Add URL previews as a Labs feature

Config/CommonConfiguration.swift

@@ -49,6 +49,9 @@ class CommonConfiguration: NSObject, Configurable {
         settings.messageDetailsAllowCopyingMedia = BuildSettings.messageDetailsAllowCopyMedia
         settings.messageDetailsAllowPastingMedia = BuildSettings.messageDetailsAllowPasteMedia
 
+        // Enable link detection if url preview are enabled
+        settings.enableBubbleComponentLinkDetection = true
+
         MXKContactManager.shared().allowLocalContactsAccess = BuildSettings.allowLocalContactsAccess
     }
 

Riot/Assets/Images.xcassets/Room/URLPreviews/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Riot/Assets/Images.xcassets/Room/URLPreviews/url_preview_close.imageset/Contents.json

@@ -0,0 +1,15 @@
+{
+  "images" : [
+    {
+      "filename" : "url_preview_close.pdf",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "properties" : {
+    "preserves-vector-representation" : true
+  }
+}

Riot/Assets/Images.xcassets/Room/URLPreviews/url_preview_close_dark.imageset/Contents.json

@@ -0,0 +1,15 @@
+{
+  "images" : [
+    {
+      "filename" : "url_preview_close_dark.pdf",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "properties" : {
+    "preserves-vector-representation" : true
+  }
+}

Riot/Assets/en.lproj/Vector.strings

@@ -537,6 +537,9 @@ Tap the + to start adding people.";
 "settings_ui_theme_picker_message_invert_colours" = "\"Auto\" uses your device's \"Invert Colours\" settings";
 "settings_ui_theme_picker_message_match_system_theme" = "\"Auto\" matches your device's system theme";
 
+"settings_show_url_previews" = "Show inline URL previews";
+"settings_show_url_previews_description" = "Previews will only be shown in unencrypted rooms.";
+
 "settings_unignore_user" = "Show all messages from %@?";
 
 "settings_contacts_discover_matrix_users" = "Use emails and phone numbers to discover users";

Riot/Generated/Images.swift

@@ -139,6 +139,8 @@ internal enum Asset {
     internal static let videoCall = ImageAsset(name: "video_call")
     internal static let voiceCallHangonIcon = ImageAsset(name: "voice_call_hangon_icon")
     internal static let voiceCallHangupIcon = ImageAsset(name: "voice_call_hangup_icon")
+    internal static let urlPreviewClose = ImageAsset(name: "url_preview_close")
+    internal static let urlPreviewCloseDark = ImageAsset(name: "url_preview_close_dark")
     internal static let voiceMessageCancelGradient = ImageAsset(name: "voice_message_cancel_gradient")
     internal static let voiceMessageLockChevron = ImageAsset(name: "voice_message_lock_chevron")
     internal static let voiceMessageLockIconLocked = ImageAsset(name: "voice_message_lock_icon_locked")

Riot/Generated/Strings.swift

@@ -4554,6 +4554,14 @@ internal enum VectorL10n {
   internal static var settingsShowNSFWPublicRooms: String { 
     return VectorL10n.tr("Vector", "settings_show_NSFW_public_rooms") 
   }
+  /// Show inline URL previews
+  internal static var settingsShowUrlPreviews: String { 
+    return VectorL10n.tr("Vector", "settings_show_url_previews") 
+  }
+  /// Previews will only be shown in unencrypted rooms.
+  internal static var settingsShowUrlPreviewsDescription: String { 
+    return VectorL10n.tr("Vector", "settings_show_url_previews_description") 
+  }
   /// Sign Out
   internal static var settingsSignOut: String { 
     return VectorL10n.tr("Vector", "settings_sign_out") 

Riot/Managers/Settings/RiotSettings.swift

@@ -160,6 +160,10 @@ final class RiotSettings: NSObject {
     @UserDefault(key: "roomScreenAllowFilesAction", defaultValue: BuildSettings.roomScreenAllowFilesAction, storage: defaults)
     var roomScreenAllowFilesAction
 
+    // labs prefix added to the key can be dropped when default value becomes true
+    @UserDefault(key: "labsRoomScreenShowsURLPreviews", defaultValue: false, storage: defaults)
+    var roomScreenShowsURLPreviews
+
     // MARK: - Room Contextual Menu
 
     @UserDefault(key: "roomContextualMenuShowMoreOptionForMessages", defaultValue: BuildSettings.roomContextualMenuShowMoreOptionForMessages, storage: defaults)

Riot/Managers/URLPreviews/ClosedURLPreview.swift

@@ -0,0 +1,25 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import CoreData
+
+extension ClosedURLPreview {
+    convenience init(context: NSManagedObjectContext, eventID: String, roomID: String) {
+        self.init(context: context)
+        self.eventID = eventID
+        self.roomID = roomID
+    }
+}

Riot/Managers/URLPreviews/URLPreviewCacheData.swift

@@ -0,0 +1,48 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import CoreData
+
+extension URLPreviewCacheData {
+    convenience init(context: NSManagedObjectContext, preview: URLPreviewData, creationDate: Date) {
+        self.init(context: context)
+        update(from: preview, on: creationDate)
+    }
+
+    func update(from preview: URLPreviewData, on date: Date) {
+        url = preview.url
+        siteName = preview.siteName
+        title = preview.title
+        text = preview.text
+        image = preview.image
+
+        creationDate = date
+    }
+
+    func preview(for event: MXEvent) -> URLPreviewData? {
+        guard let url = url else { return nil }
+
+        let viewData = URLPreviewData(url: url,
+                                      eventID: event.eventId,
+                                      roomID: event.roomId,
+                                      siteName: siteName,
+                                      title: title,
+                                      text: text)
+        viewData.image = image as? UIImage
+
+        return viewData
+    }
+}

