It works

faraday-hypermedia.gemspec

@@ -9,9 +9,9 @@ Gem::Specification.new do |spec|
   spec.authors       = ["Toru KAWAMURA"]
   spec.email         = ["tkawa@4bit.net"]
 
-  spec.summary       = %q{TODO: Write a short summary, because Rubygems requires one.}
-  spec.description   = %q{TODO: Write a longer description or delete this line.}
-  spec.homepage      = "TODO: Put your gem's website or public repo URL here."
+  spec.summary       = %q{Faraday middleware that supports hypermedia client}
+  spec.description   = %q{Faraday middleware that supports hypermedia client}
+  spec.homepage      = "https://github.com/tkawa/faraday-hypermedia"
   spec.license       = "MIT"
 
   # Prevent pushing this gem to RubyGems.org by setting 'allowed_push_host', or
@@ -27,7 +27,16 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
+  spec.add_dependency "faraday", ">= 0.8.0"
+  spec.add_dependency 'faraday_middleware'
+  spec.add_dependency 'http_link_header'
+  spec.add_dependency 'faraday_collection_json'
+  spec.add_dependency 'uri_template'
+
   spec.add_development_dependency "bundler", "~> 1.11"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "minitest", "~> 5.0"
+  spec.add_development_dependency 'awesome_print'
+  spec.add_development_dependency 'faraday-detailed_logger'
+  spec.add_development_dependency 'faraday-http-cache'
 end

lib/faraday-hypermedia.rb

@@ -0,0 +1 @@
+require 'faraday/hypermedia'

lib/faraday/hypermedia.rb

@@ -1,7 +1,17 @@
-require "faraday/hypermedia/version"
+require 'faraday'
+require 'faraday/hypermedia/history'
+require 'faraday/hypermedia/link_extractor'
+require 'faraday/hypermedia/navigation'
+require 'faraday/hypermedia/version'
+require_relative '../uri/navigation'
 
 module Faraday
   module Hypermedia
-    # Your code goes here...
+    RE_URI_TEMPLATE = /\{.*\}/
   end
+
+  Middleware.register_middleware navigation: Hypermedia::Navigation
+  Response.register_middleware link_cj: Hypermedia::LinkExtractorCJ
+  Response.register_middleware link_github: Hypermedia::LinkExtractorGithub
+
 end

lib/faraday/hypermedia/history.rb

@@ -0,0 +1,120 @@
+require 'http_link_header'
+require 'uri_template'
+
+module Faraday
+  module Hypermedia
+    class History
+      State = Struct.new(:data, :title, :url)
+
+      def initialize
+        @stored_states = [build_state]
+        @current_index = 0
+        reset_current_links
+      end
+
+      def current_state
+        @stored_states[@current_index]
+      end
+
+      # いったんここに実装
+      def current_links
+        @current_links ||= build_current_links
+      end
+
+      def pp_current_links
+        # TODO: きれいにする
+        # current_links.to_a.join("#{current_links.class::DELIMETER}\n")
+        rels = current_links.map{|url, params| params['rel'].to_a.map{|rel| [rel, [url, params]] }}.flatten(1).group_by{|rel, _| rel}
+        rels.each do |rel, links|
+          puts("rel=#{rel}")
+          if links.length >= 2
+            links.each.with_index(1) do |(_, link), i|
+              url, params = link
+              params = params.dup
+              params.delete('rel')
+              print(" (#{i}) <#{url}>")
+              print(" (#{params})") unless params.empty?
+              puts
+            end
+          else
+            url, params = links.first.last
+            params = params.dup
+            params.delete('rel')
+            print(" <#{url}>")
+            print(" (#{params})") unless params.empty?
+            puts
+          end
+        end
+        nil
+      end
+
+      def fill_in_template_params(template_params)
+        template_urls = current_links.keys.select { |k| k =~ RE_URI_TEMPLATE }
+        template_urls.each do |template_url|
+          expanded_url = URITemplate.new(template_url).expand(template_params) # Addressable のほうが良いかも
+          link_params = current_links.delete(template_url)
+          current_links.store(expanded_url, link_params)
+        end
+      end
+
+      def reset_current_links
+        @current_links = nil
+      end
+
+      def push_state(data, title, url)
+        if url == current_state.url
+          replace_state(data, title, url)
+        else
+          @stored_states.slice!((@current_index+1)..-1) # current_index の先から最後まで削除
+          state = build_state(data: data, title: title, url: url)
+          @stored_states.push(state)
+          @current_index += 1
+          reset_current_links
+          state
+        end
+      end
+
+      def replace_state(data, title, url)
+        reset_current_links
+        @stored_states[@current_index] = build_state(data: data, title: title, url: url)
+      end
+
+      def push(response_env)
+        url = response_env[:url]
+        push_state(response_env, '', url)
+      end
+
+      def back
+        if @current_index >= 1
+          @current_index -= 1
+          reset_current_links
+        end
+      end
+
+      def forward
+        if @current_index < @stored_states.length - 1
+          @current_index += 1
+          reset_current_links
+        end
+      end
+
+      private
+
+      def build_state(source = {})
+        State.new(
+          source[:data]  || {},
+          source[:title] || '',
+          source[:url]   || URI('navigation:blank')
+        )
+      end
+
+      def build_current_links
+        current_response_headers = current_state.data[:response_headers]
+        return HttpLinkHeader.new unless current_response_headers
+        links = current_response_headers['link'].to_s.scan(/<[^>]*>[^,]*/)
+        link_templates = current_response_headers['link-template'].to_s.scan(/<[^>]*>[^,]*/) # 自前でsplitする
+        HttpLinkHeader.new(links + link_templates)
+      end
+    end
+  end
+end

