/**
 * Get canonical representation of an ES256 public key JWK
 *
 * @param jwk - The JWK to parse (stringified JSON or JSON object)
 * @returns The canonical JWK
 */
export function getCanonicalJwk(jwk: unknown) {
  let jwkObject: unknown;
  if (typeof jwk === "string") {
    try {
      jwkObject = JSON.parse(jwk.trim());
    } catch {
      throw new Error("The JWK can't be parsed");
    }
  } else {
    jwkObject = jwk;
  }

  if (typeof jwkObject !== "object" || !jwkObject) {
    throw new TypeError("The JWK is not an object");
  }

  if ("alg" in jwkObject && jwkObject.alg !== "ES256") {
    throw new Error(`Unsupported JWK, alg must be ES256`);
  }

  if (!("kty" in jwkObject) || jwkObject.kty !== "EC") {
    throw new Error(`Unsupported JWK, kty must be EC`);
  }

  if (!("crv" in jwkObject) || jwkObject.crv !== "P-256") {
    throw new Error(`Unsupported JWK, crv must be P-256`);
  }

  if (!("x" in jwkObject) || typeof jwkObject.x !== "string") {
    throw new Error(`Unsupported JWK, missing x`);
  }

  if (!("y" in jwkObject) || typeof jwkObject.y !== "string") {
    throw new Error(`Unsupported JWK, missing y`);
  }

  if ("use" in jwkObject && jwkObject.use !== "sig") {
    throw new Error(`Unsupported JWK, use must be sig`);
  }

  return {
    crv: jwkObject.crv,
    kty: jwkObject.kty,
    x: jwkObject.x,
    y: jwkObject.y,
  } as const;
}