/**
 * vue-meta v2.4.0
 * (c) 2020
 * - Declan de Wet
 * - Sébastien Chopin (@Atinux)
 * - Pim (@pimlie)
 * - All the amazing contributors
 * @license MIT
 */

import deepmerge from 'deepmerge';

var version = "2.4.0";

function _typeof(obj) {
  "@babel/helpers - typeof";

  if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") {
    _typeof = function (obj) {
      return typeof obj;
    };
  } else {
    _typeof = function (obj) {
      return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;
    };
  }

  return _typeof(obj);
}

function _unsupportedIterableToArray(o, minLen) {
  if (!o) return;
  if (typeof o === "string") return _arrayLikeToArray(o, minLen);
  var n = Object.prototype.toString.call(o).slice(8, -1);
  if (n === "Object" && o.constructor) n = o.constructor.name;
  if (n === "Map" || n === "Set") return Array.from(o);
  if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen);
}

function _arrayLikeToArray(arr, len) {
  if (len == null || len > arr.length) len = arr.length;

  for (var i = 0, arr2 = new Array(len); i < len; i++) arr2[i] = arr[i];

  return arr2;
}

function _createForOfIteratorHelper(o, allowArrayLike) {
  var it;

  if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) {
    if (Array.isArray(o) || (it = _unsupportedIterableToArray(o)) || allowArrayLike && o && typeof o.length === "number") {
      if (it) o = it;
      var i = 0;

      var F = function () {};

      return {
        s: F,
        n: function () {
          if (i >= o.length) return {
            done: true
          };
          return {
            done: false,
            value: o[i++]
          };
        },
        e: function (e) {
          throw e;
        },
        f: F
      };
    }

    throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method.");
  }

  var normalCompletion = true,
      didErr = false,
      err;
  return {
    s: function () {
      it = o[Symbol.iterator]();
    },
    n: function () {
      var step = it.next();
      normalCompletion = step.done;
      return step;
    },
    e: function (e) {
      didErr = true;
      err = e;
    },
    f: function () {
      try {
        if (!normalCompletion && it.return != null) it.return();
      } finally {
        if (didErr) throw err;
      }
    }
  };
}

/**
 * checks if passed argument is an array
 * @param  {any}  arg - the object to check
 * @return {Boolean} - true if `arg` is an array
 */
function isArray(arg) {
  return Array.isArray(arg);
}
function isUndefined(arg) {
  return typeof arg === 'undefined';
}
function isObject(arg) {
  return _typeof(arg) === 'object';
}
function isPureObject(arg) {
  return _typeof(arg) === 'object' && arg !== null;
}
function isFunction(arg) {
  return typeof arg === 'function';
}
function isString(arg) {
  return typeof arg === 'string';
}

function hasGlobalWindowFn() {
  try {
    return !isUndefined(window);
  } catch (e) {
    return false;
  }
}
var hasGlobalWindow = hasGlobalWindowFn();

var _global = hasGlobalWindow ? window : global;

var console = _global.console || {};
function warn(str) {
  /* istanbul ignore next */
  if (!console || !console.warn) {
    return;
  }

  console.warn(str);
}
var showWarningNotSupportedInBrowserBundle = function showWarningNotSupportedInBrowserBundle(method) {
  return warn("".concat(method, " is not supported in browser builds"));
};
var showWarningNotSupported = function showWarningNotSupported() {
  return warn('This vue app/component has no vue-meta configuration');
};

/**
 * These are constant variables used throughout the application.
 */
// set some sane defaults
var defaultInfo = {
  title: undefined,
  titleChunk: '',
  titleTemplate: '%s',
  htmlAttrs: {},
  bodyAttrs: {},
  headAttrs: {},
  base: [],
  link: [],
  meta: [],
  style: [],
  script: [],
  noscript: [],
  __dangerouslyDisableSanitizers: [],
  __dangerouslyDisableSanitizersByTagID: {}
};
var rootConfigKey = '_vueMeta'; // This is the name of the component option that contains all the information that
// gets converted to the various meta tags & attributes for the page.

var keyName = 'metaInfo'; // This is the attribute vue-meta arguments on elements to know which it should
// manage and which it should ignore.

var attribute = 'data-vue-meta'; // This is the attribute that goes on the `html` tag to inform `vue-meta`
// that the server has already generated the meta tags for the initial render.

var ssrAttribute = 'data-vue-meta-server-rendered'; // This is the property that tells vue-meta to overwrite (instead of append)
// an item in a tag list. For example, if you have two `meta` tag list items
// that both have `vmid` of "description", then vue-meta will overwrite the
// shallowest one with the deepest one.

var tagIDKeyName = 'vmid'; // This is the key name for possible meta templates

var metaTemplateKeyName = 'template'; // This is the key name for the content-holding property

var contentKeyName = 'content'; // The id used for the ssr app

var ssrAppId = 'ssr'; // How long meta update

var debounceWait = 10; // How long meta update

var waitOnDestroyed = true;
var defaultOptions = {
  keyName: keyName,
  attribute: attribute,
  ssrAttribute: ssrAttribute,
  tagIDKeyName: tagIDKeyName,
  contentKeyName: contentKeyName,
  metaTemplateKeyName: metaTemplateKeyName,
  waitOnDestroyed: waitOnDestroyed,
  debounceWait: debounceWait,
  ssrAppId: ssrAppId
}; // might be a bit ugly, but minimizes the browser bundles a bit

var defaultInfoKeys = Object.keys(defaultInfo); // The metaInfo property keys which are used to disable escaping

var disableOptionKeys = [defaultInfoKeys[12], defaultInfoKeys[13]]; // List of metaInfo property keys which are configuration options (and dont generate html)

var metaInfoOptionKeys = [defaultInfoKeys[1], defaultInfoKeys[2], 'changed'].concat(disableOptionKeys); // List of metaInfo property keys which only generates attributes and no tags

var metaInfoAttributeKeys = [defaultInfoKeys[3], defaultInfoKeys[4], defaultInfoKeys[5]]; // HTML elements which support the onload event

