smtech / canvas-ics-sync

import.php

Indentation +247 added lines, -247 removed lines

@@ -1,12 +1,12 @@ 
 <?php
 
 if (php_sapi_name() == 'cli') {
-	// TODO there is a more streamlined way of doing this that escapes me just this second
-	$_REQUEST['cal'] = $argv[1];
-	$_REQUEST['canvas_url'] = $argv[2];
-	$_REQUEST['schedule'] = $argv[3];
+    // TODO there is a more streamlined way of doing this that escapes me just this second
+    $_REQUEST['cal'] = $argv[1];
+    $_REQUEST['canvas_url'] = $argv[2];
+    $_REQUEST['schedule'] = $argv[3];
 
-	define ('IGNORE_LTI', true);
+    define ('IGNORE_LTI', true);
 }
 
 require_once 'common.inc.php';
@@ -20,49 +20,49 @@ 
  * Check to see if a URL exists
  **/
 function urlExists($url) {
-	$handle = fopen($url, 'r');
-	return $handle !== false;
+    $handle = fopen($url, 'r');
+    return $handle !== false;
 }
 
 /**
  * compute the calendar context for the canvas object based on its URL
  **/
 function getCanvasContext($canvasUrl) {
-	global $metadata;
-
-	// TODO: accept calendar2?contexts links too (they would be an intuitively obvious link to use, after all)
-	// FIXME: users aren't working
-	// TODO: it would probably be better to look up users by email address than URL
-	/* get the context (user, course or group) for the canvas URL */
-	$canvasContext = array();
-	if (preg_match('%(https?://)?(' . parse_url($metadata['CANVAS_INSTANCE_URL'], PHP_URL_HOST) . '/((about/(\d+))|(courses/(\d+)(/groups/(\d+))?)|(accounts/\d+/groups/(\d+))))%', $_REQUEST['canvas_url'], $matches)) {
-		$canvasContext['canonical_url'] = "https://{$matches[2]}"; // https://stmarksschool.instructure.com/courses/953
-
-		// course or account groups
-		if (isset($matches[9]) || isset($matches[11])) {
-			$canvasContext['context'] = 'group'; // used to for context_code in events
-			$canvasContext['id'] = ($matches[9] > $matches[11] ? $matches[9] : $matches[11]);
-			$canvasContext['verification_url'] = "groups/{$canvasContext['id']}"; // used once to look up the object to be sure it really exists
-
-		// courses
-		} elseif (isset($matches[7])) {
-			$canvasContext['context'] = 'course';
-			$canvasContext['id'] = $matches[7];
-			$canvasContext['verification_url'] = "courses/{$canvasContext['id']}";
-
-		// users
-		} elseif (isset($matches[5])) {
-			$canvasContext['context'] = 'user';
-			$canvasContext['id'] = $matches[5];
-			$canvasContext['verification_url'] = "users/{$canvasContext['id']}/profile";
-
-		// we're somewhere where we don't know where we are
-		} else {
-			return false;
-		}
-		return $canvasContext;
-	}
-	return false;
+    global $metadata;
+
+    // TODO: accept calendar2?contexts links too (they would be an intuitively obvious link to use, after all)
+    // FIXME: users aren't working
+    // TODO: it would probably be better to look up users by email address than URL
+    /* get the context (user, course or group) for the canvas URL */
+    $canvasContext = array();
+    if (preg_match('%(https?://)?(' . parse_url($metadata['CANVAS_INSTANCE_URL'], PHP_URL_HOST) . '/((about/(\d+))|(courses/(\d+)(/groups/(\d+))?)|(accounts/\d+/groups/(\d+))))%', $_REQUEST['canvas_url'], $matches)) {
+        $canvasContext['canonical_url'] = "https://{$matches[2]}"; // https://stmarksschool.instructure.com/courses/953
+
+        // course or account groups
+        if (isset($matches[9]) || isset($matches[11])) {
+            $canvasContext['context'] = 'group'; // used to for context_code in events
+            $canvasContext['id'] = ($matches[9] > $matches[11] ? $matches[9] : $matches[11]);
+            $canvasContext['verification_url'] = "groups/{$canvasContext['id']}"; // used once to look up the object to be sure it really exists
+
+        // courses
+        } elseif (isset($matches[7])) {
+            $canvasContext['context'] = 'course';
+            $canvasContext['id'] = $matches[7];
+            $canvasContext['verification_url'] = "courses/{$canvasContext['id']}";
+
+        // users
+        } elseif (isset($matches[5])) {
+            $canvasContext['context'] = 'user';
+            $canvasContext['id'] = $matches[5];
+            $canvasContext['verification_url'] = "users/{$canvasContext['id']}/profile";
+
+        // we're somewhere where we don't know where we are
+        } else {
+            return false;
+        }
+        return $canvasContext;
+    }
+    return false;
 }
 
