//! One receipt countersigned post-quantum, and a steward's keys attested by
//! the witnesses that follow its seals (log-seal §4.2, §5.7).

use ed25519_dalek::SigningKey;
use jcp_grant::issue;
use jcp_logseal::attest::{attest_stating, attested_keys, countersign, read_key_attestation, verify_countersigned, AttestedKeys};
use jcp_logseal::{
    keys_for, prove_consistency, seal_log, seal_log_committing, verify_following, HybridKey, Policy, SealError, StewardKeys, Trust, Witness,
    Witnessing,
};
use jcp_receipt::ReceiptLog;
use jcp_runtime::{Price, Runtime};
use jcp_schema::{Capability, ContentId, Did, Energy, Frame, FrameKind, Funds, Grant, Trust as FrameTrust};

const STEWARD: &str = "did:example:sealed";

fn sk(s: u8) -> SigningKey {
    SigningKey::from_bytes(&[s; 32])
}

fn did(s: u8) -> Did {
    Did::from_verifying_key(&sk(s).verifying_key())
}

fn steward_key() -> HybridKey {
    HybridKey::new(sk(7), [9; 32])
}

fn keys_of(k: &HybridKey) -> StewardKeys {
    StewardKeys { ed: k.ed_public(), pq: k.pq_public().to_vec() }
}

/// A log of `n` decisions; from `turn` on its receipts are under `then`.
fn log(n: usize, turn: Option<(usize, SigningKey)>) -> Vec<Vec<u8>> {
    let sg = issue(
        &sk(1),
        Grant {
            issuer: did(1),
            subject: did(2),
            capability: Capability::new(ContentId::of_bytes(b"sealed"), ["pay"]),
            budget_uj: 1_000_000,
            budget_funds: Some(Funds::new("USD", 1_000_000)),
            caveats: Vec::new(),
            expiry: 0,
            parent: None,
            delegate_depth: None,
            nonce: [5; 16],
        },
    )
    .unwrap();
    let mut rt = Runtime::new();
    let mut log = ReceiptLog::new(sk(7), STEWARD);
    let mut turn = turn;
    for i in 0..n {
        if turn.as_ref().is_some_and(|(at, _)| *at == i) {
            log.rekey(turn.take().expect("one change").1);
        }
        let frame = Frame {
            kind: FrameKind::ToolCall,
            trust: FrameTrust::Control,
            grant_id: sg.grant.id(),
            action: "pay".into(),
            resource: ContentId::of_bytes(b"sealed"),
            payload_hash: ContentId::of_bytes(format!("attested:{i}").as_bytes()),
            model: None,
        };
        let d = rt.decide_priced(&frame, &sg, did(2), Energy::measured(10), &Price::new("USD", 100), 10);
        log.append(&frame, &sg.grant, &d);
    }
    log.entries().to_vec()
}

fn witness(seed: u8, key_id: ContentId) -> Witness {
    let mut w = Witness::new(HybridKey::new(sk(40 + seed), [40 + seed; 32]));
    w.watch(STEWARD, key_id);
    w
}