var tagsSupportingOnload = ['link', 'style', 'script']; // HTML elements which dont have a head tag (shortened to our needs)
var tagProperties = ['once', 'skip', 'template']; // Attributes which should be added with data- prefix

var commonDataAttributes = ['body', 'pbody']; // from: https://github.com/kangax/html-minifier/blob/gh-pages/src/htmlminifier.js#L202

var booleanHtmlAttributes = ['allowfullscreen', 'amp', 'amp-boilerplate', 'async', 'autofocus', 'autoplay', 'checked', 'compact', 'controls', 'declare', 'default', 'defaultchecked', 'defaultmuted', 'defaultselected', 'defer', 'disabled', 'enabled', 'formnovalidate', 'hidden', 'indeterminate', 'inert', 'ismap', 'itemscope', 'loop', 'multiple', 'muted', 'nohref', 'noresize', 'noshade', 'novalidate', 'nowrap', 'open', 'pauseonexit', 'readonly', 'required', 'reversed', 'scoped', 'seamless', 'selected', 'sortable', 'truespeed', 'typemustmatch', 'visible'];

var batchId = null;
function triggerUpdate(_ref, rootVm, hookName) {
  var debounceWait = _ref.debounceWait;

  // if an update was triggered during initialization or when an update was triggered by the
  // metaInfo watcher, set initialized to null
  // then we keep falsy value but know we need to run a triggerUpdate after initialization
  if (!rootVm[rootConfigKey].initialized && (rootVm[rootConfigKey].initializing || hookName === 'watcher')) {
    rootVm[rootConfigKey].initialized = null;
  }

  if (rootVm[rootConfigKey].initialized && !rootVm[rootConfigKey].pausing) {
    // batch potential DOM updates to prevent extraneous re-rendering
    // eslint-disable-next-line no-void
    batchUpdate(function () {
      return void rootVm.$meta().refresh();
    }, debounceWait);
  }
}
/**
 * Performs a batched update.
 *
 * @param  {(null|Number)} id - the ID of this update
 * @param  {Function} callback - the update to perform
 * @return {Number} id - a new ID
 */

function batchUpdate(callback, timeout) {
  timeout = timeout === undefined ? 10 : timeout;

  if (!timeout) {
    callback();
    return;
  }

  clearTimeout(batchId);
  batchId = setTimeout(function () {
    callback();
  }, timeout);
  return batchId;
}

/*
 * To reduce build size, this file provides simple polyfills without
 * overly excessive type checking and without modifying
 * the global Array.prototype
 * The polyfills are automatically removed in the commonjs build
 * Also, only files in client/ & shared/ should use these functions
 * files in server/ still use normal js function
 */
function find(array, predicate, thisArg) {
  if ( !Array.prototype.find) {
    // idx needs to be a Number, for..in returns string
    for (var idx = 0; idx < array.length; idx++) {
      if (predicate.call(thisArg, array[idx], idx, array)) {
        return array[idx];
      }
    }

    return;
  }

  return array.find(predicate, thisArg);
}
function findIndex(array, predicate, thisArg) {
  if ( !Array.prototype.findIndex) {
    // idx needs to be a Number, for..in returns string
    for (var idx = 0; idx < array.length; idx++) {
      if (predicate.call(thisArg, array[idx], idx, array)) {
        return idx;
      }
    }

    return -1;
  }

  return array.findIndex(predicate, thisArg);
}
function toArray(arg) {
  if ( !Array.from) {
    return Array.prototype.slice.call(arg);
  }

  return Array.from(arg);
}
function includes(array, value) {
  if ( !Array.prototype.includes) {
    for (var idx in array) {
      if (array[idx] === value) {
        return true;
      }
    }

    return false;
  }

  return array.includes(value);
}

var querySelector = function querySelector(arg, el) {
  return (el || document).querySelectorAll(arg);
};
function getTag(tags, tag) {
  if (!tags[tag]) {
    tags[tag] = document.getElementsByTagName(tag)[0];
  }

  return tags[tag];
}
function getElementsKey(_ref) {
  var body = _ref.body,
      pbody = _ref.pbody;
  return body ? 'body' : pbody ? 'pbody' : 'head';
}
function queryElements(parentNode, _ref2, attributes) {
  var appId = _ref2.appId,
      attribute = _ref2.attribute,
      type = _ref2.type,
      tagIDKeyName = _ref2.tagIDKeyName;
  attributes = attributes || {};
  var queries = ["".concat(type, "[").concat(attribute, "=\"").concat(appId, "\"]"), "".concat(type, "[data-").concat(tagIDKeyName, "]")].map(function (query) {
    for (var key in attributes) {
      var val = attributes[key];
      var attributeValue = val && val !== true ? "=\"".concat(val, "\"") : '';
      query += "[data-".concat(key).concat(attributeValue, "]");
    }

    return query;
  });
  return toArray(querySelector(queries.join(', '), parentNode));
}
function removeElementsByAppId(_ref3, appId) {
  var attribute = _ref3.attribute;
  toArray(querySelector("[".concat(attribute, "=\"").concat(appId, "\"]"))).map(function (el) {
    return el.remove();
  });
}
function removeAttribute(el, attributeName) {
  el.removeAttribute(attributeName);
}

function hasMetaInfo(vm) {
  vm = vm || this;
  return vm && (vm[rootConfigKey] === true || isObject(vm[rootConfigKey]));
} // a component is in a metaInfo branch when itself has meta info or one of its (grand-)children has

function inMetaInfoBranch(vm) {
  vm = vm || this;
  return vm && !isUndefined(vm[rootConfigKey]);
}

function pause(rootVm, refresh) {
  rootVm[rootConfigKey].pausing = true;
  return function () {
    return resume(rootVm, refresh);
  };
}
function resume(rootVm, refresh) {
  rootVm[rootConfigKey].pausing = false;

  if (refresh || refresh === undefined) {
    return rootVm.$meta().refresh();
  }
}

function addNavGuards(rootVm) {
  var router = rootVm.$router; // return when nav guards already added or no router exists

  if (rootVm[rootConfigKey].navGuards || !router) {
    /* istanbul ignore next */
    return;
  }

