"""add cmdb_app_resources junction table

Revision ID: 013
Revises: 012
Create Date: 2026-04-14
"""
from alembic import op
import sqlalchemy as sa

revision = '013'
down_revision = '012'
branch_labels = None
depends_on = None


def _table_exists(conn, table_name):
    result = conn.execute(sa.text(
        "SELECT COUNT(*) FROM information_schema.tables "
        "WHERE table_schema = DATABASE() AND table_name = :t"
    ), {"t": table_name})
    return result.scalar() > 0


def upgrade():
    conn = op.get_bind()
    if _table_exists(conn, 'cmdb_app_resources'):
        return
    op.create_table(
        'cmdb_app_resources',
        sa.Column('id', sa.String(36), primary_key=True, server_default=sa.text("(UUID())")),
        sa.Column('application_id', sa.String(36), sa.ForeignKey('cmdb_applications.id'), nullable=False),
        sa.Column('resource_type', sa.String(32), nullable=False),
        sa.Column('resource_id', sa.String(36), nullable=False),
        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('NOW()')),
        sa.UniqueConstraint('application_id', 'resource_type', 'resource_id', name='uq_app_resource'),
    )


def downgrade():
    op.drop_table('cmdb_app_resources')