dirlist: actually honor the DirInfo

Currently the dirlist ignores the counts provided by the dirInfo.
However some of the workers can actually provide accurate counts much quicker
than if we count the flags.

Eventually we will also want to enable displaying counts for background folders,
where the brute force counting won't work as none of the headers are fetched yet.

This commit models it in an opt-in manner, if the flag isn't set then we still
count the messages manually.

models/models.go

@@ -50,6 +50,9 @@ type DirectoryInfo struct {
 
 	// The number of unread messages
 	Unseen int
+
+	// set to true if the value counts are accurate
+	AccurateCounts bool
 }
 
 // A MessageInfo holds information about the structure of a message

widgets/dirlist.go

@@ -171,32 +171,17 @@ func (dirlist *DirectoryList) getDirString(name string, width int, recentUnseen
 }
 
 func (dirlist *DirectoryList) getRUEString(name string) string {
-	totalUnseen := 0
-	totalRecent := 0
-	totalExists := 0
-	if msgStore, ok := dirlist.MsgStore(name); ok {
-		for _, msg := range msgStore.Messages {
-			if msg == nil {
-				continue
-			}
-			seen := false
-			recent := false
-			for _, flag := range msg.Flags {
-				if flag == models.SeenFlag {
-					seen = true
-				} else if flag == models.RecentFlag {
-					recent = true
-				}
-			}
-			if !seen {
-				if recent {
-					totalRecent++
-				} else {
-					totalUnseen++
-				}
-			}
-		}
+	msgStore, ok := dirlist.MsgStore(name)
+	if !ok {
+		return ""
+	}
+	var totalRecent, totalUnseen, totalExists int
+	if msgStore.DirInfo.AccurateCounts {
+		totalRecent = msgStore.DirInfo.Recent
+		totalUnseen = msgStore.DirInfo.Unseen
 		totalExists = msgStore.DirInfo.Exists
+	} else {
+		totalRecent, totalUnseen, totalExists = countRUE(msgStore)
 	}
 	rueString := ""
 	if totalRecent > 0 {
@@ -395,3 +380,29 @@ func (dirlist *DirectoryList) getSortCriteria() []*types.SortCriterion {
 	}
 	return criteria
 }
+
+func countRUE(msgStore *lib.MessageStore) (recent, unread, exist int) {
+	for _, msg := range msgStore.Messages {
+		if msg == nil {
+			continue
+		}
+		seen := false
+		isrecent := false
+		for _, flag := range msg.Flags {
+			if flag == models.SeenFlag {
+				seen = true
+			} else if flag == models.RecentFlag {
+				isrecent = true
+			}
+		}
+		if !seen {
+			if isrecent {
+				recent++
+			} else {
+				unread++
+			}
+		}
+		exist++
+	}
+	return recent, unread, exist
+}