#![cfg(debug_assertions)]

use std::sync::Mutex;

use nu_utils::locale::LOCALE_OVERRIDE_ENV_VAR;

static LOCALE_OVERRIDE_MUTEX: Mutex<()> = Mutex::new(());

/// Run a closure in a fake locale environment.
///
/// Before the closure is executed, an environment variable whose name is
/// defined in `nu_utils::locale::LOCALE_OVERRIDE_ENV_VAR` is set to the value
/// provided by `locale_string`. When the closure is done, the previous value is
/// restored.
///
/// Environment variables are global values. So when they are changed by one
/// thread they are changed for all others. To prevent a test from overwriting
/// the environment variable of another test, a mutex is used.
pub fn with_locale_override<T>(locale_string: &str, func: fn() -> T) -> T {
    let result = {
        let _lock = LOCALE_OVERRIDE_MUTEX
            .lock()
            .expect("Failed to get mutex lock for locale override");

        let saved = std::env::var(LOCALE_OVERRIDE_ENV_VAR).ok();
        unsafe {
            std::env::set_var(LOCALE_OVERRIDE_ENV_VAR, locale_string);

            let result = std::panic::catch_unwind(func);

            if let Some(locale_str) = saved {
                std::env::set_var(LOCALE_OVERRIDE_ENV_VAR, locale_str);
            } else {
                std::env::remove_var(LOCALE_OVERRIDE_ENV_VAR);
            }
            result
        }
    };
    result.unwrap_or_else(|err| std::panic::resume_unwind(err))
}
