/// Trims a feed URL entered by the user, returning `None` when it's blank
/// so the submit handler can bail out before making a request.
pub fn normalize_feed_url(input: &str) -> Option<String> {
    let trimmed = input.trim();
    if trimmed.is_empty() {
        None
    } else {
        Some(trimmed.to_string())
    }
}

/// Success message shown after a feed subscription pulls in new articles.
pub fn subscribed_message(article_count: usize) -> String {
    format!("Subscribed — pulled in {article_count} article(s).")
}

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

    #[test]
    fn blank_input_normalizes_to_none() {
        assert_eq!(normalize_feed_url(""), None);
        assert_eq!(normalize_feed_url("   "), None);
    }

    #[test]
    fn surrounding_whitespace_is_trimmed() {
        assert_eq!(
            normalize_feed_url("  https://example.com/feed.xml  "),
            Some("https://example.com/feed.xml".to_string())
        );
    }

    #[test]
    fn message_reports_the_article_count() {
        assert_eq!(
            subscribed_message(0),
            "Subscribed — pulled in 0 article(s)."
        );
        assert_eq!(
            subscribed_message(3),
            "Subscribed — pulled in 3 article(s)."
        );
    }
}