1 files changed, 127 insertions, 2 deletions
diff --git a/markup/asciidocext/convert.go b/markup/asciidocext/convert.go
index 7dd3e3533..73ed85daa 100644
--- a/markup/asciidocext/convert.go
+++ b/markup/asciidocext/convert.go
@@ -17,6 +17,7 @@
 package asciidocext
 
 import (
+	"bytes"
 	"os/exec"
 	"path/filepath"
 
@@ -24,6 +25,8 @@ import (
 	"github.com/gohugoio/hugo/markup/asciidocext/asciidocext_config"
 	"github.com/gohugoio/hugo/markup/converter"
 	"github.com/gohugoio/hugo/markup/internal"
+	"github.com/gohugoio/hugo/markup/tableofcontents"
+	"golang.org/x/net/html"
 )
 
 /* ToDo: RelPermalink patch for svg posts not working*/
@@ -45,16 +48,32 @@ func (p provider) New(cfg converter.ProviderConfig) (converter.Provider, error)
 	}), nil
 }
 
+type asciidocResult struct {
+	converter.Result
+	toc tableofcontents.Root
+}
+
+func (r asciidocResult) TableOfContents() tableofcontents.Root {
+	return r.toc
+}
+
 type asciidocConverter struct {
 	ctx converter.DocumentContext
 	cfg converter.ProviderConfig
 }
 
 func (a *asciidocConverter) Convert(ctx converter.RenderContext) (converter.Result, error) {
-	return converter.Bytes(a.getAsciidocContent(ctx.Src, a.ctx)), nil
+	content, toc, err := extractTOC(a.getAsciidocContent(ctx.Src, a.ctx))
+	if err != nil {
+		return nil, err
+	}
+	return asciidocResult{
+		Result: converter.Bytes(content),
+		toc:    toc,
+	}, nil
 }
 
-func (c *asciidocConverter) Supports(feature identity.Identity) bool {
+func (a *asciidocConverter) Supports(_ identity.Identity) bool {
 	return false
 }
 
@@ -182,6 +201,112 @@ func getAsciidoctorExecPath() string {
 	return path
 }
 
+// extractTOC extracts the toc from the given src html.
+// It returns the html without the TOC, and the TOC data
+func extractTOC(src []byte) ([]byte, tableofcontents.Root, error) {
+	var buf bytes.Buffer
+	buf.Write(src)
+	node, err := html.Parse(&buf)
+	if err != nil {
+		return nil, tableofcontents.Root{}, err
+	}
+	var (
+		f       func(*html.Node) bool
+		toc     tableofcontents.Root
+		toVisit []*html.Node
+	)
+	f = func(n *html.Node) bool {
+		if n.Type == html.ElementNode && n.Data == "div" {
+			for _, a := range n.Attr {
+				if a.Key == "id" && a.Val == "toc" {
+					toc, err = parseTOC(n)
+					if err != nil {
+						return false
+					}
+					n.Parent.RemoveChild(n)
+					return true
+				}
+			}
+		}
+		if n.FirstChild != nil {
+			toVisit = append(toVisit, n.FirstChild)
+		}
+		if n.NextSibling != nil {
+			if ok := f(n.NextSibling); ok {
+				return true
+			}
+		}
+		for len(toVisit) > 0 {
+			nv := toVisit[0]
+			toVisit = toVisit[1:]
+			if ok := f(nv); ok {
+				return true
+			}
+		}
+		return false
+	}
+	f(node)
+	if err != nil {
+		return nil, tableofcontents.Root{}, err
+	}
+	buf.Reset()
+	err = html.Render(&buf, node)
+	if err != nil {
+		return nil, tableofcontents.Root{}, err
+	}
+	// ltrim <html><head></head><body> and rtrim </body></html> which are added by html.Render
+	res := buf.Bytes()[25:]
+	res = res[:len(res)-14]
+	return res, toc, nil
+}
+
+// parseTOC returns a TOC root from the given toc Node
+func parseTOC(doc *html.Node) (tableofcontents.Root, error) {
+	var (
+		toc tableofcontents.Root
+		f   func(*html.Node, int, int)
+	)
+	f = func(n *html.Node, parent, level int) {
+		if n.Type == html.ElementNode {
+			switch n.Data {
+			case "ul":
+				if level == 0 {
+					parent += 1
+				}
+				level += 1
+				f(n.FirstChild, parent, level)
+			case "li":
+				for c := n.FirstChild; c != nil; c = c.NextSibling {
+					if c.Type != html.ElementNode || c.Data != "a" {
+						continue
+					}
+					var href string
+					for _, a := range c.Attr {
+						if a.Key == "href" {
+							href = a.Val[1:]
+							break
+						}
+					}
+					for d := c.FirstChild; d != nil; d = d.NextSibling {
+						if d.Type == html.TextNode {
+							toc.AddAt(tableofcontents.Header{
+								Text: d.Data,
+								ID:   href,
+							}, parent, level)
+						}
+					}
+				}
+				f(n.FirstChild, parent, level)
+			}
+		}
+		if n.NextSibling != nil {
+			f(n.NextSibling, parent, level)
+		}
+	}
+	f(doc.FirstChild, 0, 0)
+	return toc, nil
+}
+
 // Supports returns whether Asciidoctor is installed on this computer.
 func Supports() bool {
 	return getAsciidoctorExecPath() != ""