improvements to message replay code

irc/responsebuffer.go

@@ -23,8 +23,19 @@ const (
 // buffer will silently create a batch if required and label the outgoing messages as
 // necessary (or leave it off and simply tag the outgoing message).
 type ResponseBuffer struct {
-	Label     string
-	batchID   string
+	Label     string // label if this is a labeled response batch
+	batchID   string // ID of the labeled response batch, if one has been initiated
+	batchType string // type of the labeled response batch (possibly `history` or `chathistory`)
+
+	// stack of batch IDs of nested batches, which are handled separately
+	// from the underlying labeled-response batch. starting a new nested batch
+	// unconditionally enqueues its batch start message; subsequent messages
+	// are tagged with the nested batch ID, until nested batch end.
+	// (the nested batch start itself may have no batch tag, or the batch tag of the
+	// underlying labeled-response batch, or the batch tag of the next outermost
+	// nested batch.)
+	nestedBatches []string
+
 	messages  []ircmsg.IrcMessage
 	finalized bool
 	target    *Client
@@ -40,8 +51,9 @@ func GetLabel(msg ircmsg.IrcMessage) string {
 // NewResponseBuffer returns a new ResponseBuffer.
 func NewResponseBuffer(session *Session) *ResponseBuffer {
 	return &ResponseBuffer{
-		session: session,
-		target:  session.client,
+		session:   session,
+		target:    session.client,
+		batchType: defaultBatchType,
 	}
 }
 
@@ -54,6 +66,9 @@ func (rb *ResponseBuffer) AddMessage(msg ircmsg.IrcMessage) {
 		return
 	}
 
+	if 0 < len(rb.nestedBatches) {
+		msg.SetTag("batch", rb.nestedBatches[len(rb.nestedBatches)-1])
+	}
 	rb.messages = append(rb.messages, msg)
 }
 
@@ -63,9 +78,11 @@ func (rb *ResponseBuffer) Add(tags map[string]string, prefix string, command str
 }
 
 // AddFromClient adds a new message from a specific client to our queue.
-func (rb *ResponseBuffer) AddFromClient(msgid string, fromNickMask string, fromAccount string, tags map[string]string, command string, params ...string) {
+func (rb *ResponseBuffer) AddFromClient(time time.Time, msgid string, fromNickMask string, fromAccount string, tags map[string]string, command string, params ...string) {
 	msg := ircmsg.MakeMessage(nil, fromNickMask, command, params...)
-	msg.UpdateTags(tags)
+	if rb.session.capabilities.Has(caps.MessageTags) {
+		msg.UpdateTags(tags)
+	}
 
 	// attach account-tag
 	if rb.session.capabilities.Has(caps.AccountTag) && fromAccount != "*" {
@@ -75,6 +92,10 @@ func (rb *ResponseBuffer) AddFromClient(msgid string, fromNickMask string, fromA
 	if len(msgid) > 0 && rb.session.capabilities.Has(caps.MessageTags) {
 		msg.SetTag("draft/msgid", msgid)
 	}
+	// attach server-time
+	if rb.session.capabilities.Has(caps.ServerTime) && !msg.HasTag("time") {
+		msg.SetTag("time", time.UTC().Format(IRCv3TimestampFormat))
+	}
 
 	rb.AddMessage(msg)
 }
@@ -82,33 +103,31 @@ func (rb *ResponseBuffer) AddFromClient(msgid string, fromNickMask string, fromA
 // AddSplitMessageFromClient adds a new split message from a specific client to our queue.
 func (rb *ResponseBuffer) AddSplitMessageFromClient(fromNickMask string, fromAccount string, tags map[string]string, command string, target string, message utils.SplitMessage) {
 	if rb.session.capabilities.Has(caps.MaxLine) || message.Wrapped == nil {
-		rb.AddFromClient(message.Msgid, fromNickMask, fromAccount, tags, command, target, message.Message)
+		rb.AddFromClient(message.Time, message.Msgid, fromNickMask, fromAccount, tags, command, target, message.Message)
 	} else {
 		for _, messagePair := range message.Wrapped {
-			rb.AddFromClient(messagePair.Msgid, fromNickMask, fromAccount, tags, command, target, messagePair.Message)
+			rb.AddFromClient(message.Time, messagePair.Msgid, fromNickMask, fromAccount, tags, command, target, messagePair.Message)
 		}
 	}
 }
 
