"""subscriptions pilot complimentary backfill

This migration converts existing pilot/dev accounts to permanent complimentary
Pro per the self-serve signup spec section 5. Forward-only; downgrade is
prohibited because original status is not preserved.
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


revision: str = "c6cbfc534fad"
down_revision: Union[str, None] = "c982a3fc4bf1"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    """Set status='complimentary' and plan='pro' for all existing accounts that
    don't have a canceled or past_due subscription. Pilot users transition to
    permanent complimentary Pro per spec section 5.

    Forward-only — does not preserve original status values."""
    conn = op.get_bind()
    # Update existing rows
    conn.execute(sa.text("""
        UPDATE subscriptions
        SET status = 'complimentary', plan = 'pro',
            current_period_end = NULL, current_period_start = NULL,
            updated_at = now()
        WHERE status NOT IN ('canceled', 'past_due')
    """))
    # Backfill: any account without a Subscription row gets one
    conn.execute(sa.text("""
        INSERT INTO subscriptions (id, account_id, plan, status, cancel_at_period_end, created_at, updated_at)
        SELECT gen_random_uuid(), a.id, 'pro', 'complimentary', false, now(), now()
        FROM accounts a
        WHERE NOT EXISTS (SELECT 1 FROM subscriptions s WHERE s.account_id = a.id)
    """))


def downgrade() -> None:
    raise RuntimeError(
        "Cannot downgrade: original subscription state is not preserved. "
        "Restore from backup if needed."
    )