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)
        ))
    }

}