seer-core 0.20.1

use std::collections::HashMap;
use std::net::Ipv6Addr;
use std::str::FromStr;
use std::sync::{Arc, Mutex, Weak};
use std::time::Duration;

use chrono::{DateTime, Utc};
use once_cell::sync::Lazy;
use regex::Regex;
use serde::{Deserialize, Serialize};
use tokio::sync::Notify;
use tracing::{debug, instrument, warn};

use tokio::time::timeout as tokio_timeout;

use crate::availability::{AvailabilityChecker, AvailabilityResult};
use crate::cache::TtlCache;
use crate::error::{Result, SeerError};
use crate::rdap::{RdapClient, RdapResponse};
use crate::whois::{get_registry_url, get_tld, WhoisClient, WhoisResponse};

/// Cache TTL for lookup results (5 minutes).
const LOOKUP_CACHE_TTL: Duration = Duration::from_secs(5 * 60);

/// Grace period for the second protocol after the first one finishes.
/// If WHOIS finishes and RDAP hasn't responded within this window, we
/// use the WHOIS result rather than waiting the full RDAP timeout.
const PROTOCOL_GRACE_PERIOD: Duration = Duration::from_secs(5);

/// Maximum length for public-facing error strings.
const MAX_PUBLIC_ERROR_LEN: usize = 256;

/// Global cache for lookup results to avoid redundant network calls.
static LOOKUP_CACHE: Lazy<TtlCache<String, LookupResult>> =
    Lazy::new(|| TtlCache::new(LOOKUP_CACHE_TTL));

/// In-flight lookup coalescing map: normalized-domain -> Weak<Notify>.
/// Only one network race runs per unique domain at a time; concurrent callers
/// wait on the shared Notify and then read the result from LOOKUP_CACHE.
static LOOKUP_INFLIGHT: Lazy<Mutex<HashMap<String, Weak<Notify>>>> =
    Lazy::new(|| Mutex::new(HashMap::new()));

/// Regex patterns for stripping IP literals from public error messages.
static IPV4_RE: Lazy<Regex> =
    Lazy::new(|| Regex::new(r"\b(?:\d{1,3}\.){3}\d{1,3}\b").expect("IPV4_RE is a valid regex"));

/// Candidate pattern for IPv6 literals: a hex/colon token containing either
/// a `::` compression or at least three colons. This catches plausible IPv6
/// addresses cheaply; each match is then validated by `Ipv6Addr::from_str`
/// before redaction, so MAC fragments, hex hashes, and similar colon-laden
/// tokens are left alone.
static IPV6_CANDIDATE_RE: Lazy<Regex> = Lazy::new(|| {
    Regex::new(r"\b[0-9a-fA-F:]*(?:::|(?:[0-9a-fA-F]{1,4}:){3,})[0-9a-fA-F:]*\b")
        .expect("IPV6_CANDIDATE_RE is a valid regex")
});

/// Redact substrings that parse as valid IPv6 addresses, leaving non-IPv6
/// tokens (e.g. `af:ba:12`) untouched.
fn strip_ipv6(msg: &str) -> String {
    IPV6_CANDIDATE_RE
        .replace_all(msg, |caps: &regex::Captures| {
            let candidate = &caps[0];
            if Ipv6Addr::from_str(candidate).is_ok() {
                "[ip-redacted]".to_string()
            } else {
                candidate.to_string()
            }
        })
        .into_owned()
}

/// Test-only hook: counts the number of times `lookup_concurrent` is actually
/// invoked (i.e., the underlying network race runs). Used to verify request
/// coalescing. Not exposed outside the crate.
#[cfg(test)]
static LOOKUP_CONCURRENT_CALLS: Lazy<std::sync::atomic::AtomicUsize> =
    Lazy::new(|| std::sync::atomic::AtomicUsize::new(0));

/// Sanitizes an error message for inclusion in a public-facing response.
///
/// Strips IPv4 and IPv6 literals (to avoid leaking internal addresses when
/// an SSRF guard rejects a resolved URL) and caps the total length to
/// [`MAX_PUBLIC_ERROR_LEN`] characters.
fn sanitize_error_for_public(msg: &str) -> String {
    let s = IPV4_RE.replace_all(msg, "[ip-redacted]");
    let s = strip_ipv6(&s);
    if s.chars().count() > MAX_PUBLIC_ERROR_LEN {
        let mut trunc: String = s.chars().take(MAX_PUBLIC_ERROR_LEN).collect();
        trunc.push('…');
        trunc
    } else {
        s
    }
}

