/******************************************************************************

	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.

	This file is part of LibMaxsi.

	LibMaxsi is free software: you can redistribute it and/or modify it under
	the terms of the GNU Lesser General Public License as published by the Free
	Software Foundation, either version 3 of the License, or (at your option)
	any later version.

	LibMaxsi 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 Lesser General Public License for
	more details.

	You should have received a copy of the GNU Lesser General Public License
	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.

	dir.c
	DIR* is an interface allowing various directory backends.

******************************************************************************/

#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>

DIR* firstdir = NULL;

void dregister(DIR* dir)
{
	dir->flags |= _DIR_REGISTERED;
	if ( !firstdir ) { firstdir = dir; return; }
	dir->next = firstdir;
	firstdir->prev = dir;
	firstdir = dir;
}

void dunregister(DIR* dir)
{
	if ( !(dir->flags & _DIR_REGISTERED) ) { return; }
	if ( !dir->prev ) { firstdir = dir->next; }
	if ( dir->prev ) { dir->prev->next = dir->next; }
	if ( dir->next ) { dir->next->prev = dir->prev; }
	dir->flags &= ~_DIR_REGISTERED;
}

struct dirent* readdir(DIR* dir)
{
	if ( !dir->read_func )
	{
		dir->flags |= _DIR_ERROR;
		errno = EBADF;
		return 0;
	}

	size_t size = dir->entrysize;
	int status = dir->read_func(dir->user, dir->entry, &size);
	if ( status < 0 )
	{
		dir->flags |= _DIR_ERROR;
		return NULL;
	}
	if ( 0 < status )
	{
		struct dirent* biggerdir = malloc(size);
		if ( !biggerdir )
		{
			dir->flags |= _DIR_ERROR;
			return NULL;
		}
		free(dir->entry);
		dir->entry = biggerdir;
		dir->entrysize = size;
		return readdir(dir);
	}

	dir->flags &= ~_DIR_ERROR;

	if ( !dir->entry->d_name[0] )
	{
		dir->flags |= _DIR_EOF;
		return NULL;
	}

	return dir->entry;
}

int closedir(DIR* dir)
{
	int result = (dir->close_func) ? dir->close_func(dir->user) : 0;
	dunregister(dir);
	free(dir->entry);
	if ( dir->free_func ) { dir->free_func(dir); }
	return result;
}

void rewinddir(DIR* dir)
{
	if ( dir->rewind_func ) { dir->rewind_func(dir->user); }
	dir->flags &= ~_DIR_EOF;
}

int dirfd(DIR* dir)
{
	if ( !dir->fd_func ) { errno = EBADF; return 0; }

	return dir->fd_func(dir->user);
}

void dclearerr(DIR* dir)
{
	dir->flags &= ~_DIR_ERROR;
}

int derror(DIR* dir)
{
	return dir->flags & _DIR_ERROR;
}

int deof(DIR* dir)
{
	return dir->flags & _DIR_EOF;
}

static void dfreedir(DIR* dir)
{
	free(dir);
}

DIR* dnewdir(void)
{
	DIR* dir = (DIR*) calloc(sizeof(DIR), 1);
	if ( !dir ) { return NULL; }
	dir->flags = 0;
	dir->free_func = dfreedir;
	dregister(dir);
	return dir;
}

int dcloseall(void)
{
	int result = 0;
	while ( firstdir ) { result |= closedir(firstdir); }
	return (result) ? EOF : 0;
}