Offline Mode: Sync Engine

WordPress/Classes/Models/AbstractPost+HashHelpers.h

@@ -7,14 +7,19 @@ NS_ASSUME_NONNULL_BEGIN
 // This value is used in Offline Posting — to calculate whether the post that the user _wanted_ to publish,
 // hasn't changed in the meantime and still is the same post.
 // It works by calculating a SHA256 hash for a subset of properties of a Post and then combining them together (including the hashes returned by the `additionalContentHashes` method, to let subclasses provide additional sources of truthfulness).
+/// - note: deprecated (kahu-offline-mode)
 - (NSString *)calculateConfirmedChangesContentHash;
 
 // This is an extension point for the subclasses to add additional sources of truthfulness.
+/// - note: deprecated (kahu-offline-mode)
 - (NSArray<NSData *> *)additionalContentHashes;
 
 
+/// - note: deprecated (kahu-offline-mode)
 - (NSData *)hashForString:(NSString *)string;
+/// - note: deprecated (kahu-offline-mode)
 - (NSData *)hashForNSInteger:(NSInteger)integer;
+/// - note: deprecated (kahu-offline-mode)
 - (NSData *)hashForDouble:(double)dbl;
 
 @end

WordPress/Classes/Models/AbstractPost+Local.swift

@@ -2,10 +2,12 @@ import Foundation
 
 extension AbstractPost {
     /// Returns true if the post is a draft and has never been uploaded to the server.
+    /// - note: deprecated (kahu-offline-mode)
     var isLocalDraft: Bool {
         return self.isDraft() && !self.hasRemote()
     }
 
+    /// - warning: deprecated (kahu-offline-mode)
     var isLocalRevision: Bool {
         return self.originalIsDraft() && self.isRevision() && self.remoteStatus == .local
     }

WordPress/Classes/Models/AbstractPost+MarkAsFailedAndDraftIfNeeded.swift

@@ -21,6 +21,7 @@
     ///     eventually be made private.
     /// - SeeAlso: PostCoordinator.resume
     ///
+    /// - note: deprecated (kahu-offline-mode)
     func markAsFailedAndDraftIfNeeded() {
         guard self.remoteStatus != .failed else {
             return

WordPress/Classes/Models/AbstractPost.h

@@ -54,12 +54,19 @@ typedef NS_ENUM(NSUInteger, AbstractPostRemoteStatus) {
 @property (nonatomic, copy, nullable) NSDate *autosaveModifiedDate;
 @property (nonatomic, copy, nullable) NSNumber *autosaveIdentifier;
 
+@property (nonatomic, strong, nullable) NSString *confirmedChangesHash;
+@property (nonatomic, strong, nullable) NSDate *confirmedChangesTimestamp;
+
 // Revision management
 - (AbstractPost *)createRevision;
+/// A new version of `createRevision` that allows you to create revisions based
+/// on other revisions.
+/// 
+/// - warning: Work-in-progress (kahu-offline-mode)
+- (AbstractPost *)_createRevision;
 - (void)deleteRevision;
 - (void)applyRevision;
 - (AbstractPost *)updatePostFrom:(AbstractPost *)revision;
-- (void)updateRevision;
 - (BOOL)isRevision;
 - (BOOL)isOriginal;
 
@@ -73,7 +80,7 @@ typedef NS_ENUM(NSUInteger, AbstractPostRemoteStatus) {
 - (BOOL)hasCategories;
 - (BOOL)hasTags;
 
-/// True if either the post failed to upload, or the post has media that failed to upload.
+/// - note: deprecated (kahu-offline-mode)
 @property (nonatomic, assign, readonly) BOOL isFailed;
 
 @property (nonatomic, assign, readonly) BOOL hasFailedMedia;
@@ -86,7 +93,9 @@ typedef NS_ENUM(NSUInteger, AbstractPostRemoteStatus) {
 - (BOOL)hasRevision;
 
 #pragma mark - Conveniece Methods
+/// - note: deprecated (kahu-offline-mode)
 - (void)publishImmediately;
+/// - note: deprecated (kahu-offline-mode)
 - (BOOL)shouldPublishImmediately;
 - (NSString *)authorNameForDisplay;
 - (NSString *)blavatarForDisplay;
@@ -176,6 +185,7 @@ typedef NS_ENUM(NSUInteger, AbstractPostRemoteStatus) {
  *
  *  @returns    YES if there ever was an attempt to upload this post, NO otherwise.
  */
+/// - warning: deprecated (kahu-offline-mode)
 - (BOOL)hasNeverAttemptedToUpload;
 
