[feature] Set/show instance language(s); show post language on frontend (#2362)

* update go text, include text/display

* [feature] Set instance langs, show post lang on frontend

* go fmt

* WebGet

* set language for whole article, don't use FA icon

* mention instance languages + other optional config vars

* little tweak

* put languages in config properly

* warn log language parse

* change some naming around

* tidy up validate a bit

* lint

* rename LanguageTmpl in template

1 files changed, 142 insertions, 0 deletions

diff --git a/internal/language/language_test.go b/internal/language/language_test.go
new file mode 100644
index 000000000..024448ab4
--- /dev/null
+++ b/internal/language/language_test.go
@@ -0,0 +1,142 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package language_test
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/superseriousbusiness/gotosocial/internal/language"
+	golanguage "golang.org/x/text/language"
+)
+
+func TestInstanceLangs(t *testing.T) {
+	for i, test := range []struct {
+		InstanceLangs       []string
+		expectedLangs       []golanguage.Tag
+		expectedLangStrs    []string
+		expectedErr         error
+		parseDisplayLang    string
+		expectedDisplayLang string
+	}{
+		{
+			InstanceLangs: []string{"en-us", "fr"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.AmericanEnglish,
+				golanguage.French,
+			},
+			expectedLangStrs: []string{
+				"American English",
+				"French (français)",
+			},
+			parseDisplayLang:    "de",
+			expectedDisplayLang: "German (Deutsch)",
+		},
+		{
+			InstanceLangs: []string{"fr", "en-us"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.French,
+				golanguage.AmericanEnglish,
+			},
+			expectedLangStrs: []string{
+				"français",
+				"anglais américain (American English)",
+			},
+			parseDisplayLang:    "de",
+			expectedDisplayLang: "allemand (Deutsch)",
+		},
+		{
+			InstanceLangs:       []string{},
+			expectedLangs:       []golanguage.Tag{},
+			expectedLangStrs:    []string{},
+			parseDisplayLang:    "de",
+			expectedDisplayLang: "German (Deutsch)",
+		},
+		{
+			InstanceLangs: []string{"zh"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.Chinese,
+			},
+			expectedLangStrs: []string{
+				"中文",
+			},
+			parseDisplayLang:    "de",
+			expectedDisplayLang: "德语 (Deutsch)",
+		},
+		{
+			InstanceLangs: []string{"ar", "en"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.Arabic,
+				golanguage.English,
+			},
+			expectedLangStrs: []string{
+				"العربية",
+				"الإنجليزية (English)",
+			},
+			parseDisplayLang:    "fi",
+			expectedDisplayLang: "الفنلندية (suomi)",
+		},
+		{
+			InstanceLangs: []string{"en-us"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.AmericanEnglish,
+			},
+			expectedLangStrs: []string{
+				"American English",
+			},
+			parseDisplayLang:    "en-us",
+			expectedDisplayLang: "American English",
+		},
+		{
+			InstanceLangs: []string{"en-us"},
+			expectedLangs: []golanguage.Tag{
+				golanguage.AmericanEnglish,
+			},
+			expectedLangStrs: []string{
+				"American English",
+			},
+			parseDisplayLang:    "en-gb",
+			expectedDisplayLang: "British English",
+		},
+	} {
+		languages, err := language.InitLangs(test.InstanceLangs)
+		if err != test.expectedErr {
+			t.Errorf("test %d expected error %v, got %v", i, test.expectedErr, err)
+		}
+
+		parsedTags := languages.Tags()
+		if !slices.Equal(test.expectedLangs, parsedTags) {
+			t.Errorf("test %d expected language tags %v, got %v", i, test.expectedLangs, parsedTags)
+		}
+
+		parsedLangStrs := languages.DisplayStrs()
+		if !slices.Equal(test.expectedLangStrs, parsedLangStrs) {
+			t.Errorf("test %d expected language strings %v, got %v", i, test.expectedLangStrs, parsedLangStrs)
+		}
+
+		parsedLang, err := language.Parse(test.parseDisplayLang)
+		if err != nil {
+			t.Errorf("unexpected error %v", err)
+			return
+		}
+
+		if test.expectedDisplayLang != parsedLang.DisplayStr {
+			t.Errorf("test %d expected to parse language %v, got %v", i, test.expectedDisplayLang, parsedLang.DisplayStr)
+		}
+	}
+}