+static int is_valid_date(const int day, const int month, const int year)
+{
+ int valid = 1;
+ int month_length[13] =
+ { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+ /*
+ * leap year
+ */
+ if ((!(year % 4)) && ((year % 100) || !(year % 400)))
+ month_length[2] = 29;
+
+ if (month < 1 || month > 12)
+ valid = 0;
+ else if (day < 1 || day > month_length[month])
+ valid = 0;
+ else if (year < 0) /* we don't accept negative year numbers */
+ valid = 0;
+
+ return valid;
+}
+
+int
+parse_date_string(char *s, int *day, int *month, int *year)
+{
+ int i = 0;
+ char *p = s;
+ assert(s && day && month && year);
+
+ if(*s == '-' && *s++ == '-') { /* omitted year */
+ *year = 0;
+ p = ++s;
+ i++;
+ }
+
+ while(*s) {
+ if(isdigit(*s)) {
+ s++;
+ continue;
+ } else if(*s == '-') {
+ if(++i > 3)
+ return FALSE;
+ *s++ = '\0';
+ switch(i) {
+ case 1: *year = safe_atoi(p); break;
+ case 2: *month = safe_atoi(p); break;
+ }
+ p = s;
+ } else
+ return FALSE;
+ }
+
+ if (i != 2 || !*p)
+ return FALSE;
+
+ *day = atoi(p);
+
+ return is_valid_date(*day, *month, *year);
+}
+
+static void
+edit_date(int item, int nb)
+{
+ int i, date[3], old = FALSE;
+ char buf[12], *s = db_fget_byid(item, nb);
+ char *field[] = { N_("Day: "), N_("Month: "), N_("Year (optional): ") };
+
+ if(s) {
+ strncpy(buf, s, sizeof(buf));
+ old = parse_date_string(buf, &date[0], &date[1], &date[2]);
+ }
+
+ for(i = 0; i < 3; i++) {
+ s = (old && date[i]) ? strdup_printf("%d", date[i]) : NULL;
+ if(change_field(gettext(field[i]), &s, 5))
+ return; /* user aborted with ^G */
+
+ date[i] = (s && is_number(s)) ? atoi(s) : 0;
+
+ if(!s) {
+ switch(i) {
+ case 0: db_fput_byid(item, nb, NULL); /*delete*/
+ case 1: /* fall through */ return;
+ }
+ } else
+ xfree(s);
+ }
+
+ /* ISO 8601 date, of the YYYY-MM-DD or --MM-DD format */
+ if(is_valid_date(date[0], date[1], date[2])) {
+ if(date[2])
+ s = strdup_printf("%04d-%02d-%02d",
+ date[2], date[1], date[0]);
+ else
+ s = strdup_printf("--%02d-%02d", date[1], date[0]);
+
+ db_fput_byid(item, nb, xstrdup(s));
+ } else
+ statusline_msg(_("Invalid date"));
+}