Implement backlinks updating

hyphae/backlinks.go

@@ -15,6 +15,25 @@ import (
 // Using set here seems like the most appropriate solution
 type linkSet map[string]struct{}
 
+func toLinkSet(xs []string) linkSet {
+	result := make(linkSet)
+	for _, x := range xs {
+		result[x] = struct{}{}
+	}
+	return result
+}
+
+func fetchText(h *Hypha) string {
+	if h.TextPath == "" {
+		return ""
+	}
+	text, err := os.ReadFile(h.TextPath)
+	if err == nil {
+		return string(text)
+	}
+	return ""
+}
+
 var backlinkIndex = make(map[string]linkSet)
 var backlinkIndexMutex = sync.Mutex{}
 
@@ -23,41 +42,85 @@ func IndexBacklinks() {
 	// It is safe to ignore the mutex, because there is only one worker.
 	src := FilterTextHyphae(YieldExistingHyphae())
 	for h := range src {
-		fileContentsT, errT := os.ReadFile(h.TextPath)
-		if errT == nil {
-			links := ExtractHyphaLinksFromContent(h.Name, string(fileContentsT))
-			for _, link := range links {
-				if _, exists := backlinkIndex[link]; !exists {
-					backlinkIndex[link] = make(linkSet)
-				}
-				backlinkIndex[link][h.Name] = struct{}{}
+		links := ExtractHyphaLinksFromContent(h.Name, fetchText(h))
+		for _, link := range links {
+			if _, exists := backlinkIndex[link]; !exists {
+				backlinkIndex[link] = make(linkSet)
 			}
+			backlinkIndex[link][h.Name] = struct{}{}
 		}
 	}
 }
 
+func BacklinksOnEdit(h *Hypha, oldText string) {
+	backlinkIndexMutex.Lock()
+	newLinks := toLinkSet(ExtractHyphaLinks(h))
+	oldLinks := toLinkSet(ExtractHyphaLinksFromContent(h.Name, oldText))
+	for link := range oldLinks {
+		if _, exists := newLinks[link]; !exists {
+			delete(backlinkIndex[link], h.Name)
+		}
+	}
+	for link := range newLinks {
+		if _, exists := oldLinks[link]; !exists {
+			if _, exists := backlinkIndex[link]; !exists {
+				backlinkIndex[link] = make(linkSet)
+			}
+			backlinkIndex[link][h.Name] = struct{}{}
+		}
+	}
+	backlinkIndexMutex.Unlock()
+}
+
+func BacklinksOnDelete(h *Hypha, oldText string) {
+	backlinkIndexMutex.Lock()
+	oldLinks := ExtractHyphaLinksFromContent(h.Name, oldText)
+	for _, link := range oldLinks {
+		if lSet, exists := backlinkIndex[link]; exists {
+			delete(lSet, h.Name)
+		}
+	}
+	backlinkIndexMutex.Unlock()
+}
+
+func BacklinksOnRename(h *Hypha, oldName string) {
+	backlinkIndexMutex.Lock()
+	actualLinks := ExtractHyphaLinks(h)
+	for _, link := range actualLinks {
+		if lSet, exists := backlinkIndex[link]; exists {
+			delete(lSet, oldName)
+			backlinkIndex[link][h.Name] = struct{}{}
+		}
+	}
+	backlinkIndexMutex.Unlock()
+}
+
+// YieldHyphaBacklinks gets backlinks for a desired hypha, sorts and iterates over them
 func YieldHyphaBacklinks(query string) <-chan string {
 	hyphaName := util.CanonicalName(query)
 	out := make(chan string)
 	sorted := PathographicSort(out)
 	go func() {
-		links := backlinkIndex[hyphaName]
-		for link := range links {
-			out <- link
+		links, exists := backlinkIndex[hyphaName]
+		if exists {
+			for link := range links {
+				out <- link
+			}
 		}
 		close(out)
 	}()
 	return sorted
 }
 
