// Utilities for writing APZ tests using the framework added in bug 961289

// ----------------------------------------------------------------------
// Functions that convert the APZ test data into a more usable form.
// Every place we have a WebIDL sequence whose elements are dictionaries
// with two elements, a key, and a value, we convert this into a JS
// object with a property for each key/value pair. (This is the structure
// we really want, but we can't express in directly in WebIDL.)
// ----------------------------------------------------------------------

// getHitTestConfig() expects apz_test_native_event_utils.js to be loaded as well.
/* import-globals-from apz_test_native_event_utils.js */

function convertEntries(entries) {
  var result = {};
  for (var i = 0; i < entries.length; ++i) {
    result[entries[i].key] = entries[i].value;
  }
  return result;
}

function parsePoint(str) {
  var pieces = str.replace(/[()\s]+/g, "").split(",");
  SimpleTest.is(pieces.length, 2, "expected string of form (x,y)");
  for (var i = 0; i < 2; i++) {
    var eq = pieces[i].indexOf("=");
    if (eq >= 0) {
      pieces[i] = pieces[i].substring(eq + 1);
    }
  }
  return {
    x: parseInt(pieces[0]),
    y: parseInt(pieces[1]),
  };
}

// Given a VisualViewport object, return the visual viewport
// rect relative to the page.
function getVisualViewportRect(vv) {
  return {
    x: vv.pageLeft,
    y: vv.pageTop,
    width: vv.width,
    height: vv.height,
  };
}

// Return the offset of the visual viewport relative to the layout viewport.
function getRelativeViewportOffset(window) {
  const offsetX = {};
  const offsetY = {};
  const utils = SpecialPowers.getDOMWindowUtils(window);
  utils.getVisualViewportOffsetRelativeToLayoutViewport(offsetX, offsetY);
  return {
    x: offsetX.value,
    y: offsetY.value,
  };
}

function parseRect(str) {
  var pieces = str.replace(/[()\s]+/g, "").split(",");
  SimpleTest.is(pieces.length, 4, "expected string of form (x,y,w,h)");
  for (var i = 0; i < 4; i++) {
    var eq = pieces[i].indexOf("=");
    if (eq >= 0) {
      pieces[i] = pieces[i].substring(eq + 1);
    }
  }
  return {
    x: parseInt(pieces[0]),
    y: parseInt(pieces[1]),
    width: parseInt(pieces[2]),
    height: parseInt(pieces[3]),
  };
}

// These functions expect rects with fields named x/y/width/height, such as
// that returned by parseRect().
function rectContains(haystack, needle) {
  return (
    haystack.x <= needle.x &&
    haystack.y <= needle.y &&
    haystack.x + haystack.width >= needle.x + needle.width &&
    haystack.y + haystack.height >= needle.y + needle.height
  );
}
function rectToString(rect) {
  return (
    "(" + rect.x + "," + rect.y + "," + rect.width + "," + rect.height + ")"
  );
}
function assertRectContainment(
  haystackRect,
  haystackDesc,
  needleRect,
  needleDesc
) {
  SimpleTest.ok(
    rectContains(haystackRect, needleRect),
    haystackDesc +
      " " +
      rectToString(haystackRect) +
      " should contain " +
      needleDesc +
      " " +
      rectToString(needleRect)
  );
}

function getPropertyAsRect(scrollFrames, scrollId, prop) {
  SimpleTest.ok(
    scrollId in scrollFrames,
    "expected scroll frame data for scroll id " + scrollId
  );
  var scrollFrameData = scrollFrames[scrollId];
  SimpleTest.ok(
    "displayport" in scrollFrameData,
    "expected a " + prop + " for scroll id " + scrollId
  );
  var value = scrollFrameData[prop];
  return parseRect(value);
}

function convertScrollFrameData(scrollFrames) {
  var result = {};
  for (var i = 0; i < scrollFrames.length; ++i) {
    result[scrollFrames[i].scrollId] = convertEntries(scrollFrames[i].entries);
  }
  return result;
}

function convertBuckets(buckets) {
  var result = {};
  for (var i = 0; i < buckets.length; ++i) {
    result[buckets[i].sequenceNumber] = convertScrollFrameData(
      buckets[i].scrollFrames
    );
  }
  return result;
}

function convertTestData(testData) {
  var result = {};
  result.paints = convertBuckets(testData.paints);
  result.repaintRequests = convertBuckets(testData.repaintRequests);
  return result;
}

// Returns the last bucket that has at least one scrollframe. This
// is useful for skipping over buckets that are from empty transactions,
// because those don't contain any useful data.
function getLastNonemptyBucket(buckets) {
  for (var i = buckets.length - 1; i >= 0; --i) {
    if (buckets[i].scrollFrames.length) {
      return buckets[i];
    }
  }
  return null;
}

// Takes something like "matrix(1, 0, 0, 1, 234.024, 528.29023)"" and returns a number array
function parseTransform(transform) {
  return /matrix\((.*),(.*),(.*),(.*),(.*),(.*)\)/
    .exec(transform)
    .slice(1)
    .map(parseFloat);
}

function isTransformClose(a, b, name) {
  is(
    a.length,
    b.length,
    `expected transforms ${a} and ${b} to be the same length`
  );
  for (let i = 0; i < a.length; i++) {
    ok(Math.abs(a[i] - b[i]) < 0.01, name);
  }
}

