From 458a373cb380d75888c73faa11407f0f38d59ccb Mon Sep 17 00:00:00 2001
From: Louis Chemineau <louis@chmn.me>
Date: Thu, 11 Aug 2022 19:26:03 +0200
Subject: [PATCH] Extract GPS data from EXIF

Signed-off-by: Louis Chemineau <louis@chmn.me>
---
 .../Metadata/Provider/ExifProvider.php        | 75 +++++++++++++++----
 1 file changed, 62 insertions(+), 13 deletions(-)

diff --git a/lib/private/Metadata/Provider/ExifProvider.php b/lib/private/Metadata/Provider/ExifProvider.php
index 892671556b368..bb252a6ec4104 100644
--- a/lib/private/Metadata/Provider/ExifProvider.php
+++ b/lib/private/Metadata/Provider/ExifProvider.php
@@ -16,8 +16,23 @@ public static function isAvailable(): bool {
 	}
 
 	public function execute(File $file): array {
+		$exifData = [];
 		$fileDescriptor = $file->fopen('rb');
-		$data = exif_read_data($fileDescriptor, 'COMPUTED', true);
+
+		// Copy image data into tmp stream as exif_read_data don't work properly with our streams wrappers.
+		$nativeFileDescriptorStream = fopen('php://temp', 'rw');
+		$result = stream_copy_to_stream(
+			$fileDescriptor,
+			$nativeFileDescriptorStream,
+		);
+
+		if ($result === false) {
+			fclose($nativeFileDescriptorStream);
+			throw new \Exception("Failed to copy into tmp stream from fileid: " . $file->getId());
+		}
+
+		$data = exif_read_data($nativeFileDescriptorStream, 'ANY_TAG', true);
+		fclose($nativeFileDescriptorStream);
 
 		$size = new FileMetadata();
 		$size->setGroupName('size');
@@ -31,29 +46,63 @@ public function execute(File $file): array {
 					'width' => $sizeResult[0],
 					'height' => $sizeResult[1],
 				]);
+
+				$exifData['size'] = $size;
 			}
 
-			return [
-				'size' => $size,
-			];
+		} elseif (array_key_exists('COMPUTED', $data)) {
+			if (array_key_exists('Width', $data['COMPUTED']) && array_key_exists('Height', $data['COMPUTED'])) {
+				$size->setMetadata([
+					'width' => $data['COMPUTED']['Width'],
+					'height' => $data['COMPUTED']['Height'],
+				]);
+
+				$exifData['size'] = $size;
+			}
 		}
 
-		if (array_key_exists('COMPUTED', $data)
-			&& array_key_exists('Width', $data['COMPUTED'])
-			&& array_key_exists('Height', $data['COMPUTED'])
+		if ($data && array_key_exists('GPS', $data)
+			&& array_key_exists('GPSLatitude', $data['GPS']) && array_key_exists('GPSLatitudeRef', $data['GPS'])
+			&& array_key_exists('GPSLongitude', $data['GPS']) && array_key_exists('GPSLongitudeRef', $data['GPS'])
 		) {
-			$size->setMetadata([
-				'width' => $data['COMPUTED']['Width'],
-				'height' => $data['COMPUTED']['Height'],
+			$gps = new FileMetadata();
+			$gps->setGroupName('gps');
+			$gps->setId($file->getId());
+			$gps->setMetadata([
+				'coordinate' => [
+					'latitude' => $this->gpsDegreesToDecimal($data['GPS']['GPSLatitude'], $data['GPS']['GPSLatitudeRef']),
+					'longitude' => $this->gpsDegreesToDecimal($data['GPS']['GPSLongitude'], $data['GPS']['GPSLongitudeRef']),
+				],
 			]);
+
+			$exifData['gps'] = $gps;
 		}
 
-		return [
-			'size' => $size,
-		];
+		return $exifData;
 	}
 
 	public static function getMimetypesSupported(): string {
 		return '/image\/.*/';
 	}
+
+	/**
+	 * @param array|string $coordinate
+	 */
+	private static function gpsDegreesToDecimal(array $coordinates, string $hemisphere): float {
+		if (is_string($coordinates)) {
+			$coordinates = array_map("trim", explode(",", $coordinates));
+		}
+
+		if (count($coordinates) !== 3) {
+			throw new \Exception('Invalid coordinate format: ' . $coordinates);
+		}
+
+		[$degrees, $minutes, $seconds] = array_map(function (string $rawDegree) {
+			$parts = explode('/', $rawDegree);
+			return floatval($parts[0])/floatval($parts[1] ?? 1);
+		}, $coordinates);
+
+		$sign = ($hemisphere === 'W' || $hemisphere === 'S') ? -1 : 1;
+		return $sign * ($degrees + $minutes/60 + $seconds/3600);
+	}
 }