Rewrite markdown rendering to blackfriday v2 and rewrite orgmode rendering to go-org (#8560)

* Rewrite markdown rendering to blackfriday v2.0

* Fix style

* Fix go mod with golang 1.13

* Fix blackfriday v2 import

* Inital orgmode renderer migration to go-org

* Vendor go-org dependency

* Ignore errors :/

* Update go-org to latest version

* Update test

* Fix go-org test

* Remove unneeded code

* Fix comments

* Fix markdown test

* Fix blackfriday regression rendering HTML block

6 files changed, 256 insertions, 335 deletions

diff --git a/modules/markup/html_test.go b/modules/markup/html_test.go
index 91ef320b40..07747e97e1 100644
--- a/modules/markup/html_test.go
+++ b/modules/markup/html_test.go
@@ -323,6 +323,6 @@ func TestRender_ShortLinks(t *testing.T) {
 		`<p><a href="`+notencodedImgurlWiki+`" rel="nofollow"><img src="`+notencodedImgurlWiki+`"/></a></p>`)
 	test(
 		"<p><a href=\"https://example.org\">[[foobar]]</a></p>",
-		`<p><a href="https://example.org" rel="nofollow">[[foobar]]</a></p>`,
-		`<p><a href="https://example.org" rel="nofollow">[[foobar]]</a></p>`)
+		`<p></p><p><a href="https://example.org" rel="nofollow">[[foobar]]</a></p><p></p>`,
+		`<p></p><p><a href="https://example.org" rel="nofollow">[[foobar]]</a></p><p></p>`)
 }
diff --git a/modules/markup/markdown/markdown.go b/modules/markup/markdown/markdown.go
index d9fc768891..ff78d7ea3a 100644
--- a/modules/markup/markdown/markdown.go
+++ b/modules/markup/markdown/markdown.go
@@ -7,13 +7,14 @@ package markdown
 
 import (
 	"bytes"
+	"io"
 	"strings"
 
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 
-	"github.com/russross/blackfriday"
+	"github.com/russross/blackfriday/v2"
 )
 
 // Renderer is a extended version of underlying render object.
@@ -25,134 +26,138 @@ type Renderer struct {
 
 var byteMailto = []byte("mailto:")
 
-// Link defines how formal links should be processed to produce corresponding HTML elements.
-func (r *Renderer) Link(out *bytes.Buffer, link []byte, title []byte, content []byte) {
-	// special case: this is not a link, a hash link or a mailto:, so it's a
-	// relative URL
-	if len(link) > 0 && !markup.IsLink(link) &&
-		link[0] != '#' && !bytes.HasPrefix(link, byteMailto) {
-		lnk := string(link)
-		if r.IsWiki {
-			lnk = util.URLJoin("wiki", lnk)
-		}
-		mLink := util.URLJoin(r.URLPrefix, lnk)
-		link = []byte(mLink)
-	}
-
-	if len(content) > 10 && string(content[0:9]) == "<a href=\"" && bytes.Contains(content[9:], []byte("<img")) {
-		// Image with link case: markdown `[![]()]()`
-		// If the content is an image, then we change the original href around it
-		// which points to itself to a new address "link"
-		rightQuote := bytes.Index(content[9:], []byte("\""))
-		content = bytes.Replace(content, content[9:9+rightQuote], link, 1)
-		out.Write(content)
-	} else {
-		r.Renderer.Link(out, link, title, content)
-	}
+var htmlEscaper = [256][]byte{
+	'&': []byte("&amp;"),
+	'<': []byte("&lt;"),
+	'>': []byte("&gt;"),
+	'"': []byte("&quot;"),
 }
 
