Add support for markdown to HTML conversion (matrix). Closes #663 (#670)

This uses our own gomatrix lib with the SendHTML function which
adds HTML to formatted_body in matrix.
golang-commonmark is used to convert markdown into valid HTML.

1 files changed, 333 insertions, 0 deletions

diff --git a/vendor/gitlab.com/golang-commonmark/markdown/render.go b/vendor/gitlab.com/golang-commonmark/markdown/render.go
new file mode 100644
index 00000000..3955f051
--- /dev/null
+++ b/vendor/gitlab.com/golang-commonmark/markdown/render.go
@@ -0,0 +1,333 @@
+// Copyright 2015 The Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package markdown
+
+import (
+	"io"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"gitlab.com/golang-commonmark/html"
+)
+
+type Renderer struct {
+	w *monadicWriter
+}
+
+func NewRenderer(w io.Writer) *Renderer {
+	return &Renderer{newMonadicWriter(w)}
+}
+
+func (r *Renderer) Render(tokens []Token, options RenderOptions) error {
+	for i, tok := range tokens {
+		if tok, ok := tok.(*Inline); ok {
+			r.renderInline(tok.Children, options)
+		} else {
+			r.renderToken(tokens, i, options)
+		}
+	}
+
+	r.w.Flush()
+
+	return r.w.err
+}
+
+func (r *Renderer) renderInline(tokens []Token, o RenderOptions) {
+	for i := range tokens {
+		r.renderToken(tokens, i, o)
+	}
+}
+
+func (r *Renderer) renderInlineAsText(tokens []Token) {
+	for _, tok := range tokens {
+		if text, ok := tok.(*Text); ok {
+			html.WriteEscapedString(r.w, text.Content)
+		} else if img, ok := tok.(*Image); ok {
+			r.renderInlineAsText(img.Tokens)
+		}
+	}
+}
+
+var rNotSpace = regexp.MustCompile(`^\S+`)
+
+func (r *Renderer) renderToken(tokens []Token, idx int, options RenderOptions) {
+	tok := tokens[idx]
+
+	if idx > 0 && tok.Block() && !tok.Closing() {
+		switch t := tokens[idx-1].(type) {
+		case *ParagraphOpen:
+			if t.Hidden {
+				r.w.WriteByte('\n')
+			}
+		case *ParagraphClose:
+			if t.Hidden {
+				r.w.WriteByte('\n')
+			}
+		}
+	}
+
+	switch tok := tok.(type) {
+	case *BlockquoteClose:
+		r.w.WriteString("</blockquote>")
+
+	case *BlockquoteOpen:
+		r.w.WriteString("<blockquote>")
+
+	case *BulletListClose:
+		r.w.WriteString("</ul>")
+
+	case *BulletListOpen:
+		r.w.WriteString("<ul>")
+
+	case *CodeBlock:
+		r.w.WriteString("<pre><code>")
+		html.WriteEscapedString(r.w, tok.Content)
+		r.w.WriteString("</code></pre>")
+
+	case *CodeInline:
+		r.w.WriteString("<code>")
+		html.WriteEscapedString(r.w, tok.Content)
+		r.w.WriteString("</code>")
+
+	case *EmphasisClose:
+		r.w.WriteString("</em>")
+
+	case *EmphasisOpen:
+		r.w.WriteString("<em>")
+
+	case *Fence:
+		r.w.WriteString("<pre><code")
+		if tok.Params != "" {
+			langName := strings.SplitN(unescapeAll(tok.Params), " ", 2)[0]
+			langName = rNotSpace.FindString(langName)
+			if langName != "" {
+				r.w.WriteString(` class="`)
+				r.w.WriteString(options.LangPrefix)
+				html.WriteEscapedString(r.w, langName)
+				r.w.WriteByte('"')
+			}
+		}
+		r.w.WriteByte('>')
+		html.WriteEscapedString(r.w, tok.Content)
+		r.w.WriteString("</code></pre>")
+
+	case *Hardbreak:
+		if options.XHTML {
+			r.w.WriteString("<br />\n")
+		} else {
+			r.w.WriteString("<br>\n")
+		}
+
+	case *HeadingClose:
+		r.w.WriteString("</h")
+		r.w.WriteByte("0123456789"[tok.HLevel])
+		r.w.WriteString(">")
+
+	case *HeadingOpen:
+		r.w.WriteString("<h")
+		r.w.WriteByte("0123456789"[tok.HLevel])
+		r.w.WriteByte('>')
+
+	case *Hr:
+		if options.XHTML {
+			r.w.WriteString("<hr />")
+		} else {
+			r.w.WriteString("<hr>")
+		}
+
+	case *HTMLBlock:
+		r.w.WriteString(tok.Content)
+		return // no newline
+
+	case *HTMLInline:
+		r.w.WriteString(tok.Content)
