Take value data type of event start into account in iCal import/export

The patch derives the item type (appointment or event) from the DTSTART
value type. It is then used to perform an extended check of date/time
values and reject non-conformant import files (like those reported in
Github issues #81, (calcurse) events.

The patch includes parsing and code corrections and minor refactoring.

Background:

Ical events are of two types, in calcurse called appointments and
events. RFC 5545 has no distinguishing names for them, but describes
them in section 3.6.1. The event type is derived from the value type of
the DTSTART property. The value type may be either DATE-TIME
(appointment) or DATE (event). If not specified by a VALUE property
parameter in DTSTART, the default value type is DATE-TIME. The value
type must be set explicitly to DATE to get an event. Other properties
and rrule parts must agree with the DTSTART value type (DTEND, DURATION,
EXDATE and UNTIL).

Previously the type of an imported event was derived from the format of
the DTSTART value. The DTSTART value type was not taken into account
when importing, and not specified for recurring events when exporting
(commit 0114289 solved it for events, see GitHub PR #97).

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

2 files changed, 45 insertions, 4 deletions

diff --git a/test/data/ical-009.ical b/test/data/ical-009.ical
index 39ae422..1828417 100644
--- a/test/data/ical-009.ical
+++ b/test/data/ical-009.ical
@@ -76,6 +76,41 @@ SUMMARY:LOCATION twice
 LOCATION:first
 LOCATION:second
 END:VEVENT
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20200406
+DURATION:PT0H15M0S
+SUMMARY:Invalid duration (must be days or weeks)
+END:VEVENT
+BEGIN:VEVENT
+DTSTART:20200406
+DURATION:P1D
+SUMMARY:Invalid DTSTART value type
+END:VEVENT
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20200406
+SUMMARY:Invalid DTEND value type
+DTEND:20200407
+END:VEVENT
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20200406
+DURATION:P1D
+RRULE:FREQ=MONTHLY;UNTIL=20201030T120000Z
+SUMMARY:Invalid UNTIL value
+END:VEVENT
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20200406
+DURATION:P1D
+RRULE:FREQ=MONTHLY;UNTIL=20201030
+EXDATE:20200606
+SUMMARY:Invalid EXDATE value type
+END:VEVENT
+BEGIN:VEVENT
+DTSTART;VALUE=DATE:20200406
+DURATION:P1D
+RRULE:FREQ=MONTHLY;UNTIL=20201030
+EXDATE;VALUE=DATE:20200606T120000Z
+SUMMARY:Invalid EXDATE value
+END:VEVENT
 BEGIN:VTODO
 SUMMARY:finally\, missing end of item
 END:VCALENDAR
diff --git a/test/ical-009.sh b/test/ical-009.sh
index d912f5c..c8c1c9c 100755
--- a/test/ical-009.sh
+++ b/test/ical-009.sh
@@ -17,9 +17,9 @@ if [ "$1" = 'actual' ]; then
   rm -rf .calcurse || exit 1
 elif [ "$1" = 'expected' ]; then
   cat <<EOD
-Import process report: 0081 lines read
-2 apps / 0 events / 1 todo / 12 skipped
-VEVENT [12]: could not retrieve event start time.
+Import process report: 0116 lines read
+2 apps / 0 events / 1 todo / 18 skipped
+VEVENT [12]: invalid or malformed event start time.
 VEVENT [17]: recurrence frequency not recognized.
 VEVENT [23]: malformed summary line.
 VTODO [28]: item priority is invalid (must be between 0 and 9).
@@ -30,7 +30,13 @@ VEVENT [50]: malformed description.
 VTODO [62]: malformed summary.
 VEVENT [66]: invalid status value.
 VEVENT [72]: only one location allowed.
-VTODO [79]: The ical file seems to be malformed. The end of item was not found.
+VEVENT [79]: invalid duration.
+VEVENT [84]: invalid or malformed event start time.
+VEVENT [89]: invalid end time value type.
+VEVENT [94]: invalid until format.
+VEVENT [100]: invalid exception date value type.
+VEVENT [107]: invalid exception.
+VTODO [114]: The ical file seems to be malformed. The end of item was not found.
 101
 EOD
 else