use std::path::Path;
use std::process::Command;

pub const DEFAULT_SET_NAME: &str = "banned";
pub const DEFAULT_TIMEOUT_SECS: u32 = 3600;

#[derive(Debug, Clone)]
pub struct Ipset {
    name: String,
}

#[derive(Debug, thiserror::Error)]
pub enum IpsetError {
    #[error("ipset binary not found in PATH")]
    NotInstalled,
    #[error("ipset command failed: {0}")]
    CommandFailed(String),
    #[error("ipset output parse error: {0}")]
    ParseError(String),
    #[error("invalid IP address: {0}")]
    InvalidIp(String),
    #[error("io error: {0}")]
    Io(#[from] std::io::Error),
}

pub type Result<T> = std::result::Result<T, IpsetError>;

impl Ipset {
    pub fn new(name: impl Into<String>) -> Self {
        Self { name: name.into() }
    }

    pub fn name(&self) -> &str {
        &self.name
    }

    pub fn is_available() -> bool {
        Command::new("ipset")
            .arg("--version")
            .output()
            .map(|o| o.status.success())
            .unwrap_or(false)
    }

    pub fn ensure_exists(&self) -> Result<()> {
        let output = Command::new("ipset")
            .args(["create", &self.name, "hash:ip", "timeout", "0", "-exist"])
            .output()?;
        if !output.status.success() {
            return Err(IpsetError::CommandFailed(
                String::from_utf8_lossy(&output.stderr).into_owned(),
            ));
        }
        Ok(())
    }

    pub fn add(&self, ip: &str, timeout_secs: Option<u32>) -> Result<()> {
        validate_ip(ip)?;
        let mut cmd = Command::new("ipset");
        cmd.args(["add", &self.name, ip, "-exist"]);
        if let Some(secs) = timeout_secs {
            cmd.args(["timeout", &secs.to_string()]);
        }
        let output = cmd.output()?;
        if !output.status.success() {
            return Err(IpsetError::CommandFailed(
                String::from_utf8_lossy(&output.stderr).into_owned(),
            ));
        }
        Ok(())
    }

    pub fn del(&self, ip: &str) -> Result<()> {
        validate_ip(ip)?;
        let output = Command::new("ipset")
            .args(["del", &self.name, ip, "-exist"])
            .output()?;
        if !output.status.success() {
            return Err(IpsetError::CommandFailed(
                String::from_utf8_lossy(&output.stderr).into_owned(),
            ));
        }
        Ok(())
    }

    pub fn contains(&self, ip: &str) -> Result<bool> {
        validate_ip(ip)?;
        let output = Command::new("ipset")
            .args(["test", &self.name, ip])
            .output()?;
        Ok(output.status.success())
    }

    pub fn list(&self) -> Result<Vec<String>> {
        let output = Command::new("ipset")
            .args(["list", &self.name])
            .output()?;
        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr).into_owned();
            if stderr.contains("does not exist") {
                return Ok(Vec::new());
            }
            return Err(IpsetError::CommandFailed(stderr));
        }
        let stdout = String::from_utf8_lossy(&output.stdout);
        let mut in_members = false;
        let mut ips = Vec::new();
        for line in stdout.lines() {
            if line.starts_with("Members:") {
                in_members = true;
                continue;
            }
            if in_members && !line.is_empty() {
                let entry = line.split_whitespace().next().unwrap_or("");
                if entry.is_empty() {
                    continue;
                }
                if entry.parse::<std::net::Ipv4Addr>().is_ok()
                    || entry.parse::<std::net::Ipv6Addr>().is_ok()
                    || entry.contains('/')
                {
                    ips.push(entry.to_string());
                }
            }
        }
        Ok(ips)
    }

    pub fn save(&self, path: &Path) -> Result<()> {
        let output = Command::new("ipset")
            .args(["save", &self.name])
            .output()?;
        if !output.status.success() {
            return Err(IpsetError::CommandFailed(
                String::from_utf8_lossy(&output.stderr).into_owned(),
            ));
        }
        std::fs::write(path, &output.stdout)?;
        Ok(())
    }

    pub fn flush(&self) -> Result<()> {
        let output = Command::new("ipset")
            .args(["flush", &self.name])
            .output()?;
        if !output.status.success() {
            return Err(IpsetError::CommandFailed(
                String::from_utf8_lossy(&output.stderr).into_owned(),
            ));
        }
        Ok(())
    }

    pub fn destroy(&self) -> Result<()> {
        let output = Command::new("ipset")
            .args(["destroy", &self.name])
            .output()?;
        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr).into_owned();
            if stderr.contains("does not exist") {
                return Ok(());
            }
            return Err(IpsetError::CommandFailed(stderr));
        }
        Ok(())
    }
}

fn validate_ip(ip: &str) -> Result<()> {
    if ip.parse::<std::net::Ipv4Addr>().is_err() && ip.parse::<std::net::Ipv6Addr>().is_err() {
        return Err(IpsetError::InvalidIp(ip.to_string()));
    }
    Ok(())
}

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

    const TEST_SET: &str = "banned_test_rs";

    fn setup() -> Option<Ipset> {
        if !Ipset::is_available() {
            eprintln!("ipset binary not available, skipping tests");
            return None;
        }
        let set = Ipset::new(TEST_SET);
        let _ = set.destroy();
        match set.ensure_exists() {
            Ok(_) => Some(set),
            Err(e) => {
                eprintln!("Cannot create ipset (need root?): {}", e);
                None
            }
        }
    }

    fn teardown(set: &Ipset) {
        let _ = set.destroy();
    }

    #[test]
    #[serial]
    fn ensure_exists_idempotent() {
        let Some(set) = setup() else { return };
        for _ in 0..5 {
            set.ensure_exists().expect("ensure_exists failed");
        }
        teardown(&set);
    }

