1 files changed, 23 insertions, 8 deletions
diff --git a/src/main/scala/xyz/driver/core/file/GcsStorage.scala b/src/main/scala/xyz/driver/core/file/GcsStorage.scala
index 6c2746e..deb8a0e 100644
--- a/src/main/scala/xyz/driver/core/file/GcsStorage.scala
+++ b/src/main/scala/xyz/driver/core/file/GcsStorage.scala
@@ -52,27 +52,42 @@ class GcsStorage(storageClient: Storage, bucketName: Name[Bucket], executionCont
     storageClient.delete(BlobId.of(bucketName.value, filePath.toString))
   }
 
-  override def list(path: Path): ListT[Future, FileLink] =
+  override def list(directoryPath: Path): ListT[Future, FileLink] =
     ListT.listT(Future {
       val page = storageClient.list(
         bucketName.value,
         BlobListOption.currentDirectory(),
-        BlobListOption.prefix(path.toString)
+        BlobListOption.prefix(s"$directoryPath/")
       )
 
-      page.iterateAll().asScala.map(blobToFileLink(path, _)).toList
+      page.iterateAll().asScala.map(blobToFileLink(directoryPath, _)).toList
     })
 
   protected def blobToFileLink(path: Path, blob: Blob): FileLink = {
+    def nullError(property: String) = throw new IllegalStateException(s"Blob $blob at $path does not have $property")
+    val name                        = Option(blob.getName).getOrElse(nullError("a name"))
+    val generation                  = Option(blob.getGeneration).getOrElse(nullError("a generation"))
+    val updateTime                  = Option(blob.getUpdateTime).getOrElse(nullError("an update time"))
+    val size                        = Option(blob.getSize).getOrElse(nullError("a size"))
+
     FileLink(
-      Name(blob.getName),
-      Paths.get(path.toString, blob.getName),
-      Revision(blob.getGeneration.toString),
-      Time(blob.getUpdateTime),
-      blob.getSize
+      Name(name),
+      Paths.get(path.toString, name),
+      Revision(generation.toString),
+      Time(updateTime),
+      size
     )
   }
 
+  override def exists(path: Path): Future[Boolean] = Future {
+    val blob = Option(
+      storageClient.get(
+        bucketName.value,
+        path.toString
+      ))
+    blob.isDefined
+  }
+
   override def signedFileUrl(filePath: Path, duration: Duration): OptionT[Future, URL] =
     OptionT.optionT(Future {
       Option(storageClient.get(bucketName.value, filePath.toString)).filterNot(_.getSize == 0).map { blob =>