// Given APZ test data for a single paint on the compositor side,
// reconstruct the APZC tree structure from the 'parentScrollId'
// entries that were logged. More specifically, the subset of the
// APZC tree structure corresponding to the layer subtree for the
// content process that triggered the paint, is reconstructed (as
// the APZ test data only contains information abot this subtree).
function buildApzcTree(paint) {
  // The APZC tree can potentially have multiple root nodes,
  // so we invent a node that is the parent of all roots.
  // This 'root' does not correspond to an APZC.
  var root = { scrollId: -1, children: [] };
  for (let scrollId in paint) {
    paint[scrollId].children = [];
    paint[scrollId].scrollId = scrollId;
  }
  for (let scrollId in paint) {
    var parentNode = null;
    if ("hasNoParentWithSameLayersId" in paint[scrollId]) {
      parentNode = root;
    } else if ("parentScrollId" in paint[scrollId]) {
      parentNode = paint[paint[scrollId].parentScrollId];
    }
    parentNode.children.push(paint[scrollId]);
  }
  return root;
}

// Given an APZC tree produced by buildApzcTree, return the RCD node in
// the tree, or null if there was none.
function findRcdNode(apzcTree) {
  // isRootContent will be undefined or "1"
  if (apzcTree.isRootContent) {
    return apzcTree;
  }
  for (var i = 0; i < apzcTree.children.length; i++) {
    var rcd = findRcdNode(apzcTree.children[i]);
    if (rcd != null) {
      return rcd;
    }
  }
  return null;
}

// Return whether an element whose id includes |elementId| has been layerized.
// Assumes |elementId| will be present in the content description for the
// element, and not in the content descriptions of other elements.
function isLayerized(elementId) {
  var contentTestData =
    SpecialPowers.getDOMWindowUtils(window).getContentAPZTestData();
  var nonEmptyBucket = getLastNonemptyBucket(contentTestData.paints);
  ok(nonEmptyBucket != null, "expected at least one nonempty paint");
  var seqno = nonEmptyBucket.sequenceNumber;
  contentTestData = convertTestData(contentTestData);
  var paint = contentTestData.paints[seqno];
  for (var scrollId in paint) {
    if ("contentDescription" in paint[scrollId]) {
      if (paint[scrollId].contentDescription.includes(elementId)) {
        return true;
      }
    }
  }
  return false;
}

// Return a rect (or null) that holds the last known content-side displayport
// for a given element. (The element selection works the same way, and with
// the same assumptions as the isLayerized function above).
function getLastContentDisplayportFor(elementId, expectPainted = true) {
  var contentTestData =
    SpecialPowers.getDOMWindowUtils(window).getContentAPZTestData();
  if (contentTestData == undefined) {
    ok(!expectPainted, "expected to have apz test data (1)");
    return null;
  }
  var nonEmptyBucket = getLastNonemptyBucket(contentTestData.paints);
  if (nonEmptyBucket == null) {
    ok(!expectPainted, "expected to have apz test data (2)");
    return null;
  }
  var seqno = nonEmptyBucket.sequenceNumber;
  contentTestData = convertTestData(contentTestData);
  var paint = contentTestData.paints[seqno];
  for (var scrollId in paint) {
    if ("contentDescription" in paint[scrollId]) {
      if (paint[scrollId].contentDescription.includes(elementId)) {
        if ("displayport" in paint[scrollId]) {
          return parseRect(paint[scrollId].displayport);
        }
      }
    }
  }
  return null;
}

// Return the APZC tree (as produced by buildApzcTree) for the last
// non-empty paint received by the compositor.
function getLastApzcTree() {
  let data = SpecialPowers.getDOMWindowUtils(window).getCompositorAPZTestData();
  if (data == undefined) {
    ok(false, "expected to have compositor apz test data");
    return null;
  }
  if (!data.paints.length) {
    ok(false, "expected to have at least one compositor paint bucket");
    return null;
  }
  var seqno = data.paints[data.paints.length - 1].sequenceNumber;
  data = convertTestData(data);
  return buildApzcTree(data.paints[seqno]);
}

// Return a promise that is resolved on the next rAF callback
function promiseFrame(aWindow = window) {
  return new Promise(resolve => {
    aWindow.requestAnimationFrame(resolve);
  });
}

// Return a promise that is resolved on the next MozAfterPaint event
function promiseAfterPaint() {
  return new Promise(resolve => {
    window.addEventListener("MozAfterPaint", resolve, { once: true });
  });
}

// This waits until any pending events on the APZ controller thread are
// processed, and any resulting repaint requests are received by the main
// thread. Note that while the repaint requests do get processed by the
// APZ handler on the main thread, the repaints themselves may not have
// occurred by the the returned promise resolves. If you want to wait
// for those repaints, consider using promiseApzFlushedRepaints instead.
function promiseOnlyApzControllerFlushedWithoutSetTimeout(aWindow = window) {
  return new Promise(function (resolve, reject) {
    var repaintDone = function () {
      dump("PromiseApzRepaintsFlushed: APZ flush done\n");
      SpecialPowers.Services.obs.removeObserver(
        repaintDone,
        "apz-repaints-flushed"
      );
      resolve();
    };
    SpecialPowers.Services.obs.addObserver(repaintDone, "apz-repaints-flushed");
    if (SpecialPowers.getDOMWindowUtils(aWindow).flushApzRepaints()) {
      dump(
        "PromiseApzRepaintsFlushed: Flushed APZ repaints, waiting for callback...\n"
      );
    } else {
      dump(
        "PromiseApzRepaintsFlushed: Flushing APZ repaints was a no-op, triggering callback directly...\n"
      );
      repaintDone();
    }
  });
}

