//! One-click client arming — the GUI equivalent of `client_arm.sh`, driven by
//! [`LauncherConfig`] so it repairs exactly what [`crate::preflight`] checks.
//!
//! Everything the game reaches by a routable address is redirected to the
//! OpenFUT server; two things are inherently local and are NOT touched here (they
//! are managed as child processes, see [`crate::local_services`]): the LSX/Origin
//! emulator on loopback `:4216` and `autopatch`.
//!
//! The three privileged steps run in ONE elevated batch (a single `pkexec`
//! prompt), mirroring the volatile state `client_arm.sh` set by hand:
//!
//! 1. `kernel.yama.ptrace_scope=0` — so `autopatch` can write FIFA's `/proc/PID/mem`.
//! 2. DNAT EA's hardcoded redirector IP → `server:redirector_port` (+ MASQUERADE
//!    on the reply path, required for a DNAT to a remote host).
//! 3. Point each dead EA hostname at the server in `/etc/hosts`.
//!
//! All of it is idempotent: the DNAT deletes any prior copy before adding, and
//! every `/etc/hosts` line for a managed hostname is removed first — including a
//! foreign single-machine-era `127.0.0.1 easw.easports.com` shadow that
//! `client_arm.sh` could not remove, because it only deleted its own `# openfut`
//! lines and glibc returns the FIRST match.

use crate::config::LauncherConfig;

/// Accept only hostname/IP characters. These values come from config fields that
/// are ever only IPs or hostnames, so a surprising character is a bug — reject it
/// rather than try to escape it into an elevated shell command.
#[cfg(unix)]
fn safe_host(s: &str) -> anyhow::Result<&str> {
    let t = s.trim();
    if t.is_empty() {
        anyhow::bail!("empty host/address");
    }
    if t.bytes()
        .all(|b| b.is_ascii_alphanumeric() || matches!(b, b'.' | b':' | b'-' | b'_'))
    {
        Ok(t)
    } else {
        anyhow::bail!("refusing to arm with an unexpected character in {t:?}");
    }
}

/// Build the privileged arming script. Pure and unit-tested; the effectful part
/// ([`arm`]) only validates config and hands this to the elevated runner.
#[cfg(unix)]
pub(crate) fn arming_script(
    server: &str,
    redirector_port: u16,
    ea_ip: &str,
    hostnames: &[String],
) -> anyhow::Result<String> {
    let server = safe_host(server)?;
    let ea_ip = safe_host(ea_ip)?;

    let mut s = String::from("set -eu\n");

    // 1) ptrace_scope for autopatch's /proc/PID/mem write.
    s.push_str("sysctl -q kernel.yama.ptrace_scope=0\n");

    // 2) DNAT EA's hardcoded redirector IP to the server; SNAT the redirected
    //    flow (a DNAT from OUTPUT to a remote host needs a matching MASQUERADE or
    //    the server's replies won't match the game's conntrack entry). Both are
    //    delete-then-add so re-running and IP changes stay clean.
    s.push_str(&format!(
        "while iptables -t nat -D OUTPUT -p tcp -d {ea_ip} -j DNAT --to-destination {server}:{redirector_port} 2>/dev/null; do :; done\n\
         iptables -t nat -A OUTPUT -p tcp -d {ea_ip} -j DNAT --to-destination {server}:{redirector_port}\n\
         while iptables -t nat -D POSTROUTING -p tcp -d {server} --dport {redirector_port} -j MASQUERADE 2>/dev/null; do :; done\n\
         iptables -t nat -A POSTROUTING -p tcp -d {server} --dport {redirector_port} -j MASQUERADE\n"
    ));

    // 3) Every dead EA hostname resolves to the server. Delete ALL existing lines
    //    listing the name (foreign shadow included) BEFORE writing ours, so the
    //    first-match-wins resolution can never land on a stale loopback line.
    for host in hostnames {
        let host = safe_host(host)?;
        let re = host.replace('.', "\\.");
        s.push_str(&format!(
            "sed -ri '/[[:space:]]{re}([[:space:]]|$)/d' /etc/hosts\n\
             printf '%s\\t%s\\t# openfut\\n' '{server}' '{host}' >> /etc/hosts\n"
        ));
    }

    Ok(s)
}

/// Human-readable list of what [`arm`] changed, in the order the script applies
/// it. Logged by the UI so the user sees exactly what was set — not just that
/// "something" ran under `pkexec`.
#[cfg(unix)]
pub(crate) fn arming_summary(
    server: &str,
    redirector_port: u16,
    ea_ip: &str,
    hostnames: &[String],
) -> Vec<String> {
    let mut out = vec![
        "kernel.yama.ptrace_scope = 0 (autopatch can attach)".to_string(),
        format!("DNAT {ea_ip} -> {server}:{redirector_port} (+ MASQUERADE reply path)"),
    ];
    for host in hostnames {
        out.push(format!("hosts: {host} -> {server}"));
    }
    out
}

/// Arm the client from config, under one elevated prompt. Requires the same
/// fields preflight reads; a missing one is a clear error, never a silent
/// loopback fallback. Returns the applied changes for the UI to surface.
/// On native Windows there is nothing to arm: routing is the `openfut.cfg` the
/// client-files step writes into the game directory (read by the version.dll
/// hook), and there is no `ptrace_scope`, DNAT, or `/etc/hosts` to set. Returns
/// no changes so the launch sequence treats client preparation as satisfied.
#[cfg(windows)]
pub fn arm(_cfg: &LauncherConfig) -> anyhow::Result<Vec<String>> {
    Ok(Vec::new())
}

