/*!
  \file lib/db/dbmi_base/dirent.c
  
  \brief DBMI Library (base) - directory entities management
  
  (C) 1999-2010 by the GRASS Development Team
  
  This program is free software under the GNU General Public License
  (>=v2). Read the file COPYING that comes with GRASS for details.
  
  \author Joel Jones (CERL/UIUC)
  \author Upgraded to GRASS 5.7 by Radim Blazek
*/

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <grass/dbmi.h>
/* NOTE: these should come from <unistd.h> or from <sys/file.h> */
#define R_OK 4
#define W_OK 2
#define X_OK 1

#include <sys/types.h>
#ifdef USE_DIRECT
# include <sys/dir.h>
typedef struct direct dir_entry;
#else
# include <dirent.h>
typedef struct dirent dir_entry;
#endif

extern DIR *opendir();
extern dir_entry *readdir();

static int cmp_dirent(const void *, const void *);
static int get_perm(char *);
static void sort_dirent(dbDirent *, int);

/*!
  \brief Read directory and build an array of dbDirent's
  
  Append one entry with name = NULL to mark end of array
  
  \param dirname directory name
  \param[out] n number of entities

  \return pointer to dbDirent
  \return NULL on error
*/
dbDirent *db_dirent(const char *dirname, int *n)
{
    DIR *dp;
    dir_entry *entry;
    dbDirent *dirent;
    int i, count;
    char *path;
    int len, max;

    db_clear_error();

    *n = 0;
    dp = opendir(dirname);
    if (dp == NULL) {
	db_syserror(dirname);
	return (dbDirent *) NULL;
    }


    /* count the number of entries and get the strlen of the longest name */
    count = 0;
    max = 0;
    while ((entry = readdir(dp))) {
	count++;
	len = strlen(entry->d_name);
	if (len > max)
	    max = len;
    }
    rewinddir(dp);

    path = db_malloc(strlen(dirname) + max + 2);	/* extra 2 for / and NULL */
    if (path == NULL) {
	closedir(dp);
	return (dbDirent *) NULL;
    }
    dirent = db_alloc_dirent_array(count);
    if (dirent == NULL) {
	closedir(dp);
	return (dbDirent *) NULL;
    }
    *n = count;
    for (i = 0; i < count; i++) {
	entry = readdir(dp);
	if (entry == NULL)	/* this shouldn't happen */
	    break;

	if (DB_OK != db_set_string(&dirent[i].name, entry->d_name))
	    break;
	sprintf(path, "%s/%s", dirname, entry->d_name);
	dirent[i].perm = get_perm(path);
	dirent[i].isdir = (db_isdir(path) == DB_OK);
    }
    closedir(dp);
    db_free(path);

    sort_dirent(dirent, *n);

    return dirent;
}

/*!
  \brief Free dbDirent

  \param dirent pointer to dbDirent
  \param count number of entities in the array
*/
void db_free_dirent_array(dbDirent * dirent, int count)
{
    int i;

    if (dirent) {
	for (i = 0; i < count; i++)
	    db_free_string(&dirent[i].name);
	db_free(dirent);
    }
}

static int get_perm(char *path)
{
    int perm;

    perm = 0;

    if (access(path, R_OK) == 0)
	perm |= DB_PERM_R;
    if (access(path, W_OK) == 0)
	perm |= DB_PERM_W;
    if (access(path, X_OK) == 0)
	perm |= DB_PERM_X;

    return perm;
}

static int cmp_dirent(const void *aa, const void *bb)
{
    const dbDirent *a = aa;
    const dbDirent *b = bb;

    return strcmp(db_get_string((dbString *) & a->name),
		  db_get_string((dbString *) & b->name));
}

static void sort_dirent(dbDirent * a, int n)
{
    qsort(a, n, sizeof(dbDirent), cmp_dirent);
}

/*!
  \brief Allocate dirent array

  \param count number of entities in the array

  \return pointer to dbDirent array
  \return NULL on failure
*/
dbDirent *db_alloc_dirent_array(int count)
{
    int i;
    dbDirent *dirent;

    dirent = (dbDirent *) db_calloc(count, sizeof(dbDirent));
    if (dirent == NULL)
	return dirent;

    for (i = 0; i < count; i++)
	db_init_string(&dirent[i].name);

    return dirent;
}