// Another variant of the above promiseOnlyApzControllerFlushedWithoutSetTimeout
// but with a setTimeout(0) callback.
function promiseOnlyApzControllerFlushed(aWindow = window) {
  return new Promise(resolve => {
    promiseOnlyApzControllerFlushedWithoutSetTimeout(aWindow).then(() => {
      setTimeout(resolve, 0);
    });
  });
}

// Flush repaints, APZ pending repaints, and any repaints resulting from that
// flush. This is particularly useful if the test needs to reach some sort of
// "idle" state in terms of repaints. Usually just waiting for all paints
// followed by flushApzRepaints is sufficient to flush all APZ state back to
// the main thread, but it can leave a paint scheduled which will get triggered
// at some later time. For tests that specifically test for painting at
// specific times, this method is the way to go. Even if in doubt, this is the
// preferred method as the extra step is "safe" and shouldn't interfere with
// most tests.
async function promiseApzFlushedRepaints() {
  await promiseAllPaintsDone();
  await promiseOnlyApzControllerFlushed();
  await promiseAllPaintsDone();
}

// This function takes a set of subtests to run one at a time in new top-level
// windows, and returns a Promise that is resolved once all the subtests are
// done running.
//
// The aSubtests array is an array of objects with the following keys:
//   file: required, the filename of the subtest.
//   prefs: optional, an array of arrays containing key-value prefs to set.
//   dp_suppression: optional, a boolean on whether or not to respect displayport
//                   suppression during the test.
//   onload: optional, a function that will be registered as a load event listener
//           for the child window that will hold the subtest. the function will be
//           passed exactly one argument, which will be the child window.
// An example of an array is:
//   aSubtests = [
//     { 'file': 'test_file_name.html' },
//     { 'file': 'test_file_2.html', 'prefs': [['pref.name', true], ['other.pref', 1000]], 'dp_suppression': false }
//     { 'file': 'file_3.html', 'onload': function(w) { w.subtestDone(); } }
//   ];
//
// Each subtest should call one of the subtestDone() or subtestFailed()
// functions when it is done, to indicate that the window should be torn
// down and the next test should run.
// These functions are injected into the subtest's window by this
// function prior to loading the subtest. For convenience, the |is| and |ok|
// functions provided by SimpleTest are also mapped into the subtest's window.
// For other things from the parent, the subtest can use window.opener.<whatever>
// to access objects.
function runSubtestsSeriallyInFreshWindows(aSubtests) {
  return new Promise(function (resolve, reject) {
    var testIndex = -1;
    var w = null;

    // If the "apz.subtest" pref has been set, only a single subtest whose name matches
    // the pref's value (if any) will be run.
    var onlyOneSubtest = SpecialPowers.getCharPref(
      "apz.subtest",
      /* default = */ ""
    );

    function advanceSubtestExecutionWithFailure(msg) {
      SimpleTest.ok(false, msg);
      advanceSubtestExecution();
    }

    async function advanceSubtestExecution() {
      var test = aSubtests[testIndex];
      if (w) {
        // Run any cleanup functions registered in the subtest
        // Guard against the subtest not loading apz_test_utils.js
        if (w.ApzCleanup) {
          w.ApzCleanup.execute();
        }
        if (typeof test.dp_suppression != "undefined") {
          // We modified the suppression when starting the test, so now undo that.
          SpecialPowers.getDOMWindowUtils(window).respectDisplayPortSuppression(
            !test.dp_suppression
          );
        }

        if (test.prefs) {
          // We pushed some prefs for this test, pop them, and re-invoke
          // advanceSubtestExecution() after that's been processed
          SpecialPowers.popPrefEnv(function () {
            w.close();
            w = null;
            advanceSubtestExecution();
          });
          return;
        }

        w.close();
      }

      testIndex++;
      if (testIndex >= aSubtests.length) {
        resolve();
        return;
      }

      await SimpleTest.promiseFocus(window);

      test = aSubtests[testIndex];

      let recognizedProps = ["file", "prefs", "dp_suppression", "onload"];
      for (let prop in test) {
        if (!recognizedProps.includes(prop)) {
          SimpleTest.ok(
            false,
            "Subtest " + test.file + " has unrecognized property '" + prop + "'"
          );
          setTimeout(function () {
            advanceSubtestExecution();
          }, 0);
          return;
        }
      }

      if (onlyOneSubtest && onlyOneSubtest != test.file) {
        SimpleTest.ok(
          true,
          "Skipping " +
            test.file +
            " because only " +
            onlyOneSubtest +
            " is being run"
        );
        setTimeout(function () {
          advanceSubtestExecution();
        }, 0);
        return;
      }

      SimpleTest.ok(true, "Starting subtest " + test.file);

      if (typeof test.dp_suppression != "undefined") {
        // Normally during a test, the displayport will get suppressed during page
        // load, and unsuppressed at a non-deterministic time during the test. The
        // unsuppression can trigger a repaint which interferes with the test, so
        // to avoid that we can force the displayport to be unsuppressed for the
        // entire test which is more deterministic.
        SpecialPowers.getDOMWindowUtils(window).respectDisplayPortSuppression(
          test.dp_suppression
        );
      }

