"""Add users table and update todos

Revision ID: 2_add_users_table_and_update_todos
Revises: 1_initial_create_todos_table
Create Date: 2023-07-20 10:00:00.000000

"""
import sqlalchemy as sa
from alembic import op

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


def upgrade():
    # Create users table if it doesn't exist
    from sqlalchemy.exc import OperationalError
    try:
        # Use inspector to check if the table exists
        from sqlalchemy import inspect
        conn = op.get_bind()
        inspector = inspect(conn)
        if 'users' not in inspector.get_table_names():
            op.create_table(
                'users',
                sa.Column('id', sa.Integer(), nullable=False),
                sa.Column('email', sa.String(), nullable=False),
                sa.Column('username', sa.String(), nullable=False),
                sa.Column('hashed_password', sa.String(), nullable=False),
                sa.Column('is_active', sa.Boolean(), nullable=True, default=True),
                sa.Column('is_superuser', sa.Boolean(), nullable=True, default=False),
                sa.Column(
                    'created_at',
                    sa.DateTime(timezone=True),
                    server_default=sa.text('(CURRENT_TIMESTAMP)'),
                    nullable=True,
                ),
                sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
                sa.PrimaryKeyConstraint('id'),
            )
            op.create_index(op.f('ix_users_email'), 'users', ['email'], unique=True)
            op.create_index(op.f('ix_users_id'), 'users', ['id'], unique=False)
            op.create_index(op.f('ix_users_username'), 'users', ['username'], unique=True)
    except OperationalError:
        # Table already exists, skip creation
        pass

    # Add owner_id column to todos table if it doesn't exist
    from sqlalchemy.exc import OperationalError

    # Check if owner_id column exists in todos table
    conn = op.get_bind()
    inspector = inspect(conn)
    columns = [col['name'] for col in inspector.get_columns('todos')]

    if 'owner_id' not in columns:
        try:
            op.add_column('todos', sa.Column('owner_id', sa.Integer(), nullable=True))

            # Create foreign key from todos to users
            op.create_foreign_key(
                'fk_todos_owner_id_users',
                'todos', 'users',
                ['owner_id'], ['id'],
            )

            # Update all existing todos to have owner_id = 1 (first user)
            op.execute("UPDATE todos SET owner_id = 1")

            # Make owner_id non-nullable after updating existing todos
            op.alter_column('todos', 'owner_id', nullable=False)
        except OperationalError as e:
            # Log the error but continue
            print(f"Operation failed with error: {str(e)}")
            # If this is because the column already exists, we can continue
            pass


def downgrade():
    from sqlalchemy import inspect
    from sqlalchemy.exc import OperationalError

    conn = op.get_bind()
    inspector = inspect(conn)

    # Check if the constraint exists before trying to drop it
    try:
        constraints = inspector.get_foreign_keys('todos')
        constraint_name = 'fk_todos_owner_id_users'
        fk_exists = any(constraint['name'] == constraint_name for constraint in constraints)
        if fk_exists:
            op.drop_constraint('fk_todos_owner_id_users', 'todos', type_='foreignkey')
    except OperationalError:
        pass

    # Check if owner_id column exists before trying to drop it
    columns = [col['name'] for col in inspector.get_columns('todos')]
    if 'owner_id' in columns:
        op.drop_column('todos', 'owner_id')

    # Check if users table exists before trying to drop it
    if 'users' in inspector.get_table_names():
        # Check for each index before dropping
        indices = inspector.get_indexes('users')
        index_names = [index['name'] for index in indices]

        if 'ix_users_username' in index_names:
            op.drop_index(op.f('ix_users_username'), table_name='users')
        if 'ix_users_id' in index_names:
            op.drop_index(op.f('ix_users_id'), table_name='users')
        if 'ix_users_email' in index_names:
            op.drop_index(op.f('ix_users_email'), table_name='users')

        op.drop_table('users')