Add speakerdeck liquid tag (#343)

* Take darker of user colors

* Add speakerdeck liquid tag

* Modify speakerdeck test

app/labor/markdown_parser.rb

@@ -197,6 +197,7 @@ class MarkdownParser
     Liquid::Template.register_tag("codepen", CodepenTag)
     Liquid::Template.register_tag("gist", GistTag)
     Liquid::Template.register_tag("instagram", InstagramTag)
+    Liquid::Template.register_tag("speakerdeck", SpeakerdeckTag)
     Liquid::Template.register_tag("replit", ReplitTag)
     Liquid::Template.register_tag("runkit", RunkitTag)
     Liquid::Template.register_tag("youtube", YoutubeTag)

app/liquid_tags/speakerdeck_tag.rb

@@ -0,0 +1,37 @@
+class SpeakerdeckTag < LiquidTagBase
+  def initialize(tag_name, id, tokens)
+    super
+    @id = parse_id(id)
+  end
+
+  def render(context)
+    html = <<-HTML
+      <iframe allowfullscreen="true"
+        allowtransparency="true"
+        frameborder="0"
+        height="463"
+        id="talk_frame_#{@id}"
+        mozallowfullscreen="true"
+        src="//speakerdeck.com/player/#{@id}"
+        style="border:0; padding:0; margin:0; background:transparent;"
+        webkitallowfullscreen="true"
+        width="710"></iframe>
+    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 Speakerdeck Id"
+    end
+  end
+
+  def valid_id?(id)
+    !!(id =~ /\A[a-z\d]*\Z/i)
+  end
+end

config/initializers/liquid.rb

@@ -13,6 +13,7 @@ Liquid::Template.register_tag("user", UserTag)
 Liquid::Template.register_tag("codepen", CodepenTag)
 Liquid::Template.register_tag("gist", GistTag)
 Liquid::Template.register_tag("instagram", InstagramTag)
+Liquid::Template.register_tag("speakerdeck", SpeakerdeckTag)
 Liquid::Template.register_tag("replit", ReplitTag)
 Liquid::Template.register_tag("runkit", RunkitTag)
 Liquid::Template.register_tag("youtube", YoutubeTag)

spec/liquid_tags/speakereck_tag_spec.rb

@@ -0,0 +1,21 @@
+require "rails_helper"
+
+RSpec.describe InstagramTag, type: :liquid_template do
+  describe "#id" do
+    let(:valid_id)      { "BXgGcAUjM39" }
+    let(:invalid_id)    { "blahblahblahbl sdsdssd // dsdssd" }
+
+    def generate_tag(id)
+      Liquid::Template.register_tag("speakerdeck", SpeakerdeckTag)
+      Liquid::Template.parse("{% speakerdeck #{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