adding strip_ics_alarms

shell/strip_ics_alarms.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+#
+# Given an ICS input file, write a new ICS output file with all the
+# alarms stripped out (BEGIN:VALARM -> END:VALARM)
+#
+# SPDX-License-Identifier: MIT
+
+if [ ! -r "$1" ]; then
+  echo "Cannot read input file $1, exiting."
+  exit 1
+fi
+
+INFILE=$1
+OUTFILE="${INFILE}.stripped"
+
+# create/truncate it so we can use >> later
+: > "${OUTFILE}"
+
+VERBOSE=1
+READLINES=0
+WROTELINES=0
+EVENTCOUNT=0
+ALARMCOUNT=0
+GOTALARM=0
+
+if [ ${VERBOSE} ]; then
+  echo -n "Working"
+fi
+
+# preserve whitespace, don't interpret escapes
+# shellcheck disable=SC2004
+while IFS=$'\n' read -r vline; do
+  READLINES=$(($READLINES+1))
+  if [ ${VERBOSE} ]; then
+    if [ $(($READLINES%100)) -eq 0 ]; then
+      echo -n "."
+    fi
+  fi
+  # use substring matching to avoid possible '\r' and '^M' on lines
+  if [ "${vline:0:12}" == "BEGIN:VEVENT" ]; then
+    EVENTCOUNT=$(($EVENTCOUNT+1))
+  fi
+  if [ ${GOTALARM} -ne 1 ]; then
+    if [ "${vline:0:12}" != "BEGIN:VALARM" ]; then
+      # don't interpret escapes while writing
+      echo -E "${vline}" >> "${OUTFILE}"
+      WROTELINES=$(($WROTELINES+1))
+      continue
+    else
+      GOTALARM=1
+      continue
+    fi
+  else
+    if [ "${vline:0:10}" == "END:VALARM" ]; then
+      GOTALARM=0
+      ALARMCOUNT=$(($ALARMCOUNT+1))
+    fi
+    continue
+  fi
+done < "${INFILE}"
+
+if [ ${VERBOSE} ]; then
+  echo "done."
+  echo "Read ${READLINES} lines"
+  echo "Wrote ${WROTELINES} lines"
+  echo "Found ${EVENTCOUNT} events"
+  echo "Stripped ${ALARMCOUNT} alarms"
+fi
+
+exit 0