"""create books table

Revision ID: 1234567890ab
Revises: 
Create Date: 2023-05-20 10:00:00.000000

"""
from alembic import op
import sqlalchemy as sa
import uuid

# revision identifiers
revision = '1234567890ab'
down_revision = None
branch_labels = None
depends_on = None


def upgrade():
    # Create books table
    op.create_table(
        'books',
        sa.Column('id', sa.String, primary_key=True, default=lambda: str(uuid.uuid4())),
        sa.Column('title', sa.String, nullable=False, index=True),
        sa.Column('description', sa.Text, nullable=True),
        sa.Column('author', sa.String, nullable=False, index=True),
        sa.Column('pages', sa.Integer, nullable=False),
        sa.Column('user_id', sa.String, sa.ForeignKey('users.id')),
        sa.Column('created_at', sa.DateTime, server_default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime, server_default=sa.func.now(), onupdate=sa.func.now()),
    )
    
    # Create index on title
    op.create_index('ix_books_title', 'books', ['title'])
    
    # Create index on author
    op.create_index('ix_books_author', 'books', ['author'])


def downgrade():
    # Drop indexes
    op.drop_index('ix_books_title', 'books')
    op.drop_index('ix_books_author', 'books')
    
    # Drop table
    op.drop_table('books')
```

This Alembic migration script creates a `books` table with the specified columns, including a primary key `id` with a UUID default value, indexes on `title` and `author`, a foreign key `user_id` referencing the `users` table, and timestamp columns `created_at` and `updated_at`. The `upgrade()` function creates the table and indexes, while the `downgrade()` function drops the indexes and the table.