From 5438223b29958459453613e88ca8ad76639af5e8 Mon Sep 17 00:00:00 2001
From: Varun Patil <varunpatil@ucla.edu>
Date: Fri, 14 Apr 2023 00:00:19 -0700
Subject: [PATCH] tw: drop invalid GPS data

Signed-off-by: Varun Patil <varunpatil@ucla.edu>
---
 lib/Db/TimelineWrite.php       |  1 +
 lib/Db/TimelineWritePlaces.php | 32 ++++++++++++++++++++++++++++++--
 lib/Exif.php                   |  6 ------
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/lib/Db/TimelineWrite.php b/lib/Db/TimelineWrite.php
index b1918545..fd881626 100644
--- a/lib/Db/TimelineWrite.php
+++ b/lib/Db/TimelineWrite.php
@@ -86,6 +86,7 @@ class TimelineWrite
 
         // Process location data
         // This also modifies the exif array in-place to set the LocationTZID
+        // and drop the GPS data if it is not valid
         [$lat, $lon, $mapCluster] = $this->processExifLocation($fileId, $exif, $prevRow);
 
         // Get date parameters (after setting timezone offset)
diff --git a/lib/Db/TimelineWritePlaces.php b/lib/Db/TimelineWritePlaces.php
index ba3489ed..bf07c4d0 100644
--- a/lib/Db/TimelineWritePlaces.php
+++ b/lib/Db/TimelineWritePlaces.php
@@ -8,6 +8,9 @@ use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 use Psr\Log\LoggerInterface;
 
+const LAT_KEY = 'GPSLatitude';
+const LON_KEY = 'GPSLongitude';
+
 trait TimelineWritePlaces
 {
     protected IDBConnection $connection;
@@ -27,8 +30,7 @@ trait TimelineWritePlaces
     protected function processExifLocation(int $fileId, array &$exif, $prevRow): array
     {
         // Store location data
-        $lat = \array_key_exists('GPSLatitude', $exif) ? (float) $exif['GPSLatitude'] : null;
-        $lon = \array_key_exists('GPSLongitude', $exif) ? (float) $exif['GPSLongitude'] : null;
+        [$lat, $lon] = self::readCoord($exif);
         $oldLat = $prevRow ? (float) $prevRow['lat'] : null;
         $oldLon = $prevRow ? (float) $prevRow['lon'] : null;
         $mapCluster = $prevRow ? (int) $prevRow['mapcluster'] : -1;
@@ -165,4 +167,30 @@ trait TimelineWritePlaces
             $exif['LocationTZID'] = $tzName;
         }
     }
+
+    /**
+     * Read coordinates from array and round to 6 decimal places.
+     *
+     * Modifies the array to remove invalid coordinates.
+     */
+    private static function readCoord(array &$exif)
+    {
+        $lat = array_key_exists(LAT_KEY, $exif) ? round((float) $exif[LAT_KEY], 6) : null;
+        $lon = array_key_exists(LON_KEY, $exif) ? round((float) $exif[LON_KEY], 6) : null;
+
+        // Make sure we have valid coordinates
+        if (null === $lat || null === $lon || abs($lat) > 90 || abs($lon) > 180 || ($lat < 0.00001 && $lon < 0.00001)) {
+            $lat = $lon = null;
+        }
+
+        // Remove invalid coordinates
+        if (null === $lat && array_key_exists(LAT_KEY, $exif)) {
+            unset($exif[LAT_KEY]);
+        }
+        if (null === $lon && array_key_exists(LON_KEY, $exif)) {
+            unset($exif[LON_KEY]);
+        }
+
+        return [$lat, $lon];
+    }
 }
diff --git a/lib/Exif.php b/lib/Exif.php
index d5bf00c0..65b243e5 100644
--- a/lib/Exif.php
+++ b/lib/Exif.php
@@ -131,12 +131,6 @@ class Exif
             }
         }
 
-        // Ignore zero lat lng
-        if (\array_key_exists('GPSLatitude', $exif) && abs((float) $exif['GPSLatitude']) < 0.0001
-            && \array_key_exists('GPSLongitude', $exif) && abs((float) $exif['GPSLongitude']) < 0.0001) {
-            unset($exif['GPSLatitude'], $exif['GPSLongitude']);
-        }
-
         return $exif;
     }