From 5dfb672a80f0def971231d42f1c51e226136b373 Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Mon, 3 Oct 2016 08:56:51 -0700
Subject: [PATCH] Mostly drive Calendar event recurrence with the RRULE engine

Summary:
Ref T10737. Today, we evalute recurrence twice: once when querying, and once in all other cases. This converts the second case to use the RRULE engine.

Next up is making the query use the RRULE engine, too.

Test Plan: Created a new recurring event, iterated through it by clicking "next instance", viewed it on Calendar view.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10737

Differential Revision: https://secure.phabricator.com/D16667
---
 .../query/PhabricatorCalendarEventQuery.php   |   4 +-
 .../storage/PhabricatorCalendarEvent.php      | 104 ++++++++++--------
 2 files changed, 60 insertions(+), 48 deletions(-)

diff --git a/src/applications/calendar/query/PhabricatorCalendarEventQuery.php b/src/applications/calendar/query/PhabricatorCalendarEventQuery.php
index 1ba40d51a6..5d06001890 100644
--- a/src/applications/calendar/query/PhabricatorCalendarEventQuery.php
+++ b/src/applications/calendar/query/PhabricatorCalendarEventQuery.php
@@ -203,8 +203,8 @@ final class PhabricatorCalendarEventQuery
         $end_times[] = $this->rangeEnd;
       }
 
-      if ($event->getRecurrenceEndDate()) {
-        $end_times[] = $event->getRecurrenceEndDate();
+      if ($event->getUntilDateTimeEpoch()) {
+        $end_times[] = $event->getUntilDateTimeEpoch();
       }
 
       if ($enforced_end) {
diff --git a/src/applications/calendar/storage/PhabricatorCalendarEvent.php b/src/applications/calendar/storage/PhabricatorCalendarEvent.php
index 8d93e839f2..db86d3980b 100644
--- a/src/applications/calendar/storage/PhabricatorCalendarEvent.php
+++ b/src/applications/calendar/storage/PhabricatorCalendarEvent.php
@@ -176,15 +176,15 @@ final class PhabricatorCalendarEvent extends PhabricatorCalendarDAO
       ->setDescription($parent->getDescription());
 
     $sequence = $this->getSequenceIndex();
-    $duration = $parent->getDuration();
-    $epochs = $parent->getSequenceIndexEpochs($actor, $sequence, $duration);
+    $start_datetime = $parent->newSequenceIndexDateTime($sequence);
 
-    $start_datetime = PhutilCalendarAbsoluteDateTime::newFromEpoch(
-      $epochs['dateFrom'],
-      $parent->newStartDateTime()->getTimezone());
-    $end_datetime = PhutilCalendarAbsoluteDateTime::newFromEpoch(
-      $epochs['dateTo'],
-      $parent->newEndDateTime()->getTimezone());
+    if (!$start_datetime) {
+      throw new Exception(
+        "Sequence {$sequence} does not exist for event!");
+    }
+
+    $duration = $parent->newDuration();
+    $end_datetime = $start_datetime->newRelativeDateTime($duration);
 
     $this
       ->setStartDateTime($start_datetime)
@@ -194,42 +194,21 @@ final class PhabricatorCalendarEvent extends PhabricatorCalendarDAO
   }
 
   public function isValidSequenceIndex(PhabricatorUser $viewer, $sequence) {
-    try {
-      $this->getSequenceIndexEpochs($viewer, $sequence, $this->getDuration());
-      return true;
-    } catch (Exception $ex) {
-      return false;
-    }
+    return (bool)$this->newSequenceIndexDateTime($sequence);
   }
 
-  private function getSequenceIndexEpochs(
-    PhabricatorUser $viewer,
-    $sequence,
-    $duration) {
-
-    $frequency = $this->getFrequencyUnit();
-    $modify_key = '+'.$sequence.' '.$frequency;
-
-    $date_time = $this->newStartDateTime()
-      ->setViewerTimezone($viewer->getTimezoneIdentifier())
-      ->newPHPDateTime();
-
-    $date_time->modify($modify_key);
-    $date = $date_time->format('U');
-
-    $end_date = $this->getUntilDateTimeEpoch();
-    if ($end_date && $date > $end_date) {
-      throw new Exception(
-        pht(
-          'Sequence "%s" is invalid for this event: it would occur after '.
-          'the event stops repeating.',
-          $sequence));
+  public function newSequenceIndexDateTime($sequence) {
+    $set = $this->newRecurrenceSet();
+    if (!$set) {
+      return null;
     }
 
-    return array(
-      'dateFrom' => $date,
-      'dateTo' => $date + $duration,
-    );
+    $instances = $set->getEventsBetween(
+      null,
+      $this->newUntilDateTime(),
+      $sequence + 1);
+
+    return idx($instances, $sequence, null);
   }
 
   public function newStub(PhabricatorUser $actor, $sequence) {
@@ -785,13 +764,12 @@ final class PhabricatorCalendarEvent extends PhabricatorCalendarDAO
       return null;
     }
 
-    $epochs = $this->getParentEvent()->getSequenceIndexEpochs(
-      new PhabricatorUser(),
-      $this->getSequenceIndex(),
-      $this->getDuration());
+    $index = $this->getSequenceIndex();
+    if (!$index) {
+      return null;
+    }
 
-    $epoch = $epochs['dateFrom'];
-    return $this->newDateTimeFromEpoch($epoch);
+    return $this->newSequenceIndexDateTime($index);
   }
 
   private function newDateTimeFromEpoch($epoch) {
@@ -845,6 +823,40 @@ final class PhabricatorCalendarEvent extends PhabricatorCalendarDAO
       $datetime->newAbsoluteDateTime()->toDictionary());
   }
 
+
+  public function newRecurrenceRule() {
+    if ($this->isChildEvent()) {
+      return $this->getParentEvent()->newRecurrenceRule();
+    }
+
+    // TODO: This is a little fragile since it relies on the convenient
+    // definition of FREQUENCY constants here and in RecurrenceRule, but
+    // should be gone soon.
+    $map = array(
+      'FREQ' => phutil_utf8_strtoupper($this->getFrequencyRule()),
+    );
+
+    $rrule = PhutilCalendarRecurrenceRule::newFromDictionary($map);
+
+    $start = $this->newStartDateTime();
+    $rrule->setStartDateTime($start);
+
+    return $rrule;
+  }
+
+  public function newRecurrenceSet() {
+    if ($this->isChildEvent()) {
+      return $this->getParentEvent()->newRecurrenceSet();
+    }
+
+    $set = new PhutilCalendarRecurrenceSet();
+
+    $rrule = $this->newRecurrenceRule();
+    $set->addSource($rrule);
+
+    return $set;
+  }
+
 /* -(  Markup Interface  )--------------------------------------------------- */