# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/how-must-an-instance-translate-references-across-incompatible-protocol-boundaries.md
# Remnant Warrant:    https://corpusfetch.com/c/how-must-an-instance-translate-references-across-incompatible-protocol-boundaries.warrant.json
# Markdown SHA-256:   3f2c348b80007ee448161f62b63668203d3a780f203b4e1379aae53f9e2c7626
# Code AST SHA-256:   d56d4bc48087d82b5212af11e5a4a8225678be3bcbc66e10961a5ecd2720efd6
# Verified Classes:   TranslationVerdict, CrossProtocolReference, TranslationPolicy, TranslationManifest, CrossProtocolTranslationGuard
# Defensive Guards:   0 fail-closed invariants (zero external deps)

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

class TranslationVerdict(Enum):
    SAME_PROTOCOL = auto()
    SEMANTICS_PRESERVED = auto()
    SEMANTICS_LOST = auto()
    OPAQUE_REFERENCE = auto()

@dataclass(frozen=True)
class CrossProtocolReference:
    reference_id: str
    source_protocol: str
    target_protocol: str
    original_semantics_hash: str
    translation_preservation: str | None
    translation_differences: tuple[str, ...]
    is_opaque: bool

@dataclass(frozen=True)
class TranslationPolicy:
    require_preservation: bool
    allow_documented_losses: bool

@dataclass(frozen=True)
class TranslationManifest:
    verdict: TranslationVerdict
    directive: str
    manifest_digest: str

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

    @classmethod
    def evaluate_translation(
        cls, ref: CrossProtocolReference, policy: TranslationPolicy
    ) -> TranslationManifest:
        
        # Gate 1: Same protocol
        if ref.source_protocol == ref.target_protocol:
            digest = cls._hash(json.dumps({
                "reference": ref.reference_id,
                "protocol": ref.source_protocol
            }, sort_keys=True))
            return TranslationManifest(
                verdict=TranslationVerdict.SAME_PROTOCOL,
                directive=f"PROCEED: Same protocol, no translation needed.",
                manifest_digest=digest
            )

        # Gate 2: Opaque reference
        if ref.is_opaque:
            digest = cls._hash(json.dumps({
                "reference": ref.reference_id,
                "type": "OPAQUE"
            }, sort_keys=True))
            return TranslationManifest(
                verdict=TranslationVerdict.OPAQUE_REFERENCE,
                directive=f"PROCEED: Opaque reference, semantics irrelevant.",
                manifest_digest=digest
            )

        # Gate 3: Preservation proof
        if policy.require_preservation:
            if ref.translation_preservation:
                digest = cls._hash(json.dumps({
                    "reference": ref.reference_id,
                    "from": ref.source_protocol,
                    "to": ref.target_protocol,
                    "preservation": ref.translation_preservation
                }, sort_keys=True))
                return TranslationManifest(
                    verdict=TranslationVerdict.SEMANTICS_PRESERVED,
                    directive=f"PROCEED: Translation {ref.source_protocol}→{ref.target_protocol} preserves semantics.",
                    manifest_digest=digest
                )

            # No preservation proof, check for documented losses
            if not policy.allow_documented_losses or not ref.translation_differences:
                return TranslationManifest(
                    verdict=TranslationVerdict.SEMANTICS_LOST,
                    directive=f"HALT: Translation lacks preservation proof and has no documented differences.",
                    manifest_digest=cls._hash(f"NO_PROOF:{ref.reference_id}")
                )

        # Gate 4: Documented loss
        digest = cls._hash(json.dumps({
            "reference": ref.reference_id,
            "losses": tuple(sorted(ref.translation_differences)),
            "policy": "DOCUMENTED_LOSS_ALLOWED"
        }, sort_keys=True))
        
        return TranslationManifest(
            verdict=TranslationVerdict.SEMANTICS_LOST,
            directive=f"PROCEED_WITH_RISK: Translation has documented losses: {sorted(ref.translation_differences)}.",
            manifest_digest=digest
        )