+
+	case *Image:
+		r.w.WriteString(`<img src="`)
+		html.WriteEscapedString(r.w, tok.Src)
+		r.w.WriteString(`" alt="`)
+		r.renderInlineAsText(tok.Tokens)
+		r.w.WriteByte('"')
+
+		if tok.Title != "" {
+			r.w.WriteString(` title="`)
+			html.WriteEscapedString(r.w, tok.Title)
+			r.w.WriteByte('"')
+		}
+		if options.XHTML {
+			r.w.WriteString(" />")
+		} else {
+			r.w.WriteByte('>')
+		}
+
+	case *LinkClose:
+		r.w.WriteString("</a>")
+
+	case *LinkOpen:
+		r.w.WriteString(`<a href="`)
+		html.WriteEscapedString(r.w, tok.Href)
+		r.w.WriteByte('"')
+		if tok.Title != "" {
+			r.w.WriteString(` title="`)
+			html.WriteEscapedString(r.w, (tok.Title))
+			r.w.WriteByte('"')
+		}
+		if tok.Target != "" {
+			r.w.WriteString(` target="`)
+			html.WriteEscapedString(r.w, tok.Target)
+			r.w.WriteByte('"')
+		}
+		if options.Nofollow {
+			r.w.WriteString(` rel="nofollow"`)
+		}
+		r.w.WriteByte('>')
+
+	case *ListItemClose:
+		r.w.WriteString("</li>")
+
+	case *ListItemOpen:
+		r.w.WriteString("<li>")
+
+	case *OrderedListClose:
+		r.w.WriteString("</ol>")
+
+	case *OrderedListOpen:
+		if tok.Order != 1 {
+			r.w.WriteString(`<ol start="`)
+			r.w.WriteString(strconv.Itoa(tok.Order))
+			r.w.WriteString(`">`)
+		} else {
+			r.w.WriteString("<ol>")
+		}
+
+	case *ParagraphClose:
+		if tok.Hidden {
+			return
+		}
+		if !tok.Tight {
+			r.w.WriteString("</p>")
+		} else if tokens[idx+1].Closing() {
+			return // no newline
+		}
+
+	case *ParagraphOpen:
+		if tok.Hidden {
+			return
+		}
+		if !tok.Tight {
+			r.w.WriteString("<p>")
+		}
+
+	case *Softbreak:
+		if options.Breaks {
+			if options.XHTML {
+				r.w.WriteString("<br />\n")
+			} else {
+				r.w.WriteString("<br>\n")
+			}
+		} else {
+			r.w.WriteByte('\n')
+		}
+		return
+
+	case *StrongClose:
+		r.w.WriteString("</strong>")
+
+	case *StrongOpen:
+		r.w.WriteString("<strong>")
+
+	case *StrikethroughClose:
+		r.w.WriteString("</s>")
+
+	case *StrikethroughOpen:
+		r.w.WriteString("<s>")
+
+	case *TableClose:
+		r.w.WriteString("</table>")
+
+	case *TableOpen:
+		r.w.WriteString("<table>")
+
+	case *TbodyClose:
+		r.w.WriteString("</tbody>")
+
+	case *TbodyOpen:
+		r.w.WriteString("<tbody>")
+
+	case *TdClose:
+		r.w.WriteString("</td>")
+
+	case *TdOpen:
+		if tok.Align != AlignNone {
+			r.w.WriteString(`<td style="text-align:`)
+			r.w.WriteString(tok.Align.String())
+			r.w.WriteString(`">`)
+		} else {
+			r.w.WriteString("<td>")
+		}
+
+	case *Text:
+		html.WriteEscapedString(r.w, tok.Content)
+
+	case *TheadClose:
+		r.w.WriteString("</thead>")
+
+	case *TheadOpen:
+		r.w.WriteString("<thead>")
+
+	case *ThClose:
+		r.w.WriteString("</th>")
+
+	case *ThOpen:
+		if align := tok.Align; align != AlignNone {
+			r.w.WriteString(`<th style="text-align:`)
+			r.w.WriteString(align.String())
+			r.w.WriteString(`">`)
+		} else {
+			r.w.WriteString("<th>")
+		}
+
+	case *TrClose:
+		r.w.WriteString("</tr>")
+
+	case *TrOpen:
+		r.w.WriteString("<tr>")
+
+	default:
+		panic("unknown token type")
+	}
+
+	needLf := false
+	if tok.Block() {
+		needLf = true
+
+		if tok.Opening() {
+			nextTok := tokens[idx+1]
+			blockquote := false
+			switch nextTok := nextTok.(type) {
+			case *Inline:
+				needLf = false
+			case *ParagraphOpen:
+				if nextTok.Tight || nextTok.Hidden {
+					needLf = false
+				}
+			case *ParagraphClose:
+				if nextTok.Tight || nextTok.Hidden {
+					needLf = false
+				}
+			case *BlockquoteClose:
+				blockquote = true
+			}
+			if !blockquote && needLf && nextTok.Closing() && nextTok.Tag() == tok.Tag() {
+				needLf = false
+			}
+		}
+	}
+
+	if needLf {
+		r.w.WriteByte('\n')
+	}
+}