      function spawnTest(aFile) {
        w = window.open("", "_blank");
        w.subtestDone = advanceSubtestExecution;
        w.subtestFailed = advanceSubtestExecutionWithFailure;
        w.isApzSubtest = true;
        w.SimpleTest = SimpleTest;
        w.dump = function (msg) {
          return dump(aFile + " | " + msg);
        };
        w.info = function (msg) {
          return info(aFile + " | " + msg);
        };
        w.is = function (a, b, msg) {
          return is(a, b, aFile + " | " + msg);
        };
        w.isnot = function (a, b, msg) {
          return isnot(a, b, aFile + " | " + msg);
        };
        w.isfuzzy = function (a, b, eps, msg) {
          return isfuzzy(a, b, eps, aFile + " | " + msg);
        };
        w.ok = function (cond, msg) {
          arguments[1] = aFile + " | " + msg;
          // Forward all arguments to SimpleTest.ok where we will check that ok() was
          // called with at most 2 arguments.
          return SimpleTest.ok.apply(SimpleTest, arguments);
        };
        w.todo_is = function (a, b, msg) {
          return todo_is(a, b, aFile + " | " + msg);
        };
        w.todo = function (cond, msg) {
          return todo(cond, aFile + " | " + msg);
        };
        if (test.onload) {
          w.addEventListener(
            "load",
            function (e) {
              test.onload(w);
            },
            { once: true }
          );
        }
        var subtestUrl =
          location.href.substring(0, location.href.lastIndexOf("/") + 1) +
          aFile;
        function urlResolves(url) {
          var request = new XMLHttpRequest();
          request.open("GET", url, false);
          request.send();
          return request.status !== 404;
        }
        if (!urlResolves(subtestUrl)) {
          SimpleTest.ok(
            false,
            "Subtest URL " +
              subtestUrl +
              " does not resolve. " +
              "Be sure it's present in the support-files section of mochitest.ini."
          );
          reject();
          return undefined;
        }
        w.location = subtestUrl;
        return w;
      }

      if (test.prefs) {
        // Got some prefs for this subtest, push them
        await SpecialPowers.pushPrefEnv({ set: test.prefs });
      }
      w = spawnTest(test.file);
    }

    advanceSubtestExecution();
  }).catch(function (e) {
    SimpleTest.ok(false, "Error occurred while running subtests: " + e);
  });
}

function pushPrefs(prefs) {
  return SpecialPowers.pushPrefEnv({ set: prefs });
}

async function waitUntilApzStable() {
  if (!SpecialPowers.isMainProcess()) {
    // We use this waitUntilApzStable function during test initialization
    // and for those scenarios we want to flush the parent-process layer
    // tree to the compositor and wait for that as well. That way we know
    // that not only is the content-process layer tree ready in the compositor,
    // the parent-process layer tree in the compositor has the appropriate
    // RefLayer pointing to the content-process layer tree.

    // Sadly this helper function cannot reuse any code from other places because
    // it must be totally self-contained to be shipped over to the parent process.
    function parentProcessFlush() {
      /* eslint-env mozilla/chrome-script */
      function apzFlush() {
        var topWin = Services.wm.getMostRecentWindow("navigator:browser");
        if (!topWin) {
          topWin = Services.wm.getMostRecentWindow("navigator:geckoview");
        }
        var topUtils = topWin.windowUtils;

        var repaintDone = function () {
          dump("WaitUntilApzStable: APZ flush done in parent proc\n");
          Services.obs.removeObserver(repaintDone, "apz-repaints-flushed");
          // send message back to content process
          sendAsyncMessage("apz-flush-done", null);
        };
        var flushRepaint = function () {
          if (topUtils.isMozAfterPaintPending) {
            topWin.addEventListener("MozAfterPaint", flushRepaint, {
              once: true,
            });
            return;
          }

          Services.obs.addObserver(repaintDone, "apz-repaints-flushed");
          if (topUtils.flushApzRepaints()) {
            dump(
              "WaitUntilApzStable: flushed APZ repaints in parent proc, waiting for callback...\n"
            );
          } else {
            dump(
              "WaitUntilApzStable: flushing APZ repaints in parent proc was a no-op, triggering callback directly...\n"
            );
            repaintDone();
          }
        };

        // Flush APZ repaints, but wait until all the pending paints have been
        // sent.
        flushRepaint();
      }
      function cleanup() {
        removeMessageListener("apz-flush", apzFlush);
        removeMessageListener("cleanup", cleanup);
      }
      addMessageListener("apz-flush", apzFlush);
      addMessageListener("cleanup", cleanup);
    }

    // This is the first time waitUntilApzStable is being called, do initialization
    if (typeof waitUntilApzStable.chromeHelper == "undefined") {
      waitUntilApzStable.chromeHelper =
        SpecialPowers.loadChromeScript(parentProcessFlush);
      ApzCleanup.register(() => {
        waitUntilApzStable.chromeHelper.sendAsyncMessage("cleanup", null);
        waitUntilApzStable.chromeHelper.destroy();
        delete waitUntilApzStable.chromeHelper;
      });
    }

    // Actually trigger the parent-process flush and wait for it to finish
    waitUntilApzStable.chromeHelper.sendAsyncMessage("apz-flush", null);
    await waitUntilApzStable.chromeHelper.promiseOneMessage("apz-flush-done");
    dump("WaitUntilApzStable: got apz-flush-done in child proc\n");
  }

  await SimpleTest.promiseFocus(window);
  dump("WaitUntilApzStable: done promiseFocus\n");
  await promiseAllPaintsDone();
  dump("WaitUntilApzStable: done promiseAllPaintsDone\n");
  await promiseOnlyApzControllerFlushed();
  dump("WaitUntilApzStable: all done\n");
}

