"""ZKP prototype for BeXProof.

This is a lightweight stand-in for a real ZKP back-end. It produces a compact
certificate-like proof deterministically derived from the log entry and policy.
"""
from __future__ import annotations
import json
import hashlib
from .policy import Policy


def generate_proof(log_entry: dict, policy: Policy) -> dict:
    # Produce a deterministic, compact proof representation (string hash)
    seed = {
        "log": log_entry,
        "policy_version": policy.version,
        "policy_rules": policy.rules,
    }
    blob = json.dumps(seed, sort_keys=True).encode("utf-8")
    proof_hash = hashlib.sha256(blob).hexdigest()
    return {"proof": f"zkp-{proof_hash}"}