from collections.abc import Sequence
from pathlib import Path

from alembic import op


def get_revision() -> str:
    return Path(__file__).name.split("-")[0]


def get_down_revision() -> str | None:
    versions_path = Path(__file__).parent
    migration_files = sorted([f.name for f in versions_path.iterdir() if f.is_file()])
    for i, file in enumerate(migration_files):
        if file == Path(__file__).name:
            return None if i == 0 else migration_files[i - 1].split("-")[0]
    return None


# revision identifiers, used by Alembic.
revision: str = get_revision()
down_revision: str | None = get_down_revision()
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    op.create_unique_constraint(
        "uq_quota_allocations_tenant_id_contract_id",
        "quota_allocations",
        ["tenant_id", "contract_id", "valid_from_date", "valid_to_date"],
    )


def downgrade() -> None:
    op.drop_constraint("uq_quota_allocations_tenant_id_contract_id", "quota_allocations", type_="unique")
