use rmcp::serde_json;
use serde::Deserialize;
use std::collections::HashMap;
use std::sync::{LazyLock, OnceLock, RwLock};

#[derive(Debug, Deserialize)]
struct Language {
    translations: HashMap<String, String>,
}

static LANGUAGES: OnceLock<HashMap<Locale, Language>> = OnceLock::new();
static LOCALE_SELECTION: LazyLock<RwLock<Locale>> = LazyLock::new(|| RwLock::new(Locale::DE));

#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub enum Locale {
    DE,
}

#[macro_export]
macro_rules! include_language {
    ($file:expr) => {
        serde_json::from_str::<Language>(include_str!($file)).unwrap()
    };
}

fn load_languages() -> &'static HashMap<Locale, Language> {
    LANGUAGES
        .get_or_init(|| HashMap::from([(Locale::DE, include_language!("translations/de.json"))]))
}

///
/// # Examples
///
/// ```
/// let formatted = format_dynamically("{...} is cool!".to_string(),
/// vec!["Rust".to_string()]);
/// assert_eq!(formatted, "Rust is cool!");
/// ```
fn format_dynamically(mut template: String, arguments: Vec<impl Into<String>>) -> String {
    let replaced_str = "{...}";

    for arg in arguments {
        template = template.replacen(replaced_str, arg.into().as_str(), 1);
    }

    template
}

pub fn translate(template_name: String, arguments: Vec<impl Into<String>>) -> String {
    let locale: Locale = *LOCALE_SELECTION.read().unwrap();
    let languages = load_languages();
    let translation = languages
        .get(&locale)
        .unwrap()
        .translations
        .get(&template_name)
        .unwrap();
    format_dynamically(translation.clone(), arguments)
}

#[macro_export]
macro_rules! tlt {
    ($template_name:tt) => {
        translate($template_name.to_string(), Vec::<String>::new())
    };
    ($template_name:tt, $($args:tt)*) => {
        translate($template_name.to_string(), vec![$($args)*])
    };
}

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

    #[test]
    fn test_dynamic_formatting() {
        let formatted = format_dynamically("{...} is cool!".to_string(), vec!["Rust".to_string()]);
        assert_eq!(formatted, "Rust is cool!");

        let formatted = format_dynamically(
            "{...}, {...} and {...} are three consecutive numbers.".to_string(),
            vec!["1".to_string(), "2".to_string(), "3".to_string()],
        );
        assert_eq!(formatted, "1, 2 and 3 are three consecutive numbers.");
    }
}