-// InitializeBatch forcibly starts a batch of batch `batchType`.
+// ForceBatchStart forcibly starts a batch of batch `batchType`.
 // Normally, Send/Flush will decide automatically whether to start a batch
 // of type draft/labeled-response. This allows changing the batch type
 // and forcing the creation of a possibly empty batch.
-func (rb *ResponseBuffer) InitializeBatch(batchType string, blocking bool) {
-	rb.sendBatchStart(batchType, blocking)
+func (rb *ResponseBuffer) ForceBatchStart(batchType string, blocking bool) {
+	rb.batchType = batchType
+	rb.sendBatchStart(blocking)
 }
 
-func (rb *ResponseBuffer) sendBatchStart(batchType string, blocking bool) {
+func (rb *ResponseBuffer) sendBatchStart(blocking bool) {
 	if rb.batchID != "" {
 		// batch already initialized
 		return
 	}
 
-	// formerly this combined time.Now.UnixNano() in base 36 with an incrementing counter,
-	// also in base 36. but let's just use a uuidv4-alike (26 base32 characters):
 	rb.batchID = utils.GenerateSecretToken()
-
-	message := ircmsg.MakeMessage(nil, rb.target.server.name, "BATCH", "+"+rb.batchID, batchType)
+	message := ircmsg.MakeMessage(nil, rb.target.server.name, "BATCH", "+"+rb.batchID, rb.batchType)
 	if rb.Label != "" {
 		message.SetTag(caps.LabelTagName, rb.Label)
 	}
@@ -125,6 +144,50 @@ func (rb *ResponseBuffer) sendBatchEnd(blocking bool) {
 	rb.session.SendRawMessage(message, blocking)
 }
 
+// Starts a nested batch (see the ResponseBuffer struct definition for a description of
+// how this works)
+func (rb *ResponseBuffer) StartNestedBatch(batchType string, params ...string) (batchID string) {
+	batchID = utils.GenerateSecretToken()
+	msgParams := make([]string, len(params)+2)
+	msgParams[0] = "+" + batchID
+	msgParams[1] = batchType
+	copy(msgParams[2:], params)
+	rb.AddMessage(ircmsg.MakeMessage(nil, rb.target.server.name, "BATCH", msgParams...))
+	rb.nestedBatches = append(rb.nestedBatches, batchID)
+	return
+}
+
+// Ends a nested batch
+func (rb *ResponseBuffer) EndNestedBatch(batchID string) {
+	if batchID == "" {
+		return
+	}
+
+	if 0 == len(rb.nestedBatches) || rb.nestedBatches[len(rb.nestedBatches)-1] != batchID {
+		rb.target.server.logger.Error("internal", "inconsistent batch nesting detected")
+		debug.PrintStack()
+		return
+	}
+
+	rb.nestedBatches = rb.nestedBatches[0 : len(rb.nestedBatches)-1]
+	rb.AddMessage(ircmsg.MakeMessage(nil, rb.target.server.name, "BATCH", "-"+batchID))
+}
+
+// Convenience to start a nested batch for history lines, at the highest level
+// supported by the client (`history`, `chathistory`, or no batch, in descending order).
+func (rb *ResponseBuffer) StartNestedHistoryBatch(params ...string) (batchID string) {
+	var batchType string
+	if rb.session.capabilities.Has(caps.EventPlayback) {
+		batchType = "history"
+	} else if rb.session.capabilities.Has(caps.Batch) {
+		batchType = "chathistory"
+	}
+	if batchType != "" {
+		batchID = rb.StartNestedBatch(batchType, params...)
+	}
+	return
+}
+
 // Send sends all messages in the buffer to the client.
 // Afterwards, the buffer is in an undefined state and MUST NOT be used further.
 // If `blocking` is true you MUST be sending to the client from its own goroutine.
@@ -158,7 +221,7 @@ func (rb *ResponseBuffer) flushInternal(final bool, blocking bool) error {
 	if useLabel && !useBatch && len(rb.messages) == 1 && rb.batchID == "" {
 		rb.messages[0].SetTag(caps.LabelTagName, rb.Label)
 	} else if useBatch {
-		rb.sendBatchStart(defaultBatchType, blocking)
+		rb.sendBatchStart(blocking)
 	}
 
 	// send each message out
@@ -168,8 +231,9 @@ func (rb *ResponseBuffer) flushInternal(final bool, blocking bool) error {
 			message.SetTag("time", time.Now().UTC().Format(IRCv3TimestampFormat))
 		}
 
-		// attach batch ID
-		if rb.batchID != "" {
+		// attach batch ID, unless this message was part of a nested batch and is
+		// already tagged
+		if rb.batchID != "" && !message.HasTag("batch") {
 			message.SetTag("batch", rb.batchID)
 		}