add HarpBlog#months and expose as GET /months

server/harp_blog.rb

@@ -110,6 +110,13 @@ class HarpBlog
     Dir[post_path('20*')].map { |x| File.basename(x) }.sort
   end
 
+  def months
+    years.map do |year|
+      # hack: month dirs (and only month dirs) are always 2 characters in length
+      Dir[post_path(year, '??')].map { |x| [year, File.basename(x)] }
+    end.flatten(1).sort
+  end
+
   def posts_for_year(year)
     posts = []
     1.upto(12) do |n|

server/server.rb

@@ -77,6 +77,16 @@ get '/years' do
   JSON.generate(years: blog.years)
 end
 
+# list months
+get '/months' do
+  unless authenticated?(request['Auth'])
+    status 403
+    return 'forbidden'
+  end
+
+  JSON.generate(months: blog.months)
+end
+
 # list posts
 get '/posts/:year/?:month?' do |year, month|
   unless authenticated?(request['Auth'])

server/spec/harp_blog_spec.rb

@@ -169,6 +169,22 @@ RSpec.describe HarpBlog do
     end
   end
 
+  describe '#months' do
+    it "should return all of the years and months with posts" do
+      months = [
+        ["2006", "02"], ["2006", "03"], ["2006", "04"], ["2006", "05"], ["2006", "06"], ["2006", "07"], ["2006", "08"], ["2006", "09"], ["2006", "12"],
+        ["2007", "03"], ["2007", "04"], ["2007", "05"], ["2007", "06"], ["2007", "07"], ["2007", "08"], ["2007", "09"], ["2007", "10"],
+        ["2008", "01"], ["2008", "02"], ["2008", "03"],
+        ["2009", "11"],
+        ["2010", "01"], ["2010", "11"],
+        ["2011", "11"], ["2011", "12"],
+        ["2012", "01"],
+        ["2013", "03"], ["2013", "09"],
+      ]
+      expect(@blog.months.first(months.length)).to eq(months)
+    end
+  end
+
   describe '#posts_for_month' do
     it "should return the correct number of posts" do
       expect(@blog.posts_for_month('2006', '02').length).to eq(12)