Feat/Added label maker custom font (#1038)

* Add label maker font config

* Add document for label maker font config

* Add test for custom font

* Fix custom font setup documentation

- Fallback font is gofont which don't support CJK characters

* Fix golangci-lint error

* Update custom-font-setup.md

* Fix typo

backend/pkgs/labelmaker/labelmaker_test.go

@@ -0,0 +1,187 @@
+package labelmaker
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/sysadminsmedia/homebox/backend/internal/sys/config"
+	"golang.org/x/image/font/gofont/gobold"
+	"golang.org/x/image/font/gofont/gomedium"
+)
+
+func TestLoadFont_WithNilConfig(t *testing.T) {
+	font, err := loadFont(nil, FontTypeRegular)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+
+	font, err = loadFont(nil, FontTypeBold)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_WithEmptyConfig(t *testing.T) {
+	cfg := &config.Config{}
+
+	font, err := loadFont(cfg, FontTypeRegular)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+
+	font, err = loadFont(cfg, FontTypeBold)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_WithCustomFontPath(t *testing.T) {
+	tempDir := t.TempDir()
+	fontPath := filepath.Join(tempDir, "test-font.ttf")
+
+	err := os.WriteFile(fontPath, gomedium.TTF, 0644)
+	require.NoError(t, err)
+
+	cfg := &config.Config{
+		LabelMaker: config.LabelMakerConf{
+			RegularFontPath: &fontPath,
+		},
+	}
+
+	font, err := loadFont(cfg, FontTypeRegular)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_WithNonExistentFontPath(t *testing.T) {
+	nonExistentPath := "/non/existent/path/font.ttf"
+	cfg := &config.Config{
+		LabelMaker: config.LabelMakerConf{
+			RegularFontPath: &nonExistentPath,
+		},
+	}
+
+	font, err := loadFont(cfg, FontTypeRegular)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_UnknownFontType(t *testing.T) {
+	cfg := &config.Config{}
+
+	_, err := loadFont(cfg, FontType(999))
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "unknown font type")
+}
+
+func TestLoadFont_BoldFontWithCustomPath(t *testing.T) {
+	tempDir := t.TempDir()
+	fontPath := filepath.Join(tempDir, "test-bold-font.ttf")
+
+	err := os.WriteFile(fontPath, gobold.TTF, 0644)
+	require.NoError(t, err)
+
+	cfg := &config.Config{
+		LabelMaker: config.LabelMakerConf{
+			BoldFontPath: &fontPath,
+		},
+	}
+
+	font, err := loadFont(cfg, FontTypeBold)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_EmptyStringPath(t *testing.T) {
+	emptyPath := ""
+	cfg := &config.Config{
+		LabelMaker: config.LabelMakerConf{
+			RegularFontPath: &emptyPath,
+		},
+	}
+
+	font, err := loadFont(cfg, FontTypeRegular)
+	require.NoError(t, err)
+	assert.NotNil(t, font)
+}
+
+func TestLoadFont_CJKRendering(t *testing.T) {
+	cjkFontPath := filepath.Join("testdata", "NotoSansKR-VF.ttf")
+
+	tests := []struct {
+		name            string
+		text            string
+		fontPath        string
+		shouldHaveGlyph bool
+	}{
+		{
+			name:            "Korean with default font",
+			text:            "한글",
+			fontPath:        "",
+			shouldHaveGlyph: false,
+		},
+		{
+			name:            "Chinese with default font",
+			text:            "中文",
+			fontPath:        "",
+			shouldHaveGlyph: false,
+		},
+		{
+			name:            "Japanese with default font",
+			text:            "ひらがなカタカナ",
+			fontPath:        "",
+			shouldHaveGlyph: false,
+		},
+		{
+			name:            "Korean with Noto Sans CJK",
+			text:            "한글",
+			fontPath:        cjkFontPath,
+			shouldHaveGlyph: true,
+		},
+		{
+			name:            "Chinese with Noto Sans CJK",
+			text:            "中文",
+			fontPath:        cjkFontPath,
+			shouldHaveGlyph: true,
+		},
+		{
+			name:            "Japanese with Noto Sans CJK",
+			text:            "ひらがなカタカナ",
+			fontPath:        cjkFontPath,
+			shouldHaveGlyph: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var cfg *config.Config
+			if tt.fontPath != "" {
+				if _, err := os.Stat(tt.fontPath); os.IsNotExist(err) {
+					t.Skipf("Font file not found: %s", tt.fontPath)
+				}
+				cfg = &config.Config{
+					LabelMaker: config.LabelMakerConf{
+						RegularFontPath: &tt.fontPath,
+					},
+				}
+			}
+
+			font, err := loadFont(cfg, FontTypeRegular)
+			require.NoError(t, err)
+			require.NotNil(t, font)
+
+			hasAllGlyphs := true
+			for _, r := range tt.text {
+				if font.Index(r) == 0 {
+					hasAllGlyphs = false
+					break
+				}
+			}
+
+			if tt.shouldHaveGlyph {
+				assert.True(t, hasAllGlyphs, "Font should render %s characters", tt.name)
+			} else {
+				assert.False(t, hasAllGlyphs, "Default font should not render %s characters", tt.name)
+			}
+		})
+	}
+}