function insertArticle(article,parent,insertPlace) {
  if (article){
    var newItem = document.createElement("DIV");
    if (article.cached_user) {
      article.user = article.cached_user.table
    }
    if (article.cached_organization) {
      article.organization = article.cached_organization.table
    }
    newItem.innerHTML = buildArticleHTML(article)
    parent.insertBefore(newItem, insertPlace);
    initializeReadingListIcons();
  }
}

function insertInitialArticles(user) {
  var el = document.getElementById("home-articles-object");
 if (!el) {return}
  el.innerHTML = "";
  insertTopArticles(user);
  el.outerHTML = "";
}

function insertTopArticles(user){
  var el = document.getElementById("home-articles-object");
  var articlesJSON = JSON.parse(el.dataset.articles)
  var insertPlace = document.getElementById("article-index-hidden-div");
  if (insertPlace) {
    articlesJSON.forEach(function(article){
      var articlePoints = 0
      var containsUserID = findOne([article.user_id], user.followed_user_ids || [])
      var containsOrganizationID = findOne([article.organization_id], user.followed_organization_ids || [])
      var intersectedTags = intersect_arrays(user.followed_tag_names, article.cached_tag_list_array)
      var followedPoints = 1
      var experienceDifference = Math.abs(article['experience_level_rating'] - user.experience_level || 5)
      var containsPreferredLanguage = findOne([article.language || 'en'], user.preferred_languages_array || ['en'])
      JSON.parse(user.followed_tags).map(function(tag) {
        if (intersectedTags.includes(tag.name)) {
          followedPoints = followedPoints + tag.points
        }
      })
      articlePoints = articlePoints + followedPoints
      if (containsUserID) {
        articlePoints = articlePoints + 1
      }
      if (containsOrganizationID) {
        articlePoints = articlePoints + 1
      }
      var rand = Math.random();
      if (rand < 0.3) {
        articlePoints = articlePoints + 3
      } else if (rand < 0.6) {
        articlePoints = articlePoints + 6
      }
      if (containsPreferredLanguage) {
        articlePoints = articlePoints + 1
      } else {
        articlePoints = articlePoints - 10
      }
      articlePoints = articlePoints - (experienceDifference/2);
      article['points'] = articlePoints
    });
    var sortedArticles = articlesJSON.sort(function(a, b) {
      return b.points - a.points;
    });
    sortedArticles.forEach(function(article){
      var parent = insertPlace.parentNode;
      if ( article.points > 0 && !document.getElementById("article-link-"+article.id) ) {
        insertArticle(article,parent,insertPlace);
      }
    });
  }
}

function findOne(haystack, arr) {
    return arr.some(function (v) {
        return haystack.indexOf(v) >= 0;
    });
};


function intersect_arrays(a, b) {
    var sorted_a = a.concat().sort();
    var sorted_b = b.concat().sort();
    var common = [];
    var a_i = 0;
    var b_i = 0;

    while (a_i < a.length
           && b_i < b.length)
    {
        if (sorted_a[a_i] === sorted_b[b_i]) {
            common.push(sorted_a[a_i]);
            a_i++;
            b_i++;
        }
        else if(sorted_a[a_i] < sorted_b[b_i]) {
            a_i++;
        }
        else {
            b_i++;
        }
    }
    return common;
}

function insertTimes() {
  var elements = document.getElementsByClassName('time-ago-indicator-initial-placeholder');
  for (var i = 0; i < elements.length; i++) {

    // getElementsByClassName will get updated everytime we change DOM
    // so elements[0] will produce the next unchanged element every iteration
    var element = elements[0];

    element.outerHTML = timeAgo({ oldTimeInSeconds: element.dataset.seconds });
  }
};