// This function returns a promise that is resolved after at least one paint
// has been sent and processed by the compositor. This function can force
// such a paint to happen if none are pending. This is useful to run after
// the waitUntilApzStable() but before reading the compositor-side APZ test
// data, because the test data for the content layers id only gets populated
// on content layer tree updates *after* the root layer tree has a RefLayer
// pointing to the contnet layer tree. waitUntilApzStable itself guarantees
// that the root layer tree is pointing to the content layer tree, but does
// not guarantee the subsequent paint; this function does that job.
async function forceLayerTreeToCompositor() {
  // Modify a style property to force a layout flush
  document.body.style.boxSizing = "border-box";
  var utils = SpecialPowers.getDOMWindowUtils(window);
  if (!utils.isMozAfterPaintPending) {
    dump("Forcing a paint since none was pending already...\n");
    var testMode = utils.isTestControllingRefreshes;
    utils.advanceTimeAndRefresh(0);
    if (!testMode) {
      utils.restoreNormalRefresh();
    }
  }
  await promiseAllPaintsDone(null, true);
  await promiseOnlyApzControllerFlushed();
}

function isApzEnabled() {
  var enabled = SpecialPowers.getDOMWindowUtils(window).asyncPanZoomEnabled;
  if (!enabled) {
    // All tests are required to have at least one assertion. Since APZ is
    // disabled, and the main test is presumably not going to run, we stick in
    // a dummy assertion here to keep the test passing.
    SimpleTest.ok(true, "APZ is not enabled; this test will be skipped");
  }
  return enabled;
}

function isKeyApzEnabled() {
  return isApzEnabled() && SpecialPowers.getBoolPref("apz.keyboard.enabled");
}

// Take a snapshot of the given rect, *including compositor transforms* (i.e.
// includes async scroll transforms applied by APZ). If you don't need the
// compositor transforms, you can probably get away with using
// SpecialPowers.snapshotWindowWithOptions or one of the friendlier wrappers.
// The rect provided is expected to be relative to the screen, for example as
// returned by rectRelativeToScreen in apz_test_native_event_utils.js.
// Example usage:
//   var snapshot = getSnapshot(rectRelativeToScreen(myDiv));
// which will take a snapshot of the 'myDiv' element. Note that if part of the
// element is obscured by other things on top, the snapshot will include those
// things. If it is clipped by a scroll container, the snapshot will include
// that area anyway, so you will probably get parts of the scroll container in
// the snapshot. If the rect extends outside the browser window then the
// results are undefined.
// The snapshot is returned in the form of a data URL.
function getSnapshot(rect) {
  function parentProcessSnapshot() {
    /* eslint-env mozilla/chrome-script */
    addMessageListener("snapshot", function (parentRect) {
      var topWin = Services.wm.getMostRecentWindow("navigator:browser");
      if (!topWin) {
        topWin = Services.wm.getMostRecentWindow("navigator:geckoview");
      }

      // reposition the rect relative to the top-level browser window
      parentRect = JSON.parse(parentRect);
      parentRect.x -= topWin.mozInnerScreenX;
      parentRect.y -= topWin.mozInnerScreenY;

      // take the snapshot
      var canvas = topWin.document.createElementNS(
        "http://www.w3.org/1999/xhtml",
        "canvas"
      );
      canvas.width = parentRect.width;
      canvas.height = parentRect.height;
      var ctx = canvas.getContext("2d");
      ctx.drawWindow(
        topWin,
        parentRect.x,
        parentRect.y,
        parentRect.width,
        parentRect.height,
        "rgb(255,255,255)",
        ctx.DRAWWINDOW_DRAW_VIEW |
          ctx.DRAWWINDOW_USE_WIDGET_LAYERS |
          ctx.DRAWWINDOW_DRAW_CARET
      );
      return canvas.toDataURL();
    });
  }

  if (typeof getSnapshot.chromeHelper == "undefined") {
    // This is the first time getSnapshot is being called; do initialization
    getSnapshot.chromeHelper = SpecialPowers.loadChromeScript(
      parentProcessSnapshot
    );
    ApzCleanup.register(function () {
      getSnapshot.chromeHelper.destroy();
    });
  }

  return getSnapshot.chromeHelper.sendQuery("snapshot", JSON.stringify(rect));
}

// Takes the document's query string and parses it, assuming the query string
// is composed of key-value pairs where the value is in JSON format. The object
// returned contains the various values indexed by their respective keys. In
// case of duplicate keys, the last value be used.
// Examples:
//   ?key="value"&key2=false&key3=500
//     produces { "key": "value", "key2": false, "key3": 500 }
//   ?key={"x":0,"y":50}&key2=[1,2,true]
//     produces { "key": { "x": 0, "y": 0 }, "key2": [1, 2, true] }
function getQueryArgs() {
  var args = {};
  if (location.search.length) {
    var params = location.search.substr(1).split("&");
    for (var p of params) {
      var [k, v] = p.split("=");
      args[k] = JSON.parse(v);
    }
  }
  return args;
}

// An async function that inserts a script element with the given URI into
// the head of the document of the given window. This function returns when
// the load or error event fires on the script element, indicating completion.
async function injectScript(aScript, aWindow = window) {
  var e = aWindow.document.createElement("script");
  e.type = "text/javascript";
  let loadPromise = new Promise((resolve, reject) => {
    e.onload = function () {
      resolve();
    };
    e.onerror = function () {
      dump("Script [" + aScript + "] errored out\n");
      reject();
    };
  });
  e.src = aScript;
  aWindow.document.getElementsByTagName("head")[0].appendChild(e);
  await loadPromise;
}