#[test]
fn a_receipt_countersigned_stands_post_quantum_before_any_seal_covers_it() {
    let key = steward_key();
    let entries = log(5, None);
    // the last receipt, after a seal of the first four
    let _seal = seal_log(&entries[..4], STEWARD, &key, None).unwrap();
    let c = countersign(&entries[4], STEWARD, &key).unwrap();
    assert_eq!(verify_countersigned(&entries[4], &c, STEWARD, &keys_of(&key)), Ok(()));
    assert_eq!(verify_countersigned(&entries[3], &c, STEWARD, &keys_of(&key)), Err(SealError::ProofInvalid));
    // the receipt key alone, beside a post-quantum key not the steward's, is not the steward's countersignature
    let half = HybridKey::new(sk(7), [12; 32]);
    let by_half = countersign(&entries[4], STEWARD, &half).unwrap();
    assert_eq!(verify_countersigned(&entries[4], &by_half, STEWARD, &keys_of(&key)), Err(SealError::WrongKey));
    // a member a countersignature does not define, its signatures otherwise intact
    let mut record: serde_json::Value = jcp_schema::from_canonical_cbor(&c).unwrap();
    record.as_object_mut().unwrap().insert("note".into(), serde_json::json!("extra"));
    let padded = jcp_receipt::jcr1::canonical_cbor(&record).unwrap();
    assert!(matches!(verify_countersigned(&entries[4], &padded, STEWARD, &keys_of(&key)), Err(SealError::Malformed(_))));
    // a bit changed in either signature
    let mut bent = c.clone();
    let at = bent.len() - 10;
    bent[at] ^= 1;
    assert!(verify_countersigned(&entries[4], &bent, STEWARD, &keys_of(&key)).is_err());
}

#[test]
fn witnesses_attest_the_keys_of_the_seals_they_cosigned() {
    let key = steward_key();
    let id = keys_of(&key).id();
    let entries = log(9, None);
    let s1 = seal_log(&entries[..4], STEWARD, &key, None).unwrap();
    let s2 = seal_log(&entries[..7], STEWARD, &key, Some(&s1)).unwrap();
    let path = prove_consistency(&entries, 4, 7).unwrap();
    let mut ws: Vec<Witness> = (1..=3).map(|i| witness(i, id)).collect();
    for w in &mut ws {
        w.cosign(STEWARD, std::slice::from_ref(&s1), &[], 100).unwrap();
        w.cosign(STEWARD, &[s1.clone(), s2.clone()], &path, 200).unwrap();
    }
    let trusted: Vec<ContentId> = ws.iter().map(|w| w.keys().id()).collect();
    let attestations: Vec<Vec<u8>> = ws.iter().map(|w| w.attest_keys(STEWARD, 300).unwrap()).collect();
    let a = read_key_attestation(&attestations[0], STEWARD).unwrap();
    assert_eq!((a.key_id, a.seal, a.count, a.time, a.witness), (id, ContentId::of_bytes(&s2), 7, 300, trusted[0]));

    let rule = Witnessing { witnesses: &trusted, quorum: 2, not_before: 250 };
    let got = attested_keys(STEWARD, &attestations, &rule).unwrap();
    assert_eq!(got, AttestedKeys { key_id: id, witnesses: { let mut t = trusted.clone(); t.sort(); t }, seal: ContentId::of_bytes(&s2), count: 7 });
    // a reader given no steward key id takes the keys from the seal the witnesses name and reads on
    let keys = keys_for(&s2, &got.key_id).unwrap();
    let reading = verify_following(&entries[..7], &[s1.clone(), s2.clone()], STEWARD, &keys, Trust::SealsAlone, Policy::RequireSealed, None).unwrap();
    assert_eq!(reading.standing.sealed, 7);

    // witnesses that last saw different seals: the reader starts from the newest one named
    let behind = attest_stating(STEWARD, &id, &ContentId::of_bytes(&s1), 4, 300, &HybridKey::new(sk(43), [43; 32])).unwrap();
    let mixed = [attestations[0].clone(), attestations[1].clone(), behind];
    let got = attested_keys(STEWARD, &mixed, &rule).unwrap();
    assert_eq!((got.seal, got.count, got.witnesses.len()), (ContentId::of_bytes(&s2), 7, 3));

