'use strict';

window.initBlock = initBlock;

let template;
let data = {};
let reload;

// Blocks Initialization.
function initBlock(blockName = '', selector = '', cb) {
  reload = function () {
    document.querySelectorAll(selector).forEach((el) => cb(el));
  }

  reload();
}

// Data Updates Listeners.
(function () {
  const block = getQueryParams().block;

  loadDataOptions();
  listenToDataOptionsUpdates();

  function listenToDataOptionsUpdates() {
    window.addEventListener('message', function (event) {
      const message = event.data;
      const prefix = 'dataUpdate:';

      if (typeof message !== "string" || !message.startsWith(prefix)) {
        return;
      }

      try {
        data = JSON.parse(message.substring(prefix.length));
        updateBlock({data});
      } catch (e) {
        console.log('Error parsing incoming data.', e);
      }
    });
  }

  function getQueryParams() {
    const urlParams = new URLSearchParams(window.location.search);
    const params = {};

    for (const [key, value] of urlParams) {
      params[key] = value;
    }

    return params;
  }

  function loadDataOptions() {
    const queryParameters = new URLSearchParams({
      block,
      name: getQueryParams().data || 'default'
    });
    fetch(`/data?${queryParameters}`)
      .then((response) => response.json())
      .then((response) => {
        data = response.data; // Update state.
        updateBlock({data});
      })
  }

  // Listen to Template updates.
  initSocket();

  function initSocket() {
    const socket = window.io.connect('', {query: `block=${block}`});

    socket.on('error', function (err) {
      console.log(err);
    });

    // socket.on('connect', function () {
    //   console.log('user connected', socket.id)
    // });

    socket.on('templateUpdate', function (args) {
      updateBlock({template: args.template});
    });

    socket.on('scriptUpdate', function (args) {
      const tag = updateTag('block-script');
      tag.onload = () => {
        updateBlock({template: args.template});
      }
    });

    socket.on('styleUpdate', function (args) {
      updateTag('block-stylesheet');
    });
  }

  function updateTag(id) {
    const tag = document.getElementById(id);
    const wrapper = tag.parentNode;

    let clone;
    let attr;
    if (tag.tagName === 'SCRIPT') {
      clone = document.createElement('script');
      clone.type = 'text/javascript';
      attr = 'src';
    } else if (tag.tagName === 'LINK') {
      clone = document.createElement('link');
      clone.rel = 'stylesheet';
      attr = 'href';
    }

    clone.id = id;

    // Add version to the stylesheet URL, make sure we override the cache and already existing version there.
    clone[attr] = tag[attr].replace(/(\?v=)[^&]+/, `$1${Date.now()}`);

    tag.remove();
    wrapper.append(clone);

    return clone;
  }

  function updateBlock(args = {}) {
    if (args.template) {
      template = args.template; // Update state.
    }

    if (args.data) {
      data = args.data; // Update state.
    }

    if (!template) {
      return;
    }

    renderBlock(template, data || {}, document.getElementById("hbs-container"));
  }

  function renderBlock(templateHbs, jsonData, target) {
    const template = Handlebars.compile(templateHbs);

    /**
     * Handlebars Helpers
     */
    Handlebars.registerHelper('esc_attr', function (attr) {
      return attr;
    });

    Handlebars.registerHelper('esc_url', function (attr) {
      return attr;
    });

    Handlebars.registerHelper('esc_html', function (attr) {
      return attr;
    });

    Handlebars.registerHelper('base_url', function () {
      const list = ['block'];

      if (block) {
        list.push(block.substr(1));
      }

      return ['', ...list, ''].join('/');
    });

    let html;

    try {
      html = template(jsonData);
    } catch (e) {
      html = `<div style="max-width: 1280px; margin: 1rem auto;">
      <h1 style="all: unset; font-size: 1.5rem; font-weight: bold; display: block;">Syntax Error:</h1>
      <pre style="all: unset; padding: 10px 15px; background-color: #ffe6e6; border: 1px solid red; border-radius: 0.25rem; overflow: auto; display: block; white-space: pre;">${e.toString()}</pre>
    </div>`;
    }

    target.innerHTML = html;
    if (reload) {
      reload();
    }
  }
})();