feat: collect backlinks

Adds support for collecting backlinks. For simplification we now assume
that all notes have unique base file names.

internal/collector/collector.go

@@ -52,10 +52,7 @@ func (c *Collector) CollectMetrics(root fs.FS, collectionTime time.Time) error {
 
 // collectMetrics collects all metrics from a Zettelkasten rooted in `root`.
 func (c *Collector) collectMetrics(root fs.FS) (metrics.Metrics, error) {
-	var noteCount uint
-	var linkCount uint
-	var wordCount uint
-	notes := make(map[string]metrics.NoteMetrics)
+	noteMetrics := make(map[string]metrics.NoteMetrics)
 
 	err := fs.WalkDir(root, ".", func(path string, dir fs.DirEntry, err error) error {
 		if err != nil {
@@ -86,11 +83,7 @@ func (c *Collector) collectMetrics(root fs.FS) (metrics.Metrics, error) {
 			slog.Error("Error reading file", slog.Any("error", err), slog.String("path", path))
 			return nil
 		}
-		metrics := CollectNoteMetrics(content)
-		notes[path] = metrics
-		linkCount += metrics.LinkCount
-		wordCount += metrics.WordCount
-		noteCount += 1
+		noteMetrics[nameFromFilename(path)] = CollectNoteMetrics(content)
 
 		slog.Debug("collected metrics from file", slog.String("path", path), slog.Any("d", dir), slog.Any("err", err))
 
@@ -102,5 +95,30 @@ func (c *Collector) collectMetrics(root fs.FS) (metrics.Metrics, error) {
 		return metrics.Metrics{}, err
 	}
 
-	return metrics.Metrics{NoteCount: noteCount, LinkCount: linkCount, WordCount: wordCount, Notes: notes}, nil
+	zettelkastenMetrics := aggregateMetrics(noteMetrics)
+	return zettelkastenMetrics, nil
+}
+
+// aggregateMetrics aggregates all individual note metrics into metrics in the context of a full Zettelkasten.
+func aggregateMetrics(noteMetrics map[string]metrics.NoteMetrics) metrics.Metrics {
+	zettelkastenMetrics := metrics.Metrics{
+		NoteCount: 0,
+		LinkCount: 0,
+		WordCount: 0,
+		Notes:     make(map[string]metrics.NoteMetrics),
+	}
+
+	for name, metric := range noteMetrics {
+		// Aggregate totals
+		zettelkastenMetrics.NoteCount += 1
+		zettelkastenMetrics.LinkCount += metric.LinkCount
+		zettelkastenMetrics.WordCount += metric.WordCount
+		// Collect backlinks
+		for _, n := range noteMetrics {
+			metric.BacklinkCount += n.Links[name]
+		}
+		zettelkastenMetrics.Notes[name] = metric
+	}
+
+	return zettelkastenMetrics
 }

internal/collector/collector_test.go

@@ -18,7 +18,7 @@ created-at: "2024-05-29"
 
 Testing a note with no links. But there's a [markdown link](./dir1/two.md)
 
-[[./dir1/two.md]]
+[[two]]
 
 ![[./image.png]]
 		`)},
@@ -42,7 +42,7 @@ Links to [[one]] but also to [[two|two with an alias]]
 ---
 created-at: "2024-05-29"
 ---
-Link to [one](./one.md) and also a full link [[./dir1/dir2/three]] and a [[./dir1/two.md|full link with .md]]
+Link to [one](one.md) and also a full link [[./dir1/dir2/three]] and a [[dir1/two.md|full link with .md]]
 		`)},
 		"ignoredir/foo":         {Data: []byte("Foo contents")},
 		"ignoredir/bar":         {Data: []byte("Bar contents")},
@@ -55,26 +55,26 @@ Link to [one](./one.md) and also a full link [[./dir1/dir2/three]] and a [[./dir
 		LinkCount: 8,
 		WordCount: 43,
 		Notes: map[string]metrics.NoteMetrics{
-			"zettel/one.md": {
-				Links:         map[string]uint{"./dir1/two.md": 2},
+			"one": {
+				Links:         map[string]uint{"two": 2},
 				LinkCount:     2,
 				WordCount:     13,
-				BacklinkCount: 0,
+				BacklinkCount: 3,
 			},
-			"zettel/dir1/two.md": {
+			"two": {
 				Links:         map[string]uint{"one": 1},
 				LinkCount:     1,
 				WordCount:     5,
-				BacklinkCount: 0,
+				BacklinkCount: 4,
 			},
-			"zettel/dir1/dir2/three.md": {
+			"three": {
 				Links:         map[string]uint{"one": 1, "two": 1},
 				LinkCount:     2,
 				WordCount:     10,
-				BacklinkCount: 0,
+				BacklinkCount: 1,
 			},
-			"zettel/four.md": {
-				Links:         map[string]uint{"./one.md": 1, "./dir1/dir2/three": 1, "./dir1/two.md": 1},
+			"four": {
+				Links:         map[string]uint{"one": 1, "three": 1, "two": 1},
 				LinkCount:     3,
 				WordCount:     15,
 				BacklinkCount: 0,

