Add auto-compact LMDB schedule setting with UI and tests

Closes: https://github.com/damus-io/damus/issues/3718
Changelog-Added: Automatic lossless storage optimization
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damusTests/NdbCompactionTests.swift

@@ -17,6 +17,9 @@ final class NdbCompactionTests: XCTestCase {
         try FileManager.default.createDirectory(at: testDirectory, withIntermediateDirectories: true)
         // Ensure the flag is cleared before each test.
         UserDefaults.standard.set(false, forKey: Ndb.compact_on_next_launch_key)
+        // Reset scheduling-related keys so tests start from a clean state.
+        UserDefaults.standard.removeObject(forKey: Ndb.auto_compact_schedule_key)
+        UserDefaults.standard.removeObject(forKey: Ndb.last_compact_date_key)
     }
 
     override func tearDown() async throws {
@@ -25,6 +28,9 @@ final class NdbCompactionTests: XCTestCase {
         }
         // Leave the flag cleared after each test.
         UserDefaults.standard.set(false, forKey: Ndb.compact_on_next_launch_key)
+        // Clean up scheduling keys.
+        UserDefaults.standard.removeObject(forKey: Ndb.auto_compact_schedule_key)
+        UserDefaults.standard.removeObject(forKey: Ndb.last_compact_date_key)
         try await super.tearDown()
     }
 
@@ -171,4 +177,117 @@ final class NdbCompactionTests: XCTestCase {
             "lock.mdb should be recreated by LMDB after opening the compacted database"
         )
     }
+
+    // MARK: - AutoCompactSchedule: interval values
+
+    func testAutoCompactSchedule_intervalValues() {
+        XCTAssertEqual(AutoCompactSchedule.daily.interval,   60 * 60 * 24,       "daily interval should be 24 hours")
+        XCTAssertEqual(AutoCompactSchedule.weekly.interval,  60 * 60 * 24 * 7,   "weekly interval should be 7 days")
+        XCTAssertEqual(AutoCompactSchedule.monthly.interval, 60 * 60 * 24 * 30,  "monthly interval should be 30 days")
+        XCTAssertNil(AutoCompactSchedule.never.interval,                          ".never should have no interval")
+    }
+
+    // MARK: - get/set auto-compact schedule
+
+    func testGetAutoCompactSchedule_returnsWeeklyByDefault() {
+        // No key stored → default should be .weekly
+        XCTAssertEqual(Ndb.get_auto_compact_schedule(), .weekly)
+    }
+
+    func testSetAndGetAutoCompactSchedule_roundTrips() {
+        for schedule in AutoCompactSchedule.allCases {
+            Ndb.set_auto_compact_schedule(schedule)
+            XCTAssertEqual(Ndb.get_auto_compact_schedule(), schedule,
+                           "Round-trip failed for schedule: \(schedule)")
+        }
+    }
+
+    // MARK: - schedule_auto_compact_if_needed
+
+    func testScheduleAutoCompact_doesNothingWhenNever() {
+        Ndb.set_auto_compact_schedule(.never)
+
+        Ndb.schedule_auto_compact_if_needed()
+
+        XCTAssertFalse(
+            UserDefaults.standard.bool(forKey: Ndb.compact_on_next_launch_key),
+            "schedule=never should never set the compact flag"
+        )
+    }
+
+    func testScheduleAutoCompact_setsFlag_whenIntervalHasElapsed() {
+        // Given: schedule is weekly, last compaction was 8 days ago
+        Ndb.set_auto_compact_schedule(.weekly)
+        let eightDaysAgo = Date().addingTimeInterval(-(60 * 60 * 24 * 8))
+        UserDefaults.standard.set(eightDaysAgo, forKey: Ndb.last_compact_date_key)
+
+        // When
+        Ndb.schedule_auto_compact_if_needed()
+
+        // Then: flag should be set
+        XCTAssertTrue(
+            UserDefaults.standard.bool(forKey: Ndb.compact_on_next_launch_key),
+            "compact flag should be set when scheduled interval has elapsed"
+        )
+    }
+
+    func testScheduleAutoCompact_doesNotSetFlag_whenIntervalHasNotElapsed() {
+        // Given: schedule is weekly, last compaction was 1 day ago
+        Ndb.set_auto_compact_schedule(.weekly)
+        let oneDayAgo = Date().addingTimeInterval(-(60 * 60 * 24))
+        UserDefaults.standard.set(oneDayAgo, forKey: Ndb.last_compact_date_key)
+
+        // When
+        Ndb.schedule_auto_compact_if_needed()
+
+        // Then: flag should NOT be set
+        XCTAssertFalse(
+            UserDefaults.standard.bool(forKey: Ndb.compact_on_next_launch_key),
+            "compact flag should not be set when the scheduled interval has not yet elapsed"
+        )
+    }
+
+    func testScheduleAutoCompact_setsFlag_whenNoLastCompactDate() {
+        // Given: schedule is daily, no last compact date stored (first launch)
+        Ndb.set_auto_compact_schedule(.daily)
+        // last_compact_date_key is absent (cleaned in setUp)
+
+        // When
+        Ndb.schedule_auto_compact_if_needed()
+
+        // Then: flag should be set (distantPast triggers compaction on first launch)
+        XCTAssertTrue(
+            UserDefaults.standard.bool(forKey: Ndb.compact_on_next_launch_key),
+            "compact flag should be set on first launch (no previous compaction date)"
+        )
+    }
+
+    // MARK: - compact_if_needed: records last compact date
+
+    func testCompactIfNeeded_recordsLastCompactDate_afterSuccessfulCompaction() {
+        let dbPath = testDirectory.appendingPathComponent("date_record_db").path
+        try? FileManager.default.createDirectory(atPath: dbPath, withIntermediateDirectories: true)
+
+        guard let ndb = Ndb(path: dbPath) else {
+            XCTFail("Could not open Ndb at \(dbPath)")
+            return
+        }
+        ndb.close()
+
+        XCTAssertNil(Ndb.get_last_compact_date(), "No last compact date should exist before first compaction")
+
+        Ndb.set_compact_on_next_launch()
+
+        let beforeCompact = Date()
+        Ndb.compact_if_needed(db_path: dbPath)
+        let afterCompact = Date()
+
+        guard let lastDate = Ndb.get_last_compact_date() else {
+            XCTFail("Last compact date should be set after successful compaction")
+            return
+        }
+
+        XCTAssertGreaterThanOrEqual(lastDate, beforeCompact, "last compact date should be >= time before compaction started")
+        XCTAssertLessThanOrEqual(lastDate, afterCompact, "last compact date should be <= time after compaction ended")
+    }
 }