-// List renders markdown bullet or digit lists to HTML
-func (r *Renderer) List(out *bytes.Buffer, text func() bool, flags int) {
-	marker := out.Len()
-	if out.Len() > 0 {
-		out.WriteByte('\n')
-	}
-
-	if flags&blackfriday.LIST_TYPE_DEFINITION != 0 {
-		out.WriteString("<dl>")
-	} else if flags&blackfriday.LIST_TYPE_ORDERED != 0 {
-		out.WriteString("<ol class='ui list'>")
-	} else {
-		out.WriteString("<ul class='ui list'>")
-	}
-	if !text() {
-		out.Truncate(marker)
-		return
+func escapeHTML(w io.Writer, s []byte) {
+	var start, end int
+	for end < len(s) {
+		escSeq := htmlEscaper[s[end]]
+		if escSeq != nil {
+			_, _ = w.Write(s[start:end])
+			_, _ = w.Write(escSeq)
+			start = end + 1
+		}
+		end++
 	}
-	if flags&blackfriday.LIST_TYPE_DEFINITION != 0 {
-		out.WriteString("</dl>\n")
-	} else if flags&blackfriday.LIST_TYPE_ORDERED != 0 {
-		out.WriteString("</ol>\n")
-	} else {
-		out.WriteString("</ul>\n")
+	if start < len(s) && end <= len(s) {
+		_, _ = w.Write(s[start:end])
 	}
 }
 
-// ListItem defines how list items should be processed to produce corresponding HTML elements.
-func (r *Renderer) ListItem(out *bytes.Buffer, text []byte, flags int) {
-	// Detect procedures to draw checkboxes.
-	prefix := ""
-	if bytes.HasPrefix(text, []byte("<p>")) {
-		prefix = "<p>"
-	}
-	switch {
-	case bytes.HasPrefix(text, []byte(prefix+"[ ] ")):
-		text = append([]byte(`<span class="ui fitted disabled checkbox"><input type="checkbox" disabled="disabled" /><label /></span>`), text[3+len(prefix):]...)
-		if prefix != "" {
-			text = bytes.Replace(text, []byte(prefix), []byte{}, 1)
+// RenderNode is a default renderer of a single node of a syntax tree. For
+// block nodes it will be called twice: first time with entering=true, second
+// time with entering=false, so that it could know when it's working on an open
+// tag and when on close. It writes the result to w.
+//
+// The return value is a way to tell the calling walker to adjust its walk
+// pattern: e.g. it can terminate the traversal by returning Terminate. Or it
+// can ask the walker to skip a subtree of this node by returning SkipChildren.
+// The typical behavior is to return GoToNext, which asks for the usual
+// traversal to the next node.
+func (r *Renderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+	switch node.Type {
+	case blackfriday.Image:
+		prefix := r.URLPrefix
+		if r.IsWiki {
+			prefix = util.URLJoin(prefix, "wiki", "raw")
 		}
-	case bytes.HasPrefix(text, []byte(prefix+"[x] ")):
-		text = append([]byte(`<span class="ui checked fitted disabled checkbox"><input type="checkbox" checked="" disabled="disabled" /><label /></span>`), text[3+len(prefix):]...)
-		if prefix != "" {
-			text = bytes.Replace(text, []byte(prefix), []byte{}, 1)
+		prefix = strings.Replace(prefix, "/src/", "/media/", 1)
+		link := node.LinkData.Destination
+		if len(link) > 0 && !markup.IsLink(link) {
+			lnk := string(link)
+			lnk = util.URLJoin(prefix, lnk)
+			lnk = strings.Replace(lnk, " ", "+", -1)
+			link = []byte(lnk)
+		}
+		node.LinkData.Destination = link
+		// Render link around image only if parent is not link already
+		if node.Parent != nil && node.Parent.Type != blackfriday.Link {
+			if entering {
+				_, _ = w.Write([]byte(`<a href="`))
+				escapeHTML(w, link)
+				_, _ = w.Write([]byte(`">`))
+				return r.Renderer.RenderNode(w, node, entering)
+			}
+			s := r.Renderer.RenderNode(w, node, entering)
+			_, _ = w.Write([]byte(`</a>`))
+			return s
+		}
+		return r.Renderer.RenderNode(w, node, entering)
+	case blackfriday.Link:
+		// special case: this is not a link, a hash link or a mailto:, so it's a
+		// relative URL
+		link := node.LinkData.Destination
+		if len(link) > 0 && !markup.IsLink(link) &&
+			link[0] != '#' && !bytes.HasPrefix(link, byteMailto) &&
+			node.LinkData.Footnote == nil {
+			lnk := string(link)
+			if r.IsWiki {
+				lnk = util.URLJoin("wiki", lnk)
+			}
+			link = []byte(util.URLJoin(r.URLPrefix, lnk))
+		}
+		node.LinkData.Destination = link
+		return r.Renderer.RenderNode(w, node, entering)
+	case blackfriday.Text:
+		isListItem := false
+		for n := node.Parent; n != nil; n = n.Parent {
+			if n.Type == blackfriday.Item {
+				isListItem = true
+				break
+			}
+		}
+		if isListItem {
+			text := node.Literal
+			switch {
+			case bytes.HasPrefix(text, []byte("[ ] ")):
+				_, _ = w.Write([]byte(`<span class="ui fitted disabled checkbox"><input type="checkbox" disabled="disabled" /><label /></span>`))
+				text = text[3:]
+			case bytes.HasPrefix(text, []byte("[x] ")):
+				_, _ = w.Write([]byte(`<span class="ui checked fitted disabled checkbox"><input type="checkbox" checked="" disabled="disabled" /><label /></span>`))
+				text = text[3:]
+			}
+			node.Literal = text
 		}
 	}
-	r.Renderer.ListItem(out, text, flags)
-}
-
-// Image defines how images should be processed to produce corresponding HTML elements.
-func (r *Renderer) Image(out *bytes.Buffer, link []byte, title []byte, alt []byte) {
-	prefix := r.URLPrefix
-	if r.IsWiki {
-		prefix = util.URLJoin(prefix, "wiki", "raw")
-	}
-	prefix = strings.Replace(prefix, "/src/", "/media/", 1)
-	if len(link) > 0 && !markup.IsLink(link) {
-		lnk := string(link)
-		lnk = util.URLJoin(prefix, lnk)
-		lnk = strings.Replace(lnk, " ", "+", -1)
-		link = []byte(lnk)
-	}
-
-	// Put a link around it pointing to itself by default
-	out.WriteString(`<a href="`)
-	out.Write(link)
-	out.WriteString(`">`)
-	r.Renderer.Image(out, link, title, alt)
-	out.WriteString("</a>")
+	return r.Renderer.RenderNode(w, node, entering)
 }
 
