Add support for X-posting in Gutenberg

- Add new Core Data model `WordPress 103` with new entity `SiteSuggestion`
- Add a one-to-many relationship between `Blog` and `SiteSuggestion`
- Add `XPostSuggestionService` for fetching xpost suggestions from the remote server
- Add xpost support to Gutenberg in `GutenbergViewController`
- Extend `SuggestionsTableView` to support xposts

MIGRATIONS.md

@@ -3,6 +3,13 @@
 This file documents changes in the data model. Please explain any changes to the
 data model as well as any custom migrations.
 
+## WordPress 103
+
+@guarani 2020-10-20
+
+- Add a new `SiteSuggestion` entity to support Gutenberg's xpost implementation
+- Add a one-to-many relationship between `Blog` and `SiteSuggestion`
+
 ## WordPress 101
 
 @emilylaguna 2020-10-09

Podfile

@@ -152,7 +152,7 @@ target 'WordPress' do
     ## Gutenberg (React Native)
     ## =====================
     ##
-    gutenberg :tag => 'v1.39.0'
+    gutenberg :commit => 'c3c47584dd18fdafc171e0fa160780ec2db41050'
 
     ## Third party libraries
     ## =====================

WordPress/Classes/Models/Blog.h

@@ -13,6 +13,7 @@ NS_ASSUME_NONNULL_BEGIN
 @class Role;
 @class QuickStartTourState;
 @class UserSuggestion;
+@class SiteSuggestion;
 @class PageTemplateCategory;
 
 extern NSString * const BlogEntityName;
@@ -103,6 +104,7 @@ typedef NS_ENUM(NSInteger, SiteVisibility) {
 @property (nonatomic, strong, readwrite, nullable) NSSet *themes;
 @property (nonatomic, strong, readwrite, nullable) NSSet *media;
 @property (nonatomic, strong, readwrite, nullable) NSSet<UserSuggestion *> *userSuggestions;
+@property (nonatomic, strong, readwrite, nullable) NSSet<SiteSuggestion *> *siteSuggestions;
 @property (nonatomic, strong, readwrite, nullable) NSOrderedSet *menus;
 @property (nonatomic, strong, readwrite, nullable) NSOrderedSet *menuLocations;
 @property (nonatomic, strong, readwrite, nullable) NSSet<Role *> *roles;

WordPress/Classes/Models/SiteSuggestion+CoreDataClass.swift

@@ -0,0 +1,34 @@
+import Foundation
+import CoreData
+
+extension CodingUserInfoKey {
+    static let managedObjectContext = CodingUserInfoKey(rawValue: "managedObjectContext")!
+}
+
+enum DecoderError: Error {
+    case missingManagedObjectContext
+}
+
+@objc(SiteSuggestion)
+public class SiteSuggestion: NSManagedObject, Decodable {
+    enum CodingKeys: String, CodingKey {
+        case title = "title"
+        case siteURL = "siteurl"
+        case subdomain = "subdomain"
+        case blavatarURL = "blavatar"
+    }
+
+    required convenience public init(from decoder: Decoder) throws {
+        guard let managedObjectContext = decoder.userInfo[CodingUserInfoKey.managedObjectContext] as? NSManagedObjectContext else {
+            throw DecoderError.missingManagedObjectContext
+        }
+
+        self.init(context: managedObjectContext)
+
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        self.title = try container.decode(String.self, forKey: .title)
+        self.siteURL = try container.decode(URL.self, forKey: .siteURL)
+        self.subdomain = try container.decode(String.self, forKey: .subdomain)
+        self.blavatarURL = try container.decode(URL.self, forKey: .blavatarURL)
+    }
+}

WordPress/Classes/Models/SiteSuggestion+CoreDataProperties.swift

@@ -0,0 +1,17 @@
+import Foundation
+import CoreData
+
+
+extension SiteSuggestion {
+
+    @nonobjc public class func fetchRequest() -> NSFetchRequest<SiteSuggestion> {
+        return NSFetchRequest<SiteSuggestion>(entityName: "SiteSuggestion")
+    }
+
+    @NSManaged public var title: String?
+    @NSManaged public var siteURL: URL?
+    @NSManaged public var subdomain: String?
+    @NSManaged public var blavatarURL: URL?
+    @NSManaged public var blog: Blog?
+
+}

