"""File hashing utilities for change detection."""
import hashlib
from pathlib import Path
from typing import Optional
import logging
logger = logging.getLogger(__name__)
def calculate_file_hash(file_path: str, algorithm: str = "sha256") -> str:
"""
Calculate hash of file content.
Args:
file_path: Path to the file
algorithm: Hash algorithm to use (default: sha256)
Returns:
Hash string in format "algorithm:hexdigest"
"""
if algorithm not in hashlib.algorithms_available:
raise ValueError(f"Unsupported hash algorithm: {algorithm}")
hash_obj = hashlib.new(algorithm)
try:
with open(file_path, "rb") as f:
# Read in chunks to handle large files efficiently
for chunk in iter(lambda: f.read(8192), b""):
hash_obj.update(chunk)
return f"{algorithm}:{hash_obj.hexdigest()}"
except Exception as e:
logger.error(f"Failed to calculate hash for {file_path}: {e}")
raise
def get_file_info(file_path: str) -> dict:
"""
Get file information including hash and metadata.
Args:
file_path: Path to the file
Returns:
Dictionary with file information
"""
path = Path(file_path)
if not path.exists():
raise FileNotFoundError(f"File not found: {file_path}")
stat = path.stat()
return {
"file_path": str(path.absolute()),
"file_hash": calculate_file_hash(file_path),
"file_size": stat.st_size,
"file_mtime": stat.st_mtime,
"exists": True
}
def has_file_changed(
file_path: str,
stored_hash: Optional[str] = None,
stored_mtime: Optional[float] = None
) -> bool:
"""
Check if file has changed compared to stored metadata.
Args:
file_path: Path to the file
stored_hash: Previously stored hash
stored_mtime: Previously stored modification time
Returns:
True if file has changed, False otherwise
"""
try:
current_info = get_file_info(file_path)
# If we have a hash, use it (most reliable)
if stored_hash:
return current_info["file_hash"] != stored_hash
# Fall back to mtime if no hash
if stored_mtime:
return current_info["file_mtime"] != stored_mtime
# If no stored info, consider it changed
return True
except FileNotFoundError:
# File deleted
return True
except Exception as e:
logger.error(f"Error checking file change for {file_path}: {e}")
# Assume changed on error to be safe
return True