  rootVm[rootConfigKey].navGuards = true;
  router.beforeEach(function (to, from, next) {
    pause(rootVm);
    next();
  });
  router.afterEach(function () {
    rootVm.$nextTick(function () {
      var _resume = resume(rootVm),
          metaInfo = _resume.metaInfo;

      if (metaInfo && isFunction(metaInfo.afterNavigation)) {
        metaInfo.afterNavigation(metaInfo);
      }
    });
  });
}

var appId = 1;
function createMixin(Vue, options) {
  // for which Vue lifecycle hooks should the metaInfo be refreshed
  var updateOnLifecycleHook = ['activated', 'deactivated', 'beforeMount'];
  var wasServerRendered = false; // watch for client side component updates

  return {
    beforeCreate: function beforeCreate() {
      var _this2 = this;

      var rootKey = '$root';
      var $root = this[rootKey];
      var $options = this.$options;
      var devtoolsEnabled = Vue.config.devtools;
      Object.defineProperty(this, '_hasMetaInfo', {
        configurable: true,
        get: function get() {
          // Show deprecation warning once when devtools enabled
          if (devtoolsEnabled && !$root[rootConfigKey].deprecationWarningShown) {
            warn('VueMeta DeprecationWarning: _hasMetaInfo has been deprecated and will be removed in a future version. Please use hasMetaInfo(vm) instead');
            $root[rootConfigKey].deprecationWarningShown = true;
          }

          return hasMetaInfo(this);
        }
      });

      if (this === $root) {
        $root.$once('hook:beforeMount', function () {
          wasServerRendered = this.$el && this.$el.nodeType === 1 && this.$el.hasAttribute('data-server-rendered'); // In most cases when you have a SSR app it will be the first app thats gonna be
          // initiated, if we cant detect the data-server-rendered attribute from Vue but we
          // do see our own ssrAttribute then _assume_ the Vue app with appId 1 is the ssr app
          // attempted fix for #404 & #562, but we rly need to refactor how we pass appIds from
          // ssr to the client

          if (!wasServerRendered && $root[rootConfigKey] && $root[rootConfigKey].appId === 1) {
            var htmlTag = getTag({}, 'html');
            wasServerRendered = htmlTag && htmlTag.hasAttribute(options.ssrAttribute);
          }
        });
      } // Add a marker to know if it uses metaInfo
      // _vnode is used to know that it's attached to a real component
      // useful if we use some mixin to add some meta tags (like nuxt-i18n)


      if (isUndefined($options[options.keyName]) || $options[options.keyName] === null) {
        return;
      }

      if (!$root[rootConfigKey]) {
        $root[rootConfigKey] = {
          appId: appId
        };
        appId++;

        if (devtoolsEnabled && $root.$options[options.keyName]) {
          // use nextTick so the children should be added to $root
          this.$nextTick(function () {
            // find the first child that lists fnOptions
            var child = find($root.$children, function (c) {
              return c.$vnode && c.$vnode.fnOptions;
            });

            if (child && child.$vnode.fnOptions[options.keyName]) {
              warn("VueMeta has detected a possible global mixin which adds a ".concat(options.keyName, " property to all Vue components on the page. This could cause severe performance issues. If possible, use $meta().addApp to add meta information instead"));
            }
          });
        }
      } // to speed up updates we keep track of branches which have a component with vue-meta info defined
      // if _vueMeta = true it has info, if _vueMeta = false a child has info


      if (!this[rootConfigKey]) {
        this[rootConfigKey] = true;
        var parent = this.$parent;

        while (parent && parent !== $root) {
          if (isUndefined(parent[rootConfigKey])) {
            parent[rootConfigKey] = false;
          }

          parent = parent.$parent;
        }
      } // coerce function-style metaInfo to a computed prop so we can observe
      // it on creation


      if (isFunction($options[options.keyName])) {
        $options.computed = $options.computed || {};
        $options.computed.$metaInfo = $options[options.keyName];

        if (!this.$isServer) {
          // if computed $metaInfo exists, watch it for updates & trigger a refresh
          // when it changes (i.e. automatically handle async actions that affect metaInfo)
          // credit for this suggestion goes to [Sébastien Chopin](https://github.com/Atinux)
          this.$on('hook:created', function () {
            this.$watch('$metaInfo', function () {
              triggerUpdate(options, this[rootKey], 'watcher');
            });
          });
        }
      } // force an initial refresh on page load and prevent other lifecycleHooks
      // to triggerUpdate until this initial refresh is finished
      // this is to make sure that when a page is opened in an inactive tab which
      // has throttled rAF/timers we still immediately set the page title


      if (isUndefined($root[rootConfigKey].initialized)) {
        $root[rootConfigKey].initialized = this.$isServer;

        if (!$root[rootConfigKey].initialized) {
          if (!$root[rootConfigKey].initializedSsr) {
            $root[rootConfigKey].initializedSsr = true;
            this.$on('hook:beforeMount', function () {
              var $root = this[rootKey]; // if this Vue-app was server rendered, set the appId to 'ssr'
              // only one SSR app per page is supported

              if (wasServerRendered) {
                $root[rootConfigKey].appId = options.ssrAppId;
              }
            });
          } // we use the mounted hook here as on page load


          this.$on('hook:mounted', function () {
            var $root = this[rootKey];

            if ($root[rootConfigKey].initialized) {
              return;
            } // used in triggerUpdate to check if a change was triggered
            // during initialization


            $root[rootConfigKey].initializing = true; // refresh meta in nextTick so all child components have loaded

            this.$nextTick(function () {
              var _$root$$meta$refresh = $root.$meta().refresh(),
                  tags = _$root$$meta$refresh.tags,
                  metaInfo = _$root$$meta$refresh.metaInfo; // After ssr hydration (identifier by tags === false) check
              // if initialized was set to null in triggerUpdate. That'd mean
              // that during initilazation changes where triggered which need
              // to be applied OR a metaInfo watcher was triggered before the
              // current hook was called
              // (during initialization all changes are blocked)


              if (tags === false && $root[rootConfigKey].initialized === null) {
                this.$nextTick(function () {
                  return triggerUpdate(options, $root, 'init');
                });
              }