// Compute some configuration information used for hit testing.
// The computed information is cached to avoid recomputing it
// each time this function is called.
// The computed information is an object with three fields:
//   utils: the nsIDOMWindowUtils instance for this window
//   isWindow: true if the platform is Windows
//   activateAllScrollFrames: true if prefs indicate all scroll frames are
//                            activated with at least a minimal display port
function getHitTestConfig() {
  if (!("hitTestConfig" in window)) {
    var utils = SpecialPowers.getDOMWindowUtils(window);
    var isWindows = getPlatform() == "windows";
    let activateAllScrollFrames =
      SpecialPowers.getBoolPref("apz.wr.activate_all_scroll_frames") ||
      (SpecialPowers.getBoolPref(
        "apz.wr.activate_all_scroll_frames_when_fission"
      ) &&
        SpecialPowers.Services.appinfo.fissionAutostart);

    window.hitTestConfig = {
      utils,
      isWindows,
      activateAllScrollFrames,
    };
  }
  return window.hitTestConfig;
}

// Compute the coordinates of the center of the given element. The argument
// can either be a string (the id of the element desired) or the element
// itself.
function centerOf(element) {
  if (typeof element === "string") {
    element = document.getElementById(element);
  }
  var bounds = element.getBoundingClientRect();
  return { x: bounds.x + bounds.width / 2, y: bounds.y + bounds.height / 2 };
}

// Peform a compositor hit test at the given point and return the result.
// |point| is expected to be in CSS coordinates relative to the layout
// viewport, since this is what sendMouseEvent() expects. (Note that this
// is different from sendNativeMouseEvent() which expects screen coordinates
// relative to the screen.)
// The returned object has two fields:
//   hitInfo: a combination of APZHitResultFlags
//   scrollId: the view-id of the scroll frame that was hit
function hitTest(point) {
  var utils = getHitTestConfig().utils;
  dump("Hit-testing point (" + point.x + ", " + point.y + ")\n");
  utils.sendMouseEvent(
    "MozMouseHittest",
    point.x,
    point.y,
    0,
    0,
    0,
    true,
    0,
    0,
    true,
    true
  );
  var data = utils.getCompositorAPZTestData();
  ok(
    data.hitResults.length >= 1,
    "Expected at least one hit result in the APZTestData"
  );
  var result = data.hitResults[data.hitResults.length - 1];
  return {
    hitInfo: result.hitResult,
    scrollId: result.scrollId,
    layersId: result.layersId,
  };
}

// Returns a canonical stringification of the hitInfo bitfield.
function hitInfoToString(hitInfo) {
  var strs = [];
  for (var flag in APZHitResultFlags) {
    if ((hitInfo & APZHitResultFlags[flag]) != 0) {
      strs.push(flag);
    }
  }
  if (!strs.length) {
    return "INVISIBLE";
  }
  strs.sort(function (a, b) {
    return APZHitResultFlags[a] - APZHitResultFlags[b];
  });
  return strs.join(" | ");
}

// Takes an object returned by hitTest, along with the expected values, and
// asserts that they match. Notably, it uses hitInfoToString to provide a
// more useful message for the case that the hit info doesn't match
function checkHitResult(
  hitResult,
  expectedHitInfo,
  expectedScrollId,
  expectedLayersId,
  desc
) {
  is(
    hitInfoToString(hitResult.hitInfo),
    hitInfoToString(expectedHitInfo),
    desc + " hit info"
  );
  is(hitResult.scrollId, expectedScrollId, desc + " scrollid");
  is(hitResult.layersId, expectedLayersId, desc + " layersid");
}

// Symbolic constants used by hitTestScrollbar().
var ScrollbarTrackLocation = {
  START: 1,
  END: 2,
};
var LayerState = {
  ACTIVE: 1,
  INACTIVE: 2,
};

// Perform a hit test on the scrollbar(s) of a scroll frame.
// This function takes a single argument which is expected to be
// an object with the following fields:
//   element: The scroll frame to perform the hit test on.
//   directions: The direction(s) of scrollbars to test.
//     If directions.vertical is true, the vertical scrollbar will be tested.
//     If directions.horizontal is true, the horizontal scrollbar will be tested.
//     Both may be true in a single call (in which case two tests are performed).
//   expectedScrollId: The scroll id that is expected to be hit, if activateAllScrollFrames is false.
//   expectedLayersId: The layers id that is expected to be hit.
//   trackLocation: One of ScrollbarTrackLocation.{START, END}.
//     Determines which end of the scrollbar track is targeted.
//   expectThumb: Whether the scrollbar thumb is expected to be present
//     at the targeted end of the scrollbar track.
//   layerState: Whether the scroll frame is active or inactive.
// The function performs the hit tests and asserts that the returned
// hit test information is consistent with the passed parameters.
// There is no return value.
// Tests that use this function must set the pref
// "layout.scrollbars.always-layerize-track".
function hitTestScrollbar(params) {
  var config = getHitTestConfig();

  var elem = params.element;

  var boundingClientRect = elem.getBoundingClientRect();

  var verticalScrollbarWidth = boundingClientRect.width - elem.clientWidth;
  var horizontalScrollbarHeight = boundingClientRect.height - elem.clientHeight;

  // On windows, the scrollbar tracks have buttons on the end. When computing
  // coordinates for hit-testing we need to account for this. We assume the
  // buttons are square, and so can use the scrollbar width/height to estimate
  // the size of the buttons
  var scrollbarArrowButtonHeight = config.isWindows
    ? verticalScrollbarWidth
    : 0;
  var scrollbarArrowButtonWidth = config.isWindows
    ? horizontalScrollbarHeight
    : 0;

