Perform grouping with existing notifications when refreshing

Closes #88

Pachyderm/Sources/Pachyderm/Utilities/NotificationGroup.swift

@@ -8,8 +8,8 @@
 
 import Foundation
 
-public class NotificationGroup: Identifiable, Hashable {
-    public let notifications: [Notification]
+public struct NotificationGroup: Identifiable, Hashable {
+    public private(set) var notifications: [Notification]
     public let id: String
     public let kind: Notification.Kind
     public let statusState: StatusState?
@@ -27,34 +27,90 @@ public class NotificationGroup: Identifiable, Hashable {
     }
     
     public static func ==(lhs: NotificationGroup, rhs: NotificationGroup) -> Bool {
-        return lhs.id == rhs.id
+        guard lhs.notifications.count == rhs.notifications.count else {
+            return false
+        }
+        for (a, b) in zip(lhs.notifications, rhs.notifications) where a.id != b.id {
+            return false
+        }
+        return true
     }
     
     public func hash(into hasher: inout Hasher) {
-        hasher.combine(id)
+        for notification in notifications {
+            hasher.combine(notification.id)
+        }
+    }
+    
+    private mutating func append(_ notification: Notification) {
+        notifications.append(notification)
+    }
+    
+    private mutating func append(group: NotificationGroup) {
+        notifications.append(contentsOf: group.notifications)
     }
 
     public static func createGroups(notifications: [Notification], only allowedTypes: [Notification.Kind]) -> [NotificationGroup] {
-        var groups = [[Notification]]()
+        var groups = [NotificationGroup]()
         for notification in notifications {
             if allowedTypes.contains(notification.kind) {
-                if let lastGroup = groups.last, let firstNotification = lastGroup.first, firstNotification.kind == notification.kind, firstNotification.status?.id == notification.status?.id {
+                if let lastGroup = groups.last, canMerge(notification: notification, into: lastGroup) {
                     groups[groups.count - 1].append(notification)
                     continue
                 } else if groups.count >= 2 {
                     let secondToLastGroup = groups[groups.count - 2]
-                    if allowedTypes.contains(groups[groups.count - 1][0].kind), let firstNotification = secondToLastGroup.first, firstNotification.kind == notification.kind, firstNotification.status?.id == notification.status?.id {
+                    if allowedTypes.contains(groups[groups.count - 1].kind), canMerge(notification: notification, into: secondToLastGroup) {
                         groups[groups.count - 2].append(notification)
                         continue
                     }
                 }
             }
             
-            groups.append([notification])
+            groups.append(NotificationGroup(notifications: [notification])!)
         }
-        return groups.map {
-            NotificationGroup(notifications: $0)!
+        return groups
     }
+    
+    private static func canMerge(notification: Notification, into group: NotificationGroup) -> Bool {
+        return notification.kind == group.kind && notification.status?.id == group.notifications.first!.status?.id
+    }
+    
+    public static func mergeGroups(first: [NotificationGroup], second: [NotificationGroup], only allowedTypes: [Notification.Kind]) -> [NotificationGroup] {
+        guard !first.isEmpty else {
+            return second
+        }
+        guard !second.isEmpty else {
+            return first
+        }
+
+        var merged = first
+        var second = second
+        merged.reserveCapacity(second.count)
+        while let firstGroupFromSecond = second.first,
+              allowedTypes.contains(firstGroupFromSecond.kind) {
+            
+            second.removeFirst()
+            
+            guard let lastGroup = merged.last,
+                  allowedTypes.contains(lastGroup.kind) else {
+                merged.append(firstGroupFromSecond)
+                break
+            }
+            
+                    
+            if canMerge(notification: firstGroupFromSecond.notifications.first!, into: lastGroup) {
+                merged[merged.count - 1].append(group: firstGroupFromSecond)
+            } else if merged.count >= 2 {
+                let secondToLastGroup = merged[merged.count - 2]
+                if allowedTypes.contains(secondToLastGroup.kind), canMerge(notification: firstGroupFromSecond.notifications.first!, into: secondToLastGroup) {
+                    merged[merged.count - 2].append(group: firstGroupFromSecond)
+                }
+            } else {
+                merged.append(firstGroupFromSecond)
+            }
+        }
+        merged.append(contentsOf: second)
+        return merged
     }
     
