seer-core 0.49.1

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use tracing::{debug, instrument};

use crate::error::Result;
use crate::lookup::{LookupResult, SmartLookup};
use crate::status::{StatusClient, StatusResponse};

/// Side-by-side comparison of two domains across registration, DNS, and SSL.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DomainDiff {
    pub domain_a: String,
    pub domain_b: String,
    pub registration: RegistrationDiff,
    pub dns: DnsDiff,
    pub ssl: SslDiff,
}

/// Registration data comparison (registrar, organization, dates).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RegistrationDiff {
    pub registrar: (Option<String>, Option<String>),
    pub organization: (Option<String>, Option<String>),
    pub created: (Option<String>, Option<String>),
    pub expires: (Option<String>, Option<String>),
}

/// DNS resolution comparison (A records, nameservers, reachability).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DnsDiff {
    pub a_records: (Vec<String>, Vec<String>),
    pub nameservers: (Vec<String>, Vec<String>),
    pub resolves: (bool, bool),
}

/// SSL certificate comparison (issuer, validity, remaining days).
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SslDiff {
    pub issuer: (Option<String>, Option<String>),
    pub valid_until: (Option<String>, Option<String>),
    pub days_remaining: (Option<i64>, Option<i64>),
    pub is_valid: (Option<bool>, Option<bool>),
}

/// Compares two domains by running lookups and status checks concurrently.
#[derive(Default)]
pub struct DomainDiffer {
    lookup: SmartLookup,
    status_client: StatusClient,
}

impl DomainDiffer {
    pub fn new() -> Self {
        Self::default()
    }

    /// Compares two domains, returning their registration, DNS, and SSL differences.
    ///
    /// All four network calls (lookup + status for each domain) run concurrently.
    #[instrument(skip(self), fields(domain_a = %domain_a, domain_b = %domain_b))]
    pub async fn diff(&self, domain_a: &str, domain_b: &str) -> Result<DomainDiff> {
        let domain_a = crate::validation::normalize_domain(domain_a)?;
        let domain_b = crate::validation::normalize_domain(domain_b)?;

        // Box::pin each branch so the four heavyweight futures live on the heap
        // instead of inlining into the join! state. Each lookup/status future
        // itself joins many protocol futures; inlined, the combined `diff`
        // future is ~105 KB and a single poll overflows a tokio worker stack in
        // debug builds (TUI `:diff a b` crash). Boxing keeps the poll shallow.
        let (lookup_a, lookup_b, status_a, status_b) = tokio::join!(
            Box::pin(self.lookup.lookup(&domain_a)),
            Box::pin(self.lookup.lookup(&domain_b)),
            Box::pin(self.status_client.check(&domain_a)),
            Box::pin(self.status_client.check(&domain_b)),
        );

        let registration = build_registration_diff(lookup_a.ok().as_ref(), lookup_b.ok().as_ref());
        let dns = build_dns_diff(status_a.as_ref().ok(), status_b.as_ref().ok());
        let ssl = build_ssl_diff(status_a.as_ref().ok(), status_b.as_ref().ok());

        debug!("Domain diff complete");

        Ok(DomainDiff {
            domain_a,
            domain_b,
            registration,
            dns,
            ssl,
        })
    }
}

/// `YYYY-MM-DD`, the date form every diff field uses.
fn ymd(date: DateTime<Utc>) -> String {
    date.format("%Y-%m-%d").to_string()
}

fn build_registration_diff(a: Option<&LookupResult>, b: Option<&LookupResult>) -> RegistrationDiff {
    // Both dates share LookupResult's RDAP-then-WHOIS fallback, so a diff is
    // never internally inconsistent about where its dates came from.
    let side = |r: Option<&LookupResult>| {
        (
            r.and_then(LookupResult::registrar),
            r.and_then(LookupResult::organization),
            r.and_then(LookupResult::creation_date).map(ymd),
            r.and_then(LookupResult::expiration_date).map(ymd),
        )
    };
    let ((registrar_a, org_a, created_a, expires_a), (registrar_b, org_b, created_b, expires_b)) =
        (side(a), side(b));

    RegistrationDiff {
        registrar: (registrar_a, registrar_b),
        organization: (org_a, org_b),
        created: (created_a, created_b),
        expires: (expires_a, expires_b),
    }
}

fn build_dns_diff(a: Option<&StatusResponse>, b: Option<&StatusResponse>) -> DnsDiff {
    let side = |s: Option<&StatusResponse>| {
        s.and_then(|s| s.dns_resolution.as_ref())
            .map(|d| (d.a_records.clone(), d.nameservers.clone(), d.resolves))
            .unwrap_or_default()
    };
    let ((a_records_a, ns_a, resolves_a), (a_records_b, ns_b, resolves_b)) = (side(a), side(b));

    DnsDiff {
        a_records: (a_records_a, a_records_b),
        nameservers: (ns_a, ns_b),
        resolves: (resolves_a, resolves_b),
    }
}

fn build_ssl_diff(a: Option<&StatusResponse>, b: Option<&StatusResponse>) -> SslDiff {
    let side = |s: Option<&StatusResponse>| {
        let cert = s.and_then(|s| s.certificate.as_ref());
        (
            cert.map(|c| c.issuer.clone()),
            cert.map(|c| ymd(c.valid_until)),
            cert.map(|c| c.days_until_expiry),
            cert.map(|c| c.is_valid),
        )
    };
    let (
        (issuer_a, valid_until_a, days_a, is_valid_a),
        (issuer_b, valid_until_b, days_b, is_valid_b),
    ) = (side(a), side(b));

