implement previewing posts & drafts

server/harp_blog.rb

@@ -80,16 +80,16 @@ class HarpBlog
     read_post(File.join(year, month), id)
   end
 
-  def get_post_html(year, month, id)
-    raise 'unimplemented'
-  end
-
   def get_draft(id)
     read_post('drafts', id, draft: true)
   end
 
-  def get_draft_html(id)
-    raise 'unimplemented'
+  def preview_post(year, month, id)
+    read_rendered_post(File.join(year, month), id)
+  end
+
+  def preview_draft(id)
+    read_rendered_post('drafts', id)
   end
 
   def create_post(title, body, url, extra_fields = nil)
@@ -191,8 +191,8 @@ class HarpBlog
     path_for(*args)
   end
 
-  def drafts_path(*components)
-    post_path('drafts', *components)
+  def rendered_post_path(dir, id)
+    path_for('www/posts', dir, id, 'index.html')
   end
 
   def read_posts(post_dir, extra_fields = nil)
@@ -235,6 +235,17 @@ class HarpBlog
     end
   end
 
+  def read_rendered_post(post_dir, id)
+    post_filename = rendered_post_path(post_dir, id)
+    if File.exists?(post_filename)
+      File.read(post_filename)
+    else
+      message = "missing rendered HTML for post #{post_dir}/#{id} at path #{post_filename}"
+      $stderr.puts "[HarpBlog#read_rendered_post] #{message}"
+      raise InvalidDataError.new(message)
+    end
+  end
+
   def save_post(action, post)
     git_fetch
     git_reset_hard('origin/master')

server/server.rb

@@ -174,7 +174,7 @@ get '/posts/:year/:month/:id' do |year, month, id|
     elsif request.accept?('text/html')
       status 200
       headers 'Content-Type' => 'text/html'
-      blog.get_post_html(year, month, id)
+      blog.preview_post(year, month, id)
     else
       status 400
       "content not available in an acceptable format: #{request.accept.join(', ')}"
@@ -202,7 +202,7 @@ get '/drafts/:id' do |id|
     elsif request.accept?('text/html')
       status 200
       headers 'Content-Type' => 'text/html'
-      blog.get_draft_html(id)
+      blog.preview_draft(id)
     else
       status 400
       "content not available in an acceptable format: #{request.accept.join(', ')}"