    #[test]
    #[serial]
    fn add_then_list_contains_ip() {
        let Some(set) = setup() else { return };
        set.add("192.0.2.1", None).expect("add failed");
        let ips = set.list().expect("list failed");
        assert!(ips.contains(&"192.0.2.1".to_string()));
        teardown(&set);
    }

    #[test]
    #[serial]
    fn add_twice_no_error() {
        let Some(set) = setup() else { return };
        set.add("192.0.2.2", None).expect("first add");
        set.add("192.0.2.2", None).expect("second add should be idempotent");
        teardown(&set);
    }

    #[test]
    #[serial]
    fn del_then_list_empty() {
        let Some(set) = setup() else { return };
        set.add("192.0.2.3", None).expect("add");
        set.del("192.0.2.3").expect("del");
        let ips = set.list().expect("list");
        assert!(!ips.contains(&"192.0.2.3".to_string()));
        teardown(&set);
    }

    #[test]
    #[serial]
    fn del_nonexistent_no_error() {
        let Some(set) = setup() else { return };
        set.del("192.0.2.4").expect("del nonexistent should not fail");
        teardown(&set);
    }

    #[test]
    #[serial]
    fn contains_true_after_add_false_after_del() {
        let Some(set) = setup() else { return };
        set.add("192.0.2.5", None).expect("add");
        assert!(set.contains("192.0.2.5").expect("contains"));
        set.del("192.0.2.5").expect("del");
        assert!(!set.contains("192.0.2.5").expect("contains after del"));
        teardown(&set);
    }

    #[test]
    #[serial]
    fn save_and_restore_roundtrip() {
        use std::env;
        let Some(set) = setup() else { return };
        set.add("192.0.2.10", None).unwrap();
        set.add("192.0.2.11", None).unwrap();

        let tmp = env::temp_dir().join("martillo_ipset_test.restore");
        set.save(&tmp).expect("save");

        let content = std::fs::read_to_string(&tmp).expect("read");
        assert!(content.contains("192.0.2.10"));
        assert!(content.contains("192.0.2.11"));

        let _ = std::fs::remove_file(&tmp);
        teardown(&set);
    }

    #[test]
    #[serial]
    fn list_parses_plain_format_correctly() {
        let Some(set) = setup() else { return };
        set.add("198.51.100.1", None).unwrap();
        set.add("198.51.100.2", None).unwrap();
        set.add("198.51.100.3", None).unwrap();
        let ips = set.list().unwrap();
        assert_eq!(ips.len(), 3);
        assert!(ips.contains(&"198.51.100.1".to_string()));
        assert!(ips.contains(&"198.51.100.2".to_string()));
        assert!(ips.contains(&"198.51.100.3".to_string()));
        teardown(&set);
    }

    #[test]
    #[serial]
    fn list_empty_set_returns_empty_vec() {
        let Some(set) = setup() else { return };
        let ips = set.list().unwrap();
        assert_eq!(ips.len(), 0);
        teardown(&set);
    }

    #[test]
    #[serial]
    fn list_filters_non_ip_lines() {
        let Some(set) = setup() else { return };
        set.add("203.0.113.1", None).unwrap();
        set.add("203.0.113.2", None).unwrap();
        let ips = set.list().unwrap();
        for ip in &ips {
            assert!(
                ip.parse::<std::net::Ipv4Addr>().is_ok()
                    || ip.parse::<std::net::Ipv6Addr>().is_ok()
                    || ip.contains('/'),
                "got non-IP entry: {ip}"
            );
        }
        assert_eq!(ips.len(), 2);
        teardown(&set);
    }

    #[test]
    fn invalid_ip_rejected() {
        let result = validate_ip("not-an-ip");
        assert!(matches!(result, Err(IpsetError::InvalidIp(_))));
        assert!(validate_ip("1.2.3.4").is_ok());
        assert!(validate_ip("::1").is_ok());
    }

    #[test]
    #[serial]
    fn flush_clears_all() {
        let Some(set) = setup() else { return };
        set.add("203.0.113.1", None).unwrap();
        set.add("203.0.113.2", None).unwrap();
        assert_eq!(set.list().unwrap().len(), 2);
        set.flush().unwrap();
        assert_eq!(set.list().unwrap().len(), 0);
        teardown(&set);
    }

    #[test]
    #[serial]
    fn add_with_timeout() {
        let Some(set) = setup() else { return };
        set.add("203.0.113.10", Some(2)).expect("add with timeout");
        assert!(set.contains("203.0.113.10").unwrap());
        std::thread::sleep(std::time::Duration::from_secs(3));
        assert!(!set.contains("203.0.113.10").unwrap(), "timeout should expire");
        teardown(&set);
    }

    #[test]
    fn list_on_nonexistent_set_returns_empty() {
        let bogus = Ipset::new("nonexistent_set_zzz_999");
        let result = bogus.list();
        assert!(result.is_ok(), "list on nonexistent should not error");
        assert_eq!(result.unwrap().len(), 0);
    }

    #[test]
    #[serial]
    fn bulk_1000_ips_performance() {
        let Some(set) = setup() else { return };
        let start = std::time::Instant::now();
        for i in 0..1000u32 {
            let ip = format!("10.99.{}.{}", i / 256, i % 256);
            set.add(&ip, None).expect("add");
        }
        let elapsed = start.elapsed();
        assert!(elapsed.as_secs() < 5, "1000 adds took {:?}", elapsed);
        assert_eq!(set.list().unwrap().len(), 1000);
        teardown(&set);
    }
}