package store

import (
	"database/sql"
	"errors"
	"fmt"
)

// bindMQScope checks the configured database owner and the immutable tenant
// mapping inside the caller's transaction, before committing any input ACK.
func bindMQScope(tx *sql.Tx, dispatcherID, tenantID, tenantKey string) error {
	var owner string
	if err := tx.QueryRow(`SELECT dispatcher_id FROM dispatcher_identity WHERE singleton=1`).Scan(&owner); err != nil {
		return fmt.Errorf("read MQ owner: %w", err)
	}
	if owner != dispatcherID {
		return ErrMessageScope
	}
	var conflicting int
	if err := tx.QueryRow(`SELECT EXISTS(SELECT 1 FROM inbox WHERE (tenant_id=? AND tenant_key<>?) OR (tenant_key=? AND tenant_id<>?))`, tenantID, tenantKey, tenantKey, tenantID).Scan(&conflicting); err != nil {
		return err
	}
	if conflicting != 0 {
		return ErrMessageScope
	}
	if _, err := tx.Exec(`INSERT INTO tenant_bindings(tenant_id,tenant_key) VALUES(?,?) ON CONFLICT DO NOTHING`, tenantID, tenantKey); err != nil {
		return err
	}
	var key string
	if err := tx.QueryRow(`SELECT tenant_key FROM tenant_bindings WHERE tenant_id=?`, tenantID).Scan(&key); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return ErrMessageScope
		}
		return err
	}
	if key != tenantKey {
		return ErrMessageScope
	}
	return nil
}