 const (
 	blackfridayExtensions = 0 |
-		blackfriday.EXTENSION_NO_INTRA_EMPHASIS |
-		blackfriday.EXTENSION_TABLES |
-		blackfriday.EXTENSION_FENCED_CODE |
-		blackfriday.EXTENSION_STRIKETHROUGH |
-		blackfriday.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK |
-		blackfriday.EXTENSION_DEFINITION_LISTS |
-		blackfriday.EXTENSION_FOOTNOTES |
-		blackfriday.EXTENSION_HEADER_IDS |
-		blackfriday.EXTENSION_AUTO_HEADER_IDS
+		blackfriday.NoIntraEmphasis |
+		blackfriday.Tables |
+		blackfriday.FencedCode |
+		blackfriday.Strikethrough |
+		blackfriday.NoEmptyLineBeforeBlock |
+		blackfriday.DefinitionLists |
+		blackfriday.Footnotes |
+		blackfriday.HeadingIDs |
+		blackfriday.AutoHeadingIDs
 	blackfridayHTMLFlags = 0 |
-		blackfriday.HTML_SKIP_STYLE |
-		blackfriday.HTML_OMIT_CONTENTS |
-		blackfriday.HTML_USE_SMARTYPANTS
+		blackfriday.Smartypants
 )
 
