From e9de9684f4da9638450c2e5088a365e020097ea3 Mon Sep 17 00:00:00 2001
From: Florian Thoma <mail@fthoma.de>
Date: Wed, 5 Jun 2024 09:33:15 +0200
Subject: [PATCH] Use character display width for table padding

Using len(...) for table cell padding produced wrong results for unicode
chracters leading to misaligned tables. Implementation changed to take
the actual terminal display width into consideration.
---
 internal/ui/format.go           | 23 +++++++++++++++++++++++
 internal/ui/format_test.go      | 18 ++++++++++++++++++
 internal/ui/table/table.go      | 14 ++++++++------
 internal/ui/table/table_test.go |  4 ++--
 4 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/internal/ui/format.go b/internal/ui/format.go
index d2e0a4d2b..de650607d 100644
--- a/internal/ui/format.go
+++ b/internal/ui/format.go
@@ -8,6 +8,8 @@ import (
 	"math/bits"
 	"strconv"
 	"time"
+
+	"golang.org/x/text/width"
 )
 
 func FormatBytes(c uint64) string {
@@ -105,3 +107,24 @@ func ToJSONString(status interface{}) string {
 	}
 	return buf.String()
 }
+
+// TerminalDisplayWidth returns the number of terminal cells needed to display s
+func TerminalDisplayWidth(s string) int {
+	width := 0
+	for _, r := range s {
+		width += terminalDisplayRuneWidth(r)
+	}
+
+	return width
+}
+
+func terminalDisplayRuneWidth(r rune) int {
+	switch width.LookupRune(r).Kind() {
+	case width.EastAsianWide, width.EastAsianFullwidth:
+		return 2
+	case width.EastAsianNarrow, width.EastAsianHalfwidth, width.EastAsianAmbiguous, width.Neutral:
+		return 1
+	default:
+		return 0
+	}
+}
diff --git a/internal/ui/format_test.go b/internal/ui/format_test.go
index 4223d4e20..d595026c4 100644
--- a/internal/ui/format_test.go
+++ b/internal/ui/format_test.go
@@ -84,3 +84,21 @@ func TestParseBytesInvalid(t *testing.T) {
 		test.Equals(t, int64(0), v)
 	}
 }
+
+func TestTerminalDisplayWidth(t *testing.T) {
+	for _, c := range []struct {
+		input string
+		want  int
+	}{
+		{"foo", 3},
+		{"aéb", 3},
+		{"ab", 3},
+		{"a’b", 3},
+		{"aあb", 4},
+	} {
+		if got := TerminalDisplayWidth(c.input); got != c.want {
+			t.Errorf("wrong display width for '%s', want %d, got %d", c.input, c.want, got)
+		}
+	}
+
+}
diff --git a/internal/ui/table/table.go b/internal/ui/table/table.go
index c3ae47f54..ae09063be 100644
--- a/internal/ui/table/table.go
+++ b/internal/ui/table/table.go
@@ -6,6 +6,8 @@ import (
 	"strings"
 
 	"text/template"
+
+	"github.com/restic/restic/internal/ui"
 )
 
 // Table contains data for a table to be printed.
@@ -89,7 +91,7 @@ func printLine(w io.Writer, print func(io.Writer, string) error, sep string, dat
 			}
 
 			// apply padding
-			pad := widths[fieldNum] - len(v)
+			pad := widths[fieldNum] - ui.TerminalDisplayWidth(v)
 			if pad > 0 {
 				v += strings.Repeat(" ", pad)
 			}
@@ -139,16 +141,16 @@ func (t *Table) Write(w io.Writer) error {
 	columnWidths := make([]int, columns)
 	for i, desc := range t.columns {
 		for _, line := range strings.Split(desc, "\n") {
-			if columnWidths[i] < len(line) {
-				columnWidths[i] = len(desc)
+			if columnWidths[i] < ui.TerminalDisplayWidth(line) {
+				columnWidths[i] = ui.TerminalDisplayWidth(desc)
 			}
 		}
 	}
 	for _, line := range lines {
 		for i, content := range line {
 			for _, l := range strings.Split(content, "\n") {
-				if columnWidths[i] < len(l) {
-					columnWidths[i] = len(l)
+				if columnWidths[i] < ui.TerminalDisplayWidth(l) {
+					columnWidths[i] = ui.TerminalDisplayWidth(l)
 				}
 			}
 		}
@@ -159,7 +161,7 @@ func (t *Table) Write(w io.Writer) error {
 	for _, width := range columnWidths {
 		totalWidth += width
 	}
-	totalWidth += (columns - 1) * len(t.CellSeparator)
+	totalWidth += (columns - 1) * ui.TerminalDisplayWidth(t.CellSeparator)
 
 	// write header
 	if len(t.columns) > 0 {
diff --git a/internal/ui/table/table_test.go b/internal/ui/table/table_test.go
index db116bbc5..7a94b7f9b 100644
--- a/internal/ui/table/table_test.go
+++ b/internal/ui/table/table_test.go
@@ -126,7 +126,7 @@ foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 					Time       string
 					Tags, Dirs []string
 				}
-				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"work", "go"}, []string{"/home/user/work", "/home/user/go"}})
+				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"work", "go’s"}, []string{"/home/user/work", "/home/user/go"}})
 				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"other"}, []string{"/home/user/other"}})
 				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"other", "bar"}, []string{"/home/user/other"}})
 				return table
@@ -135,7 +135,7 @@ foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 host name  time                 zz   tags   dirs
 ------------------------------------------------------------
 foo        2018-08-19 22:22:22  xxx  work   /home/user/work
-                                     go     /home/user/go
+                                     go’s   /home/user/go
 foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 foo        2018-08-19 22:22:22  xxx  other  /home/user/other
                                      bar