Add modified_at info at the post layout

At the bottom of every blog post, there will now be a small text containing:

1. The localized date of the last modified time the blog post was
   modified (taking Git as a reference).
2. A link to the log at git.mssola.com for the given file.

This way readers have a better understanding of the versioning of a given page.

Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/_plugins/log.rb b/_plugins/log.rb
new file mode 100644
index 0000000..2331f10
--- /dev/null
+++ b/_plugins/log.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+# Copyright (C) 2019 Miquel Sabaté Solà <mikisabate@gmail.com>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+require "date"
+require_relative "modified_time_helper"
+
+module Jekyll
+  # Render the last modification time of the given page.
+  class RenderModifiedAt < Liquid::Tag
+    include ::Jekyll::ModifiedTimeHelper
+
+    def render(context)
+      time = Time.iso8601(modified_time(context["page"]))
+
+      if context["page"]["lang"] == "en"
+        time.strftime("%B %-d, %Y, at %H:%m")
+      else
+        time.strftime("%-d de #{catalan_month(time.month)} de %Y, a les %H:%m")
+      end
+    end
+
+    protected
+
+    # Given a month number, return its catalan translation.
+    # rubocop:disable Metrics/MethodLength, Metrics/CyclomaticComplexity
+    def catalan_month(month)
+      case month
+      when 1
+        "gener"
+      when 2
+        "febrer"
+      when 3
+        "març"
+      when 4
+        "abril"
+      when 5
+        "maig"
+      when 6
+        "juny"
+      when 7
+        "juliol"
+      when 8
+        "agost"
+      when 9
+        "setembre"
+      when 10
+        "octubre"
+      when 11
+        "novembre"
+      when 12
+        "desembre"
+      else
+        ""
+      end
+    end
+    # rubocop:enable Metrics/MethodLength, Metrics/CyclomaticComplexity
+  end
+
+  # Render the link to git.mssola.com of the given page.
+  class RenderLogLink < Liquid::Tag
+    include ::Jekyll::ModifiedTimeHelper
+
+    WEBSITE_BASE = "http://git.mssola.com"
+    WEBSITE_REPO = "jo.git"
+
+    def render(context)
+      page = context["page"]
+      url  = "#{WEBSITE_BASE}/#{WEBSITE_REPO}/log/#{page["relative_path"]}"
+
+      if page["lang"] == "en"
+        "<a href=\"#{url}\" title=\"Log for this page\">here</a>"
+      else
+        "<a href=\"#{url}\" title=\"Historial d'aquesta pàgina (anglès)\">aquí</a>"
+      end
+    end
+  end
+end
+
+Liquid::Template.register_tag("render_modified_at", Jekyll::RenderModifiedAt)
+Liquid::Template.register_tag("render_log_link", Jekyll::RenderLogLink)