 /**
@@ -71,7 +71,7 @@ 
  * This must happen AFTER the event hash has been calculated!
  **/
 function filterEvent($event, $calendarCache) {
- 	return (
+        return (
         (
             // TODO actual multi-day events would be nice
             // only include first day of multi-day events
@@ -80,21 +80,21 @@ 
         ) &&
         (
             // include this event if filtering is off...
-     		$calendarCache['enable_regexp_filter'] == false ||
-     		(
-    			(
-    				( // if filtering is on, and there's an include pattern test that pattern...
-    					!empty($calendarCache['include_regexp']) &&
-    					preg_match("%{$calendarCache['include_regexp']}%", $event->getProperty('SUMMARY'))
-    				)
-    			) &&
-    			!( // if there is an exclude pattern, make sure that this event is NOT excluded
-    				!empty($calendarCache['exclude_regexp']) &&
-    				preg_match("%{$calendarCache['exclude_regexp']}%", $event->getProperty('SUMMARY'))
-    			)
-    		)
+                $calendarCache['enable_regexp_filter'] == false ||
+             (
+                (
+                    ( // if filtering is on, and there's an include pattern test that pattern...
+                        !empty($calendarCache['include_regexp']) &&
+                        preg_match("%{$calendarCache['include_regexp']}%", $event->getProperty('SUMMARY'))
+                    )
+                ) &&
+                !( // if there is an exclude pattern, make sure that this event is NOT excluded
+                    !empty($calendarCache['exclude_regexp']) &&
+                    preg_match("%{$calendarCache['exclude_regexp']}%", $event->getProperty('SUMMARY'))
+                )
+            )
         )
-	);
+    );
 }
 
 // TODO: it would be nice to be able to cleanly remove a synched calendar
@@ -106,61 +106,61 @@ 
    object)? */
 if (isset($_REQUEST['cal']) && isset($_REQUEST['canvas_url'])) {
 
-	if ($canvasContext = getCanvasContext($_REQUEST['canvas_url'])) {
-		/* check ICS feed to be sure it exists */
-		if(urlExists($_REQUEST['cal'])) {
-			/* look up the canvas object -- mostly to make sure that it exists! */
+    if ($canvasContext = getCanvasContext($_REQUEST['canvas_url'])) {
+        /* check ICS feed to be sure it exists */
+        if(urlExists($_REQUEST['cal'])) {
+            /* look up the canvas object -- mostly to make sure that it exists! */
             $canvasObject = false;
             try {
                 $canvasObject = $api->get($canvasContext['verification_url']);
             } catch (Exception $e) {
                 postMessage("Error accessing Canvas object", $canvasContext['verification_url'], NotificationMessage::DANGER);
             }
-			if ($canvasObject) {
+            if ($canvasObject) {
 
-				/* calculate the unique pairing ID of this ICS feed and canvas object */
-				$pairingHash = getPairingHash($_REQUEST['cal'], $canvasContext['canonical_url']);
-				$log = Log::singleton('file', __DIR__ . "/logs/$pairingHash.log");
-				postMessage('Sync started', getSyncTimestamp(), NotificationMessage::INFO);
+                /* calculate the unique pairing ID of this ICS feed and canvas object */
+                $pairingHash = getPairingHash($_REQUEST['cal'], $canvasContext['canonical_url']);
+                $log = Log::singleton('file', __DIR__ . "/logs/$pairingHash.log");
+                postMessage('Sync started', getSyncTimestamp(), NotificationMessage::INFO);
 
