project/
├── main.py              # Entry point with CLI
├── file_reader.py       # File I/O operations
├── data_processor.py    # Core processing logic
├── validator.py         # Data validation
├── config.py            # Configuration constants
└── utils.py             # Helper functions

def read_file_safely(filepath):
    """Read file with proper error handling"""
    try:
        if not os.path.exists(filepath):
            raise FileNotFoundError(f"File not found: {filepath}")

        with open(filepath, 'r', encoding='utf-8') as f:
            return f.read()
    except Exception as e:
        print(f"Error reading file: {e}")
        return None

import csv

def process_csv(input_file, output_file):
    """Process CSV with header detection"""
    with open(input_file, 'r', encoding='utf-8') as f:
        reader = csv.DictReader(f)

        processed = []
        for row in reader:
            # Transform each row
            processed_row = transform_row(row)
            processed.append(processed_row)

    # Write results
    with open(output_file, 'w', encoding='utf-8') as f:
        if processed:
            writer = csv.DictWriter(f, fieldnames=processed[0].keys())
            writer.writeheader()
            writer.writerows(processed)

import json

def process_json(input_file, output_file):
    """Process JSON data"""
    with open(input_file, 'r', encoding='utf-8') as f:
        data = json.load(f)

    # Process data (handle both list and dict)
    processed = process_data(data)

    with open(output_file, 'w', encoding='utf-8') as f:
        json.dump(processed, f, indent=2, ensure_ascii=False)

import argparse

def main():
    parser = argparse.ArgumentParser(description='File Processor')
    parser.add_argument('input', help='Input file path')
    parser.add_argument('output', help='Output file path')
    parser.add_argument('--format', choices=['csv', 'json'], default='csv')

    args = parser.parse_args()
    process_file(args.input, args.output, args.format)

import glob

def process_directory(input_dir, output_dir, pattern='*.csv'):
    """Process all matching files in directory"""
    files = glob.glob(os.path.join(input_dir, pattern))

    for filepath in files:
        filename = os.path.basename(filepath)
        output_path = os.path.join(output_dir, f"processed_{filename}")
        process_file(filepath, output_path)

def process_with_progress(items):
    """Process items with progress feedback"""
    total = len(items)
    for i, item in enumerate(items, 1):
        process_item(item)
        print(f"Progress: {i}/{total} ({i*100//total}%)", end='\r')
    print()  # New line when complete