 }

Pachyderm/Tests/PachydermTests/NotificationGroupTests.swift

@@ -0,0 +1,235 @@
+//
+//  NotificationGroupTests.swift
+//  
+//
+//  Created by Shadowfacts on 4/26/22.
+//
+
+import XCTest
+@testable import Pachyderm
+
+class NotificationGroupTests: XCTestCase {
+    
+    let decoder: JSONDecoder = {
+        let d = JSONDecoder()
+        d.dateDecodingStrategy = .iso8601
+        return d
+    }()
+    
+    let statusA = """
+    {
+        "id": "1",
+        "created_at": "2019-11-23T07:28:34Z",
+        "account": {
+          "id": "2",
+          "username": "bar",
+          "acct": "bar",
+          "display_name": "bar",
+          "locked": false,
+          "created_at": "2019-11-01T01:01:01Z",
+          "followers_count": 0,
+          "following_count": 0,
+          "statuses_count": 0,
+          "note": "",
+          "url": "https://example.com/@bar",
+          "uri": "https://example.com/@bar",
+        },
+        "url": "https://example.com/@bar/1",
+        "uri": "https://example.com/@bar/1",
+        "content": "",
+        "emojis": [],
+        "reblogs_count": 0,
+        "favourites_count": 0,
+        "sensitive": false,
+        "spoiler_text": "",
+        "visibility": "public",
+        "media_attachments": [],
+        "mentions": [],
+        "tags": [],
+      }
+    }
+    """
+    lazy var likeA1Data = """
+    {
+      "id": "1",
+      "type": "favourite",
+      "created_at": "2019-11-23T07:29:18Z",
+      "account": {
+        "id": "1",
+        "username": "foo",
+        "acct": "foo",
+        "display_name": "foo",
+        "locked": false,
+        "created_at": "2019-11-01T01:01:01Z",
+        "followers_count": 0,
+        "following_count": 0,
+        "statuses_count": 0,
+        "note": "",
+        "url": "https://example.com/@foo",
+        "uri": "https://example.com/@foo",
+      },
+      "status": \(statusA)
+    """.data(using: .utf8)!
+    lazy var likeA1 = try! decoder.decode(Notification.self, from: likeA1Data)
+    lazy var likeA2Data = """
+    {
+      "id": "2",
+      "type": "favourite",
+      "created_at": "2019-11-23T07:30:00Z",
+      "account": {
+        "id": "2",
+        "username": "baz",
+        "acct": "baz",
+        "display_name": "baz",
+        "locked": false,
+        "created_at": "2019-11-01T01:01:01Z",
+        "followers_count": 0,
+        "following_count": 0,
+        "statuses_count": 0,
+        "note": "",
+        "url": "https://example.com/@baz",
+        "uri": "https://example.com/@baz",
+      },
+      "status": \(statusA)
+    """.data(using: .utf8)!
+    lazy var likeA2 = try! decoder.decode(Notification.self, from: likeA2Data)
+    let statusB = """
+    {
+        "id": "2",
+        "created_at": "2019-11-23T07:28:34Z",
+        "account": {
+          "id": "2",
+          "username": "bar",
+          "acct": "bar",
+          "display_name": "bar",
+          "locked": false,
+          "created_at": "2019-11-01T01:01:01Z",
+          "followers_count": 0,
+          "following_count": 0,
+          "statuses_count": 0,
+          "note": "",
+          "url": "https://example.com/@bar",
+          "uri": "https://example.com/@bar",
+        },
+        "url": "https://example.com/@bar/1",
+        "uri": "https://example.com/@bar/1",
+        "content": "",
+        "emojis": [],
+        "reblogs_count": 0,
+        "favourites_count": 0,
+        "sensitive": false,
+        "spoiler_text": "",
+        "visibility": "public",
+        "media_attachments": [],
+        "mentions": [],
+        "tags": [],
+      }
+    }
+    """
+    lazy var likeBData = """
+    {
+      "id": "3",
+      "type": "favourite",
+      "created_at": "2019-11-23T07:29:18Z",
+      "account": {
+        "id": "1",
+        "username": "foo",
+        "acct": "foo",
+        "display_name": "foo",
+        "locked": false,
+        "created_at": "2019-11-01T01:01:01Z",
+        "followers_count": 0,
+        "following_count": 0,
+        "statuses_count": 0,
+        "note": "",
+        "url": "https://example.com/@foo",
+        "uri": "https://example.com/@foo",
+      },
+      "status": \(statusB)
+    """.data(using: .utf8)!
+    lazy var likeB = try! decoder.decode(Notification.self, from: likeBData)
+    lazy var mentionBData = """
+    {
+      "id": "4",
+      "type": "mention",
+      "created_at": "2019-11-23T07:29:18Z",
+      "account": {
+        "id": "1",
+        "username": "foo",
+        "acct": "foo",
+        "display_name": "foo",
+        "locked": false,
+        "created_at": "2019-11-01T01:01:01Z",
+        "followers_count": 0,
+        "following_count": 0,
+        "statuses_count": 0,
+        "note": "",
+        "url": "https://example.com/@foo",
+        "uri": "https://example.com/@foo",
+      },
+      "status": \(statusB)
+    """.data(using: .utf8)!
+    lazy var mentionB = try! decoder.decode(Notification.self, from: mentionBData)
+
+
+    func testGroupSimple() {
+        let groups = NotificationGroup.createGroups(notifications: [likeA1, likeA2], only: [.favourite])
+        XCTAssertEqual(groups, [NotificationGroup(notifications: [likeA1, likeA2])!])
+    }
+    
+    func testGroupWithOtherGroupableInBetween() {
+        let groups = NotificationGroup.createGroups(notifications: [likeA1, likeB, likeA2], only: [.favourite])
+        XCTAssertEqual(groups, [
+            NotificationGroup(notifications: [likeA1, likeA2])!,
+            NotificationGroup(notifications: [likeB])!,
+        ])
+    }
+    
+    func testDontGroupWithUngroupableInBetween() {
+        let groups = NotificationGroup.createGroups(notifications: [likeA1, mentionB, likeA2], only: [.favourite])
+        XCTAssertEqual(groups, [
+            NotificationGroup(notifications: [likeA1])!,
+            NotificationGroup(notifications: [mentionB])!,
+            NotificationGroup(notifications: [likeA2])!,
+        ])
+    }
+
+    func testMergeSimpleGroups() {
+        let group1 = NotificationGroup(notifications: [likeA1])!
+        let group2 = NotificationGroup(notifications: [likeA2])!
+        let merged = NotificationGroup.mergeGroups(first: [group1], second: [group2], only: [.favourite])
+        XCTAssertEqual(merged, [
+            NotificationGroup(notifications: [likeA1, likeA2])!
+        ])
+    }
+    
+    func testMergeGroupsWithOtherGroupableInBetween() {
+        let group1 = NotificationGroup(notifications: [likeA1])!
+        let group2 = NotificationGroup(notifications: [likeB])!
+        let group3 = NotificationGroup(notifications: [likeA2])!
+        let merged = NotificationGroup.mergeGroups(first: [group1, group2], second: [group3], only: [.favourite])
+        XCTAssertEqual(merged, [
+            NotificationGroup(notifications: [likeA1, likeA2])!,
+            NotificationGroup(notifications: [likeB])!,
+        ])
+        
+        let merged2 = NotificationGroup.mergeGroups(first: [group1], second: [group2, group3], only: [.favourite])
+        XCTAssertEqual(merged2, [
+            NotificationGroup(notifications: [likeA1, likeA2])!,
+            NotificationGroup(notifications: [likeB])!,
+        ])
+    }
+    
+    func testDontMergeWithUngroupableInBetween() {
+        let group1 = NotificationGroup(notifications: [likeA1])!
+        let group2 = NotificationGroup(notifications: [mentionB])!
+        let group3 = NotificationGroup(notifications: [likeA2])!
+        let merged = NotificationGroup.mergeGroups(first: [group1, group2], second: [group3], only: [.favourite])
+        XCTAssertEqual(merged, [
+            NotificationGroup(notifications: [likeA1])!,
+            NotificationGroup(notifications: [mentionB])!,
+            NotificationGroup(notifications: [likeA2])!,
+        ])
+    }
+
+}