-				/* tell users that it's started and to cool their jets */
-				if (php_sapi_name() != 'cli') {
-					$smarty->assign('content', '
+                /* tell users that it's started and to cool their jets */
+                if (php_sapi_name() != 'cli') {
+                    $smarty->assign('content', '
 						<h3>Calendar Import Started</h3>
 						<p>The calendar import that you requested has begun. You may leave this page at anytime. You can see the progress of the import by visiting <a target="_blank" href="https://' . parse_url($metadata['CANVAS_INSTANCE_URL'], PHP_URL_HOST) . "/calendar?include_contexts={$canvasContext['context']}_{$canvasObject['id']}\">this calendar</a> in Canvas.</p>"
-					);
-					$smarty->display('page.tpl');
-				}
-
-				/* parse the ICS feed */
-				$ics = new vcalendar(
-					array(
-						'unique_id' => $metadata['APP_ID'],
-						'url' => $_REQUEST['cal']
-					)
-				);
-				$ics->parse();
-
-				/* log this pairing in the database cache, if it doesn't already exist */
-				$calendarCacheResponse = $sql->query("
+                    );
+                    $smarty->display('page.tpl');
+                }
+
+                /* parse the ICS feed */
+                $ics = new vcalendar(
+                    array(
+                        'unique_id' => $metadata['APP_ID'],
+                        'url' => $_REQUEST['cal']
+                    )
+                );
+                $ics->parse();
+
+                /* log this pairing in the database cache, if it doesn't already exist */
+                $calendarCacheResponse = $sql->query("
 					SELECT *
 						FROM `calendars`
 						WHERE
 							`id` = '$pairingHash'
 				");
-				$calendarCache = $calendarCacheResponse->fetch_assoc();
+                $calendarCache = $calendarCacheResponse->fetch_assoc();
 
-				/* if the calendar is already cached, just update the sync timestamp */
-				if ($calendarCache) {
-					$sql->query("
+                /* if the calendar is already cached, just update the sync timestamp */
+                if ($calendarCache) {
+                    $sql->query("
 						UPDATE `calendars`
 							SET
 								`synced` = '" . getSyncTimestamp() . "'
 							WHERE
 								`id` = '$pairingHash'
 					");
-				} else {
-					$sql->query("
+                } else {
+                    $sql->query("
 						INSERT INTO `calendars`
 							(
 								`id`,
@@ -183,46 +183,46 @@ 
 								" . ($_REQUEST['enable_regexp_filter'] == VALUE_ENABLE_REGEXP_FILTER ? "'" . $sql->real_escape_string($_REQUEST['exclude_regexp']) . "'" : 'NULL') . "
 							)
 					");
-				}
+                }
 
-				/* refresh calendar information from cache database */
-				$calendarCacheResponse = $sql->query("
+                /* refresh calendar information from cache database */
+                $calendarCacheResponse = $sql->query("
 					SELECT *
 						FROM `calendars`
 						WHERE
 							`id` = '$pairingHash'
 				");
-				$calendarCache = $calendarCacheResponse->fetch_assoc();
+                $calendarCache = $calendarCacheResponse->fetch_assoc();
 
