Allow different HardBreaks settings for documents and comments (#11515)

GH has different HardBreaks behaviour for markdown comments and documents.

Comments have hard breaks and documents have soft breaks - therefore Gitea's rendering will always be different from GH's if we only provide one setting.

Here we split the setting in to two - one for documents and one for comments and other things.

Signed-off-by: Andrew Thornton art27@cantab.net

Changes to index.js as per @silverwind 
Co-authored-by: silverwind <me@silverwind.io>

Changes to docs as per @guillep2k 
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

3 files changed, 29 insertions, 13 deletions

diff --git a/modules/markup/markdown/goldmark.go b/modules/markup/markdown/goldmark.go
index bf02a22d5e..9447424644 100644
--- a/modules/markup/markdown/goldmark.go
+++ b/modules/markup/markdown/goldmark.go
@@ -151,6 +151,16 @@ func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc pa
 					v.AppendChild(v, newChild)
 				}
 			}
+		case *ast.Text:
+			if v.SoftLineBreak() && !v.HardLineBreak() {
+				renderMetas := pc.Get(renderMetasKey).(map[string]string)
+				mode := renderMetas["mode"]
+				if mode != "document" {
+					v.SetHardLineBreak(setting.Markdown.EnableHardLineBreakInComments)
+				} else {
+					v.SetHardLineBreak(setting.Markdown.EnableHardLineBreakInDocuments)
+				}
+			}
 		}
 		return ast.WalkContinue, nil
 	})
diff --git a/modules/markup/markdown/markdown.go b/modules/markup/markdown/markdown.go
index e50301ffe4..515d684686 100644
--- a/modules/markup/markdown/markdown.go
+++ b/modules/markup/markdown/markdown.go
@@ -29,17 +29,19 @@ var once = sync.Once{}
 
 var urlPrefixKey = parser.NewContextKey()
 var isWikiKey = parser.NewContextKey()
+var renderMetasKey = parser.NewContextKey()
 
 // NewGiteaParseContext creates a parser.Context with the gitea context set
-func NewGiteaParseContext(urlPrefix string, isWiki bool) parser.Context {
+func NewGiteaParseContext(urlPrefix string, metas map[string]string, isWiki bool) parser.Context {
 	pc := parser.NewContext(parser.WithIDs(newPrefixedIDs()))
 	pc.Set(urlPrefixKey, urlPrefix)
 	pc.Set(isWikiKey, isWiki)
+	pc.Set(renderMetasKey, metas)
 	return pc
 }
 
-// RenderRaw renders Markdown to HTML without handling special links.
-func RenderRaw(body []byte, urlPrefix string, wikiMarkdown bool) []byte {
+// render renders Markdown to HTML without handling special links.
+func render(body []byte, urlPrefix string, metas map[string]string, wikiMarkdown bool) []byte {
 	once.Do(func() {
 		converter = goldmark.New(
 			goldmark.WithExtensions(extension.Table,
@@ -75,12 +77,9 @@ func RenderRaw(body []byte, urlPrefix string, wikiMarkdown bool) []byte {
 			),
 		)
 
-		if setting.Markdown.EnableHardLineBreak {
-			converter.Renderer().AddOptions(html.WithHardWraps())
-		}
 	})
 
-	pc := NewGiteaParseContext(urlPrefix, wikiMarkdown)
+	pc := NewGiteaParseContext(urlPrefix, metas, wikiMarkdown)
 	var buf bytes.Buffer
 	if err := converter.Convert(giteautil.NormalizeEOL(body), &buf, parser.WithContext(pc)); err != nil {
 		log.Error("Unable to render: %v", err)
@@ -112,7 +111,7 @@ func (Parser) Extensions() []string {
 
 // Render implements markup.Parser
 func (Parser) Render(rawBytes []byte, urlPrefix string, metas map[string]string, isWiki bool) []byte {
-	return RenderRaw(rawBytes, urlPrefix, isWiki)
+	return render(rawBytes, urlPrefix, metas, isWiki)
 }
 
 // Render renders Markdown to HTML with all specific handling stuff.
@@ -120,6 +119,11 @@ func Render(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
 	return markup.Render("a.md", rawBytes, urlPrefix, metas)
 }
 
+// RenderRaw renders Markdown to HTML without handling special links.
+func RenderRaw(body []byte, urlPrefix string, wikiMarkdown bool) []byte {
+	return render(body, urlPrefix, map[string]string{}, wikiMarkdown)
+}
+
 // RenderString renders Markdown to HTML with special links and returns string type.
 func RenderString(raw, urlPrefix string, metas map[string]string) string {
 	return markup.RenderString("a.md", raw, urlPrefix, metas)
diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index 9507d46930..b8ec957535 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -256,12 +256,14 @@ var (
 
 	// Markdown settings
 	Markdown = struct {
-		EnableHardLineBreak bool
-		CustomURLSchemes    []string `ini:"CUSTOM_URL_SCHEMES"`
-		FileExtensions      []string
+		EnableHardLineBreakInComments  bool
+		EnableHardLineBreakInDocuments bool
+		CustomURLSchemes               []string `ini:"CUSTOM_URL_SCHEMES"`
+		FileExtensions                 []string
 	}{
-		EnableHardLineBreak: true,
-		FileExtensions:      strings.Split(".md,.markdown,.mdown,.mkd", ","),
+		EnableHardLineBreakInComments:  true,
+		EnableHardLineBreakInDocuments: false,
+		FileExtensions:                 strings.Split(".md,.markdown,.mdown,.mkd", ","),
 	}
 
 	// Admin settings