refactor: replace gulp by webpack and npm scripts (#258)

BREAKING CHANGE: We have replaced `gulp` with `webpack` and `npm scripts` to build this theme. If you build it on your own or use build commands during the deployment, you may have to adjust your setup.

BREAKING CHANGE: The `GeekblogIcons` font is using the icon name as Unicode now. As a consequence, you have to replace all references to Icons from this font if you have customized the theme.

BREAKING CHANGE: We have refactored the search integration to split Hugo templates from JavaScript code. To get it working again, you need to adjust the `outputFormats` and `outputs` in your Hugo configuration file, as [documented](https://geekdocs.de/usage/configuration/#site-configuration).

assets/js/search.js

@@ -1,171 +0,0 @@
-'use strict';
-
-{{ $searchDataFile := printf "%s.search-data.json" .Language.Lang }}
-{{ $searchData := resources.Get "search-data.json" | resources.ExecuteAsTemplate $searchDataFile . | resources.Minify }}
-
-(function() {
-  const input = document.querySelector('#gdoc-search-input');
-  const results = document.querySelector('#gdoc-search-results');
-  let showParent = {{ if .Site.Params.GeekdocSearchShowParent }}true{{ else }}false{{ end }}
-
-  if (input) {
-    input.addEventListener('focus', init);
-    input.addEventListener('keyup', search);
-  }
-
-  function init() {
-    input.removeEventListener('focus', init); // init once
-
-    loadScript('{{ index .Site.Data.assets "js/groupBy.min.js" | relURL }}');
-    loadScript('{{ index .Site.Data.assets "js/flexsearch.min.js" | relURL }}', function() {
-      const indexCfgDefaults = {
-        tokenize: 'forward'
-      }
-      const indexCfg = {{ with .Scratch.Get "geekdocSearchConfig" }}{{ . | jsonify }}{{ else }}indexCfgDefaults{{ end }};
-      const dataUrl = '{{ $searchData.RelPermalink }}'
-
-      indexCfg.document = {
-        key: 'id',
-        index: ['title', 'content'],
-        store: ['title', 'href', 'parent'],
-      };
-
-      const index = new FlexSearch.Document(indexCfg);
-      window.geekdocSearchIndex = index;
-
-      getJson(dataUrl, function(data) {
-        data.forEach(obj => {
-          window.geekdocSearchIndex.add(obj);
-        });
-      });
-    });
-  }
-
-  function search() {
-    const searchCfg = {
-      enrich: true,
-      limit: 10
-    };
-
-    while (results.firstChild) {
-      results.removeChild(results.firstChild);
-    }
-
-    if (!input.value) {
-      return results.classList.remove('has-hits');
-    }
-
-    let searchHits = flattenHits(window.geekdocSearchIndex.search(input.value, searchCfg));
-    if (searchHits.length < 1) {
-      return results.classList.remove('has-hits');
-    }
-
-    results.classList.add('has-hits');
-
-    if (showParent === true) {
-      searchHits = groupBy(searchHits, hit => hit.parent);
-    }
-
-    const items = [];
-
-    if (showParent === true) {
-      for (const section in searchHits) {
-        const item = document.createElement('li'),
-              title = item.appendChild(document.createElement('span')),
-              subList = item.appendChild(document.createElement('ul'));
-
-        title.textContent = section;
-        createLinks(searchHits[section], subList);
-
-        items.push(item);
-      }
-    } else {
-      const item = document.createElement('li'),
-            title = item.appendChild(document.createElement('span')),
-            subList = item.appendChild(document.createElement('ul'));
-
-      title.textContent = 'Results';
-      createLinks(searchHits, subList);
-
-      items.push(item);
-    }
-
-    items.forEach(item => {
-      results.appendChild(item);
-    })
-  }
-
-  /**
-   * Creates links to given fields and either returns them in an array or attaches them to a target element
-   * @param {Object} fields Page to which the link should point to
-   * @param {HTMLElement} target Element to which the links should be attatched
-   * @returns {Array} If target is not specified, returns an array of built links
-   */
-  function createLinks(pages, target) {
-    const items = [];
-
-    for (const page of pages) {
-      const item = document.createElement("li"),
-            entry = item.appendChild(document.createElement("span")),
-            a = entry.appendChild(document.createElement("a"));
-
-      entry.classList.add('flex')
-
-      a.href = page.href;
-      a.textContent = page.title;
-      a.classList.add('gdoc-search__entry')
-
-      if (target) {
-        target.appendChild(item);
-        continue
-      }
-
-      items.push(item);
-    }
-
-    return items;
-  }
-
-  function fetchErrors(response) {
-    if (!response.ok) {
-        throw Error(response.statusText);
-    }
-    return response;
-  }
-
-  function getJson(src, callback) {
-    fetch(src)
-    .then(fetchErrors)
-    .then(response => response.json())
-    .then(json => callback(json))
-    .catch(function(error) {
-      console.log(error);
-    });
-  }
-
-  function flattenHits(results) {
-    const items = [];
-    const map = new Map();
-
-    for (const field of results) {
-      for (const page of field.result) {
-        if(!map.has(page.doc.href)){
-          map.set(page.doc.href, true);
-          items.push(page.doc);
-        }
-      }
-    }
-
-    return items
-  }
-
-  function loadScript(src, callback) {
-    let script = document.createElement('script');
-    script.defer = true;
-    script.async = false;
-    script.src = src;
-    script.onload = callback;
-
-    document.body.appendChild(script);
-  }
-})();