degesch: implement the rest of buffer merging

degesch.c

@@ -2652,7 +2652,39 @@ static void
 buffer_merge (struct app_context *ctx,
 	struct buffer *buffer, struct buffer *merged)
 {
-	// TODO: try to merge the buffers as best as we can
+	// XXX: anything better to do?  This situation is arguably rare and I'm
+	//   not entirely sure what action to take.
+	buffer_send_status (ctx, buffer,
+		"Buffer %s was merged into this buffer", merged->name);
+
+	// Find all lines from "merged" newer than the newest line in "buffer"
+	struct buffer_line *start = merged->lines;
+	if (buffer->lines_tail)
+		while (start && start->when < buffer->lines_tail->when)
+			start = start->next;
+	if (!start)
+		return;
+
+	// Count how many of them we have
+	size_t n = 0;
+	for (struct buffer_line *iter = start; iter; iter = iter->next)
+		n++;
+
+	// Append the merged part to current lines in the buffer
+	buffer->lines_tail->next = start;
+	start->prev = buffer->lines_tail;
+
+	buffer->lines_tail = merged->lines_tail;
+	buffer->lines_count += n;
+
+	// And remove it from the original buffer
+	if (start == merged->lines_tail)
+		if (!(merged->lines_tail = start->prev))
+			merged->lines = NULL;
+	merged->lines_count -= n;
+
+	// XXX: we don't want to log this entry to a file
+	buffer_send_status (ctx, buffer, "End of merged content");
 }
 
 static void
@@ -2672,7 +2704,6 @@ buffer_rename (struct app_context *ctx,
 		// When there's a collision, there's not much else we can do
 		// other than somehow trying to merge them
 		buffer_merge (ctx, collision, buffer);
-		// TODO: log a status message about the merge
 		if (ctx->current_buffer == buffer)
 			buffer_activate (ctx, collision);
 		buffer_remove (ctx, buffer);