#[cfg(unix)]
pub fn arm(cfg: &LauncherConfig) -> anyhow::Result<Vec<String>> {
    let server = cfg.openfut_server_host.trim();
    if server.is_empty() {
        anyhow::bail!("Set the OpenFUT server host in Settings before arming.");
    }
    let ea_ip = cfg.ea_redirect_probe_ip.trim();
    if ea_ip.is_empty() {
        anyhow::bail!("Set the EA redirector IP (Settings) before arming.");
    }
    if cfg.ea_hostnames.is_empty() {
        anyhow::bail!(
            "Add at least one EA hostname (e.g. easw.easports.com) in Settings before arming."
        );
    }
    let redirector_port = cfg.openfut_blaze_redirector_port;
    let script = arming_script(server, redirector_port, ea_ip, &cfg.ea_hostnames)?;
    crate::setup::run_elevated(&script)?;
    Ok(arming_summary(
        server,
        redirector_port,
        ea_ip,
        &cfg.ea_hostnames,
    ))
}

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

    fn script() -> String {
        arming_script(
            "10.10.0.120",
            42127,
            "159.153.51.20",
            &["easw.easports.com".to_string()],
        )
        .unwrap()
    }

    #[test]
    fn sets_ptrace_scope_zero() {
        assert!(script().contains("sysctl -q kernel.yama.ptrace_scope=0"));
    }

    #[test]
    fn dnats_ea_ip_to_server_and_masquerades() {
        let s = script();
        assert!(s.contains(
            "iptables -t nat -A OUTPUT -p tcp -d 159.153.51.20 -j DNAT --to-destination 10.10.0.120:42127"
        ));
        assert!(s.contains(
            "iptables -t nat -A POSTROUTING -p tcp -d 10.10.0.120 --dport 42127 -j MASQUERADE"
        ));
    }

    #[test]
    fn dnat_is_delete_then_add_for_idempotence() {
        let s = script();
        // The delete loop precedes the add, so re-arming never stacks duplicates.
        let del = s.find("-D OUTPUT").unwrap();
        let add = s.find("-A OUTPUT").unwrap();
        assert!(del < add, "delete must run before add");
    }

    #[test]
    fn removes_shadowing_hosts_line_before_writing_ours() {
        let s = script();
        // Deletes any existing easw.easports.com line (foreign shadow included)…
        assert!(
            s.contains("sed -ri '/[[:space:]]easw\\.easports\\.com([[:space:]]|$)/d' /etc/hosts")
        );
        // …then appends the OpenFUT-tagged mapping to the server.
        assert!(s.contains(
            "printf '%s\\t%s\\t# openfut\\n' '10.10.0.120' 'easw.easports.com' >> /etc/hosts"
        ));
        let del = s.find("sed -ri").unwrap();
        let add = s.find("printf").unwrap();
        assert!(del < add, "shadow removal must precede our line");
    }

    #[test]
    fn multiple_hostnames_each_get_a_mapping() {
        let s = arming_script(
            "10.10.0.120",
            42127,
            "159.153.51.20",
            &["easw.easports.com".into(), "utas.fut.ea.com".into()],
        )
        .unwrap();
        assert!(s.contains("'easw.easports.com' >> /etc/hosts"));
        assert!(s.contains("'utas.fut.ea.com' >> /etc/hosts"));
    }

    #[test]
    fn rejects_shell_metacharacters_in_config() {
        assert!(arming_script("10.0.0.1; rm -rf /", 42127, "159.153.51.20", &[]).is_err());
        assert!(arming_script("10.0.0.1", 42127, "$(evil)", &[]).is_err());
        assert!(
            arming_script("10.0.0.1", 42127, "159.153.51.20", &["a b`c`".into()]).is_err(),
            "a hostname with a backtick is rejected"
        );
    }

    #[test]
    fn arm_requires_server_ea_ip_and_hostname() {
        let mut c = LauncherConfig::default();
        assert!(arm(&c).unwrap_err().to_string().contains("server host"));
        c.openfut_server_host = "10.10.0.120".into();
        assert!(arm(&c)
            .unwrap_err()
            .to_string()
            .contains("EA redirector IP"));
        c.ea_redirect_probe_ip = "159.153.51.20".into();
        assert!(arm(&c).unwrap_err().to_string().contains("EA hostname"));
    }

    #[test]
    fn summary_lists_ptrace_dnat_and_each_host() {
        let s = arming_summary(
            "10.10.0.120",
            42127,
            "159.153.51.20",
            &["easw.easports.com".into(), "utas.fut.ea.com".into()],
        );
        assert!(s.iter().any(|l| l.contains("ptrace_scope = 0")));
        assert!(s
            .iter()
            .any(|l| l.contains("DNAT 159.153.51.20 -> 10.10.0.120:42127")));
        assert!(s
            .iter()
            .any(|l| l == "hosts: easw.easports.com -> 10.10.0.120"));
        assert!(s
            .iter()
            .any(|l| l == "hosts: utas.fut.ea.com -> 10.10.0.120"));
    }
}