//! Chrome-string translations, selected by `site.yaml`'s `lang`.
//!
//! Content carries its own language; this covers only the strings the
//! portal itself speaks around it ("Asked by", the nav lead, the
//! not-found page...). Unknown languages and unknown keys fall back
//! to English, so a typo degrades to the default instead of a blank.

/// Translate `key` for `lang`. `en` is the reference table; every
/// other language falls through to it for keys it doesn't carry.
pub fn t(lang: &str, key: &str) -> &'static str {
    if let Some(s) = lookup(lang, key) {
        return s;
    }
    lookup("en", key).unwrap_or(key_missing(key))
}

fn lookup(lang: &str, key: &str) -> Option<&'static str> {
    Some(match (lang, key) {
        ("en", "also_worth_asking") => "Also worth asking",
        ("en", "asked_by") => "Asked by ",
        ("en", "contact_them") => "contact them",
        ("en", "if_stuck") => " if you get stuck.",
        ("en", "send") => "Send",
        ("en", "sign_in") => "Sign in",
        ("en", "nothing_here_yet") => "Nothing here yet.",
        ("en", "nothing_here") => "Nothing here",
        ("en", "back_to_start") => "back to the start",
        ("en", "done") => "Done.",
        ("en", "follows_answer") => {
            "This page follows from an answer you don't seem to carry yet."
        }
        ("en", "owners_only") => {
            "This part of the site is for organizational owners — sign in with that account to take a look."
        }
        ("en", "announcements") => "Announcements",

        ("no", "also_worth_asking") => "Også verdt å spørre",
        ("no", "asked_by") => "Stilt av ",
        ("no", "contact_them") => "ta kontakt",
        ("no", "if_stuck") => " om du står fast.",
        ("no", "send") => "Send",
        ("no", "sign_in") => "Logg inn",
        ("no", "nothing_here_yet") => "Ingenting her ennå.",
        ("no", "nothing_here") => "Ingenting her",
        ("no", "back_to_start") => "tilbake til start",
        ("no", "done") => "Ferdig.",
        ("no", "follows_answer") => {
            "Denne siden følger av et svar du ikke ser ut til å bære ennå."
        }
        ("no", "owners_only") => {
            "Denne delen av siden er for organisasjonens eiere — logg inn med den kontoen for å ta en titt."
        }
        ("no", "announcements") => "Kunngjøringer",

        _ => return None,
    })
}

/// A missing key is a programmer error; render the key itself so it
/// is findable, never a panic in a view.
fn key_missing(key: &str) -> &'static str {
    // Leak is bounded: keys are a small fixed set of literals.
    Box::leak(key.to_string().into_boxed_str())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn norwegian_covers_the_english_table() {
        for key in [
            "also_worth_asking",
            "asked_by",
            "contact_them",
            "if_stuck",
            "send",
            "sign_in",
            "nothing_here_yet",
            "nothing_here",
            "back_to_start",
            "done",
            "follows_answer",
            "owners_only",
            "announcements",
        ] {
            assert!(lookup("en", key).is_some(), "en missing {key}");
            assert!(lookup("no", key).is_some(), "no missing {key}");
        }
    }

    #[test]
    fn unknown_language_falls_back_to_english() {
        assert_eq!(t("de", "sign_in"), "Sign in");
        assert_eq!(t("en", "sign_in"), "Sign in");
    }
}