notify of changes by email

epsiEDTtoICS.sh

@@ -8,17 +8,19 @@
 #
 # From EPSI “edtmobilityeng” to ICS, for the current school year. Usage:
 #
-# epsiEDTtoICS.sh -u <user> [ -c [ <path> | - ]                ] [ -j ]
-# epsiEDTtoICS.sh -u <user> [ -p [ <path> | - ] [ -w <count> ] ] [ -j ]
+# epsiEDTtoICS.sh -u <user> [ -c [ <path> | - ]                ] [ -j ] [ -m <to> ]
+# epsiEDTtoICS.sh -u <user> [ -p [ <path> | - ] [ -w <count> ] ] [ -j ] [ -m <to> ]
 #   <user>:  EPSI Login (firstname.lastname)
 #   <path>:  Location where the ICS file is created (-c) or patched (-p)
 #   <count>: Number of weeks to update (including the current one), if -p is specified
+#   <to>:    Comma-separated list of email recipients (needs sendmail in the PATH)
 #
 # If no path is given, “-” is assumed, which is a placeholder for the standard output.
 # If neither -c nor -p is given, “-c -” is assumed.
 # If -p is used with “-” as a path, then only the updated weeks are sent to the standard output.
 # If -p is given without -w, the default count of updated weeks is 5.
 # If -j is used, logs are sent to systemd-journald instead of the standard error (needs systemd-cat).
+# If -m is used, the given recipients are notified of changes between runs
 
 LANG8BIT=fr_FR@euro
 
@@ -27,14 +29,16 @@ PATCH=
 OUTPUT=-
 MAXOFFSET=
 JOURNAL=
+TO=
 readonly -a LEVELS=( emerg alert crit err warning notice info debug )
 
-while getopts u:c:p:w:j arg; do case "$arg" in
+while getopts u:c:p:w:jm: arg; do case "$arg" in
 u) LOGIN="$OPTARG" ;;
 c) OUTPUT="${OPTARG:--}"; PATCH= ;;
 p) OUTPUT="${OPTARG:--}"; PATCH=true ;;
 w) MAXOFFSET="${OPTARG//[^0-9]}" ;;
 j) JOURNAL=true ;;
+m) TO="$OPTARG" ;;
 esac; done
 
 # $1: log level ∈ [0 … 7]
@@ -72,6 +76,10 @@ function check_parameters_and_set_defaults() {
     JOURNAL=
     log 4 "Command “systemd-cat” not found"
   fi
+  if [ -n "$TO" ] && ! which sendmail >/dev/null; then
+    TO=
+    log 4 "Command “sendmail” not found"
+  fi
   MAXOFFSET=$((${MAXOFFSET:-5}*7))
 }
 
@@ -83,9 +91,61 @@ function lf_to_crlf() {
   sed 's/$/\r/'
 }
 
-function write_output() {
+function crlf_to_lf() {
+  tr -d '\r'
+}
+
+# &0: standard ical, with long lines wrapped
+# &1: long lines are unwrapped
+function unwrap_ical_long_lines() {
+  sed ':n;N;s/\n //;tn;P;D'
+}
+
+# $1: path to the old file
+# $2: path to the new file
+function format_diff_and_send_mail() {
+  {
+    echo "To: $TO"
+    echo "Subject: Changes in EPSI calendar"
+    echo
+    diff -u8 \
+      <(crlf_to_lf <"$1" | unwrap_ical_long_lines | grep -vE '^DTSTAMP:|^UID:') \
+      <(crlf_to_lf <"$2" | unwrap_ical_long_lines | grep -vE '^DTSTAMP:|^UID:') \
+    | awk '
+      function out() {
+        if (inDiff+inEvent==2) printf("%s", diff)
+        inDiff=0
+        inEvent=0
+      }
+      /BEGIN:VEVENT/  { inEvent=1; diff="\n"; next }
+      $0 ~ /^[-+]/    { inDiff=1 }
+      /^@|END:VEVENT/ { out() }
+                      { diff=diff $0 "\n" }' \
+    | while IFS='' read -r l; do
+      case "$l" in
+      '')
+        echo; continue ;;
+      ?DT*)
+        h="$(sed -r 's/^.DT(.*):.*/\1/' <<<"$l")"
+        v="$(date -d $(sed -r 's/.*:(....)(..)(..T..)(..)(..Z)/\1-\2-\3:\4:\5/' <<<"$l"))" ;;
+      *)
+        IFS=: read -r h v <<<"${l#?}" ;;
+      esac
+      printf '%s %11s: %s\n' "${l:0:1}" "$h" "$v"
+    done
+  } \
+  | lf_to_crlf \
+  | sendmail -t
+}
+
+function write_output_and_send_mail() {
   [ "$OUTPUT" == - ] && cat || {
-    cat >"${OUTPUT}.tmp" && mv -f "${OUTPUT}.tmp" "$OUTPUT" || {
+    cat >"${OUTPUT}.tmp" \
+    && {
+      [ -n "$TO" ] && format_diff_and_send_mail "$OUTPUT" "${OUTPUT}.tmp"
+      mv -f "${OUTPUT}.tmp" "$OUTPUT"
+    } \
+    || {
       log 3 "Failed to write to: $OUTPUT"
       exit 20
     }
@@ -304,7 +364,7 @@ function main() {
   } \
   | fold_long_lines \
   | lf_to_crlf \
-  | write_output
+  | write_output_and_send_mail
 }
 
 main