add parser for blog articles

Signed-off-by: Tobias Erbshäußer <tobias@tesoft.dev>

backend/md/parser.go

@@ -0,0 +1,50 @@
+package md
+
+import (
+	"bytes"
+	"errors"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/parser"
+)
+
+var PropertyNotFoundError = errors.New("property not found")
+
+func Parse(transformer UrlTransformer, source []byte) (parser.Context, []byte, error) {
+	md := goldmark.New(
+		goldmark.WithExtensions(
+			extension.Footnote, extension.Strikethrough,
+			extension.Table,
+			&propertiesExtension{},
+			&urlTransformerExtension{transformer},
+		),
+		goldmark.WithRendererOptions(),
+	)
+
+	pc := parser.NewContext()
+	var readme bytes.Buffer
+	err := md.Convert(source, &readme, parser.WithContext(pc))
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return pc, readme.Bytes(), nil
+}
+
+func GetProperty(pc parser.Context, key string) (string, error) {
+	data := pc.Get(propertiesContextKey)
+	if data != nil {
+		pData := data.(*propertiesData)
+		if pData.Error != nil {
+			return "", pData.Error
+		}
+
+		value, ok := pData.properties[key]
+		if ok {
+			return value, nil
+		}
+	}
+
+	return "", PropertyNotFoundError
+}