              $root[rootConfigKey].initialized = true;
              delete $root[rootConfigKey].initializing; // add the navigation guards if they havent been added yet
              // they are needed for the afterNavigation callback

              if (!options.refreshOnceOnNavigation && metaInfo.afterNavigation) {
                addNavGuards($root);
              }
            });
          }); // add the navigation guards if requested

          if (options.refreshOnceOnNavigation) {
            addNavGuards($root);
          }
        }
      }

      this.$on('hook:destroyed', function () {
        var _this = this;

        // do not trigger refresh:
        // - when user configured to not wait for transitions on destroyed
        // - when the component doesnt have a parent
        // - doesnt have metaInfo defined
        if (!this.$parent || !hasMetaInfo(this)) {
          return;
        }

        delete this._hasMetaInfo;
        this.$nextTick(function () {
          if (!options.waitOnDestroyed || !_this.$el || !_this.$el.offsetParent) {
            triggerUpdate(options, _this.$root, 'destroyed');
            return;
          } // Wait that element is hidden before refreshing meta tags (to support animations)


          var interval = setInterval(function () {
            if (_this.$el && _this.$el.offsetParent !== null) {
              /* istanbul ignore next line */
              return;
            }

            clearInterval(interval);
            triggerUpdate(options, _this.$root, 'destroyed');
          }, 50);
        });
      }); // do not trigger refresh on the server side

      if (this.$isServer) {
        /* istanbul ignore next */
        return;
      } // no need to add this hooks on server side


      updateOnLifecycleHook.forEach(function (lifecycleHook) {
        _this2.$on("hook:".concat(lifecycleHook), function () {
          triggerUpdate(options, this[rootKey], lifecycleHook);
        });
      });
    }
  };
}

function setOptions(options) {
  // combine options
  options = isObject(options) ? options : {}; // The options are set like this so they can
  // be minified by terser while keeping the
  // user api intact
  // terser --mangle-properties keep_quoted=strict

  /* eslint-disable dot-notation */

  return {
    keyName: options['keyName'] || defaultOptions.keyName,
    attribute: options['attribute'] || defaultOptions.attribute,
    ssrAttribute: options['ssrAttribute'] || defaultOptions.ssrAttribute,
    tagIDKeyName: options['tagIDKeyName'] || defaultOptions.tagIDKeyName,
    contentKeyName: options['contentKeyName'] || defaultOptions.contentKeyName,
    metaTemplateKeyName: options['metaTemplateKeyName'] || defaultOptions.metaTemplateKeyName,
    debounceWait: isUndefined(options['debounceWait']) ? defaultOptions.debounceWait : options['debounceWait'],
    waitOnDestroyed: isUndefined(options['waitOnDestroyed']) ? defaultOptions.waitOnDestroyed : options['waitOnDestroyed'],
    ssrAppId: options['ssrAppId'] || defaultOptions.ssrAppId,
    refreshOnceOnNavigation: !!options['refreshOnceOnNavigation']
  };
  /* eslint-enable dot-notation */
}
function getOptions(options) {
  var optionsCopy = {};

  for (var key in options) {
    optionsCopy[key] = options[key];
  }

  return optionsCopy;
}

function ensureIsArray(arg, key) {
  if (!key || !isObject(arg)) {
    return isArray(arg) ? arg : [];
  }

  if (!isArray(arg[key])) {
    arg[key] = [];
  }

  return arg;
}

var clientSequences = [[/&/g, "&"], [/</g, "<"], [/>/g, ">"], [/"/g, "\""], [/'/g, "'"]]; // sanitizes potentially dangerous characters

function escape(info, options, escapeOptions, escapeKeys) {
  var tagIDKeyName = options.tagIDKeyName;
  var _escapeOptions$doEsca = escapeOptions.doEscape,
      doEscape = _escapeOptions$doEsca === void 0 ? function (v) {
    return v;
  } : _escapeOptions$doEsca;
  var escaped = {};

  for (var key in info) {
    var value = info[key]; // no need to escape configuration options

    if (includes(metaInfoOptionKeys, key)) {
      escaped[key] = value;
      continue;
    } // do not use destructuring for disableOptionKeys, it increases transpiled size
    // due to var checks while we are guaranteed the structure of the cb


    var disableKey = disableOptionKeys[0];

    if (escapeOptions[disableKey] && includes(escapeOptions[disableKey], key)) {
      // this info[key] doesnt need to escaped if the option is listed in __dangerouslyDisableSanitizers
      escaped[key] = value;
      continue;
    }

    var tagId = info[tagIDKeyName];

    if (tagId) {
      disableKey = disableOptionKeys[1]; // keys which are listed in __dangerouslyDisableSanitizersByTagID for the current vmid do not need to be escaped

      if (escapeOptions[disableKey] && escapeOptions[disableKey][tagId] && includes(escapeOptions[disableKey][tagId], key)) {
        escaped[key] = value;
        continue;
      }
    }

    if (isString(value)) {
      escaped[key] = doEscape(value);
    } else if (isArray(value)) {
      escaped[key] = value.map(function (v) {
        if (isPureObject(v)) {
          return escape(v, options, escapeOptions, true);
        }

        return doEscape(v);
      });
    } else if (isPureObject(value)) {
      escaped[key] = escape(value, options, escapeOptions, true);
    } else {
      escaped[key] = value;
    }

    if (escapeKeys) {
      var escapedKey = doEscape(key);

      if (key !== escapedKey) {
        escaped[escapedKey] = escaped[key];
        delete escaped[key];
      }
    }
  }

  return escaped;
}
function escapeMetaInfo(options, info, escapeSequences) {
  escapeSequences = escapeSequences || []; // do not use destructuring for seq, it increases transpiled size
  // due to var checks while we are guaranteed the structure of the cb

  var escapeOptions = {
    doEscape: function doEscape(value) {
      return escapeSequences.reduce(function (val, seq) {
        return val.replace(seq[0], seq[1]);
      }, value);
    }
  };
  disableOptionKeys.forEach(function (disableKey, index) {
    if (index === 0) {
      ensureIsArray(info, disableKey);
    } else if (index === 1) {
      for (var key in info[disableKey]) {
        ensureIsArray(info[disableKey], key);
      }
    }

