"""
Cryptographic Tools for arifOS
Implements signing and verification for Stage 889 (PROOF).

Constitutional Validation:
- F2 (Truth): Verifiable signatures
- F4 (Clarity): Clear cryptographic operations
"""

import hashlib
import hmac
import json
from datetime import datetime, timezone
from typing import Any, Dict

# In a real system, this would be a secure key management system
# For now, we use a session-based secret
SESSION_SECRET = b"arifos-session-secret-v50"

async def cryptography_sign(data: str) -> Dict[str, Any]:
    """
    Sign data using HMAC-SHA256 (Simulating digital signature).

    Args:
        data: The string data to sign

    Returns:
        Dict containing signature, algorithm, and timestamp
    """
    if not data:
        return {"error": "No data provided for signing"}

    timestamp = datetime.now(timezone.utc).isoformat()

    # Create signature
    signature = hmac.new(
        SESSION_SECRET,
        data.encode('utf-8'),
        hashlib.sha256
    ).hexdigest()

    return {
        "status": "success",
        "signature": signature,
        "algorithm": "HMAC-SHA256",
        "timestamp": timestamp,
        "input_preview": data[:50] + "..." if len(data) > 50 else data
    }