 // RenderRaw renders Markdown to HTML without handling special links.
 func RenderRaw(body []byte, urlPrefix string, wikiMarkdown bool) []byte {
 	renderer := &Renderer{
-		Renderer:  blackfriday.HtmlRenderer(blackfridayHTMLFlags, "", ""),
+		Renderer: blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
+			Flags: blackfridayHTMLFlags,
+		}),
 		URLPrefix: urlPrefix,
 		IsWiki:    wikiMarkdown,
 	}
 
 	exts := blackfridayExtensions
 	if setting.Markdown.EnableHardLineBreak {
-		exts |= blackfriday.EXTENSION_HARD_LINE_BREAK
+		exts |= blackfriday.HardLineBreak
 	}
 
-	body = blackfriday.Markdown(body, renderer, exts)
+	body = blackfriday.Run(body, blackfriday.WithRenderer(renderer), blackfriday.WithExtensions(exts))
 	return markup.SanitizeBytes(body)
 }
 
diff --git a/modules/markup/markdown/markdown_test.go b/modules/markup/markdown/markdown_test.go
index 669b49367e..b29f870ce5 100644
--- a/modules/markup/markdown/markdown_test.go
+++ b/modules/markup/markdown/markdown_test.go
@@ -166,13 +166,13 @@ func testAnswers(baseURLContent, baseURLImages string) []string {
 <h3 id="footnotes">Footnotes</h3>
 
 <p>Here is a simple footnote,<sup id="fnref:1"><a href="#fn:1" rel="nofollow">1</a></sup> and here is a longer one.<sup id="fnref:bignote"><a href="#fn:bignote" rel="nofollow">2</a></sup></p>
+
 <div>
 
 <hr/>
 
 <ol>
-<li id="fn:1">This is the first footnote.
-</li>
+<li id="fn:1">This is the first footnote.</li>
 
 <li id="fn:bignote"><p>Here is one with multiple paragraphs and code.</p>
 
@@ -180,9 +180,9 @@ func testAnswers(baseURLContent, baseURLImages string) []string {
 
 <p><code>{ my code }</code></p>
 
-<p>Add as many paragraphs as you like.</p>
-</li>
+<p>Add as many paragraphs as you like.</p></li>
 </ol>
+
 </div>
 `,
 	}
diff --git a/modules/markup/mdstripper/mdstripper.go b/modules/markup/mdstripper/mdstripper.go
index 7a901b17a9..d248944b68 100644
--- a/modules/markup/mdstripper/mdstripper.go
+++ b/modules/markup/mdstripper/mdstripper.go
@@ -6,43 +6,39 @@ package mdstripper
 
 import (
 	"bytes"
+	"io"
 
-	"github.com/russross/blackfriday"
+	"github.com/russross/blackfriday/v2"
 )
 
 // MarkdownStripper extends blackfriday.Renderer
 type MarkdownStripper struct {
-	blackfriday.Renderer
 	links     []string
 	coallesce bool
+	empty     bool
 }
 
 const (
 	blackfridayExtensions = 0 |
-		blackfriday.EXTENSION_NO_INTRA_EMPHASIS |
-		blackfriday.EXTENSION_TABLES |
-		blackfriday.EXTENSION_FENCED_CODE |
-		blackfriday.EXTENSION_STRIKETHROUGH |
-		blackfriday.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK |
-		blackfriday.EXTENSION_DEFINITION_LISTS |
-		blackfriday.EXTENSION_FOOTNOTES |
-		blackfriday.EXTENSION_HEADER_IDS |
-		blackfriday.EXTENSION_AUTO_HEADER_IDS |
+		blackfriday.NoIntraEmphasis |
+		blackfriday.Tables |
+		blackfriday.FencedCode |
+		blackfriday.Strikethrough |
+		blackfriday.NoEmptyLineBeforeBlock |
+		blackfriday.DefinitionLists |
+		blackfriday.Footnotes |
+		blackfriday.HeadingIDs |
+		blackfriday.AutoHeadingIDs |
 		// Not included in modules/markup/markdown/markdown.go;
 		// required here to process inline links
-		blackfriday.EXTENSION_AUTOLINK
+		blackfriday.Autolink
 )
 
