import type { ExpressionBuilder, ExpressionWrapper, SqlBool } from "kysely";
import type { LixDatabaseSchema } from "../database/schema.js";

/**
 * Selects changes that are not a parent of any other change.
 *
 * **Careful**: This filter is not specific to any version.
 * If you want to filter changes in a specific version, use `changeIsLeafInversion`.
 *
 * @example
 *   ```ts
 *   await lix.db.selectFrom("change")
 *     .where(changeIsLeaf())
 *     .selectAll()
 *     .execute();
 *   ```
 */
export function changeIsLeaf() {
	return (
		eb: ExpressionBuilder<LixDatabaseSchema, "change">
	): ExpressionWrapper<LixDatabaseSchema, "change", SqlBool> =>
		eb("change.id", "not in", (subquery) =>
			subquery.selectFrom("change_edge").select("change_edge.parent_id")
		);
}