"""phase34 — recurring inspection schedules

Creates the inspection_schedules table. A schedule materialises a real
Inspection row on a fixed cadence via the token-protected cron endpoint
POST /inspection-schedules/run (see app/routes/inspection_schedules.py).

Idempotent: guarded by an INFORMATION_SCHEMA table-existence check so it is
safe to re-run across every tenant DB (CLAUDE.md rule 14).
"""

import sqlalchemy as sa
from alembic import op

revision      = 'phase34_inspection_schedules'
down_revision = 'phase33_tenant_settings'
branch_labels = None
depends_on    = None


def _table_exists(bind, table: str) -> bool:
    result = bind.execute(sa.text(
        "SELECT COUNT(*) FROM information_schema.tables "
        "WHERE table_schema = DATABASE() AND table_name = :t"
    ), {'t': table})
    return result.scalar() > 0


def upgrade():
    bind = op.get_bind()

    if not _table_exists(bind, 'inspection_schedules'):
        op.execute(sa.text("""
            CREATE TABLE inspection_schedules (
                id           INT          NOT NULL AUTO_INCREMENT PRIMARY KEY,
                name         VARCHAR(255) NOT NULL,
                template_id  INT          NOT NULL,
                facility_id  INT          NOT NULL,
                area_id      INT          NULL,
                inspector_id INT          NOT NULL,
                frequency    ENUM('daily','weekly','monthly','quarterly')
                             NOT NULL DEFAULT 'weekly',
                active       TINYINT(1)   NOT NULL DEFAULT 1,
                created_by   INT          NULL,
                created_at   DATETIME     NOT NULL,
                last_run_at  DATETIME     NULL,
                next_run_at  DATETIME     NULL,
                CONSTRAINT fk_ischd_template FOREIGN KEY (template_id)
                    REFERENCES inspection_templates(id) ON DELETE CASCADE,
                CONSTRAINT fk_ischd_facility FOREIGN KEY (facility_id)
                    REFERENCES facilities(id) ON DELETE CASCADE,
                CONSTRAINT fk_ischd_area FOREIGN KEY (area_id)
                    REFERENCES areas(id) ON DELETE SET NULL,
                CONSTRAINT fk_ischd_inspector FOREIGN KEY (inspector_id)
                    REFERENCES users(id) ON DELETE CASCADE,
                CONSTRAINT fk_ischd_creator FOREIGN KEY (created_by)
                    REFERENCES users(id) ON DELETE SET NULL,
                INDEX ix_ischd_active_next (active, next_run_at),
                INDEX ix_ischd_facility (facility_id),
                INDEX ix_ischd_inspector (inspector_id)
            ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
        """))


def downgrade():
    bind = op.get_bind()
    if _table_exists(bind, 'inspection_schedules'):
        op.execute(sa.text('DROP TABLE inspection_schedules'))