-//revive:disable:var-naming Implementing the Rendering interface requires breaking some linting rules
-
 // StripMarkdown parses markdown content by removing all markup and code blocks
 //	in order to extract links and other references
 func StripMarkdown(rawBytes []byte) (string, []string) {
-	stripper := &MarkdownStripper{
-		links: make([]string, 0, 10),
-	}
-	body := blackfriday.Markdown(rawBytes, stripper, blackfridayExtensions)
-	return string(body), stripper.GetLinks()
+	buf, links := StripMarkdownBytes(rawBytes)
+	return string(buf), links
 }
 
 // StripMarkdownBytes parses markdown content by removing all markup and code blocks
@@ -50,205 +46,67 @@ func StripMarkdown(rawBytes []byte) (string, []string) {
 func StripMarkdownBytes(rawBytes []byte) ([]byte, []string) {
 	stripper := &MarkdownStripper{
 		links: make([]string, 0, 10),
+		empty: true,
 	}
-	body := blackfriday.Markdown(rawBytes, stripper, blackfridayExtensions)
-	return body, stripper.GetLinks()
-}
-
-// block-level callbacks
-
-// BlockCode dummy function to proceed with rendering
-func (r *MarkdownStripper) BlockCode(out *bytes.Buffer, text []byte, infoString string) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// BlockQuote dummy function to proceed with rendering
-func (r *MarkdownStripper) BlockQuote(out *bytes.Buffer, text []byte) {
-	// FIXME: perhaps it's better to leave out block quote for this?
-	r.processString(out, text, false)
-}
-
-// BlockHtml dummy function to proceed with rendering
-func (r *MarkdownStripper) BlockHtml(out *bytes.Buffer, text []byte) { //nolint
-	// Not rendered
-	r.coallesce = false
-}
-
-// Header dummy function to proceed with rendering
-func (r *MarkdownStripper) Header(out *bytes.Buffer, text func() bool, level int, id string) {
-	text()
-	r.coallesce = false
-}
-
-// HRule dummy function to proceed with rendering
-func (r *MarkdownStripper) HRule(out *bytes.Buffer) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// List dummy function to proceed with rendering
-func (r *MarkdownStripper) List(out *bytes.Buffer, text func() bool, flags int) {
-	text()
-	r.coallesce = false
-}
-
-// ListItem dummy function to proceed with rendering
-func (r *MarkdownStripper) ListItem(out *bytes.Buffer, text []byte, flags int) {
-	r.processString(out, text, false)
-}
-
-// Paragraph dummy function to proceed with rendering
-func (r *MarkdownStripper) Paragraph(out *bytes.Buffer, text func() bool) {
-	text()
-	r.coallesce = false
-}
-
-// Table dummy function to proceed with rendering
-func (r *MarkdownStripper) Table(out *bytes.Buffer, header []byte, body []byte, columnData []int) {
-	r.processString(out, header, false)
-	r.processString(out, body, false)
-}
-
-// TableRow dummy function to proceed with rendering
-func (r *MarkdownStripper) TableRow(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
-
-// TableHeaderCell dummy function to proceed with rendering
-func (r *MarkdownStripper) TableHeaderCell(out *bytes.Buffer, text []byte, flags int) {
-	r.processString(out, text, false)
-}
-
-// TableCell dummy function to proceed with rendering
-func (r *MarkdownStripper) TableCell(out *bytes.Buffer, text []byte, flags int) {
-	r.processString(out, text, false)
-}
-
-// Footnotes dummy function to proceed with rendering
-func (r *MarkdownStripper) Footnotes(out *bytes.Buffer, text func() bool) {
-	text()
-}
-
-// FootnoteItem dummy function to proceed with rendering
-func (r *MarkdownStripper) FootnoteItem(out *bytes.Buffer, name, text []byte, flags int) {
-	r.processString(out, text, false)
-}
-
-// TitleBlock dummy function to proceed with rendering
-func (r *MarkdownStripper) TitleBlock(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
-
-// Span-level callbacks
-
-// AutoLink dummy function to proceed with rendering
-func (r *MarkdownStripper) AutoLink(out *bytes.Buffer, link []byte, kind int) {
-	r.processLink(out, link, []byte{})
-}
-
-// CodeSpan dummy function to proceed with rendering
-func (r *MarkdownStripper) CodeSpan(out *bytes.Buffer, text []byte) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// DoubleEmphasis dummy function to proceed with rendering
-func (r *MarkdownStripper) DoubleEmphasis(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
-
-// Emphasis dummy function to proceed with rendering
-func (r *MarkdownStripper) Emphasis(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
 
