refactor(metadata): provide a single method for assembling the full remote path

There are many places that assemble the full remote path manually,
but it might not always be correct.

For instance in the case of the root directory, an item's `fileName`
is set to `"__NC_ROOT__"` by NextcloudKit.

Signed-off-by: Jyrki Gadinger <nilsding@nilsding.org>

Author: nilsding

Sources/NextcloudFileProviderKit/Database/FilesDatabaseManager.swift

@@ -599,11 +599,7 @@ public final class FilesDatabaseManager: Sendable {
         var handledUpdateOcIds = Set(updated.map(\.ocId))
 
         updated
-            .map {
-                var serverUrl = $0.serverUrl + "/" + $0.fileName
-                if serverUrl.last == "/" { serverUrl.removeLast() }
-                return serverUrl
-            }
+            .map { $0.remotePath() }
             .forEach { serverUrl in
                 logger.debug("Checking updated item...", [.url: serverUrl])
 
@@ -630,15 +626,7 @@ public final class FilesDatabaseManager: Sendable {
         let handledDeleteOcIds = Set(deleted.map(\.ocId))
 
         deleted
-            .map { // assemble remote location
-                var serverUrl = $0.serverUrl + "/" + $0.fileName
-
-                if serverUrl.last == "/" {
-                    serverUrl.removeLast()
-                }
-
-                return serverUrl
-            }
+            .map { $0.remotePath() }
             .forEach { serverUrl in
                 logger.debug("Verifying deleted item...", [.url: serverUrl])
 

Sources/NextcloudFileProviderKit/Enumeration/RemoteChangeObserver.swift

@@ -456,10 +456,7 @@ public final class RemoteChangeObserver: NSObject, NextcloudKitDelegate, URLSess
         // This way we ensure we visit parent folders before their children.
         let materialisedItems = dbManager
             .materialisedItemMetadatas(account: accountId)
-            .sorted {
-                ($0.serverUrl + "/" + $0.fileName).count <
-                    ($1.serverUrl + "/" + $1.fileName).count
-            }
+            .sorted { $0.remotePath().count < $1.remotePath().count }
 
         var allNewMetadatas = [SendableItemMetadata]()
         var allUpdatedMetadatas = [SendableItemMetadata]()
@@ -480,7 +477,7 @@ public final class RemoteChangeObserver: NSObject, NextcloudKitDelegate, URLSess
                 continue
             }
 
-            let itemRemoteUrl = item.serverUrl + "/" + item.fileName
+            let itemRemoteUrl = item.remotePath()
 
             let (metadatas, newMetadatas, updatedMetadatas, deletedMetadatas, _, readError) = await Enumerator.readServerUrl(
                 itemRemoteUrl,
@@ -550,7 +547,7 @@ public final class RemoteChangeObserver: NSObject, NextcloudKitDelegate, URLSess
 
                                 // Also mark any materialized children of this directory as examined
                                 let grandChildren = materialisedItems.filter {
-                                    $0.serverUrl.hasPrefix(localItem.serverUrl + "/" + localItem.fileName)
+                                    $0.serverUrl.hasPrefix(localItem.remotePath())
                                 }
                                 examinedChildFilesAndDeletedItems.formUnion(grandChildren.map(\.ocId))
                             }

Sources/NextcloudFileProviderKit/Item/Item+Create.swift

@@ -490,7 +490,7 @@ public extension Item {
                 )
                 return (nil, NSFileProviderError(.cannotSynchronize))
             }
-            parentItemRemotePath = parentItemMetadata.serverUrl + "/" + parentItemMetadata.fileName
+            parentItemRemotePath = parentItemMetadata.remotePath()
             parentItemRelativePath = parentItemRemotePath.replacingOccurrences(
                 of: account.davFilesUrl, with: ""
             )

Sources/NextcloudFileProviderKit/Item/Item+Delete.swift

@@ -24,7 +24,7 @@ public extension Item {
         }
 
         let ocId = itemIdentifier.rawValue
-        let relativePath = (metadata.serverUrl + "/" + metadata.fileName).replacingOccurrences(of: metadata.urlBase, with: "")
+        let relativePath = (metadata.remotePath()).replacingOccurrences(of: metadata.urlBase, with: "")
 
         guard metadata.isLockFileOfLocalOrigin == false else {
             return await deleteLockFile(domain: domain, dbManager: dbManager)
@@ -36,7 +36,7 @@ public extension Item {
             return nil
         }
 
-        let serverFileNameUrl = metadata.serverUrl + "/" + metadata.fileName
+        let serverFileNameUrl = metadata.remotePath()
 
         guard serverFileNameUrl != "" else {
             return NSError.fileProviderErrorForNonExistentItem(withIdentifier: itemIdentifier)

Sources/NextcloudFileProviderKit/Item/Item+Fetch.swift

@@ -50,7 +50,7 @@ public extension Item {
             progress.totalUnitCount += Int64(metadatas.count)
 
             for var metadata in metadatas {
-                let remotePath = metadata.serverUrl + "/" + metadata.fileName
+                let remotePath = metadata.remotePath()
                 let relativePath =
                     remotePath.replacingOccurrences(of: directoryRemotePath, with: "")
                 let childLocalPath = directoryLocalPath + relativePath
@@ -129,7 +129,7 @@ public extension Item {
             }
         }
 
-        let serverUrlFileName = metadata.serverUrl + "/" + metadata.fileName
+        let serverUrlFileName = metadata.remotePath()
 
         logger.debug("Fetching item.", [.name: metadata.fileName, .url: serverUrlFileName])
 

Sources/NextcloudFileProviderKit/Metadata/ItemMetadata.swift

@@ -1,6 +1,7 @@
 //  SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
 //  SPDX-License-Identifier: GPL-2.0-or-later
 
+import FileProvider
 import Foundation
 
 ///
@@ -73,7 +74,7 @@ public protocol ItemMetadata: Equatable {
     var quotaAvailableBytes: Int64 { get set }
     var resourceType: String { get set }
     var richWorkspace: String? { get set }
-    var serverUrl: String { get set } // For parent folder! Build remote url by adding fileName
+    var serverUrl: String { get set } // For parent folder! Retrieve the full remote url via .remotePath()
     var session: String? { get set }
     var sessionError: String? { get set }
     var sessionTaskIdentifier: Int? { get set }
@@ -170,4 +171,14 @@ public extension ItemMetadata {
                 .init(name: "a", value: "true"),
             ])
     }
+
+    func remotePath() -> String {
+        if ocId == NSFileProviderItemIdentifier.rootContainer.rawValue {
+            // For the root container the fileName is "__NC_ROOT__" (aka NextcloudKit.shared.nkCommonInstance.rootFileName)
+            // --> appending the fileName to that is not correct, as it most likely won't ecist
+            return serverUrl
+        }
+
+        return "\(serverUrl)/\(fileName)"
+    }
 }