import type { EbsiVerifiableAttestation } from "../types.ts";

import { ValidationError } from "../errors/ValidationError.ts";
/**
 * Validates the Verifiable Credential dates: `issuanceDate`/`validFrom`, `expirationDate`.
 *
 * Notes:
 * - make sure to run `validateEbsiVerifiableAttestation` on the payload before calling `validateDates`.
 * - this function does NOT verify if the VC is valid at the current time. It only compares the
 * provided dates.
 * @param payload - `EbsiVerifiableAttestation`
 * @param validAt - Date at which the VC must be valid. If not provided, the current date is used.
 * @param clockSkew - Clock skew in seconds. Default: 0
 */
export function validateDates(
  payload: Pick<
    EbsiVerifiableAttestation,
    "expirationDate" | "issuanceDate" | "validFrom"
  >,
  validAt?: number,
  clockSkew = 0,
): void {
  if (payload.validFrom !== payload.issuanceDate) {
    throw new ValidationError(
      "validFrom and issuanceDate MUST have the same value when they are both defined",
    );
  }

  if (
    payload.expirationDate &&
    Date.parse(payload.expirationDate) < Date.parse(payload.validFrom)
  ) {
    throw new ValidationError(
      "expirationDate MUST be more recent than validFrom",
    );
  }

  if (validAt) {
    if (
      payload.validFrom &&
      Math.floor(Date.parse(payload.validFrom) / 1000) - clockSkew > validAt
    ) {
      throw new ValidationError(
        `The credential is not valid before: ${payload.validFrom}`,
      );
    }

    if (
      payload.expirationDate &&
      validAt >
        Math.floor(Date.parse(payload.expirationDate) / 1000) + clockSkew
    ) {
      throw new ValidationError(
        `The credential is not valid after: ${payload.expirationDate}`,
      );
    }
  }
}