refactor and cleanup [skip ci]

submodules/Postbox/Sources/TimestampBasedMessageAttributesIndexTable.swift

@@ -0,0 +1,35 @@
+import Foundation
+
+final class TimestampBasedMessageAttributesIndexTable: Table {
+    static func tableSpec(_ id: Int32) -> ValueBoxTable {
+        return ValueBoxTable(id: id, keyType: .binary, compactValuesOnCreation: true)
+    }
+    
+    private func key(tag: UInt16, id: MessageId) -> ValueBoxKey {
+        let key = ValueBoxKey(length: 2 + 4 + 8 + 4)
+        key.setUInt16(0, value: tag)
+        key.setInt64(2, value: id.peerId.toInt64())
+        key.setInt32(2 + 8, value: id.namespace)
+        key.setInt32(2 + 8 + 4, value: id.id)
+        return key
+    }
+    
+    func set(tag: UInt16, id: MessageId, timestamp: Int32) {
+        var timestampValue = timestamp
+        self.valueBox.set(self.table, key: self.key(tag: tag, id: id), value: MemoryBuffer(memory: &timestampValue, capacity: 4, length: 4, freeWhenDone: false))
+    }
+    
+    func get(tag: UInt16, id: MessageId) -> Int32? {
+        if let value = self.valueBox.get(self.table, key: self.key(tag: tag, id: id)) {
+            var timestampValue: Int32 = 0
+            value.read(&timestampValue, offset: 0, length: 4)
+            return timestampValue
+        } else {
+            return nil
+        }
+    }
+    
+    func remove(tag: UInt16, id: MessageId) {
+        self.valueBox.remove(self.table, key: self.key(tag: tag, id: id), secure: false)
+    }
+}