/* ═══════════════════════════════════════════════════════════════════════════
   SovSNDLCheck.pli — SNDL Defense Governance Gate

   SOVEREIGN CONSTRAINTS:
   - Fail-closed: HALT if key strength < threshold OR key is stale (replay)
   - Uses WORM-attested key properties from SNDL key generation + freshness gate
   - Zero external dependencies (uses existing sov_monster_kernel.f90 primitives)
   - All governance events WORM-attested before state change

   INTEGRATION:
   - Called by SovFailClosed.pli as additional gate before quantum resource allocation
   - Reads SNDL key strength + freshness from WORM chain
   - Operates alongside SovZMOSCheck.pli and SovQMHESCheck.pli

   SNDL Defense Mapping:
   - Post-Quantum Cryptography → prime_encoded_state() (PIRTM-based)
   - Hybrid Encryption → XOR combination in sndl_resistant_key()
   - Crypto-Agility → sndl_key_rotation (φ-decay driven)
   - Harvest Now Defense → WORM-attested key binding (bind_to_fixed_point)
   - Decrypt Later Prevention → key freshness gate (jordan_block.f90)
   - Quantum Tamper Evidence → [U,ρ*]=0 violation → key corruption

   Prior Art: SnapKitty Foundry Intel (April 14, 2026)
   Original Research Lab: JAB Capital Trust (2021)
   ═══════════════════════════════════════════════════════════════════════════ */

dcl SovSNDLCheck entry (ptr, ptr) returns(fixed bin) external;
dcl Blake3Seal entry (char(*), char(*), ptr returns) external;
dcl WormLogGovernance entry (char(*), char(*)) external;
dcl FetchSNDLKeyStrengthFromWORM entry (ptr) returns(fixed bin) external;
dcl FetchSNDLKeyFreshnessFromWORM entry (ptr) returns(fixed bin) external;
dcl GetSNDLRotationCountFromWORM entry (ptr) returns(fixed bin) external;
dcl GetAgentEd25519Key entry returns(char(64) var) external;
dcl AgentHalt entry external;

/* ═══════════════════════════════════════════════════════════════════════════
   SNDL DEFENSE GOVERNANCE GATE

   Semantics: Allow quantum execution iff:
   1. Key strength ≥ MIN_STRENGTH (128 bits — NIST Level 1)
   2. Key is fresh (not replayed — freshness hash differs from last WORM entry)
   3. Key rotation is current (not overdue per φ-decay schedule)
   ALL conditions must pass (AND logic)
   ANY failure → WORM-attest + halt agent (fail-closed)
   ═══════════════════════════════════════════════════════════════════════════ */

SNDLDefenseGate: proc(options(main));
  dcl KEY_PTR ptr;
  dcl FRESHNESS_PTR ptr;
  dcl KEY_STRENGTH fixed bin;
  dcl IS_FRESH fixed bin;
  dcl ROTATION_COUNT fixed bin;
  dcl IS_SECURE fixed bin;
  dcl MIN_STRENGTH fixed bin init(128);
  dcl MAX_ROTATIONS_OVERDUE fixed bin init(3);
  dcl AGENT_KEY char(64) var;
  dcl DENIAL_REASON char(200) var;

  KEY_PTR = GetLatestWORMSNDLKeyPtr();
  FRESHNESS_PTR = GetLatestWORMFreshnessPtr();
  KEY_STRENGTH = FetchSNDLKeyStrengthFromWORM(KEY_PTR);
  IS_FRESH = FetchSNDLKeyFreshnessFromWORM(FRESHNESS_PTR);
  ROTATION_COUNT = GetSNDLRotationCountFromWORM(KEY_PTR);
  AGENT_KEY = GetAgentEd25519Key();

