// SPDX-License-Identifier: GPL-3.0-only

use std::str::FromStr;
use std::sync::OnceLock;

use i18n_embed::{
    fluent::{fluent_language_loader, FluentLanguageLoader},
    DefaultLocalizer, LanguageLoader, Localizer,
};
use icu_collator::{Collator, CollatorOptions, Numeric};
use icu_provider::DataLocale;
use rust_embed::RustEmbed;

#[derive(RustEmbed)]
#[folder = "i18n/"]
struct Localizations;

pub static LANGUAGE_LOADER: OnceLock<FluentLanguageLoader> = OnceLock::new();
pub static LANGUAGE_SORTER: OnceLock<Collator> = OnceLock::new();

#[macro_export]
macro_rules! fl {
    ($message_id:literal) => {{
        i18n_embed_fl::fl!($crate::localize::LANGUAGE_LOADER.get().unwrap(), $message_id)
    }};

    ($message_id:literal, $($args:expr),*) => {{
        i18n_embed_fl::fl!($crate::localize::LANGUAGE_LOADER.get().unwrap(), $message_id, $($args), *)
    }};
}

// Get the `Localizer` to be used for localizing this library.
pub fn localizer() -> Box<dyn Localizer> {
    LANGUAGE_LOADER.get_or_init(|| {
        let loader: FluentLanguageLoader = fluent_language_loader!();

        loader
            .load_fallback_language(&Localizations)
            .expect("Error while loading fallback language");

        loader
    });

    Box::from(DefaultLocalizer::new(
        LANGUAGE_LOADER.get().unwrap(),
        &Localizations,
    ))
}

pub fn localize() {
    let localizer = localizer();
    let requested_languages = i18n_embed::DesktopLanguageRequester::requested_languages();

    if let Err(error) = localizer.select(&requested_languages) {
        eprintln!("Error while loading language for App List {}", error);
    }
}

pub fn sorter() -> &'static Collator {
    LANGUAGE_SORTER.get_or_init(|| {
        let mut options = CollatorOptions::new();
        options.numeric = Some(Numeric::On);
        let localizer = localizer();
        let language_loader = localizer.language_loader();

        DataLocale::from_str(&language_loader.current_language().to_string())
            .or_else(|_| DataLocale::from_str(&language_loader.fallback_language().to_string()))
            .ok()
            .and_then(|locale| Collator::try_new(&locale, options).ok())
            .or_else(|| {
                let locale = DataLocale::from_str("en-US").expect("en-US is a valid BCP-47 tag");
                Collator::try_new(&locale, options).ok()
            })
            .expect("Creating a collator from the system's current language, the fallback language, or American English should succeed")
    })
}