Tusker.xcodeproj/xcshareddata/xcschemes/Pachyderm.xcscheme

@@ -28,6 +28,16 @@
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "PachydermTests"
+               BuildableName = "PachydermTests"
+               BlueprintName = "PachydermTests"
+               ReferencedContainer = "container:Pachyderm">
+            </BuildableReference>
+         </TestableReference>
       </Testables>
    </TestAction>
    <LaunchAction

Tusker/Screens/Notifications/NotificationsTableViewController.swift

@@ -140,11 +140,14 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
                     self.older = older
                 }
                 
-                let groups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
+                let olderGroups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
                 
                 self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
-                    var snapshot = currentSnapshot()
-                    snapshot.appendItems(groups, toSection: .notifications)
+                    let existingGroups = currentSnapshot().itemIdentifiers
+                    let merged = NotificationGroup.mergeGroups(first: existingGroups, second: olderGroups, only: self.groupTypes)
+                    var snapshot = NSDiffableDataSourceSnapshot<Section, NotificationGroup>()
+                    snapshot.appendSections([.notifications])
+                    snapshot.appendItems(merged, toSection: .notifications)
                     completion(.success(snapshot))
                 }
             }
@@ -173,15 +176,14 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
                     self.newer = newer
                 }
                 
-                let groups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
+                let newerGroups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
                 
                 self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
-                    var snapshot = currentSnapshot()
-                    if let first = snapshot.itemIdentifiers(inSection: .notifications).first {
-                        snapshot.insertItems(groups, beforeItem: first)
-                    } else {
-                        snapshot.appendItems(groups, toSection: .notifications)
-                    }
+                    let existingGroups = currentSnapshot().itemIdentifiers
+                    let merged = NotificationGroup.mergeGroups(first: newerGroups, second: existingGroups, only: self.groupTypes)
+                    var snapshot = NSDiffableDataSourceSnapshot<Section, NotificationGroup>()
+                    snapshot.appendSections([.notifications])
+                    snapshot.appendItems(merged, toSection: .notifications)
                     completion(.success(snapshot))
                 }
             }