/// RAII guard for the in-flight-lookup slot. On drop, removes the entry
/// from `LOOKUP_INFLIGHT` and notifies any waiters so they can read the
/// freshly-populated cache.
///
/// NOTE on failed-owner retry semantics:
/// When the owning task's lookup fails, `InflightGuard::drop` runs, the
/// `HashMap` entry is removed, and `notify_waiters()` fires. Waiters wake,
/// observe an empty cache, and one of them becomes the new owner — triggering
/// a fresh network race. This means transient failures are automatically
/// retried by any concurrent waiter. Callers that observe a timeout error
/// should not assume no work is in flight; another concurrent caller may
/// already be retrying.
struct InflightGuard {
    key: String,
    notify: Arc<Notify>,
}

impl Drop for InflightGuard {
    fn drop(&mut self) {
        // Recover from mutex poisoning rather than leaking the HashMap entry.
        // A poisoned mutex here would otherwise strand the key in the map
        // until process exit, permanently blocking future lookups for this
        // domain from acquiring ownership.
        let mut inflight = LOOKUP_INFLIGHT.lock().unwrap_or_else(|p| p.into_inner());
        inflight.remove(&self.key);
        self.notify.notify_waiters();
    }
}

/// Internal classification of the RDAP leg of a concurrent lookup.
///
/// Distinguishing `NoData` (HTTP 200 but response was missing useful fields)
/// from `Error` lets the orchestrator prefer a thin WHOIS result over the
/// availability fallback when RDAP silently returned nothing.
enum RdapOutcome {
    Useful(RdapResponse),
    NoData(RdapResponse),
    Error(SeerError),
    /// RDAP future did not complete within the grace period after the other
    /// protocol finished.
    GraceTimeout,
}

/// Progress callback for smart lookup operations.
/// Called with a message describing the current phase of the lookup.
pub type LookupProgressCallback = Arc<dyn Fn(&str) + Send + Sync>;

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "source", rename_all = "lowercase")]
pub enum LookupResult {
    Rdap {
        data: Box<RdapResponse>,
        #[serde(skip_serializing_if = "Option::is_none")]
        whois_fallback: Option<WhoisResponse>,
    },
    Whois {
        data: WhoisResponse,
        rdap_error: Option<String>,
        #[serde(skip_serializing_if = "Option::is_none")]
        rdap_fallback: Option<Box<RdapResponse>>,
    },
    Available {
        data: Box<AvailabilityResult>,
        rdap_error: String,
        whois_error: String,
    },
}

impl LookupResult {
    /// Returns the domain name from the lookup result.
    pub fn domain_name(&self) -> Option<String> {
        match self {
            LookupResult::Rdap { data, .. } => data.domain_name().map(String::from),
            LookupResult::Whois { data, .. } => Some(data.domain.clone()),
            LookupResult::Available { data, .. } => Some(data.domain.clone()),
        }
    }

    /// Returns the registrar name, preferring RDAP data with WHOIS fallback.
    pub fn registrar(&self) -> Option<String> {
        match self {
            LookupResult::Rdap {
                data,
                whois_fallback,
            } => data
                .get_registrar()
                .or_else(|| whois_fallback.as_ref().and_then(|w| w.registrar.clone())),
            LookupResult::Whois { data, .. } => data.registrar.clone(),
            LookupResult::Available { .. } => None,
        }
    }

    /// Returns the registrant organization, preferring RDAP data with WHOIS fallback.
    pub fn organization(&self) -> Option<String> {
        match self {
            LookupResult::Rdap {
                data,
                whois_fallback,
            } => data
                .get_registrant_organization()
                .or_else(|| whois_fallback.as_ref().and_then(|w| w.organization.clone())),
            LookupResult::Whois { data, .. } => data.organization.clone(),
            LookupResult::Available { .. } => None,
        }
    }