-				/* walk through $master_array and update the Canvas calendar to match the
+                /* walk through $master_array and update the Canvas calendar to match the
 				   ICS feed, caching changes in the database */
-				// TODO: would it be worth the performance improvement to just process things from today's date forward? (i.e. ignore old items, even if they've changed...)
-				// TODO: the best window for syncing would be the term of the course in question, right?
-				// TODO: Arbitrarily selecting events in for a year on either side of today's date, probably a better system?
-				foreach ($ics->selectComponents(
-					date('Y')-1, // startYear
-					date('m'), // startMonth
-					date('d'), // startDay
-					date('Y')+1, // endYEar
-					date('m'), // endMonth
-					date('d'), // endDay
-					'vevent', // cType
-					false, // flat
-					true, // any
-					true // split
-				) as $year) {
-					foreach ($year as $month => $days) {
-						foreach ($days as $day => $events) {
-							foreach ($events as $i => $event) {
-
-								/* does this event already exist in Canvas? */
-								$eventHash = getEventHash($event);
-
-								/* if the event should be included... */
-								if (filterEvent($event, $calendarCache)) {
-
-									/* have we cached this event already? */
-									$eventCacheResponse = $sql->query("
+                // TODO: would it be worth the performance improvement to just process things from today's date forward? (i.e. ignore old items, even if they've changed...)
+                // TODO: the best window for syncing would be the term of the course in question, right?
+                // TODO: Arbitrarily selecting events in for a year on either side of today's date, probably a better system?
+                foreach ($ics->selectComponents(
+                    date('Y')-1, // startYear
+                    date('m'), // startMonth
+                    date('d'), // startDay
+                    date('Y')+1, // endYEar
+                    date('m'), // endMonth
+                    date('d'), // endDay
+                    'vevent', // cType
+                    false, // flat
+                    true, // any
+                    true // split
+                ) as $year) {
+                    foreach ($year as $month => $days) {
+                        foreach ($days as $day => $events) {
+                            foreach ($events as $i => $event) {
+
+                                /* does this event already exist in Canvas? */
+                                $eventHash = getEventHash($event);
+
+                                /* if the event should be included... */
+                                if (filterEvent($event, $calendarCache)) {
+
+                                    /* have we cached this event already? */
+                                    $eventCacheResponse = $sql->query("
 										SELECT *
 											FROM `events`
 											WHERE
@@ -231,11 +231,11 @@ 
 									");
 
 
-									/* if we already have the event cached in its current form, just update
+                                    /* if we already have the event cached in its current form, just update
 									   the timestamp */
-									$eventCache = $eventCacheResponse->fetch_assoc();
-									if ($eventCache) {
-										$sql->query("
+                                    $eventCache = $eventCacheResponse->fetch_assoc();
+                                    if ($eventCache) {
+                                        $sql->query("
 											UPDATE `events`
 												SET
 													`synced` = '" . getSyncTimestamp() . "'
@@ -243,29 +243,29 @@ 
 													`id` = '{$eventCache['id']}'
 										");
 
-									/* otherwise, add this new event and cache it */
-									} else {
-										/* multi-day event instance start times need to be changed to _this_ date */
-										$start = new DateTime(iCalUtilityFunctions::_date2strdate($event->getProperty('DTSTART')));
-										$end = new DateTime(iCalUtilityFunctions::_date2strdate($event->getProperty('DTEND')));
+                                    /* otherwise, add this new event and cache it */
+                                    } else {
+                                        /* multi-day event instance start times need to be changed to _this_ date */
+                                        $start = new DateTime(iCalUtilityFunctions::_date2strdate($event->getProperty('DTSTART')));
+                                        $end = new DateTime(iCalUtilityFunctions::_date2strdate($event->getProperty('DTEND')));
                                                                                 if ($event->getProperty('X-RECURRENCE')) {
-											$start = new DateTime($event->getProperty('X-CURRENT-DTSTART')[1]);
-											$end = new DateTime($event->getProperty('X-CURRENT-DTEND')[1]);
-										}
-										$start->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));
-										$end->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));
+                                            $start = new DateTime($event->getProperty('X-CURRENT-DTSTART')[1]);
+                                            $end = new DateTime($event->getProperty('X-CURRENT-DTEND')[1]);
+                                        }
+                                        $start->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));
+                                        $end->setTimeZone(new DateTimeZone(LOCAL_TIMEZONE));
 
