[ADD] Functionality of tags and their atom feed file

_layouts/atom.html

@@ -0,0 +1,82 @@
+<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom" {% if site.lang %}xml:lang="{{ site.lang }}"{% endif %}>
+  <generator uri="https://jekyllrb.com/" version="{{ jekyll.version }}">Jekyll</generator>
+  <link href="{{ page.url | absolute_url }}" rel="self" type="application/atom+xml" />
+  <link href="{{ '/' | absolute_url }}" rel="alternate" type="text/html" {% if site.lang %}hreflang="{{ site.lang }}" {% endif %}/>
+  <updated>{{ site.time | date_to_xmlschema }}</updated>
+  <id>{{ '/' | absolute_url | xml_escape }}</id>
+
+  {% if site.title %}
+    <title type="html">{{ site.title | smartify | xml_escape }}</title>
+  {% elsif site.name %}
+    <title type="html">{{ site.name | smartify | xml_escape }}</title>
+  {% endif %}
+
+  {% if site.description %}
+    <subtitle>{{ site.description | xml_escape }}</subtitle>
+  {% endif %}
+
+  {% if site.author %}
+    <author>
+        <name>{{ site.author.name | default: site.author | xml_escape }}</name>
+      {% if site.author.email %}
+        <email>{{ site.author.email | xml_escape }}</email>
+      {% endif %}
+      {% if site.author.uri %}
+        <uri>{{ site.author.uri | xml_escape }}</uri>
+      {% endif %}
+    </author>
+  {% endif %}
+
+  {% assign posts = site.posts | where_exp: "post", "post.draft != true" %}
+  {%  for post in posts limit: 10  %}
+    {%  for tag in post.tags  %}
+      {%  if tag == page.tag  %}
+        <entry{% if post.lang %}{{" "}}xml:lang="{{ post.lang }}"{% endif %}>
+          <title type="html">{{ post.title | smartify | strip_html | normalize_whitespace | xml_escape }}</title>
+          <link href="{{ post.url | absolute_url }}" rel="alternate" type="text/html" title="{{ post.title | xml_escape }}" />
+          <published>{{ post.date | date_to_xmlschema }}</published>
+          <updated>{{ post.last_modified_at | default: post.date | date_to_xmlschema }}</updated>
+          <id>{{ post.id | absolute_url | xml_escape }}</id>
+          <content type="html" xml:base="{{ post.url | absolute_url | xml_escape }}">{{ post.content | strip | xml_escape }}</content>
+
+          {% assign post_author = post.author | default: post.authors[0] | default: site.author %}
+          {% assign post_author = site.data.authors[post_author] | default: post_author %}
+          {% assign post_author_email = post_author.email | default: nil %}
+          {% assign post_author_uri = post_author.uri | default: nil %}
+          {% assign post_author_name = post_author.name | default: post_author %}
+
+          <author>
+              <name>{{ post_author_name | default: "" | xml_escape }}</name>
+            {% if post_author_email %}
+              <email>{{ post_author_email | xml_escape }}</email>
+            {% endif %}
+            {% if post_author_uri %}
+              <uri>{{ post_author_uri | xml_escape }}</uri>
+            {% endif %}
+          </author>
+
+          {% if post.category %}
+            <category term="{{ post.category | xml_escape }}" />
+          {% endif %}
+
+          {% for tag in post.tags %}
+            <category term="{{ tag | xml_escape }}" />
+          {% endfor %}
+
+          {% if post.excerpt and post.excerpt != empty %}
+            <summary type="html">{{ post.excerpt | strip_html | normalize_whitespace | xml_escape }}</summary>
+          {% endif %}
+
+          {% assign post_image = post.image.path | default: post.image %}
+          {% if post_image %}
+            {% unless post_image contains "://" %}
+              {% assign post_image = post_image | absolute_url | xml_escape  %}
+            {% endunless %}
+            <media:thumbnail xmlns:media="http://search.yahoo.com/mrss/" url="{{ post_image }}" />
+          {% endif %}
+        </entry>
+      {% endif %}
+    {% endfor %}
+  {% endfor %}
+</feed>

_layouts/tag_index.html

@@ -0,0 +1,29 @@
+---
+layout: default
+---
+<div class="home">
+
+  <h1 class="page-heading">Posts</h1>
+
+  {{ content }}
+
+  <ul class="post-list">
+    {% for post in site.posts %}
+    {% for tag in post.tags  %}
+    {% if tag == page.tag  %}
+      <li>
+        {% assign date_format = site.minima.date_format | default: "%b %-d, %Y" %}
+        <span class="post-meta">{{ post.date | date: date_format }}</span>
+
+        <h2>
+          <a class="post-link" href="{{ post.url | relative_url }}">{{ post.title | escape }}</a>
+        </h2>
+      </li>
+    {% endif %}
+    {% endfor %}
+    {% endfor %}
+  </ul>
+
+  <p class="rss-subscribe">subscribe <a href="/tags/{{ page.tag  }}/feed.xml">via RSS</a></p>
+
+</div>

