Update the date separators to use "Today", "Yesterday" etc for messages in the past 7 days. (#4785)

* Update the date separators to use "Today", "Yesterday" etc for messages in the past 7 days.

* Fix the observation tests.

ElementX/Sources/Other/Extensions/Date.swift

@@ -34,6 +34,27 @@ extension Date {
         }
     }
     
+    /// Similar to ``formattedMinimal`` but returning "Today" instead of the time and
+    /// including the year when it the date is from a previous year (rather than over a year ago).
+    func formattedDateSeparator() -> String {
+        let calendar = Calendar.current
+        
+        if calendar.isDateInToday(self) || calendar.isDateInYesterday(self) {
+            // Simply "Today" or "Yesterday" if it was today or yesterday.
+            return DateFormatter.relative.string(from: self)
+        } else if let sixDaysAgo = calendar.date(byAdding: .day, value: -6, to: calendar.startOfDay(for: .now)),
+                  sixDaysAgo <= self {
+            // The named day if it was in the last 6 days.
+            return formatted(.dateTime.weekday(.wide))
+        } else if calendar.component(.year, from: self) == calendar.component(.year, from: .now) {
+            // The day and month if it was this year.
+            return formatted(.dateTime.weekday(.wide).day().month(.wide))
+        } else {
+            // The day, month and year if it is any older.
+            return formatted(.dateTime.weekday(.wide).day().month(.wide).year())
+        }
+    }
+    
     /// The date formatted as just the time, for use in timeline items specifically.
     func formattedTime() -> String {
         formatted(date: .omitted, time: .shortened)
@@ -44,3 +65,15 @@ extension Date {
         DateComponents(calendar: .current, year: 2007, month: 1, day: 9, hour: 9, minute: 41).date ?? .now
     }
 }
+
+private extension DateFormatter {
+    // There doesn't appear to be a way to get "Today" out of
+    // `Date.RelativeFormatStyle` so use the old way instead 😐
+    static let relative: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.doesRelativeDateFormatting = true
+        formatter.dateStyle = .long
+        formatter.timeStyle = .none
+        return formatter
+    }()
+}

ElementX/Sources/Screens/Timeline/View/TimelineItemViews/SeparatorRoomTimelineView.swift

@@ -12,7 +12,7 @@ struct SeparatorRoomTimelineView: View {
     let timelineItem: SeparatorRoomTimelineItem
     
     var body: some View {
-        Text(timelineItem.timestamp.formatted(date: .complete, time: .omitted))
+        Text(timelineItem.timestamp.formattedDateSeparator())
             .font(.compound.bodySMSemibold)
             .foregroundColor(.compound.textPrimary)
             .frame(maxWidth: .infinity)

UnitTests/Sources/DateTests.swift

@@ -36,6 +36,27 @@ class DateTests: XCTestCase {
         let theMillennium = calendar.date(from: DateComponents(year: 2000, month: 1, day: 1))!
         XCTAssertEqual(theMillennium.formattedMinimal(), theMillennium.formatted(.dateTime.year().day().month()))
     }
+    
+    func testDateSeparatorFormatting() {
+        let today = calendar.date(byAdding: DateComponents(hour: 9, minute: 30), to: startOfToday)!
+        XCTAssertEqual(today.formattedDateSeparator(), "Today")
+        
+        let yesterday = calendar.date(byAdding: .hour, value: 1, to: startOfYesterday)!
+        XCTAssertEqual(yesterday.formattedDateSeparator(), "Yesterday")
+        
+        let nearYesterday = calendar.date(byAdding: DateComponents(hour: -10), to: today)!
+        XCTAssertEqual(nearYesterday.formattedDateSeparator(), yesterday.formatted(Date.RelativeFormatStyle(presentation: .named, capitalizationContext: .beginningOfSentence)))
+        
+        let threeDaysAgo = calendar.date(byAdding: .day, value: -3, to: startOfToday)!
+        XCTAssertEqual(threeDaysAgo.formattedDateSeparator(), threeDaysAgo.formatted(.dateTime.weekday(.wide)))
+        
+        // This test will fail during the first 6 days of the year.
+        let sometimeThisYear = calendar.date(byAdding: .month, value: -10, to: startOfToday)!
+        XCTAssertEqual(sometimeThisYear.formattedDateSeparator(), sometimeThisYear.formatted(.dateTime.weekday(.wide).day().month(.wide)))
+        
+        let theMillennium = calendar.date(from: DateComponents(year: 2000, month: 1, day: 1))!
+        XCTAssertEqual(theMillennium.formattedDateSeparator(), theMillennium.formatted(.dateTime.weekday(.wide).day().month(.wide).year()))
+    }
 }
 
 // swiftlint:enable force_unwrapping

UnitTests/Sources/DeferredFulfillmentTests.swift

@@ -9,6 +9,7 @@
 @testable import ElementX
 import XCTest
 
+@MainActor
 class DeferredFulfillmentTests: XCTestCase {
     private let observable = SomeObservable()
     
@@ -70,7 +71,8 @@ class DeferredFulfillmentTests: XCTestCase {
 
 // MARK: - Helpers
 
-@Observable private class SomeObservable {
+@Observable
+@MainActor private class SomeObservable {
     var counter = 0
     
     func setCounter(_ newValue: Int, delay: Duration? = nil) async throws {