                                         try {
                                             $calendarEvent = $api->post("/calendar_events",
-    											array(
-    												'calendar_event[context_code]' => "{$canvasContext['context']}_{$canvasObject['id']}",
-    												'calendar_event[title]' => preg_replace('%^([^\]]+)(\s*\[[^\]]+\]\s*)+$%', '\\1', strip_tags($event->getProperty('SUMMARY'))),
-    												'calendar_event[description]' => \Michelf\Markdown::defaultTransform(str_replace('\n', "\n\n", $event->getProperty('DESCRIPTION', 1))),
-    												'calendar_event[start_at]' => $start->format(CANVAS_TIMESTAMP_FORMAT),
-    												'calendar_event[end_at]' => $end->format(CANVAS_TIMESTAMP_FORMAT),
-    												'calendar_event[location_name]' => $event->getProperty('LOCATION')
-    											)
-    										);
+                                                array(
+                                                    'calendar_event[context_code]' => "{$canvasContext['context']}_{$canvasObject['id']}",
+                                                    'calendar_event[title]' => preg_replace('%^([^\]]+)(\s*\[[^\]]+\]\s*)+$%', '\\1', strip_tags($event->getProperty('SUMMARY'))),
+                                                    'calendar_event[description]' => \Michelf\Markdown::defaultTransform(str_replace('\n', "\n\n", $event->getProperty('DESCRIPTION', 1))),
+                                                    'calendar_event[start_at]' => $start->format(CANVAS_TIMESTAMP_FORMAT),
+                                                    'calendar_event[end_at]' => $end->format(CANVAS_TIMESTAMP_FORMAT),
+                                                    'calendar_event[location_name]' => $event->getProperty('LOCATION')
+                                                )
+                                            );
                                             $sql->query("
     											INSERT INTO `events`
     												(
@@ -284,102 +284,102 @@ 
                                         } catch (Exception $e) {
                                             postMessage('Error creating calendar event', $eventHash, NotificationMessage::ERROR);
                                         }
-									}
-								}
-							}
-						}
-					}
-				}
-
-				/* clean out previously synced events that are no longer correct */
-				$deletedEventsResponse = $sql->query("
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+
+                /* clean out previously synced events that are no longer correct */
+                $deletedEventsResponse = $sql->query("
 					SELECT * FROM `events`
 						WHERE
 							`calendar` = '{$calendarCache['id']}' AND
 							`synced` != '" . getSyncTimestamp() . "'
 				");
-				while ($deletedEventCache = $deletedEventsResponse->fetch_assoc()) {
-					try {
-						$deletedEvent = $api->delete("calendar_events/{$deletedEventCache['calendar_event[id]']}",
-							array(
-								'cancel_reason' => getSyncTimestamp(),
-								'as_user_id' => ($canvasContext['context'] == 'user' ? $canvasObject['id'] : '') // TODO: this feels skeevy -- like the empty string will break
-							)
-						);
-					} catch (Pest_Unauthorized $e) {
-						/* if the event has been deleted in Canvas, we'll get an error when
+                while ($deletedEventCache = $deletedEventsResponse->fetch_assoc()) {
+                    try {
+                        $deletedEvent = $api->delete("calendar_events/{$deletedEventCache['calendar_event[id]']}",
+                            array(
+                                'cancel_reason' => getSyncTimestamp(),
+                                'as_user_id' => ($canvasContext['context'] == 'user' ? $canvasObject['id'] : '') // TODO: this feels skeevy -- like the empty string will break
+                            )
+                        );
+                    } catch (Pest_Unauthorized $e) {
+                        /* if the event has been deleted in Canvas, we'll get an error when
 						   we try to delete it a second time. We still need to delete it from
 						   our cache database, however */
-						postMessage('Cache out-of-sync', "calendar_event[{$deletedEventCache['calendar_event[id]']}] no longer exists and will be purged from cache.", NotificationMessage::INFO);
-					} catch (Pest_ClientError $e) {
-						postMessage(
-							'API Client Error',
-							'<pre>' . print_r(array(
-								'Status' => $PEST->lastStatus(),
-								'Error' => $PEST->lastBody(),
-								'Verb' => $verb,
-								'URL' => $url,
-								'Data' => $data
-							), false) . '</pre>',
-							NotificationMessage::ERROR
-						);
-						if (php_sapi_name() != 'cli') $smarty->display('page.tpl');
-						exit;
-					}
-					$sql->query("
+                        postMessage('Cache out-of-sync', "calendar_event[{$deletedEventCache['calendar_event[id]']}] no longer exists and will be purged from cache.", NotificationMessage::INFO);
+                    } catch (Pest_ClientError $e) {
+                        postMessage(
+                            'API Client Error',
+                            '<pre>' . print_r(array(
+                                'Status' => $PEST->lastStatus(),
+                                'Error' => $PEST->lastBody(),
+                                'Verb' => $verb,
+                                'URL' => $url,
+                                'Data' => $data
+                            ), false) . '</pre>',
+                            NotificationMessage::ERROR
+                        );
+                        if (php_sapi_name() != 'cli') $smarty->display('page.tpl');
+                        exit;
+                    }
+                    $sql->query("
 						DELETE FROM `events`
 							WHERE
 								`id` = '{$deletedEventCache['id']}'
 					");
-				}
+                }
 
