Add a "View in GitLab" link in notification emails

When an email notification concerns a specific object (issue, note,
merge request, etc.), add a link to the footer of the email that opens
the item's page in a web browser.

Rationale:

* The link is predictable: always the same text, always at the same
location, like any reliable tool.

* It allows to remove the inline-title in many emails, and leave only
the actual content of the message.

app/mailers/emails/groups.rb

@@ -3,7 +3,7 @@ module Emails
     def group_access_granted_email(user_group_id)
       @membership = UsersGroup.find(user_group_id)
       @group = @membership.group
-
+      @target_url = group_url(@group)
       mail(to: @membership.user.email,
            subject: subject("Access to group was granted"))
     end

app/mailers/emails/issues.rb

@@ -3,6 +3,7 @@ module Emails
     def new_issue_email(recipient_id, issue_id)
       @issue = Issue.find(issue_id)
       @project = @issue.project
+      @target_url = project_issue_url(@project, @issue)
       mail(from: sender(@issue.author_id),
            to: recipient(recipient_id),
            subject: subject("#{@issue.title} (##{@issue.iid})"))
@@ -12,6 +13,7 @@ module Emails
       @issue = Issue.find(issue_id)
       @previous_assignee = User.find_by(id: previous_assignee_id) if previous_assignee_id
       @project = @issue.project
+      @target_url = project_issue_url(@project, @issue)
       mail(from: sender(updated_by_user_id),
            to: recipient(recipient_id),
            subject: subject("#{@issue.title} (##{@issue.iid})"))
@@ -21,6 +23,7 @@ module Emails
       @issue = Issue.find issue_id
       @project = @issue.project
       @updated_by = User.find updated_by_user_id
+      @target_url = project_issue_url(@project, @issue)
       mail(from: sender(updated_by_user_id),
            to: recipient(recipient_id),
            subject: subject("#{@issue.title} (##{@issue.iid})"))
@@ -31,6 +34,7 @@ module Emails
       @issue_status = status
       @project = @issue.project
       @updated_by = User.find updated_by_user_id
+      @target_url = project_issue_url(@project, @issue)
       mail(from: sender(updated_by_user_id),
            to: recipient(recipient_id),
            subject: subject("#{@issue.title} (##{@issue.iid})"))

app/mailers/emails/merge_requests.rb

@@ -3,6 +3,7 @@ module Emails
     def new_merge_request_email(recipient_id, merge_request_id)
       @merge_request = MergeRequest.find(merge_request_id)
       @project = @merge_request.project
+      @target_url = project_merge_request_url(@project, @merge_request)
       mail(from: sender(@merge_request.author_id),
            to: recipient(recipient_id),
            subject: subject("#{@merge_request.title} (!#{@merge_request.iid})"))
@@ -12,6 +13,7 @@ module Emails
       @merge_request = MergeRequest.find(merge_request_id)
       @previous_assignee = User.find_by(id: previous_assignee_id) if previous_assignee_id
       @project = @merge_request.project
+      @target_url = project_merge_request_url(@project, @merge_request)
       mail(from: sender(updated_by_user_id),
            to: recipient(recipient_id),
            subject: subject("#{@merge_request.title} (!#{@merge_request.iid})"))
@@ -21,6 +23,7 @@ module Emails
       @merge_request = MergeRequest.find(merge_request_id)
       @updated_by = User.find updated_by_user_id
       @project = @merge_request.project
+      @target_url = project_merge_request_url(@project, @merge_request)
       mail(from: sender(updated_by_user_id),
            to: recipient(recipient_id),
            subject: subject("#{@merge_request.title} (!#{@merge_request.iid})"))
@@ -29,6 +32,7 @@ module Emails
     def merged_merge_request_email(recipient_id, merge_request_id)
       @merge_request = MergeRequest.find(merge_request_id)
       @project = @merge_request.project
+      @target_url = project_merge_request_url(@project, @merge_request)
       mail(from: sender(@merge_request.author_id_of_changes),
            to: recipient(recipient_id),
            subject: subject("#{@merge_request.title} (!#{@merge_request.iid})"))