    // one trusted attestation is not a quorum; untrusted, stale, altered and other stewards' ones do not count
    assert_eq!(attested_keys(STEWARD, &attestations[..1], &rule), Err(SealError::KeysUnattested { have: 1, need: 2 }));
    assert_eq!(
        attested_keys(STEWARD, &attestations, &Witnessing { witnesses: &trusted[..1], quorum: 2, not_before: 0 }),
        Err(SealError::KeysUnattested { have: 1, need: 2 })
    );
    assert_eq!(
        attested_keys(STEWARD, &attestations, &Witnessing { witnesses: &trusted, quorum: 2, not_before: 301 }),
        Err(SealError::KeysUnattested { have: 0, need: 2 })
    );
    let mut altered = attestations.clone();
    for a in altered.iter_mut().take(2) {
        let at = a.len() - 10;
        a[at] ^= 1;
    }
    assert_eq!(attested_keys(STEWARD, &altered, &rule), Err(SealError::KeysUnattested { have: 1, need: 2 }));
    assert_eq!(attested_keys("did:example:other", &attestations, &rule), Err(SealError::KeysUnattested { have: 0, need: 2 }));

    // a witness that attests other keys later: its latest attestation is the one that counts
    let liar = HybridKey::new(sk(41), [41; 32]);
    let other_id = keys_of(&HybridKey::new(sk(8), [10; 32])).id();
    let lie = attest_stating(STEWARD, &other_id, &ContentId::of_bytes(&s2), 7, 310, &liar).unwrap();
    let with_lie = [attestations.clone(), vec![lie.clone()]].concat();
    assert_eq!(attested_keys(STEWARD, &with_lie, &rule).map(|k| k.key_id), Ok(id), "two of three still agree");
    assert_eq!(attested_keys(STEWARD, &with_lie, &Witnessing { quorum: 3, ..rule }), Err(SealError::KeysUnattested { have: 2, need: 3 }));
    // a quorum of no more than half: two witnesses, two key ids, each with one
    assert_eq!(attested_keys(STEWARD, &[attestations[1].clone(), lie], &Witnessing { quorum: 1, ..rule }), Err(SealError::KeysDisputed));
}

#[test]
fn an_attestation_follows_the_steward_through_a_change_of_keys() {
    let old = steward_key();
    let new = HybridKey::new(sk(17), [19; 32]);
    let entries = log(9, Some((5, sk(17))));
    let first = seal_log_committing(&entries[..5], STEWARD, &old, None, &keys_of(&new).id()).unwrap();
    let second = seal_log(&entries, STEWARD, &new, Some(&first)).unwrap();
    let path = prove_consistency(&entries, 5, 9).unwrap();
    let mut ws: Vec<Witness> = (1..=3).map(|i| witness(i, keys_of(&old).id())).collect();
    for w in &mut ws {
        w.cosign(STEWARD, std::slice::from_ref(&first), &[], 100).unwrap();
    }
    let trusted: Vec<ContentId> = ws.iter().map(|w| w.keys().id()).collect();
    let rule = Witnessing { witnesses: &trusted, quorum: 2, not_before: 0 };
    let before: Vec<Vec<u8>> = ws.iter().map(|w| w.attest_keys(STEWARD, 150).unwrap()).collect();
    assert_eq!(attested_keys(STEWARD, &before, &rule).map(|k| k.key_id), Ok(keys_of(&old).id()));
    for w in &mut ws {
        w.cosign(STEWARD, &[first.clone(), second.clone()], &path, 200).unwrap();
    }
    let after: Vec<Vec<u8>> = ws.iter().map(|w| w.attest_keys(STEWARD, 250).unwrap()).collect();
    let got = attested_keys(STEWARD, &[before, after].concat(), &rule).unwrap();
    assert_eq!((got.key_id, got.seal, got.count), (keys_of(&new).id(), ContentId::of_bytes(&second), 9));
    assert_eq!(keys_for(&second, &got.key_id), Ok(keys_of(&new)));
}

#[test]
fn a_witness_attests_only_keys_it_has_seen_sign_a_seal() {
    let w = witness(1, keys_of(&steward_key()).id());
    assert_eq!(w.attest_keys(STEWARD, 1), Err(SealError::Unfollowed));
    assert_eq!(w.attest_keys("did:example:unwatched", 1), Err(SealError::WrongSteward));
}