Feat: Use custom heading anchors

Confluence Anchors are case-sensitive.

parser/confluenceids.go

@@ -0,0 +1,56 @@
+package parser
+
+import (
+	"fmt"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/util"
+)
+
+type ConfluenceIDs struct {
+	Values map[string]bool
+}
+
+
+// https://github.com/yuin/goldmark/blob/d9c03f07f08c2d36f23afe52dda865f05320ac86/parser/parser.go#L75
+func (s *ConfluenceIDs) Generate(value []byte, kind ast.NodeKind) []byte {
+	value = util.TrimLeftSpace(value)
+	value = util.TrimRightSpace(value)
+	result := []byte{}
+	for i := 0; i < len(value); {
+		v := value[i]
+		l := util.UTF8Len(v)
+		i += int(l)
+		if l != 1 {
+			continue
+		}
+		if util.IsAlphaNumeric(v) || v == '/' || v == '_' || v == '.' {
+			result = append(result, v)
+		} else if util.IsSpace(v) || v == '-' {
+			result = append(result, '-')
+		}
+	}
+	if len(result) == 0 {
+		if kind == ast.KindHeading {
+			result = []byte("heading")
+		} else {
+			result = []byte("id")
+		}
+	}
+	if _, ok := s.Values[util.BytesToReadOnlyString(result)]; !ok {
+		s.Values[util.BytesToReadOnlyString(result)] = true
+		return result
+	}
+	for i := 1; ; i++ {
+		newResult := fmt.Sprintf("%s-%d", result, i)
+		if _, ok := s.Values[newResult]; !ok {
+			s.Values[newResult] = true
+			return []byte(newResult)
+		}
+
+	}
+}
+
+func (s *ConfluenceIDs) Put(value []byte) {
+	s.Values[util.BytesToReadOnlyString(value)] = true
+}