content.js

function hijack(callback) {
  "use strict"
  var code = function() {
    var mapSpell = function(spell) {
      var ret = spell.definition;
      ret.isCantrip = spell.definition.level === 0;

      return ret;
    };

    var FindReact = function(dom) {
        for (var key in dom) {
            if (key.startsWith("__reactInternalInstance$")) {
                var compInternals = dom[key]._currentElement;
                var compWrapper = compInternals._owner;
                var comp = compWrapper._instance;
                return comp;
            }
        }
        return null;
    };

    var element = FindReact(document.getElementsByClassName('character-sheet')[0]);
    var entities = element._reactInternalInstance._context.store.getState().character.entities;
    var modifiers = entities.modifier;
    console.log(entities);

    var data = {
      classFeatures: [],
      feats: [],
      spells: []
    };

    var ignoredFeatures = ["Ability Score Improvement", "Proficiencies", "Hit Points"]

    for ( var classKey in entities.classFeature ) {
      var feature = entities.classFeature[classKey];
      if(ignoredFeatures.indexOf(feature.definition.name) === -1) {
        data.classFeatures.push({
          'name': feature.definition.name,
          'description': feature.definition.description,
          'choices': feature.dynamicModifiers.map(function(modifier) {
            return modifiers[modifier].friendlySubtypeName
          }),
          'options': feature.options
        });
      }
    }

    for ( var featKey in entities.feat ) {
      var feat = entities.feat[featKey];
      data.feats.push({
        'name': feat.definition.name,
        'description': feat.definition.description,
        'choices': feat.dynamicModifiers.map(function(modifier) {
          return modifiers[modifier].friendlySubtypeName
        }),
        'options': feat.options
      });
    }

    var spellLists = document.getElementsByClassName('class-spell-list-manager');
    for ( var i in spellLists ) {
      var spellManager = FindReact(spellLists[i]);

      if (spellManager) {
        Array.prototype.push.apply(
          data.spells,
          spellManager.props.spells.map(function(spell) { return mapSpell(spell); })
        );
      }
    }

    localStorage.setItem("__reactExport", JSON.stringify(data));
  };

  var script = document.createElement('script');
  script.textContent = '(' + code + ')()';
  (document.head||document.documentElement).appendChild(script);
  script.parentNode.removeChild(script);
  callback();
}

var executeCallback = function() {
  var dataCallback = function()  {
    chrome.runtime.sendMessage({
      "message": "data_fetched", "data":
      JSON.parse(localStorage.getItem("__reactExport"))
    });
  };
  hijack(dataCallback);
};

var messageCallback = function(request, sender, sendResponse) {
  if (request.message == "clicked_browser_action") {
    executeCallback();
  };

  if (request.message == "browser_loaded") {
    addHook();
  };
};

chrome.runtime.onMessage.addListener(messageCallback);

var addHook = function() {
  var targetElement = document.getElementsByClassName("character-info")[0];

  if(targetElement) {
    targetElement.addEventListener("click", addButton, false);
  } else {
    setTimeout(addHook, 500);
  }
};

var addButton = function() {
  var targetElement = document.getElementsByClassName("popout-menu")[0];

  if(targetElement) {
    var elt = document.createElement("div")
    elt.className = "popout-menu-item"
    elt.innerHTML = `<div class="popout-menu-item-preview">
        <i class="i-menu-downloadpdf" style="background-size: 16px 16px;"></i>
      </div>
      <div class="popout-menu-item-label">Export Features</div>`;
    elt.addEventListener("click", executeCallback, false);
    targetElement.appendChild(elt);
  } else {
    setTimeout(addButton, 500);
  }
};