WordPress/Classes/Services/XpostSuggestionService.swift

@@ -0,0 +1,108 @@
+import Foundation
+
+/// A service to fetch and persist a list of sites that can be used for x-posting.
+struct XpostSuggestionService {
+
+    enum ServiceError: Error {
+        case missingAPI
+        case missingManagedObjectContext
+        case hostnameNotAvailable
+        case noResultsAvailable
+    }
+
+    static var hasRequested = false
+
+    /**
+    Fetch cached suggestions if available, otherwise from the network if the device is online.
+
+    @param the blog/site to retrieve suggestions for
+    @param completion callback containing list of suggestions, or nil if unavailable
+    */
+    static func suggestions(for blog: Blog, completion: @escaping (Result<[SiteSuggestion], Error>) -> Void) {
+
+        if let results = retrievePersistedResults(for: blog), results.isEmpty == false {
+            completion(.success(results))
+        } else if ReachabilityUtils.isInternetReachable() {
+            fetchAndPersistSuggestions(for: blog, completion: completion)
+        } else {
+            completion(.failure(ServiceError.noResultsAvailable))
+        }
+    }
+
+    private static func fetchAndPersistSuggestions(for blog: Blog, completion: @escaping (Result<[SiteSuggestion], Error>) -> Void) {
+
+        guard !hasRequested else { return }
+        self.hasRequested = true
+
+        guard let api = blog.wordPressComRestApi() else {
+            completion(.failure(ServiceError.missingAPI))
+            return
+        }
+
+        guard let managedObjectContext = blog.managedObjectContext else {
+            completion(.failure(ServiceError.missingManagedObjectContext))
+            return
+        }
+
+        guard let hostname = blog.hostname else {
+            completion(.failure(ServiceError.hostnameNotAvailable))
+            return
+        }
+
+        let urlString = "/wpcom/v2/sites/\(hostname)/xposts"
+
+        api.GET(urlString, parameters: nil) { responseObject, httpResponse in
+            do {
+                let data = try JSONSerialization.data(withJSONObject: responseObject)
+
+                try self.purgeExistingResults(for: blog, using: managedObjectContext)
+
+                let siteSuggestions = try self.persist(data: data, to: blog, using: managedObjectContext)
+                completion(.success(siteSuggestions))
+            } catch {
+                completion(.failure(error))
+            }
+
+            self.hasRequested = false
+        } failure: { error, _ in
+            completion(.failure(error))
+            self.hasRequested = false
+        }
+    }
+
+    private static func purgeExistingResults(for blog: Blog, using managedObjectContext: NSManagedObjectContext) throws {
+        blog.siteSuggestions?.forEach { siteSuggestion in
+            managedObjectContext.delete(siteSuggestion)
+        }
+        try managedObjectContext.save()
+    }
+
+    private static func persist(data: Data, to blog: Blog, using managedObjectContext: NSManagedObjectContext) throws -> [SiteSuggestion] {
+        let decoder = JSONDecoder()
+        decoder.userInfo[CodingUserInfoKey.managedObjectContext] = managedObjectContext
+        let siteSuggestions = try decoder.decode([SiteSuggestion].self, from: data)
+        blog.siteSuggestions = Set(siteSuggestions)
+        try managedObjectContext.save()
+        return siteSuggestions
+    }
+
+    private static func retrievePersistedResults(for blog: Blog) -> [SiteSuggestion]? {
+        guard let results = blog.siteSuggestions else { return nil }
+        return Array(results)
+    }
+}
+
+extension XpostSuggestionService.ServiceError: CustomNSError {
+    static var errorDomain: String { return "XpostSuggestionService.ServiceError" }
+
+    var errorCode: Int { return 0 }
+
+    var errorUserInfo: [String : Any] {
+        switch self {
+        case .missingAPI: return [NSDebugDescriptionErrorKey: "Blog hostname not available"]
+        case .missingManagedObjectContext: return [NSDebugDescriptionErrorKey: "Managed object context not available"]
+        case .hostnameNotAvailable: return [NSDebugDescriptionErrorKey: "Blog hostname not available"]
+        case .noResultsAvailable: return [NSDebugDescriptionErrorKey: "The device is offline and there are no suggestions in the cache"]
+        }
+    }
+}

WordPress/Classes/ViewRelated/Comments/CommentViewController.m

@@ -104,7 +104,7 @@ - (void)attachSuggestionsTableViewIfNeeded
         return;
     }
 
