add vendoring

vendor/maunium.net/go/mautrix/format/markdown.go

@@ -0,0 +1,86 @@
+// Copyright (c) 2022 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package format
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/extension"
+	"github.com/yuin/goldmark/renderer/html"
+
+	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/format/mdext"
+)
+
+const paragraphStart = "<p>"
+const paragraphEnd = "</p>"
+
+var Extensions = goldmark.WithExtensions(extension.Strikethrough, extension.Table, mdext.Spoiler)
+var HTMLOptions = goldmark.WithRendererOptions(html.WithHardWraps(), html.WithUnsafe())
+
+var withHTML = goldmark.New(Extensions, HTMLOptions)
+var noHTML = goldmark.New(Extensions, HTMLOptions, goldmark.WithExtensions(mdext.EscapeHTML))
+
+// UnwrapSingleParagraph removes paragraph tags surrounding a string if the string only contains a single paragraph.
+func UnwrapSingleParagraph(html string) string {
+	html = strings.TrimRight(html, "\n")
+	if strings.HasPrefix(html, paragraphStart) && strings.HasSuffix(html, paragraphEnd) {
+		htmlBodyWithoutP := html[len(paragraphStart) : len(html)-len(paragraphEnd)]
+		if !strings.Contains(htmlBodyWithoutP, paragraphStart) {
+			return htmlBodyWithoutP
+		}
+	}
+	return html
+}
+
+func RenderMarkdownCustom(text string, renderer goldmark.Markdown) event.MessageEventContent {
+	var buf strings.Builder
+	err := renderer.Convert([]byte(text), &buf)
+	if err != nil {
+		panic(fmt.Errorf("markdown parser errored: %w", err))
+	}
+	htmlBody := UnwrapSingleParagraph(buf.String())
+	return HTMLToContent(htmlBody)
+}
+
+func HTMLToContent(html string) event.MessageEventContent {
+	text := HTMLToMarkdown(html)
+	if html != text {
+		return event.MessageEventContent{
+			FormattedBody: html,
+			Format:        event.FormatHTML,
+			MsgType:       event.MsgText,
+			Body:          text,
+		}
+	}
+	return event.MessageEventContent{
+		MsgType: event.MsgText,
+		Body:    text,
+	}
+}
+
+func RenderMarkdown(text string, allowMarkdown, allowHTML bool) event.MessageEventContent {
+	var htmlBody string
+
+	if allowMarkdown {
+		rndr := withHTML
+		if !allowHTML {
+			rndr = noHTML
+		}
+		return RenderMarkdownCustom(text, rndr)
+	} else if allowHTML {
+		htmlBody = strings.Replace(text, "\n", "<br>", -1)
+		return HTMLToContent(htmlBody)
+	} else {
+		return event.MessageEventContent{
+			MsgType: event.MsgText,
+			Body:    text,
+		}
+	}
+}