    escapeOptions[disableKey] = info[disableKey];
  }); // begin sanitization

  return escape(info, options, escapeOptions);
}

function applyTemplate(_ref, headObject, template, chunk) {
  var component = _ref.component,
      metaTemplateKeyName = _ref.metaTemplateKeyName,
      contentKeyName = _ref.contentKeyName;

  if (template === true || headObject[metaTemplateKeyName] === true) {
    // abort, template was already applied
    return false;
  }

  if (isUndefined(template) && headObject[metaTemplateKeyName]) {
    template = headObject[metaTemplateKeyName];
    headObject[metaTemplateKeyName] = true;
  } // return early if no template defined


  if (!template) {
    // cleanup faulty template properties
    delete headObject[metaTemplateKeyName];
    return false;
  }

  if (isUndefined(chunk)) {
    chunk = headObject[contentKeyName];
  }

  headObject[contentKeyName] = isFunction(template) ? template.call(component, chunk) : template.replace(/%s/g, chunk);
  return true;
}

function _arrayMerge(_ref, target, source) {
  var component = _ref.component,
      tagIDKeyName = _ref.tagIDKeyName,
      metaTemplateKeyName = _ref.metaTemplateKeyName,
      contentKeyName = _ref.contentKeyName;
  // we concat the arrays without merging objects contained in,
  // but we check for a `vmid` property on each object in the array
  // using an O(1) lookup associative array exploit
  var destination = [];

  if (!target.length && !source.length) {
    return destination;
  }

  target.forEach(function (targetItem, targetIndex) {
    // no tagID so no need to check for duplicity
    if (!targetItem[tagIDKeyName]) {
      destination.push(targetItem);
      return;
    }

    var sourceIndex = findIndex(source, function (item) {
      return item[tagIDKeyName] === targetItem[tagIDKeyName];
    });
    var sourceItem = source[sourceIndex]; // source doesnt contain any duplicate vmid's, we can keep targetItem

    if (sourceIndex === -1) {
      destination.push(targetItem);
      return;
    } // when sourceItem explictly defines contentKeyName or innerHTML as undefined, its
    // an indication that we need to skip the default behaviour or child has preference over parent
    // which means we keep the targetItem and ignore/remove the sourceItem


    if (contentKeyName in sourceItem && sourceItem[contentKeyName] === undefined || 'innerHTML' in sourceItem && sourceItem.innerHTML === undefined) {
      destination.push(targetItem); // remove current index from source array so its not concatenated to destination below

      source.splice(sourceIndex, 1);
      return;
    } // we now know that targetItem is a duplicate and we should ignore it in favor of sourceItem
    // if source specifies null as content then ignore both the target as the source


    if (sourceItem[contentKeyName] === null || sourceItem.innerHTML === null) {
      // remove current index from source array so its not concatenated to destination below
      source.splice(sourceIndex, 1);
      return;
    } // now we only need to check if the target has a template to combine it with the source


    var targetTemplate = targetItem[metaTemplateKeyName];

    if (!targetTemplate) {
      return;
    }

    var sourceTemplate = sourceItem[metaTemplateKeyName];

    if (!sourceTemplate) {
      // use parent template and child content
      applyTemplate({
        component: component,
        metaTemplateKeyName: metaTemplateKeyName,
        contentKeyName: contentKeyName
      }, sourceItem, targetTemplate); // set template to true to indicate template was already applied

      sourceItem.template = true;
      return;
    }

    if (!sourceItem[contentKeyName]) {
      // use parent content and child template
      applyTemplate({
        component: component,
        metaTemplateKeyName: metaTemplateKeyName,
        contentKeyName: contentKeyName
      }, sourceItem, undefined, targetItem[contentKeyName]);
    }
  });
  return destination.concat(source);
}
var warningShown = false;
function merge(target, source, options) {
  options = options || {}; // remove properties explicitly set to false so child components can
  // optionally _not_ overwrite the parents content
  // (for array properties this is checked in arrayMerge)

  if (source.title === undefined) {
    delete source.title;
  }

  metaInfoAttributeKeys.forEach(function (attrKey) {
    if (!source[attrKey]) {
      return;
    }

    for (var key in source[attrKey]) {
      if (key in source[attrKey] && source[attrKey][key] === undefined) {
        if (includes(booleanHtmlAttributes, key) && !warningShown) {
          warn('VueMeta: Please note that since v2 the value undefined is not used to indicate boolean attributes anymore, see migration guide for details');
          warningShown = true;
        }

        delete source[attrKey][key];
      }
    }
  });
  return deepmerge(target, source, {
    arrayMerge: function arrayMerge(t, s) {
      return _arrayMerge(options, t, s);
    }
  });
}

function getComponentMetaInfo(options, component) {
  return getComponentOption(options || {}, component, defaultInfo);
}
/**
 * Returns the `opts.option` $option value of the given `opts.component`.
 * If methods are encountered, they will be bound to the component context.
 * If `opts.deep` is true, will recursively merge all child component
 * `opts.option` $option values into the returned result.
 *
 * @param  {Object} opts - options
 * @param  {Object} opts.component - Vue component to fetch option data from
 * @param  {Boolean} opts.deep - look for data in child components as well?
 * @param  {Function} opts.arrayMerge - how should arrays be merged?
 * @param  {String} opts.keyName - the name of the option to look for
 * @param  {Object} [result={}] - result so far
 * @return {Object} result - final aggregated result
 */

function getComponentOption(options, component, result) {
  result = result || {};

  if (component._inactive) {
    return result;
  }

  options = options || {};
  var _options = options,
      keyName = _options.keyName;
  var $metaInfo = component.$metaInfo,
      $options = component.$options,
      $children = component.$children; // only collect option data if it exists

  if ($options[keyName]) {
    // if $metaInfo exists then [keyName] was defined as a function
    // and set to the computed prop $metaInfo in the mixin
    // using the computed prop should be a small performance increase
    // because Vue caches those internally
    var data = $metaInfo || $options[keyName]; // only merge data with result when its an object
    // eg it could be a function when metaInfo() returns undefined
    // dueo to the or statement above

