use lazy_regex::regex_find;
use rand::distributions::Alphanumeric;
use rand::Rng;

/// Generate a random string of a given size
pub fn rand_str(len: usize) -> String {
    rand::thread_rng()
        .sample_iter(&Alphanumeric)
        .map(char::from)
        .take(len)
        .collect()
}

/// Parse environment variables
pub fn apply_env_vars(val: &str) -> String {
    let mut val = val.to_string();

    if let Some(varname_with_wrapper) = regex_find!(r#"\$\{[a-zA-Z0-9_-]+\}"#, &val) {
        let varname = varname_with_wrapper
            .strip_prefix("${")
            .unwrap()
            .strip_suffix('}')
            .unwrap();
        let value = match std::env::var(varname) {
            Ok(v) => v,
            Err(e) => {
                log::error!("Failed to find environment variable {}!", varname);
                eprintln!("Failed to find environment variable! {:?}", e);
                std::process::exit(2);
            }
        };

        val = val.replace(varname_with_wrapper, &value);
    }

    val
}

#[cfg(test)]
mod test {
    use crate::utils::string_utils::apply_env_vars;
    use std::env;

    const VAR_ONE: &str = "VAR_ONE";
    #[test]
    fn test_apply_env_var() {
        env::set_var(VAR_ONE, "good");
        let src = format!("This is ${{{}}}", VAR_ONE);
        assert_eq!("This is good", apply_env_vars(&src));
    }

    const VAR_INVALID: &str = "VAR_INV@LID";

    #[test]
    fn test_invalid_var_syntax() {
        let src = format!("This is ${{{}}}", VAR_INVALID);
        assert_eq!(src, apply_env_vars(&src));
    }
}