Localization support for the Website service (#10)

This PR contains the work done to introduce server-side localization support to the **Website** service so the landing and error pages are served in the visitor's negotiated language, backed by a new reusable Localization package.

To provide further details about the work:

* Created the _Localization_ package — a bundle-bound `Localize` method and a `LanguageList` type.
* Language negotiation — `NegotiateLanguage` method picks the best supported language from the request's _Accept-Language_ header (falling back to the default); the `LocalizationMiddleware` middleware resolves it per request and stores it on a new `LocalizedRequestContext` / `WebsiteRequestContext` context.
* Localized responses — `LocalizedHTMLCollectionResponse` pre-renders each page once per language and caches the bytes (with `Content-Language` + `Vary: Accept-Language`), reused by the  `RootController` controller and `NotFoundMiddleware` middleware.
* The `CachedHTMLResponse` response gained custom-header support.
* Localized pages — the `IndexPage` and `ErrorPage` pages now resolve their strings via `Localize` method;
* Added `Localizable.xcstrings` catalogs.
* Wired the `LocalizationMiddleware` middlewaer into the router.

Reviewed-on: rock-n-code/loud-amsterdam#10
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>
This commit is contained in:
2026-06-29 23:08:36 +00:00
committed by javier
parent 847058d642
commit 6c66ea74cc
24 changed files with 858 additions and 49 deletions
@@ -0,0 +1,77 @@
<?xml version="1.0" encoding="UTF-8"?>
<Scheme
LastUpgradeVersion = "2700"
version = "1.7">
<BuildAction
parallelizeBuildables = "YES"
buildImplicitDependencies = "YES"
buildArchitectures = "Automatic">
<BuildActionEntries>
<BuildActionEntry
buildForTesting = "YES"
buildForRunning = "YES"
buildForProfiling = "YES"
buildForArchiving = "YES"
buildForAnalyzing = "YES">
<BuildableReference
BuildableIdentifier = "primary"
BlueprintIdentifier = "Localization"
BuildableName = "Localization"
ReferencedContainer = "container:">
</BuildableReference>
</BuildActionEntry>
</BuildActionEntries>
</BuildAction>
<TestAction
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
shouldUseLaunchSchemeArgsEnv = "YES"
shouldAutocreateTestPlan = "YES">
<Testables>
<TestableReference
skipped = "NO">
<BuildableReference
BuildableIdentifier = "primary"
BlueprintIdentifier = "LocalizationTests"
BuildableName = "LocalizationTests"
ReferencedContainer = "container:">
</BuildableReference>
</TestableReference>
</Testables>
</TestAction>
<LaunchAction
buildConfiguration = "Debug"
selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
launchStyle = "0"
useCustomWorkingDirectory = "NO"
ignoresPersistentStateOnLaunch = "NO"
debugDocumentVersioning = "YES"
debugServiceExtension = "internal"
allowLocationSimulation = "YES"
queueDebuggingEnabled = "No">
</LaunchAction>
<ProfileAction
buildConfiguration = "Release"
shouldUseLaunchSchemeArgsEnv = "YES"
savedToolIdentifier = ""
useCustomWorkingDirectory = "NO"
debugDocumentVersioning = "YES">
<MacroExpansion>
<BuildableReference
BuildableIdentifier = "primary"
BlueprintIdentifier = "Localization"
BuildableName = "Localization"
ReferencedContainer = "container:">
</BuildableReference>
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</ProfileAction>
<AnalyzeAction
buildConfiguration = "Debug">
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buildConfiguration = "Release"
revealArchiveInOrganizer = "YES">
</ArchiveAction>
</Scheme>
+37
View File
@@ -0,0 +1,37 @@
// swift-tools-version:6.3
import PackageDescription
let package = Package(
name: "Localization",
defaultLocalization: "en",
platforms: [
.macOS(.v15),
.iOS(.v18),
.tvOS(.v18),
],
products: [
.library(
name: "Localization",
targets: [
"Localization"
]
)
],
targets: [
.target(
name: "Localization",
path: "Sources",
),
.testTarget(
name: "LocalizationTests",
dependencies: [
.byName(name: "Localization")
],
path: "Tests",
resources: [
.process("Catalogs/Localizable.xcstrings")
]
),
]
)
@@ -0,0 +1,45 @@
import Foundation
/// A reusable, bundle-bound localizer that resolves String Catalog entries for an explicit locale.
///
/// A server has no single "current" locale, so each lookup must name the locale to use. An instance
/// is bound to the bundle whose catalog holds the strings, then invoked like a function to resolve a