    /// Returns true if the result came from RDAP.
    pub fn is_rdap(&self) -> bool {
        matches!(self, LookupResult::Rdap { .. })
    }

    /// Returns true if the result came from WHOIS.
    pub fn is_whois(&self) -> bool {
        matches!(self, LookupResult::Whois { .. })
    }

    /// Returns true if the result is an availability check fallback.
    pub fn is_available(&self) -> bool {
        matches!(self, LookupResult::Available { .. })
    }

    /// Returns the expiration date and registrar info from the lookup result.
    pub fn expiration_info(&self) -> (Option<DateTime<Utc>>, Option<String>) {
        match self {
            LookupResult::Rdap {
                data,
                whois_fallback,
            } => {
                // Try to get expiration from RDAP events
                let expiration_date = data
                    .events
                    .iter()
                    .find(|e| e.event_action == "expiration")
                    .and_then(|e| e.parsed_date())
                    .or_else(|| {
                        // Fallback to WHOIS if available
                        whois_fallback.as_ref().and_then(|w| w.expiration_date)
                    });

                let registrar = data
                    .get_registrar()
                    .or_else(|| whois_fallback.as_ref().and_then(|w| w.registrar.clone()));

                (expiration_date, registrar)
            }
            LookupResult::Whois { data, .. } => (data.expiration_date, data.registrar.clone()),
            LookupResult::Available { .. } => (None, None),
        }
    }
}

/// Before caching, trim raw WHOIS response to limit cache memory.
/// A full WHOIS raw_response can be up to 1 MB; we cap it at 32 KB which is
/// plenty for the parsed fields while preventing the cache from ballooning.
fn trim_for_cache(mut result: LookupResult) -> LookupResult {
    const MAX_RAW: usize = 32 * 1024;

    match result {
        LookupResult::Whois { ref mut data, .. } => {
            if data.raw_response.len() > MAX_RAW {
                data.raw_response.truncate(MAX_RAW);
                data.raw_response.push_str("\n... [truncated for cache]");
            }
        }
        LookupResult::Rdap {
            ref mut whois_fallback,
            ..
        } => {
            if let Some(ref mut w) = whois_fallback {
                if w.raw_response.len() > MAX_RAW {
                    w.raw_response.truncate(MAX_RAW);
                    w.raw_response.push_str("\n... [truncated for cache]");
                }
            }
        }
        LookupResult::Available { .. } => {}
    }

    result
}

#[derive(Debug, Clone)]
pub struct SmartLookup {
    rdap_client: RdapClient,
    whois_client: WhoisClient,
    availability_checker: AvailabilityChecker,
    /// Deprecated: both protocols are now always attempted concurrently.
    prefer_rdap: bool,
    /// Deprecated: WHOIS data is now always attached when available.
    include_fallback: bool,
}

impl Default for SmartLookup {
    fn default() -> Self {
        Self::new()
    }
}

impl SmartLookup {
    /// Creates a new SmartLookup that runs RDAP and WHOIS concurrently,
    /// falling back to an availability check if both fail.
    pub fn new() -> Self {
        Self {
            rdap_client: RdapClient::new(),
            whois_client: WhoisClient::new(),
            availability_checker: AvailabilityChecker::new(),
            prefer_rdap: true,
            include_fallback: false,
        }
    }

    /// Deprecated: both protocols are now always attempted concurrently.
    /// This method is kept for API compatibility but has no effect.
    #[deprecated(note = "This field has no effect. RDAP is always tried concurrently with WHOIS.")]
    pub fn prefer_rdap(mut self, prefer: bool) -> Self {
        self.prefer_rdap = prefer;
        self
    }

    /// Deprecated: WHOIS data is now always attached when available.
    /// This method is kept for API compatibility but has no effect.
    #[deprecated(note = "This field has no effect. RDAP is always tried concurrently with WHOIS.")]
    pub fn include_fallback(mut self, include: bool) -> Self {
        self.include_fallback = include;
        self
    }

    /// Performs a smart lookup for a domain, trying both RDAP and WHOIS concurrently.
    /// Falls back to an availability check if both fail.
    /// Results are cached for 5 minutes to avoid redundant network calls.
    #[instrument(skip(self), fields(domain = %domain))]
    pub async fn lookup(&self, domain: &str) -> Result<LookupResult> {
        self.lookup_with_progress(domain, None).await
    }

