From a9e1e71e1f27729f8a19fbaafdd9155bedec2548 Mon Sep 17 00:00:00 2001
From: Michael Kohl <citizen428@gmail.com>
Date: Wed, 2 Oct 2019 15:39:19 +0000
Subject: [PATCH] Add Asciinema Liquid tag (#4152)

* Add Asciinema Liquid tag

Closes #4135

* Fix Iframe URL

* Remove unnecessary regex modifier

* Re-add accidentally deleted closing tag and set iframe height

* Improve error message for invalid ID

Co-Authored-By: Andy Zhao <andyzhao.zhao@gmail.com>
---
 app/liquid_tags/asciinema_tag.rb            | 32 +++++++++++++++++++++
 app/views/liquids/_asciinema.html.erb       |  8 ++++++
 app/views/pages/_editor_guide_text.html.erb |  3 ++
 spec/liquid_tags/asciinema_tag_spec.rb      | 21 ++++++++++++++
 4 files changed, 64 insertions(+)
 create mode 100644 app/liquid_tags/asciinema_tag.rb
 create mode 100644 app/views/liquids/_asciinema.html.erb
 create mode 100644 spec/liquid_tags/asciinema_tag_spec.rb

diff --git a/app/liquid_tags/asciinema_tag.rb b/app/liquid_tags/asciinema_tag.rb
new file mode 100644
index 000000000..a28d9e5b7
--- /dev/null
+++ b/app/liquid_tags/asciinema_tag.rb
@@ -0,0 +1,32 @@
+class AsciinemaTag < LiquidTagBase
+  PARTIAL = "liquids/asciinema".freeze
+
+  def initialize(tag_name, id, tokens)
+    super
+    @id = parse_id(id)
+  end
+
+  def render(_context)
+    ActionController::Base.new.render_to_string(
+      partial: PARTIAL,
+      locals: {
+        id: @id
+      },
+    )
+  end
+
+  private
+
+  def parse_id(input)
+    input_no_space = input.delete(" ")
+    raise StandardError, "Invalid Asciinema ID: {% asciinema #{input_no_space} %}" unless valid_id?(input_no_space)
+
+    input_no_space
+  end
+
+  def valid_id?(id)
+    id.match?(/\A\d+\Z/)
+  end
+end
+
+Liquid::Template.register_tag("asciinema", AsciinemaTag)
diff --git a/app/views/liquids/_asciinema.html.erb b/app/views/liquids/_asciinema.html.erb
new file mode 100644
index 000000000..a583aac3f
--- /dev/null
+++ b/app/views/liquids/_asciinema.html.erb
@@ -0,0 +1,8 @@
+<div class="ltag_asciinema">
+  <iframe frameborder="0"
+    scrolling="no"
+    id="asciinema_<%= id %>"
+    src="https://asciinema.org/a/<%= id %>/iframe"
+    style="width:100%;height:50vh;">
+  </iframe>
+</div>
diff --git a/app/views/pages/_editor_guide_text.html.erb b/app/views/pages/_editor_guide_text.html.erb
index 0467863f5..57a250037 100644
--- a/app/views/pages/_editor_guide_text.html.erb
+++ b/app/views/pages/_editor_guide_text.html.erb
@@ -321,6 +321,9 @@
 {% stackexchange <span style="color: aquamarine;">170185</span> <span style="color: orange;">diy</span> %}
         </pre>
         </p>
+        <h3><strong>Asciinema Embed</strong></h3>
+        <p>All you need is the Asciinema id:</p>
+        <code>{% asciinema 239367 %}</code>
         <h3><strong>Parsing Liquid Tags as a Code Example</strong></h3>
         <p>To parse Liquid tags as code, simply wrap it with a single backtick or triple backticks.</p>
         <p><code>`{% mytag %}{{ site.SOMETHING }}{% endmytag %}`</code></p>
diff --git a/spec/liquid_tags/asciinema_tag_spec.rb b/spec/liquid_tags/asciinema_tag_spec.rb
new file mode 100644
index 000000000..bd19e4cbe
--- /dev/null
+++ b/spec/liquid_tags/asciinema_tag_spec.rb
@@ -0,0 +1,21 @@
+require "rails_helper"
+
+RSpec.describe AsciinemaTag, type: :liquid_template do
+  describe "#id" do
+    let(:valid_id)      { "1234" }
+    let(:invalid_id)    { "inv@lid" }
+
+    def generate_tag(id)
+      Liquid::Template.register_tag("asciinema", AsciinemaTag)
+      Liquid::Template.parse("{% asciinema #{id} %}")
+    end
+
+    it "rejects invalid ids" do
+      expect { generate_tag(invalid_id) }.to raise_error(StandardError)
+    end
+
+    it "accepts a valid id" do
+      expect { generate_tag(valid_id) }.not_to raise_error
+    end
+  end
+end