"""Add chat_file table

Revision ID: c440947495f3
Revises: 81cc2ce44d79
Create Date: 2025-12-21 20:27:41.694897

"""

from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

# revision identifiers, used by Alembic.
revision: str = 'c440947495f3'
down_revision: Union[str, None] = '81cc2ce44d79'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    conn = op.get_bind()
    inspector = sa.inspect(conn)
    existing_tables = set(inspector.get_table_names())

    if 'chat_file' not in existing_tables:
        op.create_table(
            'chat_file',
            sa.Column('id', sa.Text(), primary_key=True),
            sa.Column('user_id', sa.Text(), nullable=False),
            sa.Column(
                'chat_id',
                sa.Text(),
                sa.ForeignKey('chat.id', ondelete='CASCADE'),
                nullable=False,
            ),
            sa.Column(
                'file_id',
                sa.Text(),
                sa.ForeignKey('file.id', ondelete='CASCADE'),
                nullable=False,
            ),
            sa.Column('message_id', sa.Text(), nullable=True),
            sa.Column('created_at', sa.BigInteger(), nullable=False),
            sa.Column('updated_at', sa.BigInteger(), nullable=False),
            # indexes
            sa.Index('ix_chat_file_chat_id', 'chat_id'),
            sa.Index('ix_chat_file_file_id', 'file_id'),
            sa.Index('ix_chat_file_message_id', 'message_id'),
            sa.Index('ix_chat_file_user_id', 'user_id'),
            # unique constraints
            sa.UniqueConstraint('chat_id', 'file_id', name='uq_chat_file_chat_file'),  # prevent duplicate entries
        )


def downgrade() -> None:
    op.drop_table('chat_file')
