Rename Core Data objects.

URLPreviewCacheData becomes URLPreviewData in the model with a class name of URLPreviewDataMO
ClosedURLData becomes URLPreviewUserData in the model with a class name of URLPreviewUserDataMO

Riot/Managers/URLPreviews/Core Data/URLPreviewDataMO.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 URLPreviewDataMO {
+    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/Core Data/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/Core Data/URLPreviewStore.swift

@@ -0,0 +1,165 @@
+// 
+// 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 cache for URL previews backed by Core Data.
+class URLPreviewStore {
+    
+    // MARK: - Properties
+    
+    /// The Core Data container for persisting the cache to disk.
+    private let container: NSPersistentContainer
+    
+    /// The Core Data context used to store and load data on.
+    private var context: NSManagedObjectContext {
+        container.viewContext
+    }
+    
+    /// A time interval that represents how long an item in the cache is valid for.
+    private let dataValidityTime: TimeInterval = 60 * 60 * 24
+    
+    /// The oldest `creationDate` allowed for valid data.
+    private var expiryDate: Date {
+        Date().addingTimeInterval(-dataValidityTime)
+    }
+    
+    // MARK: - Lifecycle
+    
+    /// Create a URLPreview Cache optionally storing the data in memory.
+    /// - Parameter inMemory: Whether to store the data in memory.
+    init(inMemory: Bool = false) {
+        // Register the transformer for the `image` field.
+        ValueTransformer.setValueTransformer(URLPreviewImageTransformer(), forName: .urlPreviewImageTransformer)
+        
+        // Create the container, updating it's path if storing the data in memory.
+        container = NSPersistentContainer(name: "URLPreviewStore")
+        
+        if inMemory {
+            if let storeDescription = container.persistentStoreDescriptions.first {
+                storeDescription.url = URL(fileURLWithPath: "/dev/null")
+            } else {
+                MXLog.error("[URLPreviewStore] persistentStoreDescription not found.")
+            }
+        }
+        
+        // Load the persistent stores into the container
+        container.loadPersistentStores { storeDescription, error in
+            if let error = error {
+                MXLog.error("[URLPreviewStore] Core Data container error: \(error.localizedDescription)")
+            }
+        }
+    }
+    
+    // MARK: - Public
+    
+    /// Cache a preview in the store. If a preview already exists with the same URL it will be updated from the new preview.
+    /// - Parameter preview: The preview to add to the store.
+    /// - Parameter date: Optional: The date the preview was generated. When nil, the current date is assigned.
+    func cache(_ preview: URLPreviewData, generatedOn generationDate: Date? = nil) {
+        // Create a fetch request for an existing preview.
+        let request: NSFetchRequest<URLPreviewDataMO> = URLPreviewDataMO.fetchRequest()
+        request.predicate = NSPredicate(format: "url == %@", preview.url as NSURL)
+        
+        // Use the custom date if supplied (currently this is for testing purposes)
+        let date = generationDate ?? Date()
+        
+        // Update existing data if found otherwise create new data.
+        if let cachedPreview = try? context.fetch(request).first {
+            cachedPreview.update(from: preview, on: date)
+        } else {
+            _ = URLPreviewDataMO(context: context, preview: preview, creationDate: date)
+        }
+        
+        save()
+    }
+    
+    /// Fetches the preview from the cache for the supplied URL. If a preview doesn't exist or
+    /// if the preview is older than the ``dataValidityTime`` the returned value will be nil.
+    /// - Parameter url: The URL to fetch the preview for.
+    /// - Returns: The preview if found, otherwise nil.
+    func preview(for url: URL, and event: MXEvent) -> URLPreviewData? {
+        // Create a request for the url excluding any expired items
+        let request: NSFetchRequest<URLPreviewDataMO> = URLPreviewDataMO.fetchRequest()
+        request.predicate = NSCompoundPredicate(type: .and, subpredicates: [
+            NSPredicate(format: "url == %@", url as NSURL),
+            NSPredicate(format: "creationDate > %@", expiryDate as NSDate)
+        ])
+        
+        // Fetch the request, returning nil if nothing was found
+        guard
+            let cachedPreview = try? context.fetch(request).first
+        else { return nil }
+        
+        // Convert and return
+        return cachedPreview.preview(for: event)
+    }
+    
+    /// Returns the number of URL previews cached in the store.
+    func cacheCount() -> Int {
+        let request: NSFetchRequest<NSFetchRequestResult> = URLPreviewDataMO.fetchRequest()
+        return (try? context.count(for: request)) ?? 0
+    }
+    
+    /// Removes any expired cache data from the store.
+    func removeExpiredItems() {
+        let request: NSFetchRequest<NSFetchRequestResult> = URLPreviewDataMO.fetchRequest()
+        request.predicate = NSPredicate(format: "creationDate < %@", expiryDate as NSDate)
+        
+        do {
+            try context.execute(NSBatchDeleteRequest(fetchRequest: request))
+        } catch {
+            MXLog.error("[URLPreviewStore] Error executing batch delete request: \(error.localizedDescription)")
+        }
+    }
+    
+    /// Deletes all cache data and all closed previews from the store.
+    func deleteAll() {
+        do {
+            _ = try context.execute(NSBatchDeleteRequest(fetchRequest: URLPreviewDataMO.fetchRequest()))
+            _ = try context.execute(NSBatchDeleteRequest(fetchRequest: URLPreviewUserDataMO.fetchRequest()))
+        } catch {
+            MXLog.error("[URLPreviewStore] Error executing batch delete request: \(error.localizedDescription)")
+        }
+    }
+    
+    /// Store the dismissal of a preview from the event with `eventId` and `roomId`.
+    func closePreview(for eventId: String, in roomId: String) {
+        _ = URLPreviewUserDataMO(context: context, eventID: eventId, roomID: roomId, dismissed: true)
+        save()
+    }
+    
+    /// Whether a preview for an event with the given `eventId` and `roomId` has been closed or not.
+    func hasClosedPreview(for eventId: String, in roomId: String) -> Bool {
+        // Create a request for the url excluding any expired items
+        let request: NSFetchRequest<URLPreviewUserDataMO> = URLPreviewUserDataMO.fetchRequest()
+        request.predicate = NSCompoundPredicate(type: .and, subpredicates: [
+            NSPredicate(format: "eventID == %@", eventId),
+            NSPredicate(format: "roomID == %@", roomId),
+            NSPredicate(format: "dismissed == true")
+        ])
+        
+        return (try? context.count(for: request)) ?? 0 > 0
+    }
+    
+    // MARK: - Private
+    
+    /// Saves any changes that are found on the context
+    private func save() {
+        guard context.hasChanges else { return }
+        try? context.save()
+    }
+}

