/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package i18n

import (
	"os"
	"sync"
	"testing"

	"github.com/chai2010/gettext-go"
)

var knownTestLocale = "en_US.UTF-8"

func TestTranslation(t *testing.T) {
	err := LoadTranslations("test", func() string { return "default" })
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}

	result := T("test_string")
	if result != "foo" {
		t.Errorf("expected: %s, saw: %s", "foo", result)
	}
}

func TestTranslationPlural(t *testing.T) {
	err := LoadTranslations("test", func() string { return "default" })
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}

	result := T("test_plural", 3)
	if result != "there were 3 items" {
		t.Errorf("expected: %s, saw: %s", "there were 3 items", result)
	}

	result = T("test_plural", 1)
	if result != "there was 1 item" {
		t.Errorf("expected: %s, saw: %s", "there was 1 item", result)
	}
}

func TestTranslationUsingEnvVar(t *testing.T) {
	// We must backup and restore env vars before setting test values in tests
	// othervise we are risking to break other tests/test cases
	// which rely on the same env vars
	envVarsToBackup := []string{"LC_MESSAGES", "LANG", "LC_ALL"}
	expectedStrEnUSLocale := "baz"
	expectedStrFallback := "foo"

	testCases := []struct {
		name        string
		setenvFn    func()
		expectedStr string
	}{
		{
			name:        "Only LC_ALL is set",
			setenvFn:    func() { os.Setenv("LC_ALL", knownTestLocale) },
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name:        "Only LC_MESSAGES is set",
			setenvFn:    func() { os.Setenv("LC_MESSAGES", knownTestLocale) },
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name:        "Only LANG",
			setenvFn:    func() { os.Setenv("LANG", knownTestLocale) },
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name: "LC_MESSAGES overrides LANG",
			setenvFn: func() {
				os.Setenv("LANG", "be_BY.UTF-8") // Unknown locale
				os.Setenv("LC_MESSAGES", knownTestLocale)
			},
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name: "LC_ALL overrides LANG",
			setenvFn: func() {
				os.Setenv("LANG", "be_BY.UTF-8") // Unknown locale
				os.Setenv("LC_ALL", knownTestLocale)
			},
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name: "LC_ALL overrides LC_MESSAGES",
			setenvFn: func() {
				os.Setenv("LC_MESSAGES", "be_BY.UTF-8") // Unknown locale
				os.Setenv("LC_ALL", knownTestLocale)
			},
			expectedStr: expectedStrEnUSLocale,
		},
		{
			name:        "Unknown locale in LANG",
			setenvFn:    func() { os.Setenv("LANG", "be_BY.UTF-8") },
			expectedStr: expectedStrFallback,
		},
		{
			name:        "Unknown locale in LC_MESSAGES",
			setenvFn:    func() { os.Setenv("LC_MESSAGES", "be_BY.UTF-8") },
			expectedStr: expectedStrFallback,
		},
		{
			name:        "Unknown locale in LC_ALL",
			setenvFn:    func() { os.Setenv("LC_ALL", "be_BY.UTF-8") },
			expectedStr: expectedStrFallback,
		},
		{
			name:        "Invalid env var",
			setenvFn:    func() { os.Setenv("LC_MESSAGES", "fake.locale.UTF-8") },
			expectedStr: expectedStrFallback,
		},
		{
			name:        "No env vars",
			setenvFn:    func() {},
			expectedStr: expectedStrFallback,
		},
	}

	for _, test := range testCases {
		t.Run(test.name, func(t *testing.T) {
			for _, envVar := range envVarsToBackup {
				if envVarValue := os.Getenv(envVar); envVarValue != "" {
					envVarValue, envVar := envVarValue, envVar
					os.Unsetenv(envVar)
					// Restore env var at the end
					defer func() { os.Setenv(envVar, envVarValue) }()
				}
			}

			test.setenvFn()

			err := LoadTranslations("test", nil)
			if err != nil {
				t.Errorf("Unexpected error: %v", err)
			}

			result := T("test_string")
			if result != test.expectedStr {
				t.Errorf("expected: %s, saw: %s", test.expectedStr, result)
			}
		})
	}
}

