How to Update a Hosts File to Block Distractions in Python

from pathlib import Path

def update_hosts(entries):
    """
    Add or update blocking entries in the hosts file.
    Uses a local demo file by default to avoid system changes.
    """
    hosts_path = Path("demo_hosts.txt")
    
    # Create demo file if it doesn't exist
    if not hosts_path.exists():
        hosts_path.write_text("127.0.0.1 localhost\n")
    
    # Read current content
    content = hosts_path.read_text()
    lines = content.splitlines()
    
    # Add new blocking entries
    added = []
    updated = []
    for domain in entries:
        entry = f"0.0.0.0 {domain}"
        line_found = False
        
        # Check if domain already exists in hosts file
        for i, line in enumerate(lines):
            if f" {domain}" in line:
                if line.startswith("0.0.0.0"):
                    lines[i] = entry
                    updated.append(domain)
                line_found = True
                break
        
        if not line_found:
            lines.append(entry)
            added.append(domain)
    
    # Write back
    hosts_path.write_text("\n".join(lines) + "\n")
    
    # Report results
    print(f"Added {len(added)} entries: {', '.join(added)}")
    print(f"Updated {len(updated)} entries: {', '.join(updated)}")
    print("\nCurrent hosts file:")
    print(hosts_path.read_text())

if __name__ == "__main__":
    # Block distraction sites
    sites_to_block = [
        "facebook.com",
        "twitter.com",
        "instagram.com",
        "youtube.com"
    ]
    
    update_hosts(sites_to_block)