lib/faraday/hypermedia/link_extractor.rb

@@ -0,0 +1,88 @@
+require 'faraday_collection_json'
+require 'faraday_middleware'
+
+module Faraday
+  module Hypermedia
+    class LinkExtractorCJ < FaradayCollectionJSON::ParseCollectionJSON
+      def process_response(response_env)
+        # TODO: collectionのlinksしか取り出していない。itemsにも存在する
+        # TODO: itemsのselfがあれば取り出す
+        cj = parse(response_env[:body])
+        return if cj.links.empty? && cj.items.empty?
+        # link_arrays = cj.links.map do |link|
+        #   attrs = [['rel', link.rel]]
+        #   attrs << ['title', link.name] if link.name
+        #   [link.href, attrs]
+        # end
+        # link_value = LinkHeader.new(link_arrays).to_s
+        link_values = cj.links.map { |link|
+          value = %(<#{link.href}>;rel="#{link.rel}")
+          value += %(;title="#{link.name}") if link.name
+          value
+        }
+        item_values = cj.items.map { |item| %(<#{item.href}>;rel="item") if item.href }.compact
+        link_header = (link_values + item_values).join(',')
+        if response_env[:response_headers]['link']
+          response_env[:response_headers]['link'] += ",#{link_header}"
+        else
+          response_env[:response_headers]['link'] = link_header
+        end
+      end
+    end
+
+    class LinkExtractorGithub < FaradayMiddleware::ParseJson
+      def process_response(response_env)
+        doc = parse(response_env[:body])
+        if doc.is_a? Hash
+          link_template_props, link_props = doc.select { |name, _| name.end_with?('_url') }.partition { |_, url| url =~ RE_URI_TEMPLATE }
+          self_url = doc['url']
+          return if link_props.empty? && self_url.nil?
+          link_values = build_link_values(link_props)
+          link_values.unshift(%(<#{self_url}>;rel="self")) if self_url
+          item_props = doc.map { |name, c| [name, c['url']] if c.is_a?(Hash) && c['url'] }.compact
+          link_values.concat build_item_link_values(item_props)
+          link_template_values = build_link_values(link_template_props)
+        elsif doc.is_a? Array
+          # treat it as a collection
+          item_props = doc.map { |d| [d['name'], d['url']] if d['url'] }.compact
+          return if item_props.empty?
+          link_values = build_item_link_values(item_props)
+          link_template_values = []
+        else
+          return
+        end
+        link_header = link_values.join(',')
+        unless link_header.empty?
+          if response_env[:response_headers]['link']
+            response_env[:response_headers]['link'] += ",#{link_header}"
+          else
+            response_env[:response_headers]['link'] = link_header
+          end
+        end
+        link_template_header = link_template_values.join(',')
+        unless link_template_header.empty?
+          if response_env[:response_headers]['link-template']
+            response_env[:response_headers]['link-template'] += ",#{link_template_header}"
+          else
+            response_env[:response_headers]['link-template'] = link_template_header
+          end
+        end
+      end
+
+      private
+
+      def build_link_values(props)
+        props.map { |name, url|
+          rel = name.slice(0..-5) # '_url' を除いた名前
+          %(<#{url}>;rel="#{rel}") if url.to_s != ''
+        }.compact
+      end
+
+      def build_item_link_values(props)
+        props.map { |name, url|
+          %(<#{url}>;rel="item";title="#{name}") if url.to_s != ''
+        }.compact
+      end
+    end
+  end
+end

