import Elementary
import Foundation
import Localization

/// The HTML page rendered for a not-found response, with its text localized to a given locale.
struct ErrorPage: HTMLDocument, Sendable {

    // MARK: Properties

    /// The locale the page content is localized to.
    private let locale: Locale

    /// Resolves the page's text from the bundled String Catalog for the page's ``locale``.
    private let localize: Localize

    // MARK: Initializers

    /// Creates a not-found page localized to the given locale.
    /// - Parameter locale: the locale the page content is localized to.
    init(
        locale: Locale
    ) {
        self.locale = locale
        self.localize = .init(bundle: .module)
    }

    // MARK: Document

    /// The page's content: a localized heading and explanatory message.
    var body: some HTML {
        h1 {
            localize("error.heading", locale: locale)
        }
        p {
            localize("error.message", locale: locale)
        }
    }

    /// The metadata and stylesheet link placed in the document head.
    var head: some HTML {
        meta(.charset(.utf8))
        meta(
            .name(.viewport),
            .content("width=device-width, initial-scale=1")
        )
        link(
            .rel(.stylesheet),
            .href("/css/error.css")
        )
    }

    /// The document language, derived from the page's locale and falling back to the default language.
    var lang: String {
        locale.language.languageCode?.identifier
            ?? LanguageList(bundle: .module).default
    }

    /// The localized document title.
    var title: String {
        localize("error.title", locale: locale)
    }

}