"""phase37 — per-contract additional notification recipients

Creates the project_notification_recipients table. Each row subscribes one
recipient — either a staff User (in-app + email) or an external email address
(email only) — to a chosen set of notification-matrix event types, scoped to
events occurring in facilities that belong to that contract (Project).

Dispatched by notify_by_matrix() → _notify_project_recipients() in
app/utils/notifications.py, AFTER the global matrix roles and custom emails.

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

NOTE: the revision id is deliberately short — alembic_version.version_num is
VARCHAR(32); ids longer than 32 chars fail the version-pointer UPDATE with
MySQL error 1406 ("Data too long for column 'version_num'").
"""

import sqlalchemy as sa
from alembic import op

revision      = 'phase37_contract_recipients'
down_revision = 'phase36_issue_work_orders'
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, 'project_notification_recipients'):
        op.execute(sa.text("""
            CREATE TABLE project_notification_recipients (
                id         INT          NOT NULL AUTO_INCREMENT PRIMARY KEY,
                project_id INT          NOT NULL,
                user_id    INT          NULL,
                email      VARCHAR(255) NULL,
                events     TEXT         NOT NULL,
                created_at DATETIME     NOT NULL,
                CONSTRAINT fk_pnr_project FOREIGN KEY (project_id)
                    REFERENCES projects(id) ON DELETE CASCADE,
                CONSTRAINT fk_pnr_user FOREIGN KEY (user_id)
                    REFERENCES users(id) ON DELETE CASCADE,
                INDEX ix_pnr_project (project_id),
                INDEX ix_pnr_user (user_id)
            ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
        """))


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