"""Add nullable version columns without modifying historical data. Safe to rerun."""
from database import get_db_connection

def migrate(connection):
    cursor = connection.cursor()
    try:
        for table in ('analysis_batches', 'single_prediction_history'):
            cursor.execute('SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=%s AND COLUMN_NAME=%s', (table, 'model_version'))
            if not cursor.fetchone()[0]:
                cursor.execute(f'ALTER TABLE `{table}` ADD COLUMN `model_version` VARCHAR(64) NULL DEFAULT NULL')
                print(f'{table}: model_version ditambahkan.')
            else:
                print(f'{table}: sudah diperbarui.')
        connection.commit()
    finally:
        cursor.close()

if __name__ == '__main__':
    connection = get_db_connection()
    try:
        migrate(connection)
        print('Selesai. Riwayat lama tetap tersimpan dengan versi tidak tercatat.')
    finally:
        connection.close()