// resetLazyLoading allows multiple tests to test translation lazy loading by resetting the state
func resetLazyLoading() {
	translationsLoaded = false
	lazyLoadTranslationsOnce = sync.Once{}
}

func TestLazyLoadTranslationFuncIsCalled(t *testing.T) {
	resetLazyLoading()

	timesCalled := 0
	err := SetLoadTranslationsFunc(func() error {
		timesCalled++
		return LoadTranslations("test", func() string { return "en_US" })
	})
	if err != nil {
		t.Errorf("unexpected error: %v", err)
	}
	if translationsLoaded {
		t.Errorf("expected translationsLoaded to be false, but it was true")
	}

	// Translation should succeed and use the lazy loaded translations
	result := T("test_string")
	if result != "baz" {
		t.Errorf("expected: %s, saw: %s", "baz", result)
	}
	if timesCalled != 1 {
		t.Errorf("expected LoadTranslationsFunc to have been called 1 time, but it was called %d times", timesCalled)
	}
	if !translationsLoaded {
		t.Errorf("expected translationsLoaded to be true, but it was false")
	}

	// Call T() again, and timesCalled should remain 1
	T("test_string")
	if timesCalled != 1 {
		t.Errorf("expected LoadTranslationsFunc to have been called 1 time, but it was called %d times", timesCalled)
	}
}

func TestLazyLoadTranslationFuncOnlyCalledIfTranslationsNotLoaded(t *testing.T) {
	resetLazyLoading()

	// Set a custom translations func
	timesCalled := 0
	err := SetLoadTranslationsFunc(func() error {
		timesCalled++
		return LoadTranslations("test", func() string { return "en_US" })
	})
	if err != nil {
		t.Errorf("unexpected error: %v", err)
	}
	if translationsLoaded {
		t.Errorf("expected translationsLoaded to be false, but it was true")
	}

	// Explicitly load translations before lazy loading can occur
	err = LoadTranslations("test", func() string { return "default" })
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	if !translationsLoaded {
		t.Errorf("expected translationsLoaded to be true, but it was false")
	}

	// Translation should succeed, and use the explicitly loaded translations, not the lazy loaded ones
	result := T("test_string")
	if result != "foo" {
		t.Errorf("expected: %s, saw: %s", "foo", result)
	}
	if timesCalled != 0 {
		t.Errorf("expected LoadTranslationsFunc to have not been called, but it was called %d times", timesCalled)
	}
}

func TestSetCustomLoadTranslationsFunc(t *testing.T) {
	resetLazyLoading()

	// Set a custom translations func that loads translations from a directory
	err := SetLoadTranslationsFunc(func() error {
		gettext.BindLocale(gettext.New("k8s", "./translations/test"))
		gettext.SetDomain("k8s")
		gettext.SetLanguage("en_US")
		return nil
	})
	if err != nil {
		t.Errorf("unexpected error: %v", err)
	}
	if translationsLoaded {
		t.Errorf("expected translationsLoaded to be false, but it was true")
	}

	// Translation should succeed
	result := T("test_string")
	if result != "baz" {
		t.Errorf("expected: %s, saw: %s", "baz", result)
	}
	if !translationsLoaded {
		t.Errorf("expected translationsLoaded to be true, but it was false")
	}
}

func TestSetCustomLoadTranslationsFuncAfterTranslationsLoadedShouldFail(t *testing.T) {
	resetLazyLoading()

	// Explicitly load translations
	err := LoadTranslations("test", func() string { return "en_US" })
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	if !translationsLoaded {
		t.Errorf("expected translationsLoaded to be true, but it was false")
	}

	// This should fail because translations have already been loaded, and the custom function should not be called.
	timesCalled := 0
	err = SetLoadTranslationsFunc(func() error {
		timesCalled++
		return nil
	})
	if err == nil {
		t.Errorf("expected error, but it did not occur")
	}
	if timesCalled != 0 {
		t.Errorf("expected LoadTranslationsFunc to have not been called, but it was called %d times", timesCalled)
	}
}