-// Image dummy function to proceed with rendering
-func (r *MarkdownStripper) Image(out *bytes.Buffer, link []byte, title []byte, alt []byte) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// LineBreak dummy function to proceed with rendering
-func (r *MarkdownStripper) LineBreak(out *bytes.Buffer) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// Link dummy function to proceed with rendering
-func (r *MarkdownStripper) Link(out *bytes.Buffer, link []byte, title []byte, content []byte) {
-	r.processLink(out, link, content)
-}
-
-// RawHtmlTag dummy function to proceed with rendering
-func (r *MarkdownStripper) RawHtmlTag(out *bytes.Buffer, tag []byte) { //nolint
-	// Not rendered
-	r.coallesce = false
-}
-
-// TripleEmphasis dummy function to proceed with rendering
-func (r *MarkdownStripper) TripleEmphasis(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
-
-// StrikeThrough dummy function to proceed with rendering
-func (r *MarkdownStripper) StrikeThrough(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, false)
-}
-
-// FootnoteRef dummy function to proceed with rendering
-func (r *MarkdownStripper) FootnoteRef(out *bytes.Buffer, ref []byte, id int) {
-	// Not rendered
-	r.coallesce = false
-}
-
-// Low-level callbacks
-
-// Entity dummy function to proceed with rendering
-func (r *MarkdownStripper) Entity(out *bytes.Buffer, entity []byte) {
-	// FIXME: literal entities are not parsed; perhaps they should
-	r.coallesce = false
-}
-
-// NormalText dummy function to proceed with rendering
-func (r *MarkdownStripper) NormalText(out *bytes.Buffer, text []byte) {
-	r.processString(out, text, true)
-}
-
-// Header and footer
-
-// DocumentHeader dummy function to proceed with rendering
-func (r *MarkdownStripper) DocumentHeader(out *bytes.Buffer) {
+	parser := blackfriday.New(blackfriday.WithRenderer(stripper), blackfriday.WithExtensions(blackfridayExtensions))
+	ast := parser.Parse(rawBytes)
+	var buf bytes.Buffer
+	stripper.RenderHeader(&buf, ast)
+	ast.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+		return stripper.RenderNode(&buf, node, entering)
+	})
+	stripper.RenderFooter(&buf, ast)
+	return buf.Bytes(), stripper.GetLinks()
+}
+
+// RenderNode is the main rendering method. It will be called once for
+// every leaf node and twice for every non-leaf node (first with
+// entering=true, then with entering=false). The method should write its
+// rendition of the node to the supplied writer w.
+func (r *MarkdownStripper) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+	if !entering {
+		return blackfriday.GoToNext
+	}
+	switch node.Type {
+	case blackfriday.Text:
+		r.processString(w, node.Literal, node.Parent == nil)
+		return blackfriday.GoToNext
+	case blackfriday.Link:
+		r.processLink(w, node.LinkData.Destination)
+		r.coallesce = false
+		return blackfriday.SkipChildren
+	}
 	r.coallesce = false
+	return blackfriday.GoToNext
 }
 
-// DocumentFooter dummy function to proceed with rendering
-func (r *MarkdownStripper) DocumentFooter(out *bytes.Buffer) {
-	r.coallesce = false
+// RenderHeader is a method that allows the renderer to produce some
+// content preceding the main body of the output document.
+func (r *MarkdownStripper) RenderHeader(w io.Writer, ast *blackfriday.Node) {
 }
 