 /**

WordPress/Classes/Models/AbstractPost.m

@@ -5,21 +5,6 @@
 #import "BasePost.h"
 @import WordPressKit;
 
-@interface AbstractPost ()
-
-/**
- The following pair of properties is used to confirm that the post we'll be trying to automatically retry uploading,
- hasn't changed since user has tapped on "confirm", and that we're not suddenly trying to auto-upload a post that the user
- might have already forgotten about.
-
- The public-facing counterparts of those is the `shouldAttemptAutoUpload` property.
- */
-
-@property (nonatomic, strong, nullable) NSString *confirmedChangesHash;
-@property (nonatomic, strong, nullable) NSDate *confirmedChangesTimestamp;
-
-@end
-
 @implementation AbstractPost
 
 @dynamic blog;
@@ -151,8 +136,13 @@ - (AbstractPost *)createRevision
         return self.revision;
     }
 
+    return [self _createRevision];
+}
+
+- (AbstractPost *)_createRevision {
     AbstractPost *post = [NSEntityDescription insertNewObjectForEntityForName:NSStringFromClass(self.class) inManagedObjectContext:self.managedObjectContext];
     [post cloneFrom:self];
+    post.isSyncNeeded = NO;
     [post setValue:self forKey:@"original"];
     [post setValue:nil forKey:@"revision"];
     post.isFeaturedImageChanged = self.isFeaturedImageChanged;
@@ -193,14 +183,6 @@ - (AbstractPost *)updatePostFrom:(AbstractPost *)revision
     return self;
 }
 
-- (void)updateRevision
-{
-    if ([self isRevision]) {
-        [self cloneFrom:self.original];
-        self.isFeaturedImageChanged = self.original.isFeaturedImageChanged;
-    }
-}
-
 - (BOOL)isRevision
 {
     return (![self isOriginal]);
@@ -213,11 +195,6 @@ - (BOOL)isOriginal
 
 - (AbstractPost *)latest
 {
-    // Even though we currently only support 1 revision per-post, we have plans to support multiple
-    // revisions in the future.  That's the reason why we call `[[self revision] latest]` below.
-    //
-    //  - Diego Rey Mendez, May 19, 2016
-    //
     return [self hasRevision] ? [[self revision] latest] : self;
 }
 
@@ -239,7 +216,6 @@ - (AbstractPost *)original
     return original;
 }
 
-
 #pragma mark - Helpers
 
 - (BOOL)dateCreatedIsNilOrEqualToDateModified
@@ -496,6 +472,7 @@ - (BOOL)isUploading
 
 #pragma mark - Post
 
+/// - note: Deprecated (kahu-offline-mode)
 - (BOOL)canSave
 {
     NSString* titleWithoutSpaces = [self.postTitle stringByReplacingOccurrencesOfString:@" " withString:@""];

WordPress/Classes/Models/AbstractPost.swift

@@ -6,8 +6,16 @@ extension AbstractPost {
         original?.original() ?? self
     }
 
+    /// Returns `true` if the post was never uploaded to the remote and has
+    /// not revisions that were marked for syncing.
+    var isNewDraft: Bool {
+        assert(isOriginal(), "Must be called on the original")
+        return !hasRemote() && getLatestRevisionNeedingSync() == nil
+    }
+
     // MARK: - Status
 
+    /// - note: deprecated (kahu-offline-mode)
     @objc
     var statusTitle: String? {
         guard let status = self.status else {
@@ -17,6 +25,7 @@ extension AbstractPost {
         return AbstractPost.title(for: status)
     }
 
