#!/usr/bin/env python3
"""
Mail Merge Tool
Merge CSV data into email templates for personalized bulk emails
"""
import csv
from string import Template

def mail_merge(template_file, data_file, output_file):
    """Merge template with CSV data"""
    # Load template
    with open(template_file, 'r') as f:
        template = Template(f.read())

    # Load data
    with open(data_file, 'r') as f:
        reader = csv.DictReader(f)
        data = list(reader)

    # Generate personalized emails
    results = []
    for row in data:
        try:
            personalized = template.safe_substitute(row)
            results.append({
                'email': row.get('email', ''),
                'content': personalized,
                'status': 'success'
            })
        except Exception as e:
            results.append({
                'email': row.get('email', ''),
                'content': '',
                'status': f'error: {e}'
            })

    # Save results
    with open(output_file, 'w', newline='') as f:
        writer = csv.DictWriter(f, fieldnames=['email', 'content', 'status'])
        writer.writeheader()
        writer.writerows(results)

    return len([r for r in results if r['status'] == 'success'])

def preview_merge(template_str, sample_data):
    """Preview merge with sample data"""
    template = Template(template_str)
    return template.safe_substitute(sample_data)

if __name__ == '__main__':
    # Example usage
    sample = {'name': 'John', 'company': 'Acme Inc', 'role': 'CEO'}
    template = "Hi $name,\n\nAs $role at $company..."
    print(preview_merge(template, sample))