import json

import datetime

def validate_metadata(metadata_file):

"""

Validates metadata from a JSON file.

Performs defensive checks on data types, required fields, and date formats.

"""

try:

with open(metadata_file, 'r') as f:

metadata = json.load(f)

except FileNotFoundError:

print(f"Error: Metadata file '{metadata_file}' not found.")

return False

except json.JSONDecodeError:

print(f"Error: Invalid JSON format in '{metadata_file}'.")

return False

# Defensive check: metadata must be a dictionary

if not isinstance(metadata, dict):

print("Error: Metadata must be a JSON object (dictionary).")

return False

# Required fields validation

required_fields = ["script_name", "author", "creation_date", "last_modified"]

for field in required_fields:

if field not in metadata:

print(f"Error: Missing required field '{field}'.")

return False

# Data type validation

if not isinstance(metadata["script_name"], str):

print("Error: 'script_name' must be a string.")

return False

if not isinstance(metadata["author"], str):

print("Error: 'author' must be a string.")

return False

# Date validation

try:

creation_date = datetime.datetime.strptime(metadata["creation_date"], "%Y-%m-%d") #Expect YYYY-MM-DD

except ValueError:

print("Error: 'creation_date' must be in YYYY-MM-DD format.")

return False

if not isinstance(metadata["last_modified"], str):

print("Error: 'last_modified' must be a string.")

return False

try:

last_modified_date = datetime.datetime.strptime(metadata["last_modified"], "%Y-%m-%d") #Expect YYYY-MM-DD

except ValueError:

print("Error: 'last_modified' must be in YYYY-MM-DD format.")

return False

# Additional checks (example)

if len(metadata["script_name"]) < 3:

print("Warning: 'script_name' is very short.")

return True

if __name__ == '__main__':

# Example usage:

metadata_file = "metadata.json" # Replace with your metadata file

if validate_metadata(metadata_file):

print("Metadata is valid.")

else:

print("Metadata is invalid.")