mscan: add dottime formatting

man/mscan.1

@@ -1,4 +1,4 @@
-.Dd September 25, 2018
+.Dd January 2, 2020
 .Dt MSCAN 1
 .Os
 .Sh NAME
@@ -94,6 +94,11 @@ on the current message,
 otherwise a blank.
 .It Cm "%" Ns Oo Ar wd Oc Ns Cm "d"
 Adaptive date of the message.
+When
+.Ar wd
+is greater or equal to 19,
+the timestamp is shown in dottime format
+.Pq Lk https://dotti.me/ .
 .It Cm "%" Ns Oo Ar wd Oc Ns Cm "D"
 ISO date of the message
 .Pq year, month, day .

mscan.c

@@ -6,6 +6,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <locale.h>
@@ -138,6 +139,33 @@ fmt_date(struct message *msg, int w, int iso)
 			strftime(date, sizeof date, "%Y-%m-%d %H:%M", tm);
 		else
 			strftime(date, sizeof date, "%Y-%m-%d", tm);
+	} else if (w >= 19) {
+		// https://dotti.me/
+
+		tm = gmtime(&t);
+		strftime(date, sizeof date, "%Y-%m-%dT%H\xc2\xb7%M", tm);
+		char *d = date + strlen(date);
+
+		char *e = v + strlen(v);
+		while (e > v && (*e != '+' && *e != '-'))
+			e--;
+
+		if (isdigit(e[1]) && isdigit(e[2]) && isdigit(e[3]) && isdigit(e[4])) {
+			*d++ = e[0];
+			*d++ = e[1];
+			*d++ = e[2];
+			if (e[3] != '0' || e[4] != '0') {
+				*d++ = ':';
+				*d++ = e[3];
+				*d++ = e[4];
+			}
+			*d = 0;
+		} else {
+			*d++ = '+';
+			*d++ = '0';
+			*d++ = '0';
+			*d = 0;
+		}
 	} else if (w < 10) {
 		if (tm->tm_year != curyear)
 			strftime(date, sizeof date, "%b%y", tm);