42 lines
1.5 KiB
Swift
42 lines
1.5 KiB
Swift
 
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import Foundation
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import HTTPTypes
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import Hummingbird
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import Localization
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public extension Negotiate {
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// MARK: Methods
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/// The language to serve a request in.
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///
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/// The `lang` query parameter wins as a deliberate override; failing that, a leading path segment naming a supported language pins it, so an
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/// unrouted path under a language's prefix answers in that language. Anything naming no supported language is ignored, leaving the
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/// `Accept-Language` header and its fallback to the default.
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///
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/// Called where the answer is used rather than stamped onto every request on the way past: page routes that pin their language by URL never ask.
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/// - Parameter request: the request to negotiate for.
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/// - Returns: the identifier of the supported language to serve.
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func callAsFunction(
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for request: Request
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) -> String {
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let requested = request.uri.queryParameters[.Parameter.language].map(String.init)
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?? request.uri.path.split(separator: "/").first.map(String.init)
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return callAsFunction(
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requested: requested,
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acceptLanguage: request.headers[.acceptLanguage]
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)
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}
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}
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// MARK: - Constants
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private extension Substring {
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/// A namespace for the query parameters the negotiation reads.
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enum Parameter {
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/// The query parameter carrying an explicit language choice; the site's language switcher appends it to the current path.
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static let language: Substring = "lang"
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}
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}
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