app/mailers/emails/notes.rb

@@ -4,6 +4,7 @@ module Emails
       @note = Note.find(note_id)
       @commit = @note.noteable
       @project = @note.project
+      @target_url = project_commit_url(@project, @commit, anchor: "note_#{@note.id}")
       mail(from: sender(@note.author_id),
            to: recipient(recipient_id),
            subject: subject("#{@commit.title} (#{@commit.short_id})"))
@@ -13,6 +14,7 @@ module Emails
       @note = Note.find(note_id)
       @issue = @note.noteable
       @project = @note.project
+      @target_url = project_issue_url(@project, @issue)
       mail(from: sender(@note.author_id),
            to: recipient(recipient_id),
            subject: subject("#{@issue.title} (##{@issue.iid})"))
@@ -22,6 +24,7 @@ module Emails
       @note = Note.find(note_id)
       @merge_request = @note.noteable
       @project = @note.project
+      @target_url = project_merge_request_url(@project, @merge_request, anchor: "note_#{@note.id}")
       mail(from: sender(@note.author_id),
            to: recipient(recipient_id),
            subject: subject("#{@merge_request.title} (!#{@merge_request.iid})"))
@@ -30,6 +33,7 @@ module Emails
     def note_wall_email(recipient_id, note_id)
       @note = Note.find(note_id)
       @project = @note.project
+      @target_url = project_wall_url(@note.project, anchor: "note_#{@note.id}")
       mail(from: sender(@note.author_id),
            to: recipient(recipient_id),
            subject: subject("Note on wall"))

app/mailers/emails/profile.rb

@@ -3,6 +3,7 @@ module Emails
     def new_user_email(user_id, password)
       @user = User.find(user_id)
       @password = password
+      @target_url = user_url(@user)
       mail(to: @user.email, subject: subject("Account was created for you"))
     end
 
@@ -15,6 +16,7 @@ module Emails
     def new_ssh_key_email(key_id)
       @key = Key.find(key_id)
       @user = @key.user
+      @target_url = user_url(@user)
       mail(to: @user.email, subject: subject("SSH key was added to your account"))
     end
   end

app/mailers/emails/projects.rb

@@ -3,6 +3,7 @@ module Emails
     def project_access_granted_email(user_project_id)
       @users_project = UsersProject.find user_project_id
       @project = @users_project.project
+      @target_url = project_url(@project)
       mail(to: @users_project.user.email,
            subject: subject("Access to project was granted"))
     end
@@ -10,6 +11,7 @@ module Emails
     def project_was_moved_email(project_id, user_id)
       @user = User.find user_id
       @project = Project.find project_id
+      @target_url = project_url(@project)
       mail(to: @user.email,
            subject: subject("Project was moved"))
     end
@@ -21,6 +23,11 @@ module Emails
       @commits = Commit.decorate(compare.commits)
       @diffs   = compare.diffs
       @branch  = branch
+      if @commits.length > 1
+        @target_url = project_compare_url(@project, from: @commits.first, to: @commits.last)
+      else
+        @target_url = project_commit_url(@project, @compare.commit)
+      end
 
       mail(from: sender(author_id),
            to: recipient,

app/views/layouts/notify.html.haml

@@ -20,3 +20,6 @@
           %p{style: "font-size:small;color:#777"}
             - if @project
               You're receiving this notification because you are a member of the #{@project.name_with_namespace} project team.
+              %br
+            - if @target_url
+              #{link_to "View in GitLab", @target_url}

spec/mailers/notify_spec.rb

@@ -468,6 +468,8 @@ describe Notify do
     let(:example_site_path) { root_path }
     let(:user) { create(:user) }
     let(:compare) { Gitlab::Git::Compare.new(project.repository.raw_repository, 'cd5c4bac', 'b1e6a9db') }
+    let(:commits) { Commit.decorate(compare.commits) }
+    let(:diff_path) { project_compare_path(project, from: commits.first, to: commits.last) }
 
     subject { Notify.repository_push_email(project.id, 'devs@company.name', user.id, 'master', compare) }
 
@@ -492,5 +494,9 @@ describe Notify do
     it 'includes diffs' do
       should have_body_text /Checkout wiki pages for installation information/
     end
+
+    it 'contains a link to the diff' do
+      should have_body_text /#{diff_path}/
+    end
   end
 end