"""
Hashing Agent
Generates cryptographic hashes for content verification.
"""

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

from core.agent_base import Agent
from core.errors import HashingError
from config.settings import settings


class HashingAgent(Agent):
    """
    Generates SHA-256 hash for files or text content.
    """
    
    def execute(self, input_data: Dict[str, Any]) -> Dict[str, Any]:
        """
        Generate cryptographic hash.
        
        Expected input_data:
            {
                "content": bytes,
                ...other fields...
            }
        
        Returns:
            {
                "content_hash": str,
                "hash_algorithm": str,
                "hash_timestamp": str,
                ...passes through input_data...
            }
        """
        content = input_data.get("content")
        
        if not content:
            raise HashingError("Missing 'content' field")
        
        if not isinstance(content, bytes):
            raise HashingError("Content must be bytes")
        
        # Generate hash
        algorithm = settings.HASH_ALGORITHM
        hash_value = self._compute_hash(content, algorithm)
        
        # Add hash info to input data
        result = input_data.copy()
        result.update({
            "content_hash": hash_value,
            "hash_algorithm": algorithm,
            "hash_timestamp": datetime.now(timezone.utc).isoformat(),
        })
        
        return result
    
    def _compute_hash(self, content: bytes, algorithm: str) -> str:
        """
        Compute hash using specified algorithm.
        
        Args:
            content: Content bytes to hash
            algorithm: Hash algorithm name (e.g., 'sha256')
        
        Returns:
            Hexadecimal hash string
        """
        try:
            hasher = hashlib.new(algorithm)
            hasher.update(content)
            return hasher.hexdigest()
        except ValueError as e:
            raise HashingError(f"Unsupported hash algorithm: {algorithm}") from e
        except Exception as e:
            raise HashingError(f"Hash computation failed: {str(e)}") from e