/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// Promise.prototype.finally proposal, stage 3.
// Promise.prototype.finally ( onFinally )
function Promise_finally(onFinally) {
  // Step 1.
  var promise = this;

  // Step 2.
  if (!IsObject(promise)) {
    ThrowTypeError(JSMSG_INCOMPATIBLE_PROTO, "Promise", "finally", "value");
  }

  // Step 3.
  var C = SpeciesConstructor(promise, GetBuiltinConstructor("Promise"));

  // Step 4.
  assert(IsConstructor(C), "SpeciesConstructor returns a constructor function");

  // Steps 5-6.
  var thenFinally, catchFinally;
  if (!IsCallable(onFinally)) {
    thenFinally = onFinally;
    catchFinally = onFinally;
  } else {
    // ThenFinally Function.
    // The parentheses prevent the infering of a function name.
    // prettier-ignore
    (thenFinally) = function(value) {
      // Steps 1-2 (implicit).

      // Step 3.
      var result = callContentFunction(onFinally, undefined);

      // Steps 4-5 (implicit).

      // Step 6.
      var promise = PromiseResolve(C, result);

      // Step 7.
      // FIXME: spec issue - "be equivalent to a function that" is not a defined spec term.
      // https://github.com/tc39/ecma262/issues/933

      // Step 8.
      return callContentFunction(promise.then, promise, function() {
        return value;
      });
    };

    // CatchFinally Function.
    // prettier-ignore
    (catchFinally) = function(reason) {
      // Steps 1-2 (implicit).

      // Step 3.
      var result = callContentFunction(onFinally, undefined);

      // Steps 4-5 (implicit).

      // Step 6.
      var promise = PromiseResolve(C, result);

      // Step 7.
      // FIXME: spec issue - "be equivalent to a function that" is not a defined spec term.
      // https://github.com/tc39/ecma262/issues/933

      // Step 8.
      return callContentFunction(promise.then, promise, function() {
        throw reason;
      });
    };
  }

  // Step 7.
  return callContentFunction(promise.then, promise, thenFinally, catchFinally);
}