    if (isObject(data)) {
      result = merge(result, data, options);
    }
  } // collect & aggregate child options if deep = true


  if ($children.length) {
    $children.forEach(function (childComponent) {
      // check if the childComponent is in a branch
      // return otherwise so we dont walk all component branches unnecessarily
      if (!inMetaInfoBranch(childComponent)) {
        return;
      }

      result = getComponentOption(options, childComponent, result);
    });
  }

  return result;
}

var callbacks = [];
function isDOMComplete(d) {
  return (d || document).readyState === 'complete';
}
function addCallback(query, callback) {
  if (arguments.length === 1) {
    callback = query;
    query = '';
  }

  callbacks.push([query, callback]);
}
function addCallbacks(_ref, type, tags, autoAddListeners) {
  var tagIDKeyName = _ref.tagIDKeyName;
  var hasAsyncCallback = false;
  tags.forEach(function (tag) {
    if (!tag[tagIDKeyName] || !tag.callback) {
      return;
    }

    hasAsyncCallback = true;
    addCallback("".concat(type, "[data-").concat(tagIDKeyName, "=\"").concat(tag[tagIDKeyName], "\"]"), tag.callback);
  });

  if (!autoAddListeners || !hasAsyncCallback) {
    return hasAsyncCallback;
  }

  return addListeners();
}
function addListeners() {
  if (isDOMComplete()) {
    applyCallbacks();
    return;
  } // Instead of using a MutationObserver, we just apply

  /* istanbul ignore next */


  document.onreadystatechange = function () {
    applyCallbacks();
  };
}
function applyCallbacks(matchElement) {
  callbacks.forEach(function (args) {
    // do not use destructuring for args, it increases transpiled size
    // due to var checks while we are guaranteed the structure of the cb
    var query = args[0];
    var callback = args[1];
    var selector = "".concat(query, "[onload=\"this.__vm_l=1\"]");
    var elements = [];

    if (!matchElement) {
      elements = toArray(querySelector(selector));
    }

    if (matchElement && matchElement.matches(selector)) {
      elements = [matchElement];
    }

    elements.forEach(function (element) {
      /* __vm_cb: whether the load callback has been called
       * __vm_l: set by onload attribute, whether the element was loaded
       * __vm_ev: whether the event listener was added or not
       */
      if (element.__vm_cb) {
        return;
      }

      var onload = function onload() {
        /* Mark that the callback for this element has already been called,
         * this prevents the callback to run twice in some (rare) conditions
         */
        element.__vm_cb = true;
        /* onload needs to be removed because we only need the
         * attribute after ssr and if we dont remove it the node
         * will fail isEqualNode on the client
         */

        removeAttribute(element, 'onload');
        callback(element);
      };
      /* IE9 doesnt seem to load scripts synchronously,
       * causing a script sometimes/often already to be loaded
       * when we add the event listener below (thus adding an onload event
       * listener has no use because it will never be triggered).
       * Therefore we add the onload attribute during ssr, and
       * check here if it was already loaded or not
       */


      if (element.__vm_l) {
        onload();
        return;
      }

      if (!element.__vm_ev) {
        element.__vm_ev = true;
        element.addEventListener('load', onload);
      }
    });
  });
}

// instead of adding it to the html

var attributeMap = {};
/**
 * Updates the document's html tag attributes
 *
 * @param  {Object} attrs - the new document html attributes
 * @param  {HTMLElement} tag - the HTMLElement tag to update with new attrs
 */

function updateAttribute(appId, options, type, attrs, tag) {
  var _ref = options || {},
      attribute = _ref.attribute;

  var vueMetaAttrString = tag.getAttribute(attribute);

  if (vueMetaAttrString) {
    attributeMap[type] = JSON.parse(decodeURI(vueMetaAttrString));
    removeAttribute(tag, attribute);
  }

  var data = attributeMap[type] || {};
  var toUpdate = []; // remove attributes from the map
  // which have been removed for this appId

  for (var attr in data) {
    if (data[attr] !== undefined && appId in data[attr]) {
      toUpdate.push(attr);

      if (!attrs[attr]) {
        delete data[attr][appId];
      }
    }
  }

  for (var _attr in attrs) {
    var attrData = data[_attr];

    if (!attrData || attrData[appId] !== attrs[_attr]) {
      toUpdate.push(_attr);

      if (attrs[_attr] !== undefined) {
        data[_attr] = data[_attr] || {};
        data[_attr][appId] = attrs[_attr];
      }
    }
  }

  for (var _i = 0, _toUpdate = toUpdate; _i < _toUpdate.length; _i++) {
    var _attr2 = _toUpdate[_i];
    var _attrData = data[_attr2];
    var attrValues = [];

    for (var _appId in _attrData) {
      Array.prototype.push.apply(attrValues, [].concat(_attrData[_appId]));
    }

    if (attrValues.length) {
      var attrValue = includes(booleanHtmlAttributes, _attr2) && attrValues.some(Boolean) ? '' : attrValues.filter(function (v) {
        return v !== undefined;
      }).join(' ');
      tag.setAttribute(_attr2, attrValue);
    } else {
      removeAttribute(tag, _attr2);
    }
  }

  attributeMap[type] = data;
}

/**
 * Updates the document title
 *
 * @param  {String} title - the new title of the document
 */
function updateTitle(title) {
  if (!title && title !== '') {
    return;
  }

  document.title = title;
}

/**
 * Updates meta tags inside <head> and <body> on the client. Borrowed from `react-helmet`:
 * https://github.com/nfl/react-helmet/blob/004d448f8de5f823d10f838b02317521180f34da/src/Helmet.js#L195-L245
 *
 * @param  {('meta'|'base'|'link'|'style'|'script'|'noscript')} type - the name of the tag
 * @param  {(Array<Object>|Object)} tags - an array of tag objects or a single object in case of base
 * @return {Object} - a representation of what tags changed
 */

function updateTag(appId, options, type, tags, head, body) {
  var _ref = options || {},
      attribute = _ref.attribute,
      tagIDKeyName = _ref.tagIDKeyName;

