// Adapted from js/src/tests/non262/ReadableStream/subclassing.js to suit requirements of xpcshell-testing.

function assertEq(a, b) {
  Assert.equal(a, b);
}
function assertThrowsInstanceOf(fun, err) {
  var regexp = new RegExp(err.name);
  print(regexp);
  Assert.throws(fun, regexp);
}

// Spot-check subclassing of stream constructors.

// ReadableStream can be subclassed.
class PartyStreamer extends ReadableStream {}

let started = false;
add_task(function subclass_helper() {
  // The base class constructor is called.
  let stream = new PartyStreamer({
    // (The ReadableStream constructor calls this start method.)
    start() {
      started = true;
    },
  });

  assertEq(started, true);

  // The instance's prototype chain is correct.
  assertEq(stream.__proto__, PartyStreamer.prototype);
  assertEq(stream.__proto__.__proto__, ReadableStream.prototype);
  assertEq(stream.__proto__.__proto__.__proto__, Object.prototype);
  assertEq(stream.__proto__.__proto__.__proto__.__proto__, null);
  assertEq(stream instanceof ReadableStream, true);

  // Non-generic methods can be called on the resulting stream.
  stream.getReader();
  assertEq(stream.locked, true);
});

add_task(function strategy_helper() {
  // CountQueuingStrategy can be subclassed.
  class PixelStrategy extends CountQueuingStrategy {}
  assertEq(
    new PixelStrategy({ highWaterMark: 4 }).__proto__,
    PixelStrategy.prototype
  );

  // The base class constructor is called.
  assertThrowsInstanceOf(() => new PixelStrategy(), TypeError);
  assertEq(new PixelStrategy({ highWaterMark: -1 }).highWaterMark, -1);

  // // VerySmartStrategy can be subclassed.
  // class VerySmartStrategy extends ByteLengthQueuingStrategy {
  //     size(chunk) {
  //         return super.size(chunk) * 8;
  //     }
  // }
  // let vss = new VerySmartStrategy({ highWaterMark: 12 });
  // assertEq(vss.size(new ArrayBuffer(8)), 64);
  // assertEq(vss.__proto__, VerySmartStrategy.prototype);
});

// Even ReadableStreamDefaultReader can be subclassed.
add_task(async function readerTest() {
  const ReadableStreamDefaultReader = new ReadableStream().getReader()
    .constructor;
  class MindReader extends ReadableStreamDefaultReader {
    async read() {
      let foretold = { value: "death", done: false };
      let actual = await super.read();
      actual = foretold; // ZOMG I WAS RIGHT, EXACTLY AS FORETOLD they should call me a righter
      return actual;
    }
  }

  let stream = new ReadableStream({
    start(c) {
      c.enqueue("one");
      c.enqueue("two");
    },
    pull(c) {
      c.close();
    },
  });
  let reader = new MindReader(stream);
  let result = await reader.read();
  assertEq(result.value, "death");
  reader.releaseLock();

  reader = stream.getReader();
  result = await reader.read();
  assertEq(result.done, false);
  assertEq(result.value, "two");
  result = await reader.read();
  assertEq(result.done, true);
  assertEq(result.value, undefined);
});

add_task(function default_controller() {
  // Even ReadableStreamDefaultController, which can't be constructed,
  // can be subclassed.
  let ReadableStreamDefaultController;
  new ReadableStream({
    start(c) {
      ReadableStreamDefaultController = c.constructor;
    },
  });
  class MasterController extends ReadableStreamDefaultController {
    constructor() {
      // don't call super, it'll just throw
      return Object.create(MasterController.prototype);
    }
  }
  let c = new MasterController();

  // The prototype chain is per spec.
  assertEq(c instanceof ReadableStreamDefaultController, true);

  // But the instance does not have the internal slots of a
  // ReadableStreamDefaultController, so the non-generic methods can't be used.
  assertThrowsInstanceOf(() => c.enqueue("horse"), TypeError);
});