[Storage] timestamp sorting and filtering (#1218)

* feat(backend): combined sorting by index and timestamp

* feat(backend): write the only last timestamp message in a row

backend/pkg/messages/session-iterator.go

@@ -9,11 +9,12 @@ import (
 )
 
 type msgInfo struct {
-	index   uint64
-	start   int64
-	end     int64
-	body    Message
-	msgType uint64
+	index     uint64
+	start     int64
+	end       int64
+	body      Message
+	msgType   uint64
+	timestamp uint64
 }
 
 func (m *msgInfo) Print() string {
@@ -23,6 +24,7 @@ func (m *msgInfo) Print() string {
 func SplitMessages(data []byte) ([]*msgInfo, error) {
 	messages := make([]*msgInfo, 0)
 	indexes := make(map[uint64]bool)
+	var lastTimestamp uint64
 	reader := NewBytesReader(data)
 	for {
 		// Get message start
@@ -59,20 +61,34 @@ func SplitMessages(data []byte) ([]*msgInfo, error) {
 		}
 		indexes[msgIndex] = true
 
+		// Update current timestamp
+		if msgType == MsgTimestamp {
+			msgBody := body.(*Timestamp)
+			lastTimestamp = msgBody.Timestamp
+		}
+
 		// Add new message info to messages slice
 		messages = append(messages, &msgInfo{
-			index:   msgIndex,
-			start:   msgStart,
-			end:     reader.Pointer(),
-			body:    body,
-			msgType: msgType,
+			index:     msgIndex,
+			start:     msgStart + 8, // start pointer without index (that's why we use +8)
+			end:       reader.Pointer(),
+			body:      body,
+			msgType:   msgType,
+			timestamp: lastTimestamp,
 		})
 	}
 }
 
 func SortMessages(messages []*msgInfo) []*msgInfo {
+	// Sort messages by index
 	sort.SliceStable(messages, func(i, j int) bool {
-		return messages[i].index < messages[j].index
+		if messages[i].timestamp < messages[j].timestamp {
+			return true
+		}
+		if messages[i].timestamp == messages[j].timestamp {
+			return messages[i].index < messages[j].index
+		}
+		return false
 	})
 	return messages
 }
@@ -81,9 +97,24 @@ func MergeMessages(data []byte, messages []*msgInfo) []byte {
 	sortedSession := bytes.NewBuffer(make([]byte, 0, len(data)))
 	// Add maximum possible index value to the start of the session to inform player about new version of mob file
 	sortedSession.Write([]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff})
-	for _, info := range messages {
-		// Write message without index (that's why we use +8)
-		sortedSession.Write(data[info.start+8 : info.end])
+
+	var lastTsIndex int = -1 // not set
+	for i, info := range messages {
+		if info.msgType == MsgTimestamp {
+			// Save index of last timestamp message and continue to read next message
+			lastTsIndex = i
+			continue
+		}
+
+		// Write last timestamp message if it exists
+		if lastTsIndex != -1 {
+			tsInfo := messages[lastTsIndex]
+			sortedSession.Write(data[tsInfo.start:tsInfo.end])
+			lastTsIndex = -1
+		}
+
+		// Write current message
+		sortedSession.Write(data[info.start:info.end])
 	}
 	return sortedSession.Bytes()
 }