-    self.suggestionsTableView = [[SuggestionsTableView alloc] initWithSiteID:self.comment.blog.dotComID suggestionType:SuggestionTypeMention delegate:self];
+    self.suggestionsTableView = [[SuggestionsTableView alloc] initWithSiteID:self.comment.blog.dotComID suggestionType:SuggestionTypeMentions delegate:self];
     [self.suggestionsTableView setTranslatesAutoresizingMaskIntoConstraints:NO];
     [self.view addSubview:self.suggestionsTableView];
 }

WordPress/Classes/ViewRelated/Comments/FullScreenCommentReplyViewController.swift

@@ -69,7 +69,7 @@ public class FullScreenCommentReplyViewController: EditCommentViewController, Su
         }
 
         guard let siteID = siteID else { return }
-        let tableView = SuggestionsTableView(siteID: siteID, suggestionType: .mention, delegate: self)
+        let tableView = SuggestionsTableView(siteID: siteID, suggestionType: .mentions, delegate: self)
         tableView.useTransparentHeader = true
         tableView.translatesAutoresizingMaskIntoConstraints = false
 

WordPress/Classes/ViewRelated/Gutenberg/GutenbergViewController.swift

@@ -851,7 +851,13 @@ extension GutenbergViewController: GutenbergBridgeDelegate {
 
     func gutenbergDidRequestMention(callback: @escaping (Swift.Result<String, NSError>) -> Void) {
         DispatchQueue.main.async(execute: { [weak self] in
-            self?.showSuggestions(type: .mention, callback: callback)
+            self?.showSuggestions(type: .mentions, callback: callback)
+        })
+    }
+
+    func gutenbergDidRequestXpost(callback: @escaping (Swift.Result<String, NSError>) -> Void) {
+        DispatchQueue.main.async(execute: { [weak self] in
+            self?.showSuggestions(type: .xposts, callback: callback)
         })
     }
 
@@ -882,8 +888,10 @@ extension GutenbergViewController {
         }
 
         switch type {
-        case .mention:
+        case .mentions:
             guard SuggestionService.shared.shouldShowSuggestions(for: blog) else { return }
+        case .xposts:
+            break
         }
 
         previousFirstResponder = view.findFirstResponder()

WordPress/Classes/ViewRelated/Notifications/Controllers/NotificationDetailsViewController.swift

@@ -435,7 +435,7 @@ extension NotificationDetailsViewController {
 
     func setupSuggestionsView() {
         guard let siteID = note.metaSiteID else { return }
-        suggestionsTableView = SuggestionsTableView(siteID: siteID, suggestionType: .mention, delegate: self)
+        suggestionsTableView = SuggestionsTableView(siteID: siteID, suggestionType: .mentions, delegate: self)
         suggestionsTableView.translatesAutoresizingMaskIntoConstraints = false
     }
 

WordPress/Classes/ViewRelated/Reader/ReaderCommentsViewController.m

@@ -385,7 +385,7 @@ - (void)configureSuggestionsTableView
     NSNumber *siteID = self.siteID;
     NSParameterAssert(siteID);
 
-    self.suggestionsTableView = [[SuggestionsTableView alloc] initWithSiteID:siteID suggestionType:SuggestionTypeMention delegate:self];
+    self.suggestionsTableView = [[SuggestionsTableView alloc] initWithSiteID:siteID suggestionType:SuggestionTypeMentions delegate:self];
     [self.suggestionsTableView setTranslatesAutoresizingMaskIntoConstraints:NO];
     [self.view addSubview:self.suggestionsTableView];
 }

WordPress/Classes/ViewRelated/Suggestions/SuggestionsTableView.h

@@ -1,7 +1,8 @@
 #import <UIKit/UIKit.h>
 
 typedef NS_CLOSED_ENUM(NSUInteger, SuggestionType) {
-    SuggestionTypeMention
+    SuggestionTypeMentions,
+    SuggestionTypeXposts
 };
 
 @protocol SuggestionsTableViewDelegate;
@@ -20,7 +21,7 @@ typedef NS_CLOSED_ENUM(NSUInteger, SuggestionType) {
 
 - (nonnull instancetype)initWithSiteID:(NSNumber *_Nullable)siteID
                          suggestionType:(SuggestionType)suggestionType
-                               delegate:(id <SuggestionsTableViewDelegate>_Nonnull)suggestionsDelegate;
+                               delegate:(id <SuggestionsTableViewDelegate>_Nonnull)suggestionsDelegate NS_DESIGNATED_INITIALIZER;
 
 /**
   Enables or disables the SuggestionsTableView component.