    /// Performs a lookup with an optional progress callback.
    /// The callback is called with messages describing the current phase.
    /// Results are cached for 5 minutes. Concurrent lookups for the same
    /// domain are coalesced — only one network race runs per domain at a time.
    #[instrument(skip(self, progress), fields(domain = %domain))]
    pub async fn lookup_with_progress(
        &self,
        domain: &str,
        progress: Option<LookupProgressCallback>,
    ) -> Result<LookupResult> {
        let normalized = crate::validation::normalize_domain(domain)?;

        // Check cache first
        if let Some(cached) = LOOKUP_CACHE.get(&normalized) {
            debug!(domain = %normalized, "Returning cached lookup result");
            return Ok(cached);
        }

        // Coalesce in-flight lookups: if another task is already running a
        // race for this domain, wait on its Notify rather than starting a
        // second race. Two branches:
        //   - Waiter: another task owns the slot; await its notify, then
        //     read the cache. If the cache is still empty (owner failed),
        //     loop and re-contend for ownership.
        //   - Owner: no entry exists; insert a Weak handle, hold the Arc
        //     for the duration of the work, then remove and notify on drop.
        //
        // A `loop` with a separate lock-scope per iteration keeps the
        // `MutexGuard` from being held across any `.await`.
        let _guard = loop {
            enum Slot {
                Waiter(Arc<Notify>),
                Owner(InflightGuard),
            }

            let slot = {
                let mut inflight = LOOKUP_INFLIGHT
                    .lock()
                    .expect("LOOKUP_INFLIGHT mutex poisoned");
                match inflight.get(&normalized).and_then(|w| w.upgrade()) {
                    Some(existing) => Slot::Waiter(existing),
                    None => {
                        let n = Arc::new(Notify::new());
                        inflight.insert(normalized.clone(), Arc::downgrade(&n));
                        Slot::Owner(InflightGuard {
                            key: normalized.clone(),
                            notify: n,
                        })
                    }
                }
            };

            match slot {
                Slot::Waiter(n) => {
                    debug!(domain = %normalized, "Waiting for in-flight lookup to complete");
                    n.notified().await;
                    if let Some(cached) = LOOKUP_CACHE.get(&normalized) {
                        return Ok(cached);
                    }
                    // Owner finished without populating the cache (failed
                    // or errored). Re-contend for ownership.
                    continue;
                }
                Slot::Owner(guard) => break guard,
            }
        };

        let result = self.lookup_concurrent(&normalized, progress).await?;

        // Cache a trimmed copy to limit memory usage before releasing
        // waiters (via guard drop) so they observe the cached value.
        LOOKUP_CACHE.insert(normalized.clone(), trim_for_cache(result.clone()));

        Ok(result)
    }

    /// Clears the lookup result cache.
    pub fn clear_cache() {
        LOOKUP_CACHE.clear();
    }

    #[instrument(skip(self, progress), fields(domain = %domain))]
    async fn lookup_concurrent(
        &self,
        domain: &str,
        progress: Option<LookupProgressCallback>,
    ) -> Result<LookupResult> {
        #[cfg(test)]
        LOOKUP_CONCURRENT_CALLS.fetch_add(1, std::sync::atomic::Ordering::SeqCst);

        debug!(domain = %domain, "Attempting RDAP and WHOIS concurrently");

        if let Some(ref cb) = progress {
            cb("Querying RDAP and WHOIS concurrently");
        }

        let rdap_fut = self.rdap_client.lookup_domain(domain);
        let whois_fut = self.whois_client.lookup(domain);

        tokio::pin!(rdap_fut);
        tokio::pin!(whois_fut);