-				/* if this was a scheduled import (i.e. a sync), update that schedule */
-				if (isset($_REQUEST['schedule'])) {
-					$sql->query("
+                /* if this was a scheduled import (i.e. a sync), update that schedule */
+                if (isset($_REQUEST['schedule'])) {
+                    $sql->query("
 						UPDATE `schedules`
 							SET
 								`synced` = '" . getSyncTimestamp() . "'
 							WHERE
 								`id` = '{$_REQUEST['schedule']}'
 					");
-				}
-				/* are we setting up a regular synchronization? */
-				if (isset($_REQUEST['sync']) && $_REQUEST['sync'] != SCHEDULE_ONCE) {
+                }
+                /* are we setting up a regular synchronization? */
+                if (isset($_REQUEST['sync']) && $_REQUEST['sync'] != SCHEDULE_ONCE) {
 
-					// FIXME CRON SYNC SETUP GOES HERE
+                    // FIXME CRON SYNC SETUP GOES HERE
 
-					/* add to the cache database schedule, replacing any schedules for this
+                    /* add to the cache database schedule, replacing any schedules for this
 					   calendar that are already there */
-					$schedulesResponse = $sql->query("
+                    $schedulesResponse = $sql->query("
 						SELECT *
 							FROM `schedules`
 							WHERE
 								`calendar` = '{$calendarCache['id']}'
 					");
 
-					if ($schedule = $schedulesResponse->fetch_assoc()) {
+                    if ($schedule = $schedulesResponse->fetch_assoc()) {
 
-						/* only need to worry if the cached schedule is different from the
+                        /* only need to worry if the cached schedule is different from the
 						   new one we just set */
-						if ($shellArguments[INDEX_SCHEDULE] != $schedule['schedule']) {
-							/* was this the last schedule to require this trigger? */
-							$schedulesResponse = $sql->query("
+                        if ($shellArguments[INDEX_SCHEDULE] != $schedule['schedule']) {
+                            /* was this the last schedule to require this trigger? */
+                            $schedulesResponse = $sql->query("
 								SELECT *
 									FROM `schedules`
 									WHERE
 										`calendar` != '{$calendarCache['id']}' AND
 										`schedule` == '{$schedule['schedule']}'
 							");
-							/* we're the last one, delete it from crontab */
-							if ($schedulesResponse->num_rows == 0) {
-								$crontabs = preg_replace("%^.*{$schedule['schedule']}.*" . PHP_EOL . '%', '', shell_exec('crontab -l'));
-								$filename = md5(getSyncTimestamp()) . '.txt';
-								file_put_contents("/tmp/$filename", $crontabs);
-								shell_exec("crontab /tmp/$filename");
-								postMessage('Unused schedule', "removed schedule '{$schedule['schedule']}' from crontab", NotificationMessage::INFO);
-							}
-
-							$sql->query("
+                            /* we're the last one, delete it from crontab */
+                            if ($schedulesResponse->num_rows == 0) {
+                                $crontabs = preg_replace("%^.*{$schedule['schedule']}.*" . PHP_EOL . '%', '', shell_exec('crontab -l'));
+                                $filename = md5(getSyncTimestamp()) . '.txt';
+                                file_put_contents("/tmp/$filename", $crontabs);
+                                shell_exec("crontab /tmp/$filename");
+                                postMessage('Unused schedule', "removed schedule '{$schedule['schedule']}' from crontab", NotificationMessage::INFO);
+                            }
+
+                            $sql->query("
 								UPDATE `schedules`
 									SET
 										`schedule` = '" . $shellArguments[INDEX_SCHEDULE] . "',
@@ -387,9 +387,9 @@ 
 									WHERE
 										`calendar` = '{$calendarCache['id']}'
 							");
-						}
-					} else {
-						$sql->query("
+                        }
+                    } else {
+                        $sql->query("
 							INSERT INTO `schedules`
 								(
 									`calendar`,
@@ -402,46 +402,46 @@ 
 									'" . getSyncTimestamp() . "'
 								)
 						");
-					}
-				}
+                    }
+                }
 