lib/faraday/hypermedia/navigation.rb

@@ -0,0 +1,52 @@
+module Faraday
+  module Hypermedia
+    class Navigation < Middleware
+      attr_reader :history
+
+      def initialize(app, history = nil, options = {})
+        super(app)
+        puts 'Navigation Enabled!'
+        @history = history || History.new
+        # state = self
+        # connection.define_singleton_method(:history) do
+        #   state.history
+        # end
+      end
+
+      def call(request_env)
+        # request
+        url = request_env[:url]
+        if url.scheme == 'navigation'
+          case url.to
+          when 'back'
+            @history.back
+            request_env[:url] = @history.current_state.url
+          when 'forward'
+            @history.forward
+            request_env[:url] = @history.current_state.url
+          when 'go'
+            # TODO
+          when /\Alink(?:\((\d+)\))?\z/ # link or link(index)
+            index = (Regexp.last_match(1) || 1).to_i # one origin
+            matched_links = @history.current_links
+            unless url.queries.empty?
+              attr_name, attr_value = url.queries.first # TODO: multiple
+              matched_links = matched_links.select { |_ ,v| v[attr_name] && v[attr_name].include?(attr_value) } # TODO: multiple
+            end
+            raise 'cannot find link' if matched_links.empty?
+            matched_url = matched_links.to_a[index - 1].first
+            matched_url = URITemplate.new(matched_url).expand if matched_url =~ RE_URI_TEMPLATE
+            request_env[:url] = URI(matched_url)
+          else
+            raise "cannot use #{url.to}"
+          end
+        end
+
+        # response
+        @app.call(request_env).on_complete do |response_env|
+          @history.push response_env
+        end
+      end
+    end
+  end
+end

lib/uri/navigation.rb

@@ -0,0 +1,39 @@
+require 'uri'
+
+module URI
+  class Navigation < Generic
+    DEFAULT_PORT = nil
+    COMPONENT = [ :scheme, :to, :query ].freeze
+
+    def initialize(*arg)
+      super(*arg)
+      to, query = @opaque.split('?', 2)
+      @to = to
+      self.query = query
+    end
+
+    attr_reader :to
+
+    def query=(v)
+      return @query = nil unless v
+
+      x = v.to_str
+      v = x.dup if x.equal? v
+      v.encode!(Encoding::UTF_8) rescue nil
+      v.delete!("\t\r\n")
+      v.force_encoding(Encoding::ASCII_8BIT)
+      v.gsub!(/(?!%\h\h|[!$-&(-;=?-_a-~])./n.freeze){'%%%02X' % $&.ord}
+      v.force_encoding(Encoding::US_ASCII)
+      @query = v
+    end
+
+    def queries
+      @query.split('&').map { |x| x.split(/=/, 2) }.to_h
+    end
+
+    def to_s
+      "#{@scheme}:#{@to}" + (@query && !@query.empty? ? "?#{@query}" : '')
+    end
+  end
+  @@schemes['NAVIGATION'] = Navigation
+end