Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });

const types = require('../../../types.js');
const getActivationStart = require('./getActivationStart.js');

/*
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


let firstHiddenTime = -1;

const initHiddenTime = () => {
  // If the document is hidden when this code runs, assume it was always
  // hidden and the page was loaded in the background, with the one exception
  // that visibility state is always 'hidden' during prerendering, so we have
  // to ignore that case until prerendering finishes (see: `prerenderingchange`
  // event logic below).
  return types.WINDOW.document?.visibilityState === 'hidden' && !types.WINDOW.document?.prerendering ? 0 : Infinity;
};

const onVisibilityUpdate = (event) => {
  // If the document is 'hidden' and no previous hidden timestamp has been
  // set, update it based on the current event data.
  if (types.WINDOW.document.visibilityState === 'hidden' && firstHiddenTime > -1) {
    // If the event is a 'visibilitychange' event, it means the page was
    // visible prior to this change, so the event timestamp is the first
    // hidden time.
    // However, if the event is not a 'visibilitychange' event, then it must
    // be a 'prerenderingchange' event, and the fact that the document is
    // still 'hidden' from the above check means the tab was activated
    // in a background state and so has always been hidden.
    firstHiddenTime = event.type === 'visibilitychange' ? event.timeStamp : 0;

    // Remove all listeners now that a `firstHiddenTime` value has been set.
    removeChangeListeners();
  }
};

const addChangeListeners = () => {
  addEventListener('visibilitychange', onVisibilityUpdate, true);
  // IMPORTANT: when a page is prerendering, its `visibilityState` is
  // 'hidden', so in order to account for cases where this module checks for
  // visibility during prerendering, an additional check after prerendering
  // completes is also required.
  addEventListener('prerenderingchange', onVisibilityUpdate, true);
};

const removeChangeListeners = () => {
  removeEventListener('visibilitychange', onVisibilityUpdate, true);
  removeEventListener('prerenderingchange', onVisibilityUpdate, true);
};

const getVisibilityWatcher = () => {
  if (types.WINDOW.document && firstHiddenTime < 0) {
    // Check if we have a previous hidden `visibility-state` performance entry.
    const activationStart = getActivationStart.getActivationStart();
    const firstVisibilityStateHiddenTime = !types.WINDOW.document.prerendering
      ? globalThis.performance
          .getEntriesByType('visibility-state')
          .filter(e => e.name === 'hidden' && e.startTime > activationStart)[0]?.startTime
      : undefined;

    // Prefer that, but if it's not available and the document is hidden when
    // this code runs, assume it was hidden since navigation start. This isn't
    // a perfect heuristic, but it's the best we can do until the
    // `visibility-state` performance entry becomes available in all browsers.
    firstHiddenTime = firstVisibilityStateHiddenTime ?? initHiddenTime();
    // We're still going to listen to for changes so we can handle things like
    // bfcache restores and/or prerender without having to examine individual
    // timestamps in detail.
    addChangeListeners();
  }
  return {
    get firstHiddenTime() {
      return firstHiddenTime;
    },
  };
};

exports.getVisibilityWatcher = getVisibilityWatcher;//# sourceMappingURL=http://go/sourcemap/sourcemaps/bf249e6efb5b097f23d7e21d7283429f0760b740/node_modules/@sentry-internal/browser-utils/build/cjs/metrics/web-vitals/lib/getVisibilityWatcher.js.map
