytes. If the bytes cannot be locked, the program immediately tries again after 1 second. If, after 10 attempts, the bytes cannot be locked, the constant returns an error.
	   _LK_NBLCK   Locks the specified bytes. If the bytes cannot be locked, the constant returns an error.
	   _LK_NBRLCK  Same as _LK_NBLCK.
	   _LK_RLCK    Same as _LK_LOCK.
	   _LK_UNLCK   Unlocks the specified bytes, which must have been previously locked.

	   Regions should be locked only briefly and should be unlocked before closing a file or exiting the program.

	   http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vclib/html/_crt__locking.asp
	*/
	int lkmode;
	switch (*mode) {
		case 'r': lkmode = _LK_NBLCK; break;
		case 'w': lkmode = _LK_NBLCK; break;
		case 'u': lkmode = _LK_UNLCK; break;
		default : luaL_error (L, "%s: invalid mode", funcname);
	}
	if (!len) {
		fseek (fh, 0L, SEEK_END);
		len = ftell (fh);
	}
	fseek (fh, start, SEEK_SET);
	code = _locking (fileno(fh), lkmode, len);
#else
	struct flock f;
	switch (*mode) {
		case 'w': f.l_type = F_WRLCK; break;
		case 'r': f.l_type = F_RDLCK; break;
		case 'u': f.l_type = F_UNLCK; break;
		default : luaL_error (L, "%s: invalid mode", funcname);
	}
	f.l_whence = SEEK_SET;
	f.l_start = (off_t)start;
	f.l_len = (off_t)len;
	code = fcntl (fileno(fh), F_SETLK, &f);
#endif
	return (code != -1);
}


/*
** Locks a file.
** @param #1 File handle.
** @param #2 String with lock mode ('w'rite, 'r'ead).
** @param #3 Number with start position (optional).
** @param #4 Number with length (optional).
*/
static int file_lock (lua_State *L) {
	FILE *fh = check_file (L, 1, "lock");
	const char *mode = luaL_checkstring (L, 2);
	const long start = luaL_optlong (L, 3, 0);
	long len = luaL_optlong (L, 4, 0);
	if (_file_lock (L, fh, mode, start, len, "lock")) {
		lua_pushboolean (L, 1);
		return 1;
	} else {
		lua_pushboolean (L, 0);
		lua_pushfstring (L, "%s", strerror(errno));
		return 2;
	}
}


/*
** Unlocks a file.
** @param #1 File handle.
** @param #2 Number with start position (optional).
** @param #3 Number with length (optional).
*/
static int file_unlock (lua_State *L) {
	FILE *fh = check_file (L, 1, "unlock");
	const long start = luaL_optlong (L, 2, 0);
	long len = luaL_optlong (L, 3, 0);
	if (_file_lock (L, fh, "u", start, len, "unlock")) {
		lua_pushboolean (L, 1);
		return 1;
	} else {
		lua_pushboolean (L, 0);
		lua_pushfstring (L, "%s", strerror(errno));
		return 2;
	}
}


/*
static void cgilua_sleep( lua_State *L )
{
  unsigned int usec = (unsigned int)luaL_check_number( L, 1 );

#ifndef WIN32
  sleep( (unsigned int)ceil( usec/1000.0 ));
#else
  Sleep( (DWORD)usec );
#endif
}

static void cgilua_filesize( lua_State *L )
{
  struct stat info;
  char *file = luaL_check_string( L, 1 );

  if (stat(file, &info))
  {
    lua_pushnil( L );
    lua_pushstring( L, "Cannot retrieve stat info from file" );
    return;
  }
  lua_pushnumber(L, info.st_size);
}
*/

static int make_dir (lua_State *L) {
	const char *path = luaL_checkstring (L, 1);
	int fail;
#ifdef WIN32
	int oldmask = umask (0);
	fail = _mkdir (path);
#else
	mode_t oldmask = umask( (mode_t)0 );
	fail =  mkdir (path, S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP |
	                     S_IWGRP | S_IXGRP | S_IROTH | S_IXOTH );
#endif
	lua_pushboolean (L, fail);
	umask (oldmask);
	return 1;
}


/*
** Directory iterator
*/
static int dir_iter (lua_State *L) {
#ifdef _WIN32
	dir_data *d = (dir_data *)lua_touserdata (L, lua_upvalueindex (1));
	struct _finddata_t c_file;
	if (d->hFile == 0L) { /* first entry */
		if ((d->hFile = _findfirst (d->pattern, &c_file)) == -1L) {
			lua_pushnil (L);
			lua_pushstring (L, strerror (errno));
			return 2;
		} else {
			lua_pushstring (L, c_file.name);
			return 1;
		}
	} else { /* next entry */
		if (_findnext (d->hFile, &c_file) == -1L)
			return 0;
		else {
			lua_pushstring (L, c_file.name);
			return 1;
		}
	}
#else
	DIR *d = *(DIR **) lua_touserdata (L, lua_upvalueindex (1));
	struct dirent *entry;
	if ((entry = readdir (d)) != NULL) {
		lua_pushstring (L, entry->d_name);
		return 1;
	}
	else
		return 0;
#endif
}


/*
** Closes directory iterators
*/
static int dir_close (lua_State *L) {
#ifdef _WIN32
	dir_data *d = (dir_data *)lua_touserdata (L, 1);
	if (d->hFile) {
		_findclose (d->hFile);
	}
#else
	DIR *d = *(DIR **)lua_touserdata (L, 1);
	if (d)
		closedir (d);
#endif
	return 0;
}


/*
** Factory of directory iterators
*/
static int dir_iter_factory (lua_State *L) {
	const char *path = luaL_checkstring (L, 1);
#ifdef _WIN32
	dir_data *dir = (dir_data *) lua_newuserdata (L, sizeof(dir_data));
	dir->hFile = 0L;
	if (strlen(path) > MAX_DIR_LENGTH)
		luaL_error (L, "path too long: %s", path);
	else
		sprintf (dir->pattern, "%s/*", path);
	luaL_getmetatable (L, DIR_METATABLE);
	lua_setmetatable (L, -2);
#else
	DIR **d = (DIR **) lua_newuserdata (L, sizeof(DIR *));
	luaL_getmetatable (L, DIR_METATABLE);
	lua_setmetatable (L, -2);
	*d = opendir (path);
	if (*d == NULL)
		luaL_error (L, "cannot open %s: %s", path, strerror (errno));
#endif
	lua_pushcclosure (L, dir_iter, 1);
	return 1;
}


/*
** Creates directory metatable.
*/
static int dir_create_meta (lua_State *L) {
	luaL_newmetatable (L, DIR_METATABLE);
	/* set its __gc field */
	lua_pushstring (L, "__gc");
	lua_pushcfunction (L, dir_close);
	lua_settable (L, -3);

	return 1;
}


static const struct luaL_reg fslib[] = {
	{"chdir", change_dir},
	{"currentdir", get_dir},
	{"dir", dir_iter_factory},
	{"lock", file_lock},
	{"mkdir", make_dir},
	{"unlock", file_unlock},
	{NULL, NULL},
};

int luaopen_luafilesystem (lua_State *L) {
	dir_create_meta (L);
	luaL_openlib (L, "luafilesystem", fslib, 0);
	return 1;
}