  // Compute the expected hit result flags.
  // The direction flag (APZHitResultFlags.SCROLLBAR_VERTICAL) is added in
  // later, for the vertical test only.
  // The APZHitResultFlags.SCROLLBAR flag will be present regardless of whether
  // the layer is active or inactive because we force layerization of scrollbar
  // tracks. Unfortunately not forcing the layerization results in different
  // behaviour on different platforms which makes testing harder.
  var expectedHitInfo = APZHitResultFlags.VISIBLE | APZHitResultFlags.SCROLLBAR;
  if (params.expectThumb) {
    // The thumb has listeners which are APZ-aware.
    expectedHitInfo |= APZHitResultFlags.APZ_AWARE_LISTENERS;
    var expectActive =
      config.activateAllScrollFrames || params.layerState == LayerState.ACTIVE;
    if (!expectActive) {
      expectedHitInfo |= APZHitResultFlags.INACTIVE_SCROLLFRAME;
    }
    // We do not generate the layers for thumbs on inactive scrollframes.
    if (expectActive) {
      expectedHitInfo |= APZHitResultFlags.SCROLLBAR_THUMB;
    }
  }

  var expectedScrollId = params.expectedScrollId;
  if (config.activateAllScrollFrames) {
    expectedScrollId = config.utils.getViewId(params.element);
    if (params.layerState == LayerState.ACTIVE) {
      is(
        expectedScrollId,
        params.expectedScrollId,
        "Expected scrollId for active scrollframe should match"
      );
    }
  }

  var scrollframeMsg =
    params.layerState == LayerState.ACTIVE
      ? "active scrollframe"
      : "inactive scrollframe";

  // Hit-test the targeted areas, assuming we don't have overlay scrollbars
  // with zero dimensions.
  if (params.directions.vertical && verticalScrollbarWidth > 0) {
    var verticalScrollbarPoint = {
      x: boundingClientRect.right - verticalScrollbarWidth / 2,
      y:
        params.trackLocation == ScrollbarTrackLocation.START
          ? boundingClientRect.y + scrollbarArrowButtonHeight + 5
          : boundingClientRect.bottom -
            horizontalScrollbarHeight -
            scrollbarArrowButtonHeight -
            5,
    };
    checkHitResult(
      hitTest(verticalScrollbarPoint),
      expectedHitInfo | APZHitResultFlags.SCROLLBAR_VERTICAL,
      expectedScrollId,
      params.expectedLayersId,
      scrollframeMsg + " - vertical scrollbar"
    );
  }

  if (params.directions.horizontal && horizontalScrollbarHeight > 0) {
    var horizontalScrollbarPoint = {
      x:
        params.trackLocation == ScrollbarTrackLocation.START
          ? boundingClientRect.x + scrollbarArrowButtonWidth + 5
          : boundingClientRect.right -
            verticalScrollbarWidth -
            scrollbarArrowButtonWidth -
            5,
      y: boundingClientRect.bottom - horizontalScrollbarHeight / 2,
    };
    checkHitResult(
      hitTest(horizontalScrollbarPoint),
      expectedHitInfo,
      expectedScrollId,
      params.expectedLayersId,
      scrollframeMsg + " - horizontal scrollbar"
    );
  }
}

// Return a list of prefs for the given test identifier.
function getPrefs(ident) {
  switch (ident) {
    case "TOUCH_EVENTS:PAN":
      return [
        // Dropping the touch slop to 0 makes the tests easier to write because
        // we can just do a one-pixel drag to get over the pan threshold rather
        // than having to hard-code some larger value.
        ["apz.touch_start_tolerance", "0.0"],
        // The touchstart from the drag can turn into a long-tap if the touch-move
        // events get held up. Try to prevent that by making long-taps require
        // a 10 second hold. Note that we also cannot enable chaos mode on this
        // test for this reason, since chaos mode can cause the long-press timer
        // to fire sooner than the pref dictates.
        ["ui.click_hold_context_menus.delay", 10000],
        // The subtests in this test do touch-drags to pan the page, but we don't
        // want those pans to turn into fling animations, so we increase the
        // fling min velocity requirement absurdly high.
        ["apz.fling_min_velocity_threshold", "10000"],
        // The helper_div_pan's div gets a displayport on scroll, but if the
        // test takes too long the displayport can expire before the new scroll
        // position is synced back to the main thread. So we disable displayport
        // expiry for these tests.
        ["apz.displayport_expiry_ms", 0],
        // We need to disable touch resampling during these tests because we
        // rely on touch move events being processed without delay. Touch
        // resampling only processes them once vsync fires.
        ["android.touch_resampling.enabled", false],
      ];
    case "TOUCH_ACTION":
      return [
        ...getPrefs("TOUCH_EVENTS:PAN"),
        ["apz.test.fails_with_native_injection", getPlatform() == "windows"],
      ];
    default:
      return [];
  }
}

var ApzCleanup = {
  _cleanups: [],

  register(func) {
    if (!this._cleanups.length) {
      if (!window.isApzSubtest) {
        SimpleTest.registerCleanupFunction(this.execute.bind(this));
      } // else ApzCleanup.execute is called from runSubtestsSeriallyInFreshWindows
    }
    this._cleanups.push(func);
  },

  execute() {
    while (this._cleanups.length) {
      var func = this._cleanups.pop();
      try {
        func();
      } catch (ex) {
        SimpleTest.ok(
          false,
          "Subtest cleanup function [" +
            func.toString() +
            "] threw exception [" +
            ex +
            "] on page [" +
            location.href +
            "]"
        );
      }
    }
  },
};

