Align topdata wiki canonical paths (#11)

Reviewed-on: https://gitea.westgate.pw/ShadowsOverWestgate/sow-tools/pulls/11
Co-authored-by: Michał Piasecki <mpiasecki720@protonmail.com>
Co-committed-by: Michał Piasecki <mpiasecki720@protonmail.com>

internal/topdata/wiki_slug.go

@@ -8,6 +8,16 @@ import (
 	"golang.org/x/text/unicode/norm"
 )
 
+var reservedCanonicalWikiFirstSegments = map[string]struct{}{
+	"admin":     {},
+	"api":       {},
+	"category":  {},
+	"compose":   {},
+	"edit":      {},
+	"namespace": {},
+	"search":    {},
+}
+
 func canonicalWikiSegment(value string) string {
 	value = html.UnescapeString(strings.TrimSpace(value))
 	var b strings.Builder
@@ -40,6 +50,72 @@ func canonicalWikiSegment(value string) string {
 	return strings.Trim(b.String(), "_")
 }
 
+func canonicalWikiSegmentFoldedKey(value string) string {
+	return strings.Join(strings.Fields(strings.ToLower(strings.ReplaceAll(canonicalWikiSegment(value), "_", " "))), " ")
+}
+
+func canonicalWikiSlashPath(value string) string {
+	segments := []string{}
+	for _, part := range strings.Split(strings.Trim(strings.TrimSpace(value), "/"), "/") {
+		canonical := canonicalWikiSegment(part)
+		if canonical != "" {
+			segments = append(segments, canonical)
+		}
+	}
+	return strings.Join(segments, "/")
+}
+
+func canonicalWikiSlashPathFoldedKey(value string) string {
+	segments := []string{}
+	for _, part := range strings.Split(strings.Trim(strings.TrimSpace(value), "/"), "/") {
+		folded := canonicalWikiSegmentFoldedKey(part)
+		if folded != "" {
+			segments = append(segments, folded)
+		}
+	}
+	return strings.Join(segments, "/")
+}
+
+func canonicalWikiSlashPathSegments(value string) []string {
+	segments := []string{}
+	for _, part := range strings.Split(strings.Trim(strings.TrimSpace(value), "/"), "/") {
+		canonical := canonicalWikiSegment(part)
+		if canonical != "" {
+			segments = append(segments, canonical)
+		}
+	}
+	return segments
+}
+
+func isReservedCanonicalWikiFirstSegment(path string) bool {
+	segments := canonicalWikiSlashPathSegments(path)
+	if len(segments) == 0 {
+		return false
+	}
+	first := strings.ToLower(segments[0])
+	if isCanonicalWikiNumericSegment(first) {
+		return true
+	}
+	_, reserved := reservedCanonicalWikiFirstSegments[first]
+	return reserved
+}
+
+func isCanonicalWikiNumericSegment(segment string) bool {
+	if segment == "" {
+		return false
+	}
+	for _, r := range segment {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+func isNestedCanonicalWikiPath(path string) bool {
+	return len(canonicalWikiSlashPathSegments(path)) > 2
+}
+
 func matchWikiTransliterationCase(r rune, value string) string {
 	if unicode.IsUpper(r) {
 		if len(value) == 1 {