/// key in a chosen locale.
public struct Localize: Sendable {
// MARK: Properties
/// The bundle whose compiled String Catalog the keys are resolved against.
private let bundle: Bundle
// MARK: Initializers
/// Creates a localizer backed by the given bundle.
/// - Parameter bundle: the bundle whose String Catalog contains the keys to resolve.
public init(
bundle: Bundle
) {
self.bundle = bundle
}
// MARK: Methods
/// Resolves a catalog key in the given locale.
///
/// Invoked by calling the instance directly, for example `localize("index.title", locale: locale)`.
/// - Parameters:
/// - key: the String Catalog key to look up.
/// - locale: the locale to resolve the key in.
/// - Returns: the localized string for the locale, or the key itself when the bundle's catalog has no entry for it.
public func callAsFunction(
_ key: String.LocalizationValue,
locale: Locale
) -> String {
.init(localized: .init(
key,
locale: locale,
bundle: .atURL(bundle.bundleURL)
))
}
}
@@ -0,0 +1,46 @@
import Foundation
/// The list of languages an app can serve, derived from a bundle's String Catalog.
///
/// The languages are read from the injected `bundle`'s compiled localizations, so the catalog that
/// ships in that bundle is the single source of truth: adding a language is a translation-only
/// change once a locale exists in the catalog, it appears in ``all`` with no code change required.
public struct LanguageList: Sendable {
// MARK: Properties
/// The language served when none of the supported languages match a request.
///
/// Should match the catalog bundle's development localization.
public let `default`: String
/// The bundle whose compiled String Catalog defines the available languages.
private let bundle: Bundle
// MARK: Initializers
/// Creates a language list backed by the given bundle.
/// - Parameters:
/// - bundle: the bundle whose String Catalog defines the available languages.
/// - default: the language served when none of the supported languages match. Defaults to `"en"`.
public init(
bundle: Bundle,
`default`: String = "en"
) {
self.bundle = bundle
self.`default` = `default`
}
// MARK: Computed
/// Every language the bundle's String Catalog provides a localization for.
///
/// The `Base` internationalization is excluded, as it is a development placeholder rather than a
/// real language.
public var all: [String] {
bundle
.localizations
.filter { $0 != "Base" }
}
}
@@ -0,0 +1,45 @@
import Foundation
import Testing
@testable import Localization
@Suite("Localize method")
struct LocalizeTests {
// MARK: Constants
private let localize = Localize(bundle: .module)
// MARK: Functional tests
@Test
func `resolves a key in the default locale`() {
let text = localize(
"test.greeting",
locale: Locale(identifier: "en")
)
#expect(text == "Hello")
}
@Test
func `resolves a key in another locale`() {
let text = localize(
"test.greeting",
locale: Locale(identifier: "de"),
)
#expect(text == "Hallo")
}
@Test
func `falls back to the key for an unknown entry`() {
let text = localize(
"unknown.key",
locale: Locale(identifier: "en"),
)
#expect(text == "unknown.key")
}
}
@@ -0,0 +1,65 @@
import Foundation
import Testing
@testable import Localization
@Suite("LanguageList type")
struct LanguageListTests {
// MARK: Properties tests
@Suite("default")
struct Default {
@Test
func `defaults to english`() {
let list = LanguageList(
bundle: .module
)
#expect(list.default == "en")
}
@Test
func `uses the provided default language`() {
let list = LanguageList(
bundle: .module,
default: "de"
)
#expect(list.default == "de")
}
}
@Suite("all")
struct All {
@Test
func `lists the catalog languages`() {
let list = LanguageList(
bundle: .module
)
#expect(list.all.contains("en"))
#expect(list.all.contains("de"))
}
@Test
func `excludes the base localization`() {
let list = LanguageList(
bundle: .module
)
#expect(!list.all.contains("Base"))
}
@Test
func `lists each language only once`() {
let list = LanguageList(
bundle: .module
)
let all = list.all
#expect(all.count == Set(all).count)
}
}
}
@@ -0,0 +1,23 @@
{
"sourceLanguage" : "en",
"strings" : {
"test.greeting" : {
"comment" : "Fixture string used by the Localization test suite.",
"localizations" : {
"de" : {
"stringUnit" : {
"state" : "translated",
"value" : "Hallo"
}
},
"en" : {
"stringUnit" : {
"state" : "translated",
"value" : "Hello"
}
}
}
}
},
"version" : "1.0"
}