        // Race: whichever finishes first gets a grace period for the other.
        //
        // We track whether each side completed naturally or was truncated by
        // the grace period, so downstream error messages can distinguish a
        // true timeout from a loser-truncation.
        enum LegOutcome<T> {
            Completed(T),
            GraceTruncated,
        }

        let (rdap_leg, whois_leg) = tokio::select! {
            rdap_res = &mut rdap_fut => {
                // RDAP finished first — give WHOIS a grace period
                let whois_leg = match tokio_timeout(PROTOCOL_GRACE_PERIOD, whois_fut).await {
                    Ok(res) => LegOutcome::Completed(res),
                    Err(_) => {
                        debug!("WHOIS did not finish within grace period, proceeding with RDAP only");
                        LegOutcome::GraceTruncated
                    }
                };
                (LegOutcome::Completed(rdap_res), whois_leg)
            }
            whois_res = &mut whois_fut => {
                // WHOIS finished first — give RDAP a grace period
                let rdap_leg = match tokio_timeout(PROTOCOL_GRACE_PERIOD, rdap_fut).await {
                    Ok(res) => LegOutcome::Completed(res),
                    Err(_) => {
                        debug!("RDAP did not finish within grace period, proceeding with WHOIS only");
                        LegOutcome::GraceTruncated
                    }
                };
                (rdap_leg, LegOutcome::Completed(whois_res))
            }
        };

        // Classify the RDAP leg.
        let rdap_outcome = match rdap_leg {
            LegOutcome::Completed(Ok(data)) => {
                if self.is_rdap_response_useful(&data) {
                    RdapOutcome::Useful(data)
                } else {
                    RdapOutcome::NoData(data)
                }
            }
            LegOutcome::Completed(Err(e)) => RdapOutcome::Error(e),
            LegOutcome::GraceTruncated => RdapOutcome::GraceTimeout,
        };

        // Phase 1: If RDAP returned useful data, use it as primary.
        if let RdapOutcome::Useful(rdap_data) = rdap_outcome {
            debug!("RDAP lookup successful");
            let whois_fallback = match whois_leg {
                LegOutcome::Completed(Ok(w)) => Some(w),
                _ => None,
            };
            return Ok(LookupResult::Rdap {
                data: Box::new(rdap_data),
                whois_fallback,
            });
        }

        // RDAP was not useful (NoData, Error, or GraceTimeout). Prefer WHOIS
        // if it returned any response, even a thin one — this is safer than
        // falling back to the availability heuristic when we have actual
        // registry data in hand.
        let (rdap_error_str, rdap_fallback_data) = match rdap_outcome {
            RdapOutcome::Useful(_) => {
                // Unreachable in this branch (we returned above), but handle
                // defensively rather than panicking across the FFI boundary.
                debug!("Unexpected RdapOutcome::Useful in fallback branch");
                (String::from("RDAP ok"), None)
            }
            RdapOutcome::NoData(data) => {
                ("RDAP response incomplete".to_string(), Some(Box::new(data)))
            }
            RdapOutcome::Error(e) => (e.to_string(), None),
            RdapOutcome::GraceTimeout => (
                format!(
                    "RDAP did not return within {}s grace period after WHOIS won",
                    PROTOCOL_GRACE_PERIOD.as_secs()
                ),
                None,
            ),
        };

        if let LegOutcome::Completed(Ok(whois_data)) = whois_leg {
            debug!("Using WHOIS result (RDAP not useful)");
            if let Some(ref cb) = progress {
                cb("RDAP not available (using WHOIS)");
            }
            return Ok(LookupResult::Whois {
                data: whois_data,
                rdap_error: Some(rdap_error_str),
                rdap_fallback: rdap_fallback_data,
            });
        }

        // Both sides failed to provide useful data. Craft a precise WHOIS
        // error string that distinguishes true errors from grace-period
        // truncation.
        let whois_error_str = match whois_leg {
            LegOutcome::Completed(Err(e)) => e.to_string(),
            LegOutcome::Completed(Ok(_)) => {
                // Already handled above; treat defensively.
                debug!("Unexpected completed-Ok WHOIS in availability fallback branch");
                "WHOIS returned but was not used".to_string()
            }
            LegOutcome::GraceTruncated => format!(
                "WHOIS did not return within {}s grace period after RDAP won",
                PROTOCOL_GRACE_PERIOD.as_secs()
            ),
        };

        self.availability_fallback(domain, rdap_error_str, whois_error_str, progress)
            .await
    }