/**
 * Returns a promise that will resolve if `eventTarget` receives an event of the
 * given type that passes the given filter. Only the first matching message is
 * used. The filter must be a function (or null); it is called with the event
 * object and the call must return true to resolve the promise.
 */
function promiseOneEvent(eventTarget, eventType, filter) {
  return new Promise((resolve, reject) => {
    eventTarget.addEventListener(eventType, function listener(e) {
      let success = false;
      if (filter == null) {
        success = true;
      } else if (typeof filter == "function") {
        try {
          success = filter(e);
        } catch (ex) {
          dump(
            `ERROR: Filter passed to promiseOneEvent threw exception: ${ex}\n`
          );
          reject();
          return;
        }
      } else {
        dump(
          "ERROR: Filter passed to promiseOneEvent was neither null nor a function\n"
        );
        reject();
        return;
      }
      if (success) {
        eventTarget.removeEventListener(eventType, listener);
        resolve(e);
      }
    });
  });
}

function visualViewportAsZoomedRect() {
  let vv = window.visualViewport;
  return {
    x: vv.pageLeft,
    y: vv.pageTop,
    w: vv.width,
    h: vv.height,
    z: vv.scale,
  };
}

// Pulls the latest compositor APZ test data and checks to see if the
// scroller with id `scrollerId` was checkerboarding. It also ensures that
// a scroller with id `scrollerId` was actually found in the test data.
// This function requires that "apz.test.logging_enabled" be set to true,
// in order for the test data to be logged.
function assertNotCheckerboarded(utils, scrollerId, msgPrefix) {
  utils.advanceTimeAndRefresh(0);
  var data = utils.getCompositorAPZTestData();
  //dump(JSON.stringify(data, null, 4));
  var found = false;
  for (apzcData of data.additionalData) {
    if (apzcData.key == scrollerId) {
      var checkerboarding = apzcData.value
        .split(",")
        .includes("checkerboarding");
      ok(!checkerboarding, `${msgPrefix}: scroller is not checkerboarding`);
      found = true;
    }
  }
  ok(found, `${msgPrefix}: Found the scroller in the APZ data`);
  utils.restoreNormalRefresh();
}

async function waitToClearOutAnyPotentialScrolls(aWindow) {
  await promiseFrame(aWindow);
  await promiseFrame(aWindow);
  await promiseOnlyApzControllerFlushed(aWindow);
  await promiseFrame(aWindow);
  await promiseFrame(aWindow);
}

function waitForScrollEvent(target) {
  return new Promise(resolve => {
    target.addEventListener("scroll", resolve, { once: true });
  });
}

// This is another variant of promiseApzFlushedRepaints.
// We need this function because, unfortunately, there is no easy way to use
// paint_listeners.js' functions and apz_test_utils.js' functions in popup
// contents opened by extensions either as scripts in the popup contents or
// scripts inside SpecialPowers.spawn because we can't use privileged functions
// in the popup contents' script, we can't use functions basically as it as in
// the sandboxed context either.
async function promiseApzFlushedRepaintsInPopup(popup) {
  // Flush APZ repaints and waits for MozAfterPaint.
  await SpecialPowers.spawn(popup, [], async () => {
    const utils = SpecialPowers.getDOMWindowUtils(content.window);

    async function promiseAllPaintsDone() {
      return new Promise(resolve => {
        function waitForPaints() {
          if (utils.isMozAfterPaintPending) {
            dump("Waits for a MozAfterPaint event\n");
            content.window.addEventListener(
              "MozAfterPaint",
              () => {
                dump("Got a MozAfterPaint event\n");
                waitForPaints();
              },
              { once: true }
            );
          } else {
            dump("No more pending MozAfterPaint\n");
            content.window.setTimeout(resolve, 0);
          }
        }
        waitForPaints();
      });
    }
    await promiseAllPaintsDone();

    await new Promise(resolve => {
      var repaintDone = function () {
        dump("APZ flush done\n");
        SpecialPowers.Services.obs.removeObserver(
          repaintDone,
          "apz-repaints-flushed"
        );
        content.window.setTimeout(resolve, 0);
      };
      SpecialPowers.Services.obs.addObserver(
        repaintDone,
        "apz-repaints-flushed"
      );
      if (utils.flushApzRepaints()) {
        dump("Flushed APZ repaints, waiting for callback...\n");
      } else {
        dump(
          "Flushing APZ repaints was a no-op, triggering callback directly...\n"
        );
        repaintDone();
      }
    });

    await promiseAllPaintsDone();
  });
}

// A utility function to make sure there's no scroll animation on the given
// |aElement|.
async function cancelScrollAnimation(aElement, aWindow = window) {
  // In fact there's no good way to directly cancel the active animation on the
  // element, so we destroy the corresponding scrollable frame then reconstruct
  // a new scrollable frame so that it clobbers the animation.
  const originalStyle = aElement.style.display;
  aElement.style.display = "none";
  await aWindow.promiseApzFlushedRepaints();
  aElement.style.display = originalStyle;
  await aWindow.promiseApzFlushedRepaints();
}

function collectSampledScrollOffsets(aElement) {
  let data = SpecialPowers.DOMWindowUtils.getCompositorAPZTestData();
  let sampledResults = data.sampledResults;

  const layersId = SpecialPowers.DOMWindowUtils.getLayersId();
  const scrollId = SpecialPowers.DOMWindowUtils.getViewId(aElement);

  return sampledResults.filter(
    result =>
      SpecialPowers.wrap(result).layersId == layersId &&
      SpecialPowers.wrap(result).scrollId == scrollId
  );
}