Implement Blogcast liquid tag (#1891)

app/liquid_tags/blogcast_tag.rb

@@ -0,0 +1,38 @@
+class BlogcastTag < LiquidTagBase
+  def initialize(tag_name, id, tokens)
+    super
+    @id = parse_id(id)
+  end
+
+  def render(_context)
+    html = <<-HTML
+      <div class="ltag_blogcast">
+        <iframe frameborder="0"
+          scrolling="no"
+          id="blogcast_#{@id}"
+          mozallowfullscreen="true"
+          src="https://blogcast.host/embed/#{@id}"
+          style="width:100%;height:132px;overflow:hidden;"
+          webkitallowfullscreen="true"></iframe>
+      </div>
+    HTML
+    finalize_html(html)
+  end
+
+  private
+
+  def parse_id(input)
+    input_no_space = input.delete(" ")
+    if valid_id?(input_no_space)
+      input_no_space
+    else
+      raise StandardError, "Invalid Blogcast Id"
+    end
+  end
+
+  def valid_id?(id)
+    (id =~ /\A\d{1,9}\Z/i)&.zero?
+  end
+end
+
+Liquid::Template.register_tag("blogcast", BlogcastTag)

app/views/pages/_editor_guide_text.html.erb

@@ -226,6 +226,12 @@
     <pre>
       {% spotify <span style="color: #1DB954;">spotify:episode:5V4XZWqZQJvbddd31n56mf</span> %}
     </pre>
+       
+    <h3><strong>Blogcast Tag</strong></h3>
+    <p>All you need is the article id code from the embed code:</p>
+    <pre>
+      {% blogcast <span style="color: orange;">1234</span> %}
+    </pre>
 
     <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>

spec/liquid_tags/blogcast_tag_spec.rb

@@ -0,0 +1,21 @@
+require "rails_helper"
+
+RSpec.describe BlogcastTag, type: :liquid_template do
+  describe "#id" do
+    let(:valid_id)      { "1234" }
+    let(:invalid_id)    { "inv@lid" }
+
+    def generate_tag(id)
+      Liquid::Template.register_tag("blogcast", BlogcastTag)
+      Liquid::Template.parse("{% blogcast #{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