MDL-74379 language: injecting am/pm in date string

patching the date_format_string() function in moodlelib to add am/pm for languages that don't suuport it.

lang/en/langconfig.php

@@ -23,6 +23,8 @@
  */
 
 $string['alphabet'] = 'A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z';
+$string['am'] = 'am';
+$string['amcaps'] = 'AM';
 $string['backupnameformat'] = '%Y%m%d-%H%M';
 $string['dateintervaldayshoursmins'] = '%ad %hh %im'; // See https://www.php.net/manual/en/dateinterval.format.php for format.
 $string['decsep'] = '.';
@@ -37,6 +39,8 @@ $string['localewin'] = 'English_Australia.1252';
 $string['localewincharset'] = '';
 $string['oldcharset'] = 'ISO-8859-1';
 $string['parentlanguage'] = '';
+$string['pm'] = 'pm';
+$string['pmcaps'] = 'PM';
 $string['strftimedate'] = '%d %B %Y';
 $string['strftimedatemonthabbr'] = '%d %b %Y';
 $string['strftimedatefullshort'] = '%d/%m/%y';

lib/moodlelib.php

@@ -2353,6 +2353,21 @@ function date_format_string($date, $format, $tz = 99) {
     }
 
     date_default_timezone_set(core_date::get_user_timezone($tz));
+
+    $datearray = getdate($date);
+
+    if (nl_langinfo(AM_STR) == nl_langinfo(PM_STR)) {
+
+        $format = str_replace([
+            '%P',
+            '%p',
+        ], [
+            $datearray['hours'] < 12 ? get_string('am', 'langconfig') : get_string('pm', 'langconfig'),
+            $datearray['hours'] < 12 ? get_string('amcaps', 'langconfig') : get_string('pmcaps', 'langconfig'),
+            ],
+        $format);
+    }
+
     $datestring = strftime($format, $date);
     core_date::set_default_server_timezone();