    async fn availability_fallback(
        &self,
        domain: &str,
        rdap_error: String,
        whois_error: String,
        progress: Option<LookupProgressCallback>,
    ) -> Result<LookupResult> {
        if let Some(ref cb) = progress {
            cb("RDAP and WHOIS unavailable (checking availability)");
        }
        warn!(
            domain = %domain,
            rdap_error = %rdap_error,
            whois_error = %whois_error,
            "Both RDAP and WHOIS failed, falling back to availability check"
        );

        match self.availability_checker.check(domain).await {
            Ok(avail) => Ok(LookupResult::Available {
                data: Box::new(avail),
                rdap_error: sanitize_error_for_public(&rdap_error),
                whois_error: sanitize_error_for_public(&whois_error),
            }),
            Err(avail_err) => {
                let tld = get_tld(domain).unwrap_or("unknown");
                let registry_url = get_registry_url(tld).unwrap_or_else(|| {
                    format!("https://www.iana.org/domains/root/db/{}.html", tld)
                });
                Err(SeerError::LookupFailed {
                    domain: domain.to_string(),
                    details: format!(
                        "RDAP failed ({}), WHOIS failed ({}), availability check failed ({})",
                        rdap_error, whois_error, avail_err
                    ),
                    registry_url,
                })
            }
        }
    }

    fn is_rdap_response_useful(&self, response: &RdapResponse) -> bool {
        // Check if we have at least some meaningful data
        let has_name = response.ldh_name.is_some() || response.unicode_name.is_some();
        let has_dates = response
            .events
            .iter()
            .any(|e| e.event_action == "registration" || e.event_action == "expiration");
        let has_entities = !response.entities.is_empty();
        let has_nameservers = !response.nameservers.is_empty();
        let has_status = !response.status.is_empty();

        // Consider useful if we have the name plus at least one other piece of info
        has_name && (has_dates || has_entities || has_nameservers || has_status)
    }
}

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

    #[test]
    fn test_lookup_result_domain_name_whois() {
        let result = LookupResult::Whois {
            data: WhoisResponse {
                domain: "example.com".to_string(),
                registrar: Some("Test Registrar".to_string()),
                registrant: None,
                organization: None,
                registrant_email: None,
                registrant_phone: None,
                registrant_address: None,
                registrant_country: None,
                admin_name: None,
                admin_organization: None,
                admin_email: None,
                admin_phone: None,
                tech_name: None,
                tech_organization: None,
                tech_email: None,
                tech_phone: None,
                creation_date: None,
                expiration_date: None,
                updated_date: None,
                status: vec![],
                nameservers: vec![],
                dnssec: None,
                whois_server: "whois.example.com".to_string(),
                raw_response: String::new(),
            },
            rdap_error: None,
            rdap_fallback: None,
        };

        assert_eq!(result.domain_name(), Some("example.com".to_string()));
        assert_eq!(result.registrar(), Some("Test Registrar".to_string()));
        assert!(result.is_whois());
        assert!(!result.is_rdap());
        assert!(!result.is_available());
    }

    #[test]
    fn test_lookup_result_serialization() {
        let result = LookupResult::Whois {
            data: WhoisResponse {
                domain: "test.com".to_string(),
                registrar: None,
                registrant: None,
                organization: None,
                registrant_email: None,
                registrant_phone: None,
                registrant_address: None,
                registrant_country: None,
                admin_name: None,
                admin_organization: None,
                admin_email: None,
                admin_phone: None,
                tech_name: None,
                tech_organization: None,
                tech_email: None,
                tech_phone: None,
                creation_date: None,
                expiration_date: None,
                updated_date: None,
                status: vec![],
                nameservers: vec![],
                dnssec: None,
                whois_server: String::new(),
                raw_response: String::new(),
            },
            rdap_error: Some("RDAP failed".to_string()),
            rdap_fallback: None,
        };

        let json = serde_json::to_string(&result).unwrap();
        assert!(json.contains("\"source\":\"whois\""));
        assert!(json.contains("RDAP failed"));
    }