-// GetFlags returns rendering flags
-func (r *MarkdownStripper) GetFlags() int {
-	return 0
+// RenderFooter is a symmetric counterpart of RenderHeader.
+func (r *MarkdownStripper) RenderFooter(w io.Writer, ast *blackfriday.Node) {
 }
 
-//revive:enable:var-naming
-
-func doubleSpace(out *bytes.Buffer) {
-	if out.Len() > 0 {
-		out.WriteByte('\n')
+func (r *MarkdownStripper) doubleSpace(w io.Writer) {
+	if !r.empty {
+		_, _ = w.Write([]byte{'\n'})
 	}
 }
 
-func (r *MarkdownStripper) processString(out *bytes.Buffer, text []byte, coallesce bool) {
+func (r *MarkdownStripper) processString(w io.Writer, text []byte, coallesce bool) {
 	// Always break-up words
 	if !coallesce || !r.coallesce {
-		doubleSpace(out)
+		r.doubleSpace(w)
 	}
-	out.Write(text)
+	_, _ = w.Write(text)
 	r.coallesce = coallesce
+	r.empty = false
 }
-func (r *MarkdownStripper) processLink(out *bytes.Buffer, link []byte, content []byte) {
+
+func (r *MarkdownStripper) processLink(w io.Writer, link []byte) {
 	// Links are processed out of band
 	r.links = append(r.links, string(link))
 	r.coallesce = false
diff --git a/modules/markup/orgmode/orgmode.go b/modules/markup/orgmode/orgmode.go
index f63155201e..54188d2734 100644
--- a/modules/markup/orgmode/orgmode.go
+++ b/modules/markup/orgmode/orgmode.go
@@ -5,12 +5,16 @@
 package markup
 
 import (
+	"bytes"
+	"fmt"
+	"html"
+	"strings"
+
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
-	"code.gitea.io/gitea/modules/markup/markdown"
+	"code.gitea.io/gitea/modules/util"
 
-	"github.com/chaseadamsio/goorgeous"
-	"github.com/russross/blackfriday"
+	"github.com/niklasfasching/go-org/org"
 )
 
 func init() {
@@ -32,23 +36,23 @@ func (Parser) Extensions() []string {
 }
 
 // Render renders orgmode rawbytes to HTML
-func Render(rawBytes []byte, urlPrefix string, metas map[string]string, isWiki bool) (result []byte) {
-	defer func() {
-		if err := recover(); err != nil {
-			log.Error("Panic in orgmode.Render: %v Just returning the rawBytes", err)
-			result = rawBytes
-		}
-	}()
-	htmlFlags := blackfriday.HTML_USE_XHTML
-	htmlFlags |= blackfriday.HTML_SKIP_STYLE
-	htmlFlags |= blackfriday.HTML_OMIT_CONTENTS
-	renderer := &markdown.Renderer{
-		Renderer:  blackfriday.HtmlRenderer(htmlFlags, "", ""),
-		URLPrefix: urlPrefix,
-		IsWiki:    isWiki,
+func Render(rawBytes []byte, urlPrefix string, metas map[string]string, isWiki bool) []byte {
+	htmlWriter := org.NewHTMLWriter()
+
+	renderer := &Renderer{
+		HTMLWriter: htmlWriter,
+		URLPrefix:  urlPrefix,
+		IsWiki:     isWiki,
+	}
+
+	htmlWriter.ExtendingWriter = renderer
+
+	res, err := org.New().Silent().Parse(bytes.NewReader(rawBytes), "").Write(renderer)
+	if err != nil {
+		log.Error("Panic in orgmode.Render: %v Just returning the rawBytes", err)
+		return rawBytes
 	}
-	result = goorgeous.Org(rawBytes, renderer)
-	return
+	return []byte(res)
 }
 
 // RenderString reners orgmode string to HTML string
@@ -56,7 +60,63 @@ func RenderString(rawContent string, urlPrefix string, metas map[string]string,
 	return string(Render([]byte(rawContent), urlPrefix, metas, isWiki))
 }
 
