//! Shared language-resource validation.
//!
//! Rust embeds the same TOML file that Vite compiles into the browser bundle.
//! Backend persistence accepts only locale codes declared by that resource, so
//! the database and deployed frontend cannot drift into unsupported values.

use std::{collections::HashMap, sync::OnceLock};

use serde::Deserialize;

const RESOURCE: &str = include_str!("../../../resources/i18n.toml");

#[derive(Deserialize)]
struct Catalog {
    default_language: String,
    locales: HashMap<String, Locale>,
}

#[derive(Deserialize)]
struct Locale {
    #[allow(dead_code)]
    name: String,
    messages: HashMap<String, String>,
}

fn catalog() -> &'static Catalog {
    static CATALOG: OnceLock<Catalog> = OnceLock::new();
    CATALOG.get_or_init(|| {
        let catalog: Catalog = toml::from_str(RESOURCE).expect("resources/i18n.toml must be valid");
        let default = catalog
            .locales
            .get(&catalog.default_language)
            .expect("default language must be declared");
        for (code, locale) in &catalog.locales {
            for key in default.messages.keys() {
                assert!(
                    locale.messages.contains_key(key),
                    "locale {code} is missing translation key {key}"
                );
            }
        }
        catalog
    })
}

pub fn default_language() -> &'static str {
    &catalog().default_language
}

pub fn is_supported(language: &str) -> bool {
    catalog().locales.contains_key(language)
}

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

    #[test]
    fn shared_catalog_is_complete_and_declares_supported_languages() {
        assert_eq!(default_language(), "zh-CN");
        assert!(is_supported("zh-CN"));
        assert!(is_supported("en-US"));
        assert!(!is_supported("unknown"));
    }
}