Add page descriptions and images

A limited number of pages have defined their own descriptions, but
otherwise we default to the Project's description (if `@project` is
set), or the old `brand_title` fallback.

The image will either be the uploaded project icon (never a generated
one), the user's uploaded icon or Gravatar, or, finally, the GitLab
logo.

app/helpers/page_layout_helper.rb

@@ -8,6 +8,56 @@ module PageLayoutHelper
     @page_title.join(" \u00b7 ")
   end
 
+  # Define or get a description for the current page
+  #
+  # description - String (default: nil)
+  #
+  # If this helper is called multiple times with an argument, only the last
+  # description will be returned when called without an argument. Descriptions
+  # have newlines replaced with spaces and all HTML tags are sanitized.
+  #
+  # Examples:
+  #
+  #   page_description # => "GitLab Community Edition"
+  #   page_description("Foo")
+  #   page_description # => "Foo"
+  #
+  #   page_description("<b>Bar</b>\nBaz")
+  #   page_description # => "Bar Baz"
+  #
+  # Returns an HTML-safe String.
+  def page_description(description = nil)
+    @page_description ||= page_description_default
+
+    if description.present?
+      @page_description = description
+    else
+      sanitize(@page_description.squish, tags: [])
+    end
+  end
+
+  # Default value for page_description when one hasn't been defined manually by
+  # a view
+  def page_description_default
+    if @project
+      @project.description
+    else
+      brand_title
+    end
+  end
+
+  def page_image
+    default = image_url('gitlab_logo.png')
+
+    if @project
+      @project.avatar_url || default
+    elsif @user
+      avatar_icon(@user)
+    else
+      default
+    end
+  end
+
   def header_title(title = nil, title_url = nil)
     if title
       @header_title     = title

app/views/layouts/_head.html.haml

 - page_title "GitLab"
+
 %head{prefix: "og: http://ogp.me/ns#"}
   %meta{charset: "utf-8"}
   %meta{'http-equiv' => 'X-UA-Compatible', content: 'IE=edge'}
-  %meta{content: "GitLab Community Edition", name: "description"}
-  %meta{name: 'referrer', content: 'origin-when-cross-origin'}
+
+  %meta{name: "description", content: page_description}
+  %meta{name: 'referrer',    content: 'origin-when-cross-origin'}
 
   -# Open Graph - http://ogp.me/
-  %meta{property: 'og:title', content: page_title}
-  %meta{property: 'og:url',   content: url_for(only_path: false)}
+  %meta{property: 'og:title',       content: page_title}
+  %meta{property: 'og:description', content: page_description}
+  %meta{property: 'og:image',       content: page_image}
+  %meta{property: 'og:url',         content: url_for(only_path: false)}
 
   %title= page_title
 

app/views/projects/issues/show.html.haml

-- page_title "#{@issue.title} (##{@issue.iid})", "Issues"
+- page_title       "#{@issue.title} (##{@issue.iid})", "Issues"
+- page_description @issue.description
+
 = render "header_title"
 
 .issue

app/views/projects/merge_requests/_show.html.haml

-- page_title "#{@merge_request.title} (##{@merge_request.iid})", "Merge Requests"
+- page_title       "#{@merge_request.title} (##{@merge_request.iid})", "Merge Requests"
+- page_description @merge_request.description
+
 = render "header_title"
 
 - if params[:view] == 'parallel'

app/views/projects/milestones/show.html.haml

-- page_title @milestone.title, "Milestones"
+- page_title       @milestone.title, "Milestones"
+- page_description @milestone.description
+
 = render "header_title"
 
 .detail-page-header

app/views/users/show.html.haml

-- page_title    @user.name
-- header_title  @user.name, user_path(@user)
+- page_title       @user.name
+- page_description @user.bio
+- header_title     @user.name, user_path(@user)
 
 = content_for :meta_tags do
   = auto_discovery_link_tag(:atom, user_url(@user, format: :atom), title: "#{@user.name} activity")

spec/helpers/page_layout_helper_spec.rb

+require 'rails_helper'
+
+describe PageLayoutHelper do
+  describe 'page_description' do
+    it 'defaults to value returned by page_description_default helper' do
+      allow(helper).to receive(:page_description_default).and_return('Foo')
+
+      expect(helper.page_description).to eq 'Foo'
+    end
+
+    it 'returns the last-pushed description' do
+      helper.page_description('Foo')
+      helper.page_description('Bar')
+      helper.page_description('Baz')
+
+      expect(helper.page_description).to eq 'Baz'
+    end
+
+    it 'squishes multiple newlines' do
+      helper.page_description("Foo\nBar\nBaz")
+
+      expect(helper.page_description).to eq 'Foo Bar Baz'
+    end
+
+    it 'sanitizes all HTML' do
+      helper.page_description("<b>Bold</b> <h1>Header</h1>")
+
+      expect(helper.page_description).to eq 'Bold Header'
+    end
+  end
+
+  describe 'page_description_default' do
+    it 'uses Project description when available' do
+      project = double(description: 'Project Description')
+      helper.instance_variable_set(:@project, project)
+
+      expect(helper.page_description_default).to eq 'Project Description'
+    end
+
+    it 'falls back to brand_title' do
+      allow(helper).to receive(:brand_title).and_return('Brand Title')
+
+      expect(helper.page_description_default).to eq 'Brand Title'
+    end
+  end
+
+  describe 'page_image' do
+    it 'defaults to the GitLab logo' do
+      expect(helper.page_image).to end_with 'assets/gitlab_logo.png'
+    end
+
+    context 'with @project' do
+      it 'uses Project avatar if available' do
+        project = double(avatar_url: 'http://example.com/uploads/avatar.png')
+        helper.instance_variable_set(:@project, project)
+
+        expect(helper.page_image).to eq project.avatar_url
+      end
+
+      it 'falls back to the default' do
+        project = double(avatar_url: nil)
+        helper.instance_variable_set(:@project, project)
+
+        expect(helper.page_image).to end_with 'assets/gitlab_logo.png'
+      end
+    end
+
+    context 'with @user' do
+      it 'delegates to avatar_icon helper' do
+        user = double('User')
+        helper.instance_variable_set(:@user, user)
+
+        expect(helper).to receive(:avatar_icon).with(user)
+
+        helper.page_image
+      end
+    end
+  end
+end