-// Render implements markup.Parser
+// Render reners orgmode string to HTML string
 func (Parser) Render(rawBytes []byte, urlPrefix string, metas map[string]string, isWiki bool) []byte {
 	return Render(rawBytes, urlPrefix, metas, isWiki)
 }
+
+// Renderer implements org.Writer
+type Renderer struct {
+	*org.HTMLWriter
+	URLPrefix string
+	IsWiki    bool
+}
+
+var byteMailto = []byte("mailto:")
+
+// WriteRegularLink renders images, links or videos
+func (r *Renderer) WriteRegularLink(l org.RegularLink) {
+	link := []byte(html.EscapeString(l.URL))
+	if l.Protocol == "file" {
+		link = link[len("file:"):]
+	}
+	if len(link) > 0 && !markup.IsLink(link) &&
+		link[0] != '#' && !bytes.HasPrefix(link, byteMailto) {
+		lnk := string(link)
+		if r.IsWiki {
+			lnk = util.URLJoin("wiki", lnk)
+		}
+		link = []byte(util.URLJoin(r.URLPrefix, lnk))
+	}
+
+	description := string(link)
+	if l.Description != nil {
+		description = r.nodesAsString(l.Description...)
+	}
+	switch l.Kind() {
+	case "image":
+		r.WriteString(fmt.Sprintf(`<img src="%s" alt="%s" title="%s" />`, link, description, description))
+	case "video":
+		r.WriteString(fmt.Sprintf(`<video src="%s" title="%s">%s</video>`, link, description, description))
+	default:
+		r.WriteString(fmt.Sprintf(`<a href="%s" title="%s">%s</a>`, link, description, description))
+	}
+}
+
+func (r *Renderer) emptyClone() *Renderer {
+	wcopy := *(r.HTMLWriter)
+	wcopy.Builder = strings.Builder{}
+
+	rcopy := *r
+	rcopy.HTMLWriter = &wcopy
+
+	wcopy.ExtendingWriter = &rcopy
+
+	return &rcopy
+}
+
+func (r *Renderer) nodesAsString(nodes ...org.Node) string {
+	tmp := r.emptyClone()
+	org.WriteNodes(tmp, nodes...)
+	return tmp.String()
+}
diff --git a/modules/markup/orgmode/orgmode_test.go b/modules/markup/orgmode/orgmode_test.go
index 3846922c25..40323912b4 100644
--- a/modules/markup/orgmode/orgmode_test.go
+++ b/modules/markup/orgmode/orgmode_test.go
@@ -27,12 +27,12 @@ func TestRender_StandardLinks(t *testing.T) {
 		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer))
 	}
 
-	googleRendered := `<p><a href="https://google.com/" title="https://google.com/">https://google.com/</a></p>`
+	googleRendered := "<p>\n<a href=\"https://google.com/\" title=\"https://google.com/\">https://google.com/</a>\n</p>"
 	test("[[https://google.com/]]", googleRendered)
 
 	lnk := util.URLJoin(AppSubURL, "WikiPage")
 	test("[[WikiPage][WikiPage]]",
-		`<p><a href="`+lnk+`" title="WikiPage">WikiPage</a></p>`)
+		"<p>\n<a href=\""+lnk+"\" title=\"WikiPage\">WikiPage</a>\n</p>")
 }
 
 func TestRender_Images(t *testing.T) {
@@ -45,10 +45,8 @@ func TestRender_Images(t *testing.T) {
 	}
 
 	url := "../../.images/src/02/train.jpg"
-	title := "Train"
 	result := util.URLJoin(AppSubURL, url)
 
-	test(
-		"[[file:"+url+"]["+title+"]]",
-		`<p><a href="`+result+`"><img src="`+result+`" alt="`+title+`" title="`+title+`" /></a></p>`)
+	test("[[file:"+url+"]]",
+		"<p>\n<img src=\""+result+"\" alt=\""+result+"\" title=\""+result+"\" />\n</p>")
 }