"""Add username field

Revision ID: 2a3b4c5d6e7f
Revises: 1a2b3c4d5e6f
Create Date: 2023-11-17 00:00:00.000000

"""
from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision = '2a3b4c5d6e7f'
down_revision = '1a2b3c4d5e6f'
branch_labels = None
depends_on = None


def upgrade() -> None:
    # Add username column to user table
    with op.batch_alter_table('user') as batch_op:
        batch_op.add_column(sa.Column('username', sa.String(), nullable=True))
        batch_op.create_index('ix_user_username', ['username'], unique=True)
        
    # For existing users, initialize username from email
    # This is just SQL template code - in a real migration with existing data,
    # you would need to handle this appropriately
    op.execute("""
        UPDATE "user" SET username = email
        WHERE username IS NULL
    """)
    
    # Now make username non-nullable for future records
    with op.batch_alter_table('user') as batch_op:
        batch_op.alter_column('username', nullable=False)


def downgrade() -> None:
    # Remove username column from user table
    with op.batch_alter_table('user') as batch_op:
        batch_op.drop_index('ix_user_username')
        batch_op.drop_column('username')