From 36922b6e952ddd87bedca16e38b34b913fcb6236 Mon Sep 17 00:00:00 2001
From: Timur Demin <me@tdem.in>
Date: Fri, 13 Aug 2021 09:49:06 +0500
Subject: [PATCH] Keep line breaks in blockquotes

This makes the renderer preserve existing line breaks in blockquotes,
provided they do not split paragraphs. Some clients/sites may use this
to form semantic around line breaks (for instance, for poems).

See #5.
---
 internal/gemini/renderer.go | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/internal/gemini/renderer.go b/internal/gemini/renderer.go
index c022e14..39702ec 100644
--- a/internal/gemini/renderer.go
+++ b/internal/gemini/renderer.go
@@ -18,6 +18,7 @@
 package gemini
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"regexp"
@@ -32,6 +33,7 @@ var (
 	lineBreak          = []byte{'\n'}
 	space              = []byte{' '}
 	linkPrefix         = []byte("=> ")
+	quoteBrPrefix      = []byte("\n> ")
 	quotePrefix        = []byte("> ")
 	itemPrefix         = []byte("* ")
 	itemIndent         = []byte{'\t'}
@@ -89,8 +91,7 @@ func (r Renderer) blockquote(w io.Writer, node *ast.BlockQuote, entering bool) {
 		if node := node.AsContainer(); node != nil {
 			for _, child := range node.Children {
 				w.Write(quotePrefix)
-				// assume children would be paragraphs
-				r.text(w, child)
+				r.blockquoteText(w, child)
 				// double linebreak to ensure Gemini clients don't merge
 				// quotes; gomarkdown assumes separate blockquotes are
 				// paragraphs of the same blockquote while we don't
@@ -260,6 +261,21 @@ func (r Renderer) text(w io.Writer, node ast.Node) {
 	}
 }
 
+// TODO: this really should've been unified with text(), but having two
+// extra params for prefix/line breaks is not neat
+func (r Renderer) blockquoteText(w io.Writer, node ast.Node) {
+	if node := node.AsLeaf(); node != nil {
+		// pad every line break with blockquote symbol
+		w.Write([]byte(bytes.ReplaceAll(node.Literal, lineBreak, quoteBrPrefix)))
+		return
+	}
+	if node := node.AsContainer(); node != nil {
+		for _, child := range node.Children {
+			r.blockquoteText(w, child)
+		}
+	}
+}
+
 func extractText(node ast.Node) string {
 	if node := node.AsLeaf(); node != nil {
 		return strings.ReplaceAll(string(node.Literal), "\n", " ")