use crate::{
    config::Config,
    netns::{DockerExecTransport, NsTransport, NsenterTransport, nsenter_available},
};

pub fn detect_interface(cfg: &Config, pid: u32, container: &str) -> anyhow::Result<String> {
    let boxed: Box<dyn NsTransport> = if nsenter_available() {
        Box::new(NsenterTransport { pid })
    } else {
        Box::new(DockerExecTransport {
            container: container.to_string(),
        })
    };

    detect_interface_with_transport(cfg, boxed.as_ref())
}

pub fn detect_interface_with_transport(
    cfg: &Config,
    transport: &dyn NsTransport,
) -> anyhow::Result<String> {
    for ifname in &cfg.amnezia.interface_candidates {
        if transport
            .run(&["ip", "link", "show", ifname])
            .is_ok()
        {
            return Ok(ifname.clone());
        }
    }

    let links = transport.run(&["sh", "-c", "ip -o link show | awk -F': ' '{print $2}'"])?;

    for raw in links.lines() {
        let name = raw.trim();
        for p in &cfg.amnezia.interface_patterns {
            if glob_like_match(p, name) {
                return Ok(name.to_string());
            }
        }
    }

    anyhow::bail!("unable to detect amnezia interface")
}

fn glob_like_match(pattern: &str, value: &str) -> bool {
    if let Some(prefix) = pattern.strip_suffix('*') {
        value.starts_with(prefix)
    } else {
        pattern == value
    }
}