{%- if theme.firestore.enable %}
  <script src="{{ theme.vendors.firebase_app }}"></script>
  <script src="{{ theme.vendors.firebase_firestore }}"></script>
  <script>
    firebase.initializeApp({
      apiKey   : '{{ theme.firestore.apiKey }}',
      projectId: '{{ theme.firestore.projectId }}'
    });

    function getCount(doc, increaseCount) {
      // IncreaseCount will be false when not in article page
      return doc.get().then(d => {
        // Has no data, initialize count
        let count = d.exists ? d.data().count : 0;
        // If first view this article
        if (increaseCount) {
          // Increase count
          count++;
          doc.set({
            count
          });
        }
        return count;
      });
    }

    function appendCountTo(el) {
      return count => {
        el.innerText = count;
      };
    }
  </script>
  <script{{ pjax }}>
    (function() {
      const db = firebase.firestore();
      const articles = db.collection('{{ theme.firestore.collection }}');

      if (CONFIG.page.isPost) {
        // Fix issue #118
        // https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent
        const title = document.querySelector('.post-title').textContent.trim();
        const doc = articles.doc(title);
        let increaseCount = CONFIG.hostname === location.hostname;
        if (localStorage.getItem(title)) {
          increaseCount = false;
        } else {
          // Mark as visited
          localStorage.setItem(title, true);
        }
        getCount(doc, increaseCount).then(appendCountTo(document.querySelector('.firestore-visitors-count')));
      } else if (CONFIG.page.isHome) {
        const promises = [...document.querySelectorAll('.post-title')].map(element => {
          const title = element.textContent.trim();
          const doc = articles.doc(title);
          return getCount(doc);
        });
        Promise.all(promises).then(counts => {
          const metas = document.querySelectorAll('.firestore-visitors-count');
          counts.forEach((val, idx) => {
            appendCountTo(metas[idx])(val);
          });
        });
      }
    })();
  </script>
{%- endif %}