from __future__ import annotations

import json
import time
import hmac
import hashlib

class GovernanceLedger:
    def __init__(self, key: bytes):
        self.key = key
        self.entries = []  # list of dicts

    def attest(self, data: dict) -> dict:
        # produce a simple HMAC signature over the serialized data
        payload = json.dumps(data, sort_keys=True).encode("utf-8")
        signature = hmac.new(self.key, payload, hashlib.sha256).hexdigest()
        entry = {"timestamp": time.time(), "data": data, "signature": signature}
        self.entries.append(entry)
        return entry

    def verify(self, entry: dict) -> bool:
        payload = json.dumps(entry["data"], sort_keys=True).encode("utf-8")
        expected = hmac.new(self.key, payload, hashlib.sha256).hexdigest()
        return hmac.compare_digest(expected, entry.get("signature", ""))

    def to_json(self) -> str:
        return json.dumps(self.entries, default=str)


def create_attestation(ledger: GovernanceLedger, data: dict) -> dict:
    return ledger.attest(data)