/* Any copyright is dedicated to the Public Domain.
   http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

// When a transition finishes, no "removed" event is sent because it may still
// be used, but when it restarts again (transitions back), then a new
// AnimationPlayerFront should be sent, and the old one should be removed.

add_task(async function () {
  const { target, walker, animations } = await initAnimationsFrontForUrl(
    MAIN_DOMAIN + "animation.html"
  );

  info("Retrieve the test node");
  const node = await walker.querySelector(walker.rootNode, ".all-transitions");

  info("Retrieve the animation players for the node");
  const players = await animations.getAnimationPlayersForNode(node);
  is(players.length, 0, "The node has no animation players yet");

  info("Play a transition by adding the expand class, wait for mutations");
  let onMutations = expectMutationEvents(animations, 2);
  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
    const el = content.document.querySelector(".all-transitions");
    el.classList.add("expand");
  });
  let reportedMutations = await onMutations;

  is(reportedMutations.length, 2, "2 mutation events were received");
  is(reportedMutations[0].type, "added", "The first event was 'added'");
  is(reportedMutations[1].type, "added", "The second event was 'added'");

  info("Wait for the transitions to be finished");
  await waitForEnd(reportedMutations[0].player);
  await waitForEnd(reportedMutations[1].player);

  info("Play the transition back by removing the class, wait for mutations");
  onMutations = expectMutationEvents(animations, 4);
  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
    const el = content.document.querySelector(".all-transitions");
    el.classList.remove("expand");
  });
  reportedMutations = await onMutations;

  is(reportedMutations.length, 4, "4 new mutation events were received");
  is(
    reportedMutations.filter(m => m.type === "removed").length,
    2,
    "2 'removed' events were sent (for the old transitions)"
  );
  is(
    reportedMutations.filter(m => m.type === "added").length,
    2,
    "2 'added' events were sent (for the new transitions)"
  );

  await target.destroy();
  gBrowser.removeCurrentTab();
});

function expectMutationEvents(animationsFront, nbOfEvents) {
  return new Promise(resolve => {
    let reportedMutations = [];
    function onMutations(mutations) {
      reportedMutations = [...reportedMutations, ...mutations];
      info(
        "Received " +
          reportedMutations.length +
          " mutation events, " +
          "expecting " +
          nbOfEvents
      );
      if (reportedMutations.length === nbOfEvents) {
        animationsFront.off("mutations", onMutations);
        resolve(reportedMutations);
      }
    }

    info("Start listening for mutation events from the AnimationsFront");
    animationsFront.on("mutations", onMutations);
  });
}

async function waitForEnd(animationFront) {
  let playState;
  while (playState !== "finished") {
    const state = await animationFront.getCurrentState();
    playState = state.playState;
    info(
      "Wait for transition " +
        animationFront.state.name +
        " to finish, playState=" +
        playState
    );
  }
}