-// YieldHyphaLinks extracts hypha links from a desired hypha and iterates over them
+// YieldHyphaLinks extracts hypha links from a desired hypha, sorts and iterates over them
 func YieldHyphaLinks(query string) <-chan string {
 	// That is merely a debug function, but it could be useful.
 	// Should we extract them into link-specific subfile? -- chekoopa
 	hyphaName := util.CanonicalName(query)
 	out := make(chan string)
 	go func() {
-		links := ExtractHyphaLinks(hyphaName)
+		var h = ByName(hyphaName)
+		links := ExtractHyphaLinks(h)
 		for _, link := range links {
 			out <- link
 		}
@@ -67,15 +130,8 @@ func YieldHyphaLinks(query string) <-chan string {
 }
 
 // ExtractHyphaLinks extracts hypha links from a desired hypha
-func ExtractHyphaLinks(hyphaName string) []string {
-	var h = ByName(hyphaName)
-	if h.Exists {
-		fileContentsT, errT := os.ReadFile(h.TextPath)
-		if errT == nil {
-			return ExtractHyphaLinksFromContent(hyphaName, string(fileContentsT))
-		}
-	}
-	return make([]string, 0)
+func ExtractHyphaLinks(h *Hypha) []string {
+	return ExtractHyphaLinksFromContent(h.Name, fetchText(h))
 }
 
 // ExtractHyphaLinksFromContent extracts hypha links from a provided text

shroom/delete.go

@@ -17,12 +17,14 @@ func DeleteHypha(u *user.User, h *hyphae.Hypha) (hop *history.HistoryOp, errtitl
 		return hop, errtitle
 	}
 
+	originalText, _ := FetchTextPart(h)
 	hop.
 		WithFilesRemoved(h.TextPath, h.BinaryPath).
 		WithMsg(fmt.Sprintf("Delete ‘%s’", h.Name)).
 		WithUser(u).
 		Apply()
 	if !hop.HasErrors() {
+		hyphae.BacklinksOnDelete(h, originalText)
 		h.Delete()
 	}
 	return hop, ""

shroom/rename.go

@@ -67,11 +67,13 @@ func RenameHypha(h *hyphae.Hypha, newHypha *hyphae.Hypha, recursive bool, u *use
 		Apply()
 	if len(hop.Errs) == 0 {
 		for _, h := range hyphaeToRename {
+			oldName := h.Name
 			h.RenameTo(replaceName(h.Name))
 			h.Lock()
 			h.TextPath = replaceName(h.TextPath)
 			h.BinaryPath = replaceName(h.BinaryPath)
 			h.Unlock()
+			hyphae.BacklinksOnRename(h, oldName)
 		}
 	}
 	return hop, ""

shroom/search.go

@@ -7,6 +7,7 @@ import (
 	"github.com/bouncepaw/mycorrhiza/util"
 )
 
+// YieldHyphaNamesContainingString picks hyphae with have a string in their title, sorts and iterates over them.
 func YieldHyphaNamesContainingString(query string) <-chan string {
 	query = util.CanonicalName(query)
 	out := make(chan string)

shroom/upload.go

@@ -66,6 +66,7 @@ func uploadHelp(h *hyphae.Hypha, hop *history.HistoryOp, ext string, data []byte
 	var (
 		fullPath         = filepath.Join(files.HyphaeDir(), h.Name+ext)
 		originalFullPath = &h.TextPath
+		originalText     = "" // for backlink update
 	)
 	// Reject if the path is outside the hyphae dir
 	if !strings.HasPrefix(fullPath, files.HyphaeDir()) {
@@ -80,6 +81,10 @@ func uploadHelp(h *hyphae.Hypha, hop *history.HistoryOp, ext string, data []byte
 		return hop.WithErrAbort(err), err.Error()
 	}
 
+	if hop.Type == history.TypeEditText {
+		originalText, _ = FetchTextPart(h)
+	}
+
 	if err := os.WriteFile(fullPath, data, 0666); err != nil {
 		return hop.WithErrAbort(err), err.Error()
 	}
@@ -96,5 +101,8 @@ func uploadHelp(h *hyphae.Hypha, hop *history.HistoryOp, ext string, data []byte
 		return hop.Abort(), "No changes"
 	}
 	*originalFullPath = fullPath
+	if hop.Type == history.TypeEditText {
+		hyphae.BacklinksOnEdit(h, originalText)
+	}
 	return hop.WithFiles(fullPath).WithUser(u).Apply(), ""
 }