From ac0ad56053c26329887a0eb9075bffaaa43ebd27 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=B8=D0=BB=D1=8F=D0=BD=20=D0=9F=D0=B0=D0=BB=D0=B0?=
 =?UTF-8?q?=D1=83=D0=B7=D0=BE=D0=B2?= <git-dpa@aegee.org>
Date: Tue, 29 Nov 2022 09:34:59 +0200
Subject: [PATCH] recur_expansion: EXDATE can be DATE and DTSTART can be
 DATE-TIME

When EXDATE is in DATE format and DTSTART is DATE-TIME, then
to determine whether an occurrence shall be excluded, the
occurrence shall be converted to DATE and then compared to EXDATE.

This applies also for the very first EXDATE, when it coincides with
DTSTART.
---
 lib/ical/recur_expansion.js  | 24 +++++++++++++++++++++---
 samples/rdate_exdate.ics     |  8 ++++++++
 test/recur_expansion_test.js | 13 +++++++++++++
 3 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 samples/rdate_exdate.ics

diff --git a/lib/ical/recur_expansion.js b/lib/ical/recur_expansion.js
index 2694b3a1..1da38e94 100644
--- a/lib/ical/recur_expansion.js
+++ b/lib/ical/recur_expansion.js
@@ -198,6 +198,21 @@ class RecurExpansion {
     }
   }
 
+  /**
+   * Compare two ICAL.Time objects.  When the second parameter is a timeless date
+   * and the first parameter is date-with-time, strip the time and compare only
+   * the days.
+   *
+   * @private
+   * @param {ICAL.Time} a   The one object to compare
+   * @param {ICAL.Time} b   The other object to compare
+   */
+  _compare_special(a, b) {
+    if (!a.isDate && b.isDate)
+      return new Time({ year: a.year, month: a.month, day: a.day }).compare(b);
+    return a.compare(b);
+  }
+
   /**
    * Retrieve the next occurrence in the series.
    * @return {ICAL.Time}
@@ -248,9 +263,10 @@ class RecurExpansion {
 
       // check the negative rules
       if (this.exDate) {
-        compare = this.exDate.compare(this.last);
+        //EXDATE can be in DATE format, but DTSTART is in DATE-TIME format
+        compare = this._compare_special(this.last, this.exDate);
 
-        if (compare < 0) {
+        if (compare > 0) {
           this._nextExDay();
         }
 
@@ -397,10 +413,12 @@ class RecurExpansion {
     if (component.hasProperty('exdate')) {
       this.exDates = this._extractDates(component, 'exdate');
       // if we have a .last day we increment the index to beyond it.
+      // When DTSTART is in DATE-TIME format, EXDATE is in DATE format and EXDATE is
+      // the date of DTSTART, _compare_special finds this out and compareTime fails.
       this.exDateInc = binsearchInsert(
         this.exDates,
         this.last,
-        (a, b) => a.compare(b)
+        this._compare_special
       );
 
       this.exDate = this.exDates[this.exDateInc];
diff --git a/samples/rdate_exdate.ics b/samples/rdate_exdate.ics
new file mode 100644
index 00000000..4ff511f6
--- /dev/null
+++ b/samples/rdate_exdate.ics
@@ -0,0 +1,8 @@
+BEGIN:VCALENDAR
+BEGIN:VEVENT
+UID:123
+DTSTART:20240609T030000Z
+RRULE:FREQ=DAILY;INTERVAL=1;COUNT=4
+EXDATE;VALUE=DATE:20240611
+END:VEVENT
+END:VCALENDAR
diff --git a/test/recur_expansion_test.js b/test/recur_expansion_test.js
index eb5d37d1..3cdfc7b9 100644
--- a/test/recur_expansion_test.js
+++ b/test/recur_expansion_test.js
@@ -329,4 +329,17 @@ suite('recur_expansion', function() {
 
   });
 
+  suite('EXDATE and DTSTART have different value type', function() {
+    createSubject('rdate_exdate.ics');
+    test('Compare EXDATE;VALUE=DATE and DTSTART;VALUE=DATE-TIME', function() {
+      let dates = [], next;
+      while ((next = subject.next()))
+        dates.push(next.toJSDate());
+      assert.deepEqual(dates, [
+        new Date('2024-06-09T03:00:00.000Z'),
+        new Date('2024-06-10T03:00:00.000Z'),
+        new Date('2024-06-12T03:00:00.000Z')
+      ]);
+    });
+  });
 });