  var dataAttributes = commonDataAttributes.slice();
  dataAttributes.push(tagIDKeyName);
  var newElements = [];
  var queryOptions = {
    appId: appId,
    attribute: attribute,
    type: type,
    tagIDKeyName: tagIDKeyName
  };
  var currentElements = {
    head: queryElements(head, queryOptions),
    pbody: queryElements(body, queryOptions, {
      pbody: true
    }),
    body: queryElements(body, queryOptions, {
      body: true
    })
  };

  if (tags.length > 1) {
    // remove duplicates that could have been found by merging tags
    // which include a mixin with metaInfo and that mixin is used
    // by multiple components on the same page
    var found = [];
    tags = tags.filter(function (x) {
      var k = JSON.stringify(x);
      var res = !includes(found, k);
      found.push(k);
      return res;
    });
  }

  tags.forEach(function (tag) {
    if (tag.skip) {
      return;
    }

    var newElement = document.createElement(type);

    if (!tag.once) {
      newElement.setAttribute(attribute, appId);
    }

    Object.keys(tag).forEach(function (attr) {
      /* istanbul ignore next */
      if (includes(tagProperties, attr)) {
        return;
      }

      if (attr === 'innerHTML') {
        newElement.innerHTML = tag.innerHTML;
        return;
      }

      if (attr === 'json') {
        newElement.innerHTML = JSON.stringify(tag.json);
        return;
      }

      if (attr === 'cssText') {
        if (newElement.styleSheet) {
          /* istanbul ignore next */
          newElement.styleSheet.cssText = tag.cssText;
        } else {
          newElement.appendChild(document.createTextNode(tag.cssText));
        }

        return;
      }

      if (attr === 'callback') {
        newElement.onload = function () {
          return tag[attr](newElement);
        };

        return;
      }

      var _attr = includes(dataAttributes, attr) ? "data-".concat(attr) : attr;

      var isBooleanAttribute = includes(booleanHtmlAttributes, attr);

      if (isBooleanAttribute && !tag[attr]) {
        return;
      }

      var value = isBooleanAttribute ? '' : tag[attr];
      newElement.setAttribute(_attr, value);
    });
    var oldElements = currentElements[getElementsKey(tag)]; // Remove a duplicate tag from domTagstoRemove, so it isn't cleared.

    var indexToDelete;
    var hasEqualElement = oldElements.some(function (existingTag, index) {
      indexToDelete = index;
      return newElement.isEqualNode(existingTag);
    });

    if (hasEqualElement && (indexToDelete || indexToDelete === 0)) {
      oldElements.splice(indexToDelete, 1);
    } else {
      newElements.push(newElement);
    }
  });
  var oldElements = [];

  for (var _type in currentElements) {
    Array.prototype.push.apply(oldElements, currentElements[_type]);
  } // remove old elements


  oldElements.forEach(function (element) {
    element.parentNode.removeChild(element);
  }); // insert new elements

  newElements.forEach(function (element) {
    if (element.hasAttribute('data-body')) {
      body.appendChild(element);
      return;
    }

    if (element.hasAttribute('data-pbody')) {
      body.insertBefore(element, body.firstChild);
      return;
    }

    head.appendChild(element);
  });
  return {
    oldTags: oldElements,
    newTags: newElements
  };
}

/**
 * Performs client-side updates when new meta info is received
 *
 * @param  {Object} newInfo - the meta info to update to
 */

function updateClientMetaInfo(appId, options, newInfo) {
  options = options || {};
  var _options = options,
      ssrAttribute = _options.ssrAttribute,
      ssrAppId = _options.ssrAppId; // only cache tags for current update

  var tags = {};
  var htmlTag = getTag(tags, 'html'); // if this is a server render, then dont update

  if (appId === ssrAppId && htmlTag.hasAttribute(ssrAttribute)) {
    // remove the server render attribute so we can update on (next) changes
    removeAttribute(htmlTag, ssrAttribute); // add load callbacks if the

    var addLoadListeners = false;
    tagsSupportingOnload.forEach(function (type) {
      if (newInfo[type] && addCallbacks(options, type, newInfo[type])) {
        addLoadListeners = true;
      }
    });

    if (addLoadListeners) {
      addListeners();
    }

    return false;
  } // initialize tracked changes


  var tagsAdded = {};
  var tagsRemoved = {};

  for (var type in newInfo) {
    // ignore these
    if (includes(metaInfoOptionKeys, type)) {
      continue;
    }

    if (type === 'title') {
      // update the title
      updateTitle(newInfo.title);
      continue;
    }

    if (includes(metaInfoAttributeKeys, type)) {
      var tagName = type.substr(0, 4);
      updateAttribute(appId, options, type, newInfo[type], getTag(tags, tagName));
      continue;
    } // tags should always be an array, ignore if it isnt


    if (!isArray(newInfo[type])) {
      continue;
    }

    var _updateTag = updateTag(appId, options, type, newInfo[type], getTag(tags, 'head'), getTag(tags, 'body')),
        oldTags = _updateTag.oldTags,
        newTags = _updateTag.newTags;

    if (newTags.length) {
      tagsAdded[type] = newTags;
      tagsRemoved[type] = oldTags;
    }
  }

  return {
    tagsAdded: tagsAdded,
    tagsRemoved: tagsRemoved
  };
}

var appsMetaInfo;
function addApp(rootVm, appId, options) {
  return {
    set: function set(metaInfo) {
      return setMetaInfo(rootVm, appId, options, metaInfo);
    },
    remove: function remove() {
      return removeMetaInfo(rootVm, appId, options);
    }
  };
}
function setMetaInfo(rootVm, appId, options, metaInfo) {
  // if a vm exists _and_ its mounted then immediately update
  if (rootVm && rootVm.$el) {
    return updateClientMetaInfo(appId, options, metaInfo);
  } // store for later, the info
  // will be set on the first refresh


  appsMetaInfo = appsMetaInfo || {};
  appsMetaInfo[appId] = metaInfo;
}
function removeMetaInfo(rootVm, appId, options) {
  if (rootVm && rootVm.$el) {
    var tags = {};

    var _iterator = _createForOfIteratorHelper(metaInfoAttributeKeys),
        _step;

    try {
      for (_iterator.s(); !(_step = _iterator.n()).done;) {
        var type = _step.value;
        var tagName = type.substr(0, 4);
        updateAttribute(appId, options, type, {}, getTag(tags, tagName));
      }
    } catch (err) {
      _iterator.e(err);
    } finally {
      _iterator.f();
    }

    return removeElementsByAppId(options, appId);
  }

  if (appsMetaInfo[appId]) {
    delete appsMetaInfo[appId];
    clearAppsMetaInfo();
  }
}
function getAppsMetaInfo() {
  return appsMetaInfo;
}
function clearAppsMetaInfo(force) {
  if (force || !Object.keys(appsMetaInfo).length) {
    appsMetaInfo = undefined;
  }
}

