From 074aedc187e20a6bb00a4c996121fa851d29b394 Mon Sep 17 00:00:00 2001
From: Konstantin Haase <konstantin.mailinglists@googlemail.com>
Date: Thu, 24 Mar 2011 08:46:55 +0100
Subject: [PATCH] new extensions: sinatra-link-helper

---
 sinatra-contrib/lib/sinatra/link_header.rb |  84 +++++++++++++++++
 sinatra-contrib/spec/link_header_spec.rb   | 100 +++++++++++++++++++++
 2 files changed, 184 insertions(+)
 create mode 100644 sinatra-contrib/lib/sinatra/link_header.rb
 create mode 100644 sinatra-contrib/spec/link_header_spec.rb

diff --git a/sinatra-contrib/lib/sinatra/link_header.rb b/sinatra-contrib/lib/sinatra/link_header.rb
new file mode 100644
index 00000000..c7fc1903
--- /dev/null
+++ b/sinatra-contrib/lib/sinatra/link_header.rb
@@ -0,0 +1,84 @@
+require 'sinatra/base'
+
+module Sinatra
+  ##
+  # Helper methods for generating Link HTTP headers and HTML tags.
+  module LinkHeader
+    ##
+    # Set Link HTTP header and returns HTML tags for telling the browser to
+    # prefetch given resources (only supported by Opera and Firefox at the 
+    # moment).
+    def prefetch(*urls)
+      link(:prefetch, *urls)
+    end
+
+    ##
+    # Sets Link HTTP header and returns HTML tags for using stylesheets.
+    def stylesheet(*urls)
+      urls << {} unless urls.last.respond_to? :to_hash
+      urls.last[:type] ||= mime_type(:css)
+      link(:stylesheet, *urls)
+    end
+
+    ##
+    # Sets Link HTTP header and returns corresponding HTML tags.
+    #
+    # Example:
+    #
+    #   # Sets header:
+    #   #   Link: </foo>; rel="next"
+    #   # Returns String:
+    #   #   '<link href="/foo" rel="next" />'
+    #   link '/foo', :rel => :next
+    #
+    #   # Multiple URLs
+    #   link :stylesheet, '/a.css', '/b.css'
+    def link(*urls)
+      opts          = urls.last.respond_to?(:to_hash) ? urls.pop : {}
+      opts[:rel]    = urls.shift unless urls.first.respond_to? :to_str
+      options       = opts.map { |k, v| " #{k}=#{v.to_s.inspect}" }
+      html_pattern  = "<link href=\"%s\"#{options.join} />"
+      http_pattern  = ["<%s>", *options].join ";"
+      link          = (response["Link"] ||= "")
+
+      urls.map do |url|
+        link << "\n" unless link.empty?
+        link << (http_pattern % url)
+        html_pattern % url
+      end.join "\n"
+    end
+
+    ##
+    # Takes the current value of th Link header(s) and generates HTML tags
+    # from it.
+    #
+    # Example:
+    #
+    #   get '/' do
+    #     # You can of course use fancy helpers like #link, #stylesheet
+    #     # or #prefetch
+    #     response["Link"] = '</foo>; rel="next"'
+    #     haml :some_page
+    #   end
+    #
+    #   __END__
+    #
+    #   @@ layout
+    #   %head= link_headers
+    #   %body= yield
+    def link_headers
+      yield if block_given?
+      return "" unless response.include? "Link"
+      response["Link"].lines.map do |line|
+        url, *opts = line.split(';').map(&:strip)
+        "<link href=\"#{url[1..-2]}\" #{opts.join " "} />"
+      end.join "\n"
+    end
+
+    def self.registered(base)
+      puts "WARNING: #{self} is a helpers module, not an extension."
+    end
+  end
+
+  helpers LinkHeader
+end
diff --git a/sinatra-contrib/spec/link_header_spec.rb b/sinatra-contrib/spec/link_header_spec.rb
new file mode 100644
index 00000000..cf8d30b0
--- /dev/null
+++ b/sinatra-contrib/spec/link_header_spec.rb
@@ -0,0 +1,100 @@
+require 'backports'
+require_relative 'spec_helper'
+
+describe Sinatra::LinkHeader do
+  before do
+    mock_app do
+      helpers Sinatra::LinkHeader
+      before('/') { link 'something', :rel => 'from-filter', :foo => :bar }
+
+      get '/' do
+        link :something, 'booyah'
+      end
+
+      get '/style' do
+        stylesheet '/style.css'
+      end
+
+      get '/prefetch' do
+        prefetch '/foo'
+      end
+
+      get '/link_headers' do
+        response['Link'] = "<foo>     ;bar=\"baz\""
+        stylesheet '/style.css'
+        prefetch '/foo'
+        link_headers
+      end
+    end
+  end
+
+  describe :link do
+    it "sets link headers" do
+      get '/'
+      headers['Link'].lines.should include('<booyah>; rel="something"')
+    end
+
+    it "returns link html tags" do
+      get '/'
+      body.should == '<link href="booyah" rel="something" />'
+    end
+
+    it "takes an options hash" do
+      get '/'
+      elements = ["<something>", "foo=\"bar\"", "rel=\"from-filter\""]
+      headers['Link'].lines.first.strip.split('; ').sort.should == elements
+    end
+  end
+
+  describe :stylesheet do
+    it 'sets link headers' do
+      get '/style'
+      headers['Link'].should match(%r{^</style\.css>;})
+    end
+
+    it 'sets type to text/css' do
+      get '/style'
+      headers['Link'].should include('type="text/css"')
+    end
+
+    it 'sets rel to stylesheet' do
+      get '/style'
+      headers['Link'].should include('rel="stylesheet"')
+    end
+
+    it 'returns html tag' do
+      get '/style'
+      body.should match(%r{^<link href="/style\.css"})
+    end
+  end
+
+  describe :prefetch do
+    it 'sets link headers' do
+      get '/prefetch'
+      headers['Link'].should match(%r{^</foo>;})
+    end
+
+    it 'sets rel to prefetch' do
+      get '/prefetch'
+      headers['Link'].should include('rel="prefetch"')
+    end
+
+    it 'returns html tag' do
+      get '/prefetch'
+      body.should == '<link href="/foo" rel="prefetch" />'
+    end
+  end
+
+  describe :link_headers do
+    it 'generates html for all link headers' do
+      get '/link_headers'
+      body.should include('<link href="/foo" rel="prefetch" />')
+      body.should include('<link href="/style.css" ')
+    end
+
+    it "respects Link headers not generated on its own" do
+      get '/link_headers'
+      body.should include('<link href="foo" bar="baz" />')
+    end
+  end
+end