  /* ─────────────────────────────────────────────────────────────────────
     FAIL-CLOSED SNDL DEFENSE LOGIC
     Default: DENIED (IS_SECURE starts at 0)
     Must PROVE key strength + freshness + rotation currency
     ───────────────────────────────────────────────────────────────────── */
  IS_SECURE = 0;
  DENIAL_REASON = '';

  /* Gate 1: Key strength check (NIST Level 1 minimum) */
  if (KEY_STRENGTH < MIN_STRENGTH) then do;
    DENIAL_REASON = 'SNDL_WEAK_KEY: Strength=' || char(KEY_STRENGTH)
                    || ' Min=' || char(MIN_STRENGTH);
    goto DENY_EXECUTION;
  end;

  /* Gate 2: Key freshness check (replay prevention) */
  if (IS_FRESH = 0) then do;
    DENIAL_REASON = 'SNDL_REPLAY_DETECTED: Key is stale — '
                    || 'freshness hash matches previous WORM entry';
    goto DENY_EXECUTION;
  end;

  /* Gate 3: Rotation currency check (crypto-agility enforcement) */
  if (ROTATION_COUNT > MAX_ROTATIONS_OVERDUE) then do;
    DENIAL_REASON = 'SNDL_ROTATION_OVERDUE: MissedRotations='
                    || char(ROTATION_COUNT)
                    || ' Max=' || char(MAX_ROTATIONS_OVERDUE);
    goto DENY_EXECUTION;
  end;

  /* ALL gates passed — SNDL-defended execution allowed */
  IS_SECURE = 1;

  /* WORM-attest the APPROVAL (provenance for audit) */
  call WormLogGovernance('SNDL_DEFENSE_APPROVED',
   & 'KeyStrength=' || char(KEY_STRENGTH)
   & || ' Fresh=' || char(IS_FRESH)
   & || ' RotationStatus=CURRENT');

  return;

  /* ─────────────────────────────────────────────────────────────────────
     DENY PATH: Hard fail, WORM-attest, halt agent
     No state corruption possible (execution never reached)
     ───────────────────────────────────────────────────────────────────── */
  DENY_EXECUTION:
    /* WORM-attest the DENIAL (immutable audit record) */
    call WormLogGovernance('SNDL_DEFENSE_DENIED', DENIAL_REASON);

    /* Seal denial with agent's Ed25519 key (provable intent) */
    call Blake3Seal(
      'SNDL_FAIL_CLOSED:' || DENIAL_REASON,
      AGENT_KEY,
      null());

    /* Hard halt — agent suspended until SNDL defense restored */
    call AgentHalt();
    /* Control never reaches here */
  return;
end SNDLDefenseGate;

/* ═══════════════════════════════════════════════════════════════════════════
   HELPER: SovSNDLCheck (Fortran-callable via C ABI)

   Called by sov_monster_kernel.f90 as pre-execution gate
   Reads latest WORM-attested SNDL key properties
   Returns: 1 = SNDL-defended (safe), 0 = defense compromised (denied)
   ═══════════════════════════════════════════════════════════════════════════ */

SovSNDLCheck: proc(key_ptr, freshness_ptr) returns(fixed bin);
  dcl key_ptr ptr;
  dcl freshness_ptr ptr;
  dcl key_strength fixed bin;
  dcl is_fresh fixed bin;
  dcl rotation_count fixed bin;
  dcl min_strength fixed bin init(128);
  dcl max_overdue fixed bin init(3);

  /* Fetch WORM-attested values */
  key_strength = FetchSNDLKeyStrengthFromWORM(key_ptr);
  is_fresh = FetchSNDLKeyFreshnessFromWORM(freshness_ptr);
  rotation_count = GetSNDLRotationCountFromWORM(key_ptr);

  /* Fail-closed: default deny */
  if (key_strength < min_strength) then return(0);
  if (is_fresh = 0) then return(0);
  if (rotation_count > max_overdue) then return(0);

  /* All three gates pass — SNDL-defended */
  return(1);
end SovSNDLCheck;