    SslDiff {
        issuer: (issuer_a, issuer_b),
        valid_until: (valid_until_a, valid_until_b),
        days_remaining: (days_a, days_b),
        is_valid: (is_valid_a, is_valid_b),
    }
}

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

    #[test]
    fn test_domain_diff_serialization() {
        let diff = DomainDiff {
            domain_a: "example.com".to_string(),
            domain_b: "google.com".to_string(),
            registration: RegistrationDiff {
                registrar: (Some("IANA".to_string()), Some("MarkMonitor".to_string())),
                organization: (None, Some("Google LLC".to_string())),
                created: (
                    Some("1995-08-14".to_string()),
                    Some("1997-09-15".to_string()),
                ),
                expires: (
                    Some("2026-08-13".to_string()),
                    Some("2028-09-14".to_string()),
                ),
            },
            dns: DnsDiff {
                a_records: (
                    vec!["93.184.216.34".to_string()],
                    vec!["142.250.185.46".to_string()],
                ),
                nameservers: (
                    vec!["a.iana-servers.net".to_string()],
                    vec!["ns1.google.com".to_string()],
                ),
                resolves: (true, true),
            },
            ssl: SslDiff {
                issuer: (
                    Some("DigiCert Inc".to_string()),
                    Some("Google Trust Services".to_string()),
                ),
                valid_until: (
                    Some("2025-03-01".to_string()),
                    Some("2025-02-15".to_string()),
                ),
                days_remaining: (Some(89), Some(75)),
                is_valid: (Some(true), Some(true)),
            },
        };

        let json = serde_json::to_string(&diff).unwrap();
        assert!(json.contains("example.com"));
        assert!(json.contains("google.com"));
        assert!(json.contains("IANA"));
        assert!(json.contains("MarkMonitor"));
    }

    #[test]
    fn extract_dates_rdap_falls_back_to_whois_creation_date() {
        use crate::rdap::RdapResponse;
        use crate::whois::WhoisResponse;

        // RDAP response with no `registration` event -> creation_date() is None.
        let rdap = RdapResponse::default();
        assert!(rdap.creation_date().is_none());

        // WHOIS fallback carries a creation date.
        let whois = WhoisResponse::parse_internal(
            "example.com",
            "whois.verisign-grs.com",
            "Domain Name: example.com\nCreation Date: 1995-08-14T04:00:00Z\n",
        );
        assert!(
            whois.creation_date.is_some(),
            "whois should parse creation date"
        );

        let result = LookupResult::Rdap {
            data: Box::new(rdap),
            whois_fallback: Some(whois),
        };
        // created must use the WHOIS fallback, matching the expiration ladder,
        // rather than being left None.
        let diff = build_registration_diff(Some(&result), None);
        assert_eq!(diff.created.0.as_deref(), Some("1995-08-14"));
    }

    #[test]
    fn test_build_registration_diff_both_none() {
        let diff = build_registration_diff(None, None);
        assert!(diff.registrar.0.is_none());
        assert!(diff.registrar.1.is_none());
        assert!(diff.organization.0.is_none());
        assert!(diff.organization.1.is_none());
        assert!(diff.created.0.is_none());
        assert!(diff.created.1.is_none());
        assert!(diff.expires.0.is_none());
        assert!(diff.expires.1.is_none());
    }

    #[test]
    fn test_build_dns_diff_both_none() {
        let diff = build_dns_diff(None, None);
        assert!(diff.a_records.0.is_empty());
        assert!(diff.a_records.1.is_empty());
        assert!(diff.nameservers.0.is_empty());
        assert!(diff.nameservers.1.is_empty());
        assert!(!diff.resolves.0);
        assert!(!diff.resolves.1);
    }

    #[test]
    fn test_build_ssl_diff_both_none() {
        let diff = build_ssl_diff(None, None);
        assert!(diff.issuer.0.is_none());
        assert!(diff.issuer.1.is_none());
        assert!(diff.valid_until.0.is_none());
        assert!(diff.valid_until.1.is_none());
        assert!(diff.days_remaining.0.is_none());
        assert!(diff.days_remaining.1.is_none());
        assert!(diff.is_valid.0.is_none());
        assert!(diff.is_valid.1.is_none());
    }

    #[test]
    fn test_domain_differ_default() {
        let differ = DomainDiffer::default();
        // Just verify construction works
        let _ = differ;
    }

    /// Regression guard for a debug-build stack overflow (TUI `:diff a b`).
    ///
    /// `diff()` joins four heavyweight futures (lookup ×2, status ×2), each of
    /// which internally joins many protocol futures (RDAP/WHOIS/DNS/SSL/...).
    /// If those four are inlined into the `join!` state instead of boxed, the
    /// combined future balloons to tens of KB; a single inline poll then
    /// overflows a 2 MB tokio worker stack once nested under the TUI's extra
    /// `handle_action → data::fetch` wrapper frames. Boxing the joined futures
    /// keeps this future small and the poll shallow.
    #[test]
    fn diff_future_stays_small_enough_for_the_stack() {
        let differ = DomainDiffer::new();
        // Construct but never await — keeps the test hermetic (no network).
        let fut = differ.diff("example.com", "example.org");
        let size = size_of_val(&fut);
        assert!(
            size < 8_192,
            "diff() future is {size} bytes; the four joined lookup/status \
             futures must be boxed so they don't inline onto the poll stack"
        );
    }
}