Riot/Managers/URLPreviews/Core Data/URLPreviewStore.xcdatamodeld/URLPreviewStore.xcdatamodel/contents

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<model type="com.apple.IDECoreDataModeler.DataModel" documentVersion="1.0" lastSavedToolsVersion="18154" systemVersion="20G95" minimumToolsVersion="Automatic" sourceLanguage="Swift" userDefinedModelVersionIdentifier="">
+    <entity name="URLPreviewData" representedClassName="URLPreviewDataMO" syncable="YES" codeGenerationType="class">
+        <attribute name="creationDate" attributeType="Date" usesScalarValueType="NO"/>
+        <attribute name="image" optional="YES" attributeType="Transformable" valueTransformerName="URLPreviewImageTransformer"/>
+        <attribute name="siteName" optional="YES" attributeType="String"/>
+        <attribute name="text" optional="YES" attributeType="String"/>
+        <attribute name="title" optional="YES" attributeType="String"/>
+        <attribute name="url" attributeType="URI"/>
+    </entity>
+    <entity name="URLPreviewUserData" representedClassName="URLPreviewUserDataMO" syncable="YES" codeGenerationType="class">
+        <attribute name="dismissed" attributeType="Boolean" usesScalarValueType="YES"/>
+        <attribute name="eventID" attributeType="String"/>
+        <attribute name="roomID" attributeType="String"/>
+        <uniquenessConstraints>
+            <uniquenessConstraint>
+                <constraint value="eventID"/>
+                <constraint value="roomID"/>
+            </uniquenessConstraint>
+        </uniquenessConstraints>
+    </entity>
+    <elements>
+        <element name="URLPreviewUserData" positionX="0" positionY="45" width="128" height="74"/>
+        <element name="URLPreviewData" positionX="160" positionY="192" width="128" height="119"/>
+    </elements>
+</model>

Riot/Managers/URLPreviews/Core Data/URLPreviewUserDataMO.swift

@@ -0,0 +1,26 @@
+// 
+// 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 URLPreviewUserDataMO {
+    convenience init(context: NSManagedObjectContext, eventID: String, roomID: String, dismissed: Bool) {
+        self.init(context: context)
+        self.eventID = eventID
+        self.roomID = roomID
+        self.dismissed = dismissed
+    }
+}