Eagles Nest Class Calendar Filter/Generator

class_filter.awk

# ICS file filter

BEGIN {
   FS = ":"
   buffer = ""
   notevent = 0
}
($1~/^BEGIN/ && $2~/VEVENT/) {
   keep = 1;
}
($1~/^BEGIN/ && $2!~/VEVENT/) {
   notevent = 1;
}

$1~/SUMMARY/ && notevent==0 {
   if ($2~/[A-Z]{2} [0-9]{3}.+[0-9]+.*/)
   {
      keep = 1;
   }
   else
   {
      # clear the event buffer and inform not to keep whole record
      buffer = "";
      keep = 0;
   }
}

notevent==0 {
   if (keep==1)
   {
      buffer=buffer$0"\n"
   }
}


($1~/^END/ && $2~/VEVENT/) {
   if (keep == 1)
   {
      printf("%s", buffer);
      buffer = "";
      keep   = 0;
   }
}
($1~/^END/ && $2!~/VEVENT/) {
   notevent = 0;
   print $0;
}

notevent==1 { print $0 }

gen_calendar.sh

#!/bin/bash
CALENDAR_URL="put_your_eagles_nest_calendar_url_here"
wget -q -O - "${CALENDAR_URL/webcal/http}" | awk -f ./class_filter.awk > class_calendar.ics