    #[test]
    fn test_lookup_result_available_serialization() {
        let result = LookupResult::Available {
            data: Box::new(AvailabilityResult {
                domain: "test123.xyz".to_string(),
                available: true,
                confidence: "medium".to_string(),
                method: "whois_error".to_string(),
                details: Some("WHOIS server indicates no matching records".to_string()),
            }),
            rdap_error: "RDAP failed".to_string(),
            whois_error: "WHOIS failed".to_string(),
        };

        let json = serde_json::to_string(&result).unwrap();
        assert!(json.contains("\"source\":\"available\""));
        assert!(json.contains("\"available\":true"));
        assert!(json.contains("test123.xyz"));

        assert_eq!(result.domain_name(), Some("test123.xyz".to_string()));
        assert!(result.is_available());
        assert!(!result.is_rdap());
        assert!(!result.is_whois());
        assert!(result.registrar().is_none());
        assert_eq!(result.expiration_info(), (None, None));
    }

    #[test]
    #[allow(deprecated)]
    fn test_smart_lookup_builder() {
        let lookup = SmartLookup::new().prefer_rdap(false).include_fallback(true);
        assert!(!lookup.prefer_rdap);
        assert!(lookup.include_fallback);
    }

    #[test]
    fn test_lookup_cache_clear() {
        SmartLookup::clear_cache();
        assert!(LOOKUP_CACHE.is_empty());
    }

    // ---------------- sanitize_error_for_public ----------------

    #[test]
    fn test_sanitize_strips_ipv4() {
        let msg = "RDAP URL resolves to reserved IP 10.0.0.1 which is forbidden";
        let sanitized = sanitize_error_for_public(msg);
        assert!(
            !sanitized.contains("10.0.0.1"),
            "IPv4 should be stripped, got: {}",
            sanitized
        );
        assert!(sanitized.contains("[ip-redacted]"));
    }

    #[test]
    fn test_sanitize_strips_multiple_ipv4() {
        let msg = "Could not connect to 192.168.1.1 after trying 127.0.0.1";
        let sanitized = sanitize_error_for_public(msg);
        assert!(!sanitized.contains("192.168.1.1"));
        assert!(!sanitized.contains("127.0.0.1"));
        // Two redactions expected.
        assert_eq!(sanitized.matches("[ip-redacted]").count(), 2);
    }

    #[test]
    fn test_sanitize_strips_ipv6() {
        let msg = "RDAP URL resolves to reserved IP fe80::1 which is forbidden";
        let sanitized = sanitize_error_for_public(msg);
        assert!(!sanitized.contains("fe80::1"));
        assert!(sanitized.contains("[ip-redacted]"));
    }

    #[test]
    fn sanitize_leaves_mac_address_like_tokens_alone() {
        let msg = "error code af:ba:12 at line 5";
        let out = sanitize_error_for_public(msg);
        assert!(
            out.contains("af:ba:12"),
            "MAC fragment should not be stripped: {}",
            out
        );
    }

    #[test]
    fn sanitize_strips_real_ipv6() {
        let msg = "cannot reach 2001:db8::1 — timeout";
        let out = sanitize_error_for_public(msg);
        assert!(!out.contains("2001:db8::1"));
        assert!(out.contains("[ip-redacted]"));
    }

    #[test]
    fn sanitize_strips_fe80_link_local() {
        let msg = "peer at fe80::1 unreachable";
        let out = sanitize_error_for_public(msg);
        assert!(out.contains("[ip-redacted]"));
    }

    #[test]
    fn test_sanitize_truncates_long_message() {
        // Build a 500-char message with no IPs.
        let long = "a".repeat(500);
        let sanitized = sanitize_error_for_public(&long);
        // Should cap at MAX_PUBLIC_ERROR_LEN chars + ellipsis.
        let char_count = sanitized.chars().count();
        assert_eq!(char_count, MAX_PUBLIC_ERROR_LEN + 1);
        assert!(sanitized.ends_with('…'));
    }

    #[test]
    fn test_sanitize_preserves_short_messages() {
        let msg = "RDAP timed out after 15s";
        let sanitized = sanitize_error_for_public(msg);
        assert_eq!(sanitized, msg);
    }

