Walks a directory and lists links and text for markdown files.

md_link.go

package main

import (
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"

	bf "github.com/russross/blackfriday/v2"
)

const (
	walkPath = `loki\docs\sources`
)

func linkCollector(n *bf.Node, entering bool) bf.WalkStatus {
	// Do nothing when exiting a node.
	if !entering {
		return bf.GoToNext
	}

	// If the current node is a link.
	if n.Type == bf.Link {
		// Render descendant content into a buffer.
		buf := &bytes.Buffer{}
		n.Walk(render(buf))

		// Print the link and it's content.
		fmt.Printf("  %q %q\n", buf.String(), n.Destination)

		// We've already walked the children, skip them.
		return bf.SkipChildren
	}

	return bf.GoToNext
}

// Render returns a visitor that writes the node+descendant content to the
// supplied writer.
func render(w io.Writer) bf.NodeVisitor {
	return func(n *bf.Node, entering bool) bf.WalkStatus {
		if !entering {
			return bf.GoToNext
		}

		w.Write(n.Literal)
		return bf.GoToNext
	}
}

func init() {
	log.SetFlags(log.Lshortfile | log.Lmicroseconds)
}

func main() {
	// Walk the specified path.
	err := filepath.Walk(walkPath, func(path string, fi os.FileInfo, err error) error {
		// Skip directories.
		if fi.IsDir() {
			return nil
		}

		// Skip files that aren't markdown.
		ext := strings.ToLower(filepath.Ext(path))
		if ext != ".md" {
			return nil
		}

		fmt.Println(path)

		// Read the file.
		mdBytes, err := ioutil.ReadFile(path)
		if err != nil {
			log.Fatal(fmt.Errorf("ioutil.ReadFile: %w", err))
		}

		// Make a new markdown parser.
		md := bf.New(bf.WithExtensions(bf.CommonExtensions))

		// Parse the file's contents.
		root := md.Parse(mdBytes)
		if err != nil {
			log.Fatal(fmt.Errorf("md.Parse: %w", err))
		}

		// Walk the root node
		root.Walk(linkCollector)

		return nil
	})
	if err != nil {
		log.Fatal(fmt.Errorf("filepath.Walk: %w", err))
	}
}