"""Data migration script to fix corrupted username fields.

This script fixes the bug where user.username was incorrectly set to full_name
instead of preserving the actual username. It migrates existing users by:
1. Setting username to a slug version of full_name (e.g., 'sarah-johnson')
2. Clearing full_name to empty string (will be collected via profile edit)

Run this script once to fix existing database records.
"""

from app import create_app
from extensions import db
from models import User

def slugify(name):
    """Convert a name to a username-friendly slug.
    
    Args:
        name (str): Full name to convert.
        
    Returns:
        str: Slugified username.
    """
    return name.lower().replace(' ', '-').replace("'", '')

def migrate():
    """Migrate existing users to fix corrupted username/full_name fields."""
    with app.app_context():
        users = User.query.all()
        migrated = 0
        
        for user in users:
            # If username looks like a full name (contains spaces), migrate it
            if ' ' in user.username:
                # Save the current username (which is actually the full name)
                actual_full_name = user.username
                # Generate a username from the full name
                new_username = slugify(actual_full_name)
                # Ensure uniqueness
                base_username = new_username
                counter = 1
                while User.query.filter_by(username=new_username).first() and User.query.get(user.id).username != new_username:
                    new_username = f"{base_username}-{counter}"
                    counter += 1
                
                user.username = new_username
                user.full_name = actual_full_name
                migrated += 1
                print(f"Migrated: '{actual_full_name}' -> username='{new_username}', full_name='{actual_full_name}'")
        
        db.session.commit()
        print(f"\n[MIGRATION] Migrated {migrated} users")
        print("Done! Usernames are now properly stored.")
        print("Users should edit their profile to set a proper username and full name.")

if __name__ == '__main__':
    app = create_app()
    migrate()