/**
 * Returns the correct meta info for the given component
 * (child components will overwrite parent meta info)
 *
 * @param  {Object} component - the Vue instance to get meta info from
 * @return {Object} - returned meta info
 */

function getMetaInfo(options, info, escapeSequences, component) {
  options = options || {};
  escapeSequences = escapeSequences || [];
  var _options = options,
      tagIDKeyName = _options.tagIDKeyName; // Remove all "template" tags from meta
  // backup the title chunk in case user wants access to it

  if (info.title) {
    info.titleChunk = info.title;
  } // replace title with populated template


  if (info.titleTemplate && info.titleTemplate !== '%s') {
    applyTemplate({
      component: component,
      contentKeyName: 'title'
    }, info, info.titleTemplate, info.titleChunk || '');
  } // convert base tag to an array so it can be handled the same way
  // as the other tags


  if (info.base) {
    info.base = Object.keys(info.base).length ? [info.base] : [];
  }

  if (info.meta) {
    // remove meta items with duplicate vmid's
    info.meta = info.meta.filter(function (metaItem, index, arr) {
      var hasVmid = !!metaItem[tagIDKeyName];

      if (!hasVmid) {
        return true;
      }

      var isFirstItemForVmid = index === findIndex(arr, function (item) {
        return item[tagIDKeyName] === metaItem[tagIDKeyName];
      });
      return isFirstItemForVmid;
    }); // apply templates if needed

    info.meta.forEach(function (metaObject) {
      return applyTemplate(options, metaObject);
    });
  }

  return escapeMetaInfo(options, info, escapeSequences);
}

/**
 * When called, will update the current meta info with new meta info.
 * Useful when updating meta info as the result of an asynchronous
 * action that resolves after the initial render takes place.
 *
 * Credit to [Sébastien Chopin](https://github.com/Atinux) for the suggestion
 * to implement this method.
 *
 * @return {Object} - new meta info
 */

function refresh(rootVm, options) {
  options = options || {}; // make sure vue-meta was initiated

  if (!rootVm[rootConfigKey]) {
    showWarningNotSupported();
    return {};
  } // collect & aggregate all metaInfo $options


  var rawInfo = getComponentMetaInfo(options, rootVm);
  var metaInfo = getMetaInfo(options, rawInfo, clientSequences, rootVm);
  var appId = rootVm[rootConfigKey].appId;
  var tags = updateClientMetaInfo(appId, options, metaInfo); // emit "event" with new info

  if (tags && isFunction(metaInfo.changed)) {
    metaInfo.changed(metaInfo, tags.tagsAdded, tags.tagsRemoved);
    tags = {
      addedTags: tags.tagsAdded,
      removedTags: tags.tagsRemoved
    };
  }

  var appsMetaInfo = getAppsMetaInfo();

  if (appsMetaInfo) {
    for (var additionalAppId in appsMetaInfo) {
      updateClientMetaInfo(additionalAppId, options, appsMetaInfo[additionalAppId]);
      delete appsMetaInfo[additionalAppId];
    }

    clearAppsMetaInfo(true);
  }

  return {
    vm: rootVm,
    metaInfo: metaInfo,
    // eslint-disable-line object-shorthand
    tags: tags
  };
}

function $meta(options) {
  options = options || {};
  /**
   * Returns an injector for server-side rendering.
   * @this {Object} - the Vue instance (a root component)
   * @return {Object} - injector
   */

  var $root = this.$root;
  return {
    getOptions: function getOptions$1() {
      return getOptions(options);
    },
    setOptions: function setOptions(newOptions) {
      var refreshNavKey = 'refreshOnceOnNavigation';

      if (newOptions && newOptions[refreshNavKey]) {
        options.refreshOnceOnNavigation = !!newOptions[refreshNavKey];
        addNavGuards($root);
      }

      var debounceWaitKey = 'debounceWait';

      if (newOptions && debounceWaitKey in newOptions) {
        var debounceWait = parseInt(newOptions[debounceWaitKey]);

        if (!isNaN(debounceWait)) {
          options.debounceWait = debounceWait;
        }
      }

      var waitOnDestroyedKey = 'waitOnDestroyed';

      if (newOptions && waitOnDestroyedKey in newOptions) {
        options.waitOnDestroyed = !!newOptions[waitOnDestroyedKey];
      }
    },
    refresh: function refresh$1() {
      return refresh($root, options);
    },
    inject: function inject(injectOptions) {
      return  showWarningNotSupportedInBrowserBundle('inject');
    },
    pause: function pause$1() {
      return pause($root);
    },
    resume: function resume$1() {
      return resume($root);
    },
    addApp: function addApp$1(appId) {
      return addApp($root, appId, options);
    }
  };
}

/**
 * Plugin install function.
 * @param {Function} Vue - the Vue constructor.
 */

function install(Vue, options) {
  if (Vue.__vuemeta_installed) {
    return;
  }

  Vue.__vuemeta_installed = true;
  options = setOptions(options);

  Vue.prototype.$meta = function () {
    return $meta.call(this, options);
  };

  Vue.mixin(createMixin(Vue, options));
}

{
  // automatic install
  if (!isUndefined(window) && !isUndefined(window.Vue)) {
    /* istanbul ignore next */
    install(window.Vue);
  }
}

var index = {
  version: version,
  install: install,
  generate: function generate(metaInfo, options) {
    return  showWarningNotSupportedInBrowserBundle('generate');
  },
  hasMetaInfo: hasMetaInfo
};

export default index;