"""bootstrap administrator + registration gate

The first account created on a fresh install becomes the administrator and
registration closes behind it, so an exposed port cannot be claimed by a
stranger. Existing installs keep their oldest account as administrator and start
closed; an admin reopens registration from the admin panel.

Revision ID: 0016
Revises: 0015
Create Date: 2026-09-15
"""

from __future__ import annotations

from collections.abc import Sequence

from alembic import op

revision: str = "0016"
down_revision: str | None = "0015"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    op.execute("ALTER TABLE users ADD COLUMN is_admin boolean NOT NULL DEFAULT false")
    op.execute(
        """
        CREATE TABLE app_settings (
            id                integer PRIMARY KEY DEFAULT 1,
            registration_open boolean NOT NULL DEFAULT false,
            updated_at        timestamptz NOT NULL DEFAULT now(),
            CONSTRAINT ck_app_settings_singleton CHECK (id = 1)
        )
        """
    )
    # Existing deployment: the oldest account is the one that set the instance up,
    # so it becomes the administrator. Ties on created_at break by id.
    op.execute(
        """
        UPDATE users SET is_admin = true
         WHERE id = (SELECT id FROM users ORDER BY created_at, id LIMIT 1)
        """
    )
    # Fresh install (no users yet) starts open so the first signup can happen;
    # anything else starts closed.
    op.execute(
        "INSERT INTO app_settings (id, registration_open) "
        "VALUES (1, NOT EXISTS (SELECT 1 FROM users))"
    )


def downgrade() -> None:
    op.execute("DROP TABLE IF EXISTS app_settings")
    op.execute("ALTER TABLE users DROP COLUMN IF EXISTS is_admin")