Riot/Managers/URLPreviews/URLPreviewData.swift

@@ -0,0 +1,52 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+@objcMembers
+class URLPreviewData: NSObject {
+    /// The URL that's represented by the preview data. This may have been sanitized.
+    /// Note: The original URL, can be found in the bubble components with `eventID` and `roomID`.
+    let url: URL
+
+    /// The ID of the event that created this preview.
+    let eventID: String
+
+    /// The ID of the room that this preview is from.
+    let roomID: String
+
+    /// The OpenGraph site name for the URL.
+    let siteName: String?
+
+    /// The OpenGraph title for the URL.
+    let title: String?
+
+    /// The OpenGraph description for the URL.
+    let text: String?
+
+    /// The OpenGraph image for the URL.
+    var image: UIImage?
+
+    init(url: URL, eventID: String, roomID: String, siteName: String?, title: String?, text: String?) {
+        self.url = url
+        self.eventID = eventID
+        self.roomID = roomID
+        self.siteName = siteName
+        self.title = title
+        // Remove line breaks from the description text
+        self.text = text?.replacingOccurrences(of: "\n", with: " ")
+    }
+}

Riot/Managers/URLPreviews/URLPreviewImageTransformer.swift

@@ -0,0 +1,45 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import CoreData
+
+/// A `ValueTransformer` for ``URLPreviewCacheData``'s `image` field.
+/// This class transforms between `UIImage` and it's `pngData()` representation.
+class URLPreviewImageTransformer: ValueTransformer {
+    override class func transformedValueClass() -> AnyClass {
+        UIImage.self
+    }
+
+    override class func allowsReverseTransformation() -> Bool {
+        true
+    }
+
+    /// Transforms a `UIImage` into it's `pngData()` representation.
+    override func transformedValue(_ value: Any?) -> Any? {
+        guard let image = value as? UIImage else { return nil }
+        return image.pngData()
+    }
+
+    /// Transforms `Data` into a `UIImage`
+    override func reverseTransformedValue(_ value: Any?) -> Any? {
+        guard let data = value as? Data else { return nil }
+        return UIImage(data: data)
+    }
+}
+
+extension NSValueTransformerName {
+    static let urlPreviewImageTransformer = NSValueTransformerName("URLPreviewImageTransformer")
+}

Riot/Managers/URLPreviews/URLPreviewManager.swift

@@ -0,0 +1,116 @@
+//
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+@objcMembers
+class URLPreviewManager: NSObject {
+    static let shared = URLPreviewManager()
+
+    // Core Data store to reduce network requests
+    private let store = URLPreviewStore()
+
+    private override init() { }
+
+    func preview(for url: URL,
+                 and event: MXEvent,
+                 with session: MXSession,
+                 success: @escaping (URLPreviewData) -> Void,
+                 failure: @escaping (Error?) -> Void) {
+        // Sanitize the URL before checking the store or performing lookup
+        let sanitizedURL = sanitize(url)
+
+        if let preview = store.preview(for: sanitizedURL, and: event) {
+            MXLog.debug("[URLPreviewManager] Using cached preview.")
+            success(preview)
+            return
+        }
+
+        session.matrixRestClient.preview(for: sanitizedURL, success: { previewResponse in
+            MXLog.debug("[URLPreviewManager] Cached preview not found. Requesting from homeserver.")
+
+            if let previewResponse = previewResponse {
+                self.makePreviewData(from: previewResponse, for: sanitizedURL, and: event, with: session) { previewData in
+                    self.store.store(previewData)
+                    success(previewData)
+                }
+            }
+
+        }, failure: failure)
+    }
+
+    func makePreviewData(from previewResponse: MXURLPreview,
+                         for url: URL,
+                         and event: MXEvent,
+                         with session: MXSession,
+                         completion: @escaping (URLPreviewData) -> Void) {
+        let previewData = URLPreviewData(url: url,
+                                         eventID: event.eventId,
+                                         roomID: event.roomId,
+                                         siteName: previewResponse.siteName,
+                                         title: previewResponse.title,
+                                         text: previewResponse.text)
+
+        guard let imageURL = previewResponse.imageURL else {
+            completion(previewData)
+            return
+        }
+
+        if let cachePath = MXMediaManager.cachePath(forMatrixContentURI: imageURL, andType: previewResponse.imageType, inFolder: nil),
+           let image = MXMediaManager.loadThroughCache(withFilePath: cachePath) {
+            previewData.image = image
+            completion(previewData)
+            return
+        }
+
+        // Don't de-dupe image downloads as the manager should de-dupe preview generation.
+
+        session.mediaManager.downloadMedia(fromMatrixContentURI: imageURL, withType: previewResponse.imageType, inFolder: nil) { path in
+            guard let image = MXMediaManager.loadThroughCache(withFilePath: path) else {
+                completion(previewData)
+                return
+            }
+            previewData.image = image
+            completion(previewData)
+        } failure: { error in
+            completion(previewData)
+        }
+    }
+
+    func removeExpiredCacheData() {
+        store.removeExpiredItems()
+    }
+
+    func clearStore() {
+        store.deleteAll()
+    }
+
+    func closePreview(for eventID: String, in roomID: String) {
+        store.closePreview(for: eventID, in: roomID)
+    }
+
+    func hasClosedPreview(from event: MXEvent) -> Bool {
+        store.hasClosedPreview(for: event.eventId, in: event.roomId)
+    }
+
+    private func sanitize(_ url: URL) -> URL {
+        // Remove the fragment from the URL.
+        var components = URLComponents(url: url, resolvingAgainstBaseURL: false)
+        components?.fragment = nil
+
+        return components?.url ?? url
+    }
+}