+    /// - note: deprecated (kahu-offline-mode)
     @objc
     var remoteStatus: AbstractPostRemoteStatus {
         get {
@@ -150,4 +159,64 @@ extension AbstractPost {
     func hasPermanentFailedMedia() -> Bool {
         return media.first(where: { !$0.willAttemptToUploadLater() }) != nil
     }
+
+    /// Returns the changes made in the current revision compared to the
+    /// previous revision or the original post if there is only one revision.
+    var changes: RemotePostUpdateParameters {
+        guard let original else {
+            return RemotePostUpdateParameters() // Empty
+        }
+        return RemotePostUpdateParameters.changes(from: original, to: self)
+    }
+
+    /// Returns all revisions of the post including the original one.
+    var allRevisions: [AbstractPost] {
+        var revisions: [AbstractPost] = [self]
+        var current = self
+        while let next = current.revision {
+            revisions.append(next)
+            current = next
+        }
+        return revisions
+
+    }
+
+    // TODO: Replace with a new flag
+    /// - note: Work-in-progress (kahu-offline-mode)
+    @objc var isSyncNeeded: Bool {
+        get { confirmedChangesHash == AbstractPost.syncNeededKey }
+        set { confirmedChangesHash = newValue ? AbstractPost.syncNeededKey : "" }
+    }
+
+    static let syncNeededKey = "sync-needed"
+
+    /// Returns the latest saved revisions that needs to be synced with the server.
+    /// Returns `nil` if there are no such revisions.
+    func getLatestRevisionNeedingSync() -> AbstractPost? {
+        assert(original == nil, "Must be called on an original revision")
+        let revision = allRevisions.last(where: \.isSyncNeeded)
+        guard revision != self else {
+            return nil
+        }
+        return revision
+    }
+
+    /// Deletes all of the synced revisions until and including the `latest`
+    /// one passed as a parameter.
+    func deleteSyncedRevisions(until latest: AbstractPost) {
+        assert(original == nil, "Must be called on an original revision")
+        let tail = latest.revision
+
+        var current = self
+        while current !== latest, let next = current.revision {
+            current.deleteRevision()
+            current = next
+        }
+
+        if let tail {
+            willChangeValue(forKey: "revision")
+            setPrimitiveValue(tail, forKey: "revision")
+            didChangeValue(forKey: "revision")
+        }
+    }
 }

WordPress/Classes/Models/Post.swift

@@ -55,41 +55,12 @@ class Post: AbstractPost {
         }
     }
 
-    // MARK: - Properties
-
-    fileprivate var storedContentPreviewForDisplay = ""
-
     // MARK: - NSManagedObject
 
     override class func entityName() -> String {
         return "Post"
     }
 
-    override func awakeFromFetch() {
-        super.awakeFromFetch()
-        buildContentPreview()
-    }
-
-    override func willSave() {
-        super.willSave()
-
-        if isDeleted {
-            return
-        }
-
-        storedContentPreviewForDisplay = ""
-    }
-
-    // MARK: - Content Preview
-
-    fileprivate func buildContentPreview() {
-        if let excerpt = mt_excerpt, excerpt.count > 0 {
-            storedContentPreviewForDisplay = excerpt.makePlainText()
-        } else if let content = content {
-            storedContentPreviewForDisplay = content.summarized()
-        }
-    }
-
     // MARK: - Format
 
     @objc func postFormatText() -> String? {
@@ -301,11 +272,23 @@ class Post: AbstractPost {
     // MARK: - BasePost
 
     override func contentPreviewForDisplay() -> String {
-        if storedContentPreviewForDisplay.count == 0 {
-            buildContentPreview()
+        if let excerpt = mt_excerpt, excerpt.count > 0 {
+            if let preview = PostPreviewCache.shared.excerpt[excerpt] {
+                return preview
+            }
+            let preview = excerpt.makePlainText()
+            PostPreviewCache.shared.excerpt[excerpt] = preview
+            return preview
+        } else if let content = content {
+            if let preview = PostPreviewCache.shared.content[content] {
+                return preview
+            }
+            let preview = content.summarized()
+            PostPreviewCache.shared.content[content] = preview
+            return preview
+        } else {
+            return ""
         }
-
-        return storedContentPreviewForDisplay
     }
 
     override func hasLocalChanges() -> Bool {
@@ -387,3 +370,20 @@ class Post: AbstractPost {
                 hash(for: isStickyPost ? 1 : 0)]
     }
 }
+
+private final class PostPreviewCache {
+    static let shared = PostPreviewCache()
+
+    let excerpt = Cache<String, String>()
+    let content = Cache<String, String>()
+}
+
+private final class Cache<Key: Hashable, Value> {
+    private let lock = NSLock()
+    private var dictionary: [Key: Value] = [:]
+
+    subscript(key: Key) -> Value? {
+        get { lock.withLock { dictionary[key] } }
+        set { lock.withLock { dictionary[key] = newValue } }
+    }
+}