From adee82100658dcdf7ad37372ac122ce1b5788cb6 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Fri, 13 Sep 2024 12:32:04 +0300
Subject: [PATCH] msgconv/matrixfmt: fix trimming space from whitespace-only
 string

---
 pkg/msgconv/matrixfmt/convert_test.go |  7 +++++++
 pkg/msgconv/matrixfmt/html.go         | 14 +++++++++-----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/pkg/msgconv/matrixfmt/convert_test.go b/pkg/msgconv/matrixfmt/convert_test.go
index 240ca98d..1ade3169 100644
--- a/pkg/msgconv/matrixfmt/convert_test.go
+++ b/pkg/msgconv/matrixfmt/convert_test.go
@@ -65,6 +65,13 @@ func TestParse_HTML(t *testing.T) {
 			Length: 5,
 			Value:  signalfmt.StyleBold,
 		}}},
+		{name: "UnnecessaryWhitespace", in: "<strong>  Hello  </strong>, World!", out: "Hello, World!", ent: signalfmt.BodyRangeList{{
+			Start:  0,
+			Length: 5,
+			Value:  signalfmt.StyleBold,
+		}}},
+		{name: "UnnecessaryWhitespaceParagraph", in: "<p>  Hello  </p>", out: "Hello"},
+		{name: "EmptyParagraph", in: "<p>Hello</p><p>   </p>", out: "Hello"},
 		{
 			name: "MultiBasic",
 			in:   "<strong><em>Hell</em>o</strong>, <del>Wo<span data-mx-spoiler>rld</span></del><code>!</code>",
diff --git a/pkg/msgconv/matrixfmt/html.go b/pkg/msgconv/matrixfmt/html.go
index 1e3d249d..5c4a37f4 100644
--- a/pkg/msgconv/matrixfmt/html.go
+++ b/pkg/msgconv/matrixfmt/html.go
@@ -81,22 +81,26 @@ func (es *EntityString) TrimSpace() *EntityString {
 		return nil
 	}
 	DebugLog("TRIMSPACE %q %+v\n", es.String, es.Entities)
-	var cutEnd, cutStart int
-	for cutStart = 0; cutStart < len(es.String); cutStart++ {
+	cutStart := 0
+	for ; cutStart < len(es.String); cutStart++ {
 		switch es.String[cutStart] {
 		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0:
 			continue
 		}
 		break
 	}
-	for cutEnd = len(es.String) - 1; cutEnd >= 0; cutEnd-- {
-		switch es.String[cutEnd] {
+	cutEnd := len(es.String)
+	for ; cutEnd > cutStart; cutEnd-- {
+		switch es.String[cutEnd-1] {
 		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0:
 			continue
 		}
 		break
 	}
-	cutEnd++
+	if cutEnd == cutStart {
+		DebugLog("  -> EMPTY\n")
+		return NewEntityString("")
+	}
 	if cutStart == 0 && cutEnd == len(es.String) {
 		DebugLog("  -> NOOP\n")
 		return es