refactor: releasepr markdown handling

internal/markdown/goldmark.go

@@ -2,13 +2,17 @@ package markdown
 
 import (
 	"bytes"
+	"strings"
 
 	markdown "github.com/teekennedy/goldmark-markdown"
 	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
 	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
 	"github.com/yuin/goldmark/util"
 
 	"github.com/apricote/releaser-pleaser/internal/markdown/extensions"
+	"github.com/apricote/releaser-pleaser/internal/markdown/extensions/ast"
 )
 
 func New() goldmark.Markdown {
@@ -34,3 +38,82 @@ func Format(input string) (string, error) {
 
 	return buf.String(), nil
 }
+
+func GetCodeBlockText(source []byte, language string, output *string) gast.Walker {
+	return func(n gast.Node, entering bool) (gast.WalkStatus, error) {
+		if !entering {
+			return gast.WalkContinue, nil
+		}
+
+		if n.Kind() != gast.KindFencedCodeBlock {
+			return gast.WalkContinue, nil
+		}
+
+		codeBlock := n.(*gast.FencedCodeBlock)
+
+		if string(codeBlock.Language(source)) != language {
+			return gast.WalkContinue, nil
+		}
+
+		*output = textFromLines(source, codeBlock)
+		// Stop looking after we find the first result
+		return gast.WalkStop, nil
+	}
+}
+
+func GetSectionText(source []byte, name string, output *string) gast.Walker {
+	return func(n gast.Node, entering bool) (gast.WalkStatus, error) {
+		if !entering {
+			return gast.WalkContinue, nil
+		}
+
+		if n.Kind() != ast.KindSection {
+			return gast.WalkContinue, nil
+		}
+
+		section := n.(*ast.Section)
+
+		if section.Name != name {
+			return gast.WalkContinue, nil
+		}
+
+		// Do not show section markings in output, we only care about the content
+		section.HideInOutput()
+
+		// Found the right section
+		outputBuffer := new(bytes.Buffer)
+		err := New().Renderer().Render(outputBuffer, source, section)
+		if err != nil {
+			return gast.WalkStop, err
+		}
+
+		*output = outputBuffer.String()
+		// Stop looking after we find the first result
+		return gast.WalkStop, nil
+	}
+}
+
+func textFromLines(source []byte, n gast.Node) string {
+	content := make([]byte, 0)
+
+	l := n.Lines().Len()
+	for i := 0; i < l; i++ {
+		line := n.Lines().At(i)
+		content = append(content, line.Value(source)...)
+	}
+
+	return strings.TrimSpace(string(content))
+}
+
+func WalkAST(source []byte, walkers ...gast.Walker) (err error) {
+	doc := New().Parser().Parse(text.NewReader(source))
+
+	for _, walker := range walkers {
+		err = gast.Walk(doc, walker)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}