_layouts/tags_folder_index.html

@@ -0,0 +1,16 @@
+---
+layout: page
+title: Tags
+permalink: /tags/
+---
+
+{% assign sorted_posts = site.tags | sort %}
+
+{% for post in sorted_posts %}
+{% assign tag = post | first %}
+  <ul class="post-list">
+    <h2>
+      <a class="post-link" href="/tags/{{ tag }}/">{{ tag | escape }}</a>
+    </h2>
+  </ul>
+{% endfor %}

_plugins/rss_tag.rb

@@ -0,0 +1,27 @@
+module Jekyll
+  class TagAtom < Page
+    def initialize(site, base, dir, tag)
+      @site = site
+      @base = base
+      @dir = dir
+      @name = "feed.xml"
+
+      process(@name)
+      read_yaml(File.join(base, '_layouts'), 'atom.html')
+      data['tag'] = tag
+    end
+  end
+
+  class TagPageGenerator < Generator
+    safe true
+
+    # Generate tag page and atom feed for each tag used in the blogs
+    def generate(site)
+      # if site.layouts.key? 'tagpage'
+        site.tags.each_key do |tag|
+          site.pages << TagAtom.new(site, site.source, File.join('tags',tag), tag)
+        end
+      # end
+    end
+  end
+end

_plugins/tag_gen.rb

@@ -0,0 +1,35 @@
+module Jekyll
+
+  class TagIndex < Page
+    def initialize(site, base, dir, tag)
+      @site = site
+      @base = base
+      @dir = dir
+      @name = 'index.html'
+
+      self.process(@name)
+      self.read_yaml(File.join(base, '_layouts'), 'tag_index.html')
+      self.data['tag'] = tag
+    end
+  end
+
+  class TagGenerator < Generator
+    safe true
+
+    def generate(site)
+      if site.layouts.key? 'tag_index'
+        dir = 'tags'
+        site.tags.keys.each do |tag|
+          write_tag_index(site, File.join(dir, tag), tag)
+        end
+      end
+    end
+
+    def write_tag_index(site, dir, tag)
+      index = TagIndex.new(site, site.source, dir, tag)
+      index.render(site.layouts, site.site_payload)
+      index.write(site.dest)
+      site.pages << index
+    end
+  end
+end

_plugins/tags_folder.rb

@@ -0,0 +1,24 @@
+module Jekyll
+
+  class TagList < Page
+    def initialize(site, base, dir)
+      @site = site
+      @base = base
+      @dir = dir
+      @name = 'index.html'
+
+      self.process(@name)
+      self.read_yaml(File.join(base, '_layouts'), 'tags_folder_index.html')
+    end
+  end
+
+  class TagListGenerator < Generator
+    safe true
+
+    def generate(site)
+      if site.layouts.key? 'tags_folder_index'
+        site.pages << TagList.new(site, site.source, 'tags')
+      end
+    end
+  end
+end

_posts/2017-01-08-2016-a-year-dedicated-to-python-workshops.md

@@ -1,7 +1,10 @@
 ---
 layout: post
 title: 2016 A year dedicated to Python Workshops
-tag: pythonworkshop
+tag:
+  - python
+  - workshop
+  - pythonexpress
 excerpt: >
   Beautiful 2017 has already started. While everybody is busy with preparing
   resolutions for their new year I decided to look back and share my journey

_posts/2017-02-28-book-review-introduction-to-the-commandline.md

@@ -2,7 +2,10 @@
 layout: post
 categories: book review
 title: Book review 'Introduction to the Command Line'
-tag: books linux programming
+tag:
+  - books
+  - linux
+  - programming
 excerpt: >
   Every chapter will introduce a bunch of comands and will point to its
   respective documentation for further learning. You should expect chapters

_posts/2017-03-14-pycon-pune-2017-a-wonderful-python-conference.md

@@ -2,7 +2,9 @@
 layout: post
 title: "Pycon Pune 2017: A wonderful Python conference"
 date: "2017-03-14 18:18:02 +0530"
-tag: python conference
+tag:
+  - python
+  - conference
 excerpt: >
   The conference is worth attending if you are a student, programmer or a
   hobbyist.  If you are a swag-hungry then don't expect much as a swag from this

_posts/2017-04-10-goyo-doc-vim-helpfile-for-goyo-plugin.md

@@ -2,6 +2,9 @@
 layout: post
 title: "goyo-doc: Vim helpfile for goyo.vim plugin"
 date: "2017-04-10 17:51:48 +0530"
+tags:
+  - vim
+  - goyo_doc
 excerpt: >
   Goyo is the vim plugin which allows writers to focus on their writing while
   they are writing. The plugin deactivates not required fancy windows which are