-				/* if we're ovewriting data (for example, if this is a recurring sync, we
+                /* if we're ovewriting data (for example, if this is a recurring sync, we
 				   need to remove the events that were _not_ synced this in this round */
-				if (isset($_REQUEST['overwrite']) && $_REQUEST['overwrite'] == VALUE_OVERWRITE_CANVAS_CALENDAR) {
-					// TODO: actually deal with this
-				}
-
-				// TODO: deal with messaging based on context
-
-				postMessage('Finished sync', getSyncTimestamp(), NotificationMessage::INFO);
-				exit;
-			} else {
-				postMessage(
-					'Canvas Object  Not Found',
-					'The object whose URL you submitted could not be found.<pre>' . print_r(array(
-						'Canvas URL' => $_REQUEST['canvas_url'],
-						'Canvas Context' => $canvasContext,
-						'Canvas Object' => $canvasObject
-					), false) . '</pre>',
-					NotificationMessage::ERROR
-				);
-			}
-		} else {
-			postMessage(
-				'ICS feed  Not Found',
-				'The calendar whose URL you submitted could not be found.<pre>' . $_REQUEST['cal'] . '</pre>',
-				NotificationMessage::ERROR
-			);
-		}
-	} else {
-		postMessage(
-			'Invalid Canvas URL',
-			'The Canvas URL you submitted could not be parsed.<pre>' . $_REQUEST['canvas_url'] . '</pre>',
-			NotificationMessage::ERROR
-		);
-		if (php_sapi_name() != 'cli') $smarty->display('page.tpl');
-		exit;
-	}
+                if (isset($_REQUEST['overwrite']) && $_REQUEST['overwrite'] == VALUE_OVERWRITE_CANVAS_CALENDAR) {
+                    // TODO: actually deal with this
+                }
+
+                // TODO: deal with messaging based on context
+
+                postMessage('Finished sync', getSyncTimestamp(), NotificationMessage::INFO);
+                exit;
+            } else {
+                postMessage(
+                    'Canvas Object  Not Found',
+                    'The object whose URL you submitted could not be found.<pre>' . print_r(array(
+                        'Canvas URL' => $_REQUEST['canvas_url'],
+                        'Canvas Context' => $canvasContext,
+                        'Canvas Object' => $canvasObject
+                    ), false) . '</pre>',
+                    NotificationMessage::ERROR
+                );
+            }
+        } else {
+            postMessage(
+                'ICS feed  Not Found',
+                'The calendar whose URL you submitted could not be found.<pre>' . $_REQUEST['cal'] . '</pre>',
+                NotificationMessage::ERROR
+            );
+        }
+    } else {
+        postMessage(
+            'Invalid Canvas URL',
+            'The Canvas URL you submitted could not be parsed.<pre>' . $_REQUEST['canvas_url'] . '</pre>',
+            NotificationMessage::ERROR
+        );
+        if (php_sapi_name() != 'cli') $smarty->display('page.tpl');
+        exit;
+    }
 }
 
 ?>