import * as z from "zod/mini";

/**
 * Monotonically increasing identifier for one protocol document generation.
 * Hosts use it to reject messages from replaced documents.
 */
export const generationSchema = z
	.number()
	.check(z.int(), z.minimum(0))
	.brand("Generation");

export type Generation = z.output<typeof generationSchema>;

export function createGeneration(value: number): Generation {
	const result = generationSchema.safeParse(value);
	if (!result.success) {
		throw new Error(`Invalid generation: ${value}`);
	}
	return result.data;
}