use anyhow::{Result, bail};
use regex::Regex;

/// Resolves the latest release tag for `repo` via its public Atom feed.
///
/// Deliberately not a full XML parse: the feed's newest entry is always
/// first, and its `<link rel="alternate" .../releases/tag/<tag>"/>` is the
/// first such link in the document, so a single regex match is sufficient.
/// Revisit with a real XML parser if GitHub's feed shape ever changes.
pub fn latest_github_release(client: &reqwest::blocking::Client, repo: &str) -> Result<String> {
    let url = format!("https://github.com/{repo}/releases.atom");
    let body = client.get(&url).send()?.error_for_status()?.text()?;

    let pattern = format!(r#"releases/tag/([^"]+)""#);
    let re = Regex::new(&pattern)?;
    match re.captures(&body) {
        Some(caps) => Ok(caps[1].to_string()),
        None => bail!("no release tag found in {url}"),
    }
}