# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-verify-a-peers-authority-to-bind-its-principal.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-verify-a-peers-authority-to-bind-its-principal.warrant.json
# Markdown SHA-256:   6811b2e830b55144a597f149bf8cbdaf659cfd0b94912121822bdfe508c17cef
# Code AST SHA-256:   d33e72c4c711aa2bd26986020437b88a35a34794dfb0171c4ab95bec4da89bf0
# Verified Classes:   AuthorityVerdict, PeerAuthority, AuthorityPolicy, AuthorityManifest, PeerAuthorityGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

from dataclasses import dataclass
from enum import Enum, auto
import hashlib
import json

class AuthorityVerdict(Enum):
    PEER_IS_PRINCIPAL = auto()
    DELEGATED_AUTHORITY_VERIFIED = auto()
    AUTHORITY_EXCEEDS_SCOPE = auto()
    AUTHORITY_UNVERIFIED = auto()

@dataclass(frozen=True)
class PeerAuthority:
    peer_id: str
    is_principal: bool
    attestation_verified: bool
    scope_covers_contract: bool
    revocation_current: bool
    authority_value_limit: float
    contract_value: float

@dataclass(frozen=True)
class AuthorityPolicy:
    require_attestation_verification: bool

@dataclass(frozen=True)
class AuthorityManifest:
    verdict: AuthorityVerdict
    directive: str
    manifest_digest: str

class PeerAuthorityGuard:
    @staticmethod
    def _hash(data: str) -> str:
        return hashlib.sha256(data.encode("utf-8")).hexdigest()

    @classmethod
    def evaluate_authority(
        cls, authority: PeerAuthority, policy: AuthorityPolicy
    ) -> AuthorityManifest:
        
        # Gate 1: Peer is principal
        if authority.is_principal:
            digest = cls._hash(json.dumps({
                "peer": authority.peer_id,
                "type": "PRINCIPAL"
            }, sort_keys=True))
            return AuthorityManifest(
                verdict=AuthorityVerdict.PEER_IS_PRINCIPAL,
                directive=f"PROCEED: Peer {authority.peer_id} is principal.",
                manifest_digest=digest
            )

        # Gate 2: Attestation verification
        if policy.require_attestation_verification and not authority.attestation_verified:
            return AuthorityManifest(
                verdict=AuthorityVerdict.AUTHORITY_UNVERIFIED,
                directive=f"HALT: Peer {authority.peer_id} attestation unverified.",
                manifest_digest=cls._hash(f"UNVERIFIED:{authority.peer_id}")
            )

        # Gate 3: Scope
        if not authority.scope_covers_contract:
            return AuthorityManifest(
                verdict=AuthorityVerdict.AUTHORITY_EXCEEDS_SCOPE,
                directive=f"HALT: Peer {authority.peer_id} authority exceeds scope.",
                manifest_digest=cls._hash(f"SCOPE:{authority.peer_id}")
            )

        # Gate 4: Value limit
        if authority.contract_value > authority.authority_value_limit:
            return AuthorityManifest(
                verdict=AuthorityVerdict.AUTHORITY_EXCEEDS_SCOPE,
                directive=f"HALT: Contract value {authority.contract_value:.2f} > limit {authority.authority_value_limit:.2f}.",
                manifest_digest=cls._hash(f"VALUE:{authority.peer_id}")
            )

        # Gate 5: Revocation
        if not authority.revocation_current:
            return AuthorityManifest(
                verdict=AuthorityVerdict.AUTHORITY_UNVERIFIED,
                directive=f"HALT: Peer {authority.peer_id} authority revoked.",
                manifest_digest=cls._hash(f"REVOKED:{authority.peer_id}")
            )

        # Gate 6: Verified
        digest = cls._hash(json.dumps({
            "peer": authority.peer_id,
            "scope": True,
            "value": f"{authority.contract_value:.3f}"
        }, sort_keys=True))
        
        return AuthorityManifest(
            verdict=AuthorityVerdict.DELEGATED_AUTHORITY_VERIFIED,
            directive=f"PROCEED: Peer {authority.peer_id} authority verified.",
            manifest_digest=digest
        )