    // ---------------- RdapOutcome classification ----------------

    #[test]
    fn test_is_rdap_response_useful_detects_no_data() {
        use crate::rdap::RdapResponse;
        // Construct a response with a name but no events, entities, NS, or status
        // — this is the "200 OK but no useful fields" case that should be
        // classified as RdapOutcome::NoData (not Useful, not Error).
        let resp = RdapResponse {
            ldh_name: Some("example.com".to_string()),
            ..Default::default()
        };
        let lookup = SmartLookup::new();
        assert!(
            !lookup.is_rdap_response_useful(&resp),
            "Response with only a name should be classified as NoData"
        );

        // And one with a name + status IS useful (sanity check).
        let useful = RdapResponse {
            ldh_name: Some("example.com".to_string()),
            status: vec!["active".to_string()],
            ..Default::default()
        };
        assert!(lookup.is_rdap_response_useful(&useful));
    }

    // ---------------- Coalescing ----------------

    // Verifies that when multiple concurrent lookups hit the in-flight map
    // for the same domain, later arrivals observe the existing Weak<Notify>
    // and become waiters rather than racing a second lookup. We test the
    // map-level primitive here because the full SmartLookup pipeline
    // requires network access to exercise.
    #[tokio::test]
    async fn test_inflight_coalescing_map() {
        // Clear any prior state.
        {
            let mut m = LOOKUP_INFLIGHT.lock().unwrap();
            m.clear();
        }

        let domain = "__test_coalesce.example.".to_string();

        // First caller: no entry → becomes owner.
        let owner_notify = Arc::new(Notify::new());
        {
            let mut m = LOOKUP_INFLIGHT.lock().unwrap();
            assert!(m.get(&domain).and_then(|w| w.upgrade()).is_none());
            m.insert(domain.clone(), Arc::downgrade(&owner_notify));
        }

        // Second caller: sees the existing Weak and upgrades.
        let waiter = {
            let m = LOOKUP_INFLIGHT.lock().unwrap();
            m.get(&domain)
                .and_then(|w| w.upgrade())
                .expect("Second caller must observe in-flight entry")
        };

        // Waiter listens in the background.
        let waiter_clone = waiter.clone();
        let handle = tokio::spawn(async move {
            waiter_clone.notified().await;
        });

        // Simulate owner completing.
        tokio::time::sleep(Duration::from_millis(20)).await;
        {
            let mut m = LOOKUP_INFLIGHT.lock().unwrap();
            m.remove(&domain);
        }
        owner_notify.notify_waiters();

        // Waiter should unblock quickly.
        tokio::time::timeout(Duration::from_secs(1), handle)
            .await
            .expect("waiter must unblock after notify")
            .expect("waiter task joined cleanly");

        // After owner removes entry and drops its Arc, the Weak is dead.
        drop(owner_notify);
        drop(waiter);
        let m = LOOKUP_INFLIGHT.lock().unwrap();
        assert!(m.get(&domain).and_then(|w| w.upgrade()).is_none());
    }

    // Demonstrates that the `sanitize_error_for_public` helper is applied
    // to the rdap_error / whois_error fields written into the `Available`
    // variant. We check the call site indirectly: construct a Available
    // manually and then verify a raw error with an IP becomes redacted.
    // (Integration via real clients would require network.)
    #[test]
    fn test_sanitize_applied_to_available_fields() {
        let rdap_raw = "RDAP URL resolves to reserved IP 10.0.0.1";
        let whois_raw = "connection refused at 192.168.0.5";
        let sanitized_rdap = sanitize_error_for_public(rdap_raw);
        let sanitized_whois = sanitize_error_for_public(whois_raw);
        let result = LookupResult::Available {
            data: Box::new(AvailabilityResult {
                domain: "unreg.test".to_string(),
                available: true,
                confidence: "low".to_string(),
                method: "heuristic".to_string(),
                details: None,
            }),
            rdap_error: sanitized_rdap,
            whois_error: sanitized_whois,
        };
        if let LookupResult::Available {
            rdap_error,
            whois_error,
            ..
        } = result
        {
            assert!(!rdap_error.contains("10.0.0.1"));
            assert!(!whois_error.contains("192.168.0.5"));
            assert!(rdap_error.contains("[ip-redacted]"));
            assert!(whois_error.contains("[ip-redacted]"));
        } else {
            panic!("expected Available variant");
        }
    }
}