internal/collector/note.go

@@ -54,11 +54,12 @@ func CollectNoteMetrics(content []byte) metrics.NoteMetrics {
 			return ast.WalkContinue, nil
 		}
 
-		v, ok := noteMetrics.Links[linkTarget]
+		targetName := nameFromFilename(linkTarget)
+		v, ok := noteMetrics.Links[targetName]
 		if !ok {
-			noteMetrics.Links[linkTarget] = 0
+			noteMetrics.Links[targetName] = 0
 		}
-		noteMetrics.Links[linkTarget] = v + 1
+		noteMetrics.Links[targetName] = v + 1
 		return ast.WalkContinue, nil
 	})
 	if err != nil {
@@ -89,3 +90,8 @@ func isNoteTarget(target string) bool {
 	isNoteTarget := extension == "" || extension == ".md"
 	return isNoteTarget
 }
+
+// nameFromFilename extracts the base note name from a full path.
+func nameFromFilename(filename string) string {
+	return strings.TrimSuffix(filepath.Base(filename), filepath.Ext(filename))
+}

internal/collector/note_test.go

@@ -40,17 +40,17 @@ another [[link]]`,
 			name:    "markdown link",
 			content: "[Link](target.md)",
 			expected: metrics.NoteMetrics{
-				Links:         map[string]uint{"target.md": 1},
+				Links:         map[string]uint{"target": 1},
 				LinkCount:     1,
 				WordCount:     1,
 				BacklinkCount: 0,
 			},
 		},
 		{
 			name:    "repeated links",
-			content: "[[target.md|link]] [link](target.md) [[link]]",
+			content: "[[target|link]] [link](target.md) [[link]]",
 			expected: metrics.NoteMetrics{
-				Links:         map[string]uint{"target.md": 2, "link": 1},
+				Links:         map[string]uint{"target": 2, "link": 1},
 				LinkCount:     3,
 				WordCount:     3,
 				BacklinkCount: 0,
@@ -60,7 +60,7 @@ another [[link]]`,
 			name:    "ignore links to non markdown files",
 			content: "![[note.md]] [[test.pdf]] ![[target.png]] ![](another.jpeg) [[link]] [](link)",
 			expected: metrics.NoteMetrics{
-				Links:         map[string]uint{"link": 2, "note.md": 1},
+				Links:         map[string]uint{"link": 2, "note": 1},
 				LinkCount:     3,
 				WordCount:     4,
 				BacklinkCount: 0,
@@ -70,7 +70,7 @@ another [[link]]`,
 			name:    "ignore http links",
 			content: "[[one]] [this is an http link](https://go.dev/) [[not/an/http/link]]",
 			expected: metrics.NoteMetrics{
-				Links:         map[string]uint{"one": 1, "not/an/http/link": 1},
+				Links:         map[string]uint{"one": 1, "link": 1},
 				LinkCount:     2,
 				WordCount:     7,
 				BacklinkCount: 0,
@@ -95,7 +95,7 @@ Another list:
 1. First
 2. Second [link](link-ordered.md)`,
 			expected: metrics.NoteMetrics{
-				Links:         map[string]uint{"target.md": 1, "linked": 1, "another": 1, "yet-another.md": 1, "link-unordered.md": 1, "link-ordered.md": 1},
+				Links:         map[string]uint{"target": 1, "linked": 1, "another": 1, "yet-another": 1, "link-unordered": 1, "link-ordered": 1},
 				LinkCount:     6,
 				WordCount:     23,
 				BacklinkCount: 0,