use std::any::type_name;

pub fn topic_for_type<T>(prefix: &str) -> String {
    let raw = type_name::<T>();
    format!("{prefix}.{}", sanitize_topic_component(raw))
}

pub fn sanitize_topic_component(raw: &str) -> String {
    let mut out = String::with_capacity(raw.len());
    let mut last_was_underscore = false;
    for ch in raw.chars() {
        let allowed = ch.is_ascii_alphanumeric() || ch == '.' || ch == '-';
        if allowed {
            out.push(ch);
            last_was_underscore = false;
        } else if !last_was_underscore {
            out.push('_');
            last_was_underscore = true;
        }
    }
    let trimmed = out.trim_matches('_').to_string();
    if trimmed.is_empty() {
        "unknown".to_string()
    } else {
        trimmed
    }
}