Add Algolia search provider (#1531)

* Support Lunr and Algolia search providers
* Document search providers and configuration
* Update CHANGELOG and history

close #1416

_includes/scripts.html

@@ -13,16 +13,13 @@
 {% endif %}
 
 {% if site.search == true or page.layout == "search" %}
-  {% assign lang = site.locale | slice: 0,2 | default: "en" %}
-  {% case lang %}
-  {% when "gr" %}
-    {% assign lang = "gr" %}
-  {% else %}
-    {% assign lang = "en" %}
-  {% endcase %}
-  <script src="{{ '/assets/js/lunr/lunr.min.js' | absolute_url }}"></script>
-  <script src="{{ '/assets/js/lunr/lunr-store.js' | absolute_url }}"></script>
-  <script src="{{ '/assets/js/lunr/lunr-' | append: lang | append: '.js' | absolute_url }}"></script>
+  {%- assign search_provider = site.search_provider | default: "lunr" -%}
+  {%- case search_provider -%}
+    {%- when "lunr" -%}
+      {% include search/lunr-search-scripts.html %}
+    {%- when "algolia" -%}
+      {% include search/algolia-search-scripts.html %}
+  {%- endcase -%}
 {% endif %}
 
 {% include analytics.html %}

_includes/search/algolia-search-scripts.html

@@ -0,0 +1,54 @@
+<!-- Including InstantSearch.js library and styling -->
+<script src="https://cdn.jsdelivr.net/npm/instantsearch.js@2.3.3/dist/instantsearch.min.js"></script>
+<link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/instantsearch.js@2.3.3/dist/instantsearch.min.css">
+<link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/npm/instantsearch.js@2.3.3/dist/instantsearch-theme-algolia.min.css">
+
+<script>
+// Instanciating InstantSearch.js with Algolia credentials
+const search = instantsearch({
+  appId: '{{ site.algolia.application_id }}',
+  apiKey: '{{ site.algolia.search_only_api_key }}',
+  indexName: '{{ site.algolia.index_name }}',
+  searchParameters: {
+    restrictSearchableAttributes: [
+      'title',
+      'content'
+    ]
+  }
+});
+
+const hitTemplate = function(hit) {
+  const url = hit.url;
+  const title = hit._highlightResult.title.value;
+  const content = hit._highlightResult.html.value;
+
+  return `
+    <div class="list__item">
+      <article class="archive__item" itemscope itemtype="http://schema.org/CreativeWork">
+        <h2 class="archive__item-title" itemprop="headline"><a href="{{ site.baseurl }}${url}">${title}</a></h2>
+        <div class="archive__item-excerpt" itemprop="description">${content}</div>
+      </article>
+    </div>
+  `;
+}
+
+// Adding searchbar and results widgets
+search.addWidget(
+  instantsearch.widgets.searchBox({
+    container: '.search-searchbar',
+    {% unless site.algolia.powered_by == false %}poweredBy: true,{% endunless %}
+    placeholder: '{{ site.data.ui-text[site.locale].search_placeholder_text | default: "Enter your search term..." }}'
+  })
+);
+search.addWidget(
+  instantsearch.widgets.hits({
+    container: '.search-hits',
+    templates: {
+      item: hitTemplate
+    }
+  })
+);
+
+// Starting the search
+search.start();
+</script>

_includes/search/lunr-search-scripts.html

@@ -0,0 +1,10 @@
+{% assign lang = site.locale | slice: 0,2 | default: "en" %}
+{% case lang %}
+{% when "gr" %}
+  {% assign lang = "gr" %}
+{% else %}
+  {% assign lang = "en" %}
+{% endcase %}
+<script src="{{ '/assets/js/lunr/lunr.min.js' | absolute_url }}"></script>
+<script src="{{ '/assets/js/lunr/lunr-store.js' | absolute_url }}"></script>
+<script src="{{ '/assets/js/lunr/lunr-' | append: lang | append: '.js' | absolute_url }}"></script>

_includes/search/search_form.html

@@ -0,0 +1,11 @@
+<div class="search-content__inner-wrap">
+{%- assign search_provider = site.search_provider | default: "lunr" -%}
+{%- case search_provider -%}
+  {%- when "lunr" -%}
+    <input type="text" id="search" class="search-input" tabindex="-1" placeholder="{{ site.data.ui-text[site.locale].search_placeholder_text | default: 'Enter your search term...' }}" />
+    <div id="results" class="results"></div>
+  {%- when "algolia" -%}
+    <div class="search-searchbar"></div>
+    <div class="search-hits"></div>
+{%- endcase -%}
+</div>

_includes/search_form.html

@@ -1,4 +0,0 @@
-<div class="search-content__inner-wrap">
-  <input type="text" id="search" class="search-input" tabindex="-1" placeholder="{{ site.data.ui-text[site.locale].search_placeholder_text | default: 'Enter your search term...' }}" />
-  <div id="results" class="results"></div>
-</div>