Merge branch 'dm-merge-request-creations-controller' into 'master'

Split up MergeRequestsController

See merge request !12150

43 files changed, 554 insertions, 557 deletions

diff --git a/app/assets/javascripts/dispatcher.js b/app/assets/javascripts/dispatcher.js
index 31a86090242..4247540de22 100644
--- a/app/assets/javascripts/dispatcher.js
+++ b/app/assets/javascripts/dispatcher.js
@@ -209,8 +209,8 @@ import initExperimentalFlags from './experimental_flags';
           new MilestoneSelect();
           new gl.IssuableTemplateSelectors();
           break;
-        case 'projects:merge_requests:new':
-        case 'projects:merge_requests:new_diffs':
+        case 'projects:merge_requests:creations:new':
+        case 'projects:merge_requests:creations:diffs':
         case 'projects:merge_requests:edit':
           new gl.Diff();
           shortcut_handler = new ShortcutsNavigation();
@@ -247,10 +247,6 @@ import initExperimentalFlags from './experimental_flags';
           shortcut_handler = new ShortcutsIssuable(true);
           new ZenMode();
           break;
-        case "projects:merge_requests:diffs":
-          new gl.Diff();
-          new ZenMode();
-          break;
         case 'dashboard:activity':
           new gl.Activities();
           break;
@@ -319,7 +315,7 @@ import initExperimentalFlags from './experimental_flags';
           new gl.Members();
           new UsersSelect();
           break;
-        case 'projects:members:show':
+        case 'projects:settings:members:show':
           new gl.MemberExpirationDate('.js-access-expiration-date-groups');
           new GroupsSelect();
           new gl.MemberExpirationDate();
@@ -386,7 +382,7 @@ import initExperimentalFlags from './experimental_flags';
         case 'search:show':
           new Search();
           break;
-        case 'projects:repository:show':
+        case 'projects:settings:repository:show':
           // Initialize Protected Branch Settings
           new gl.ProtectedBranchCreate();
           new gl.ProtectedBranchEditList();
@@ -396,7 +392,7 @@ import initExperimentalFlags from './experimental_flags';
           // Initialize expandable settings panels
           initSettingsPanels();
           break;
-        case 'projects:ci_cd:show':
+        case 'projects:settings:ci_cd:show':
           new gl.ProjectVariables();
           break;
         case 'ci:lints:create':
diff --git a/app/assets/javascripts/merge_request_tabs.js b/app/assets/javascripts/merge_request_tabs.js
index 786b6014dc6..3cf3233cc65 100644
--- a/app/assets/javascripts/merge_request_tabs.js
+++ b/app/assets/javascripts/merge_request_tabs.js
@@ -168,9 +168,8 @@ import BlobForkSuggestion from './blob/blob_fork_suggestion';
 
     // Activate a tab based on the current action
     activateTab(action) {
-      const activate = action === 'show' ? 'notes' : action;
       // important note: the .tab('show') method triggers 'shown.bs.tab' event itself
-      $(`.merge-request-tabs a[data-action='${activate}']`).tab('show');
+      $(`.merge-request-tabs a[data-action='${action}']`).tab('show');
     }
 
     // Replaces the current Merge Request-specific action in the URL with a new one
@@ -185,7 +184,7 @@ import BlobForkSuggestion from './blob/blob_fork_suggestion';
     //   location.pathname # => "/namespace/project/merge_requests/1/diffs"
     //
     //   location.pathname # => "/namespace/project/merge_requests/1/diffs"
-    //   setCurrentAction('notes')
+    //   setCurrentAction('show')
     //   location.pathname # => "/namespace/project/merge_requests/1"
     //
     //   location.pathname # => "/namespace/project/merge_requests/1/diffs"
@@ -194,13 +193,13 @@ import BlobForkSuggestion from './blob/blob_fork_suggestion';
     //
     // Returns the new URL String
     setCurrentAction(action) {
-      this.currentAction = action === 'show' ? 'notes' : action;
+      this.currentAction = action;
 
-      // Remove a trailing '/commits' '/diffs' '/pipelines' '/new' '/new/diffs'
-      let newState = location.pathname.replace(/\/(commits|diffs|pipelines|new|new\/diffs)(\.html)?\/?$/, '');
+      // Remove a trailing '/commits' '/diffs' '/pipelines'
+      let newState = location.pathname.replace(/\/(commits|diffs|pipelines)(\.html)?\/?$/, '');
 
       // Append the new action if we're on a tab other than 'notes'
-      if (this.currentAction !== 'notes') {
+      if (this.currentAction !== 'show' && this.currentAction !== 'new') {
         newState += `/${this.currentAction}`;
       }
 
diff --git a/app/controllers/concerns/creates_commit.rb b/app/controllers/concerns/creates_commit.rb
index 1a9904bbe57..f87db4d9e84 100644
--- a/app/controllers/concerns/creates_commit.rb
+++ b/app/controllers/concerns/creates_commit.rb
@@ -78,7 +78,7 @@ module CreatesCommit
   end
 
   def new_merge_request_path
-    new_namespace_project_merge_request_path(
+    namespace_project_new_merge_request_path(
       @project_to_commit_into.namespace,
       @project_to_commit_into,
       merge_request: {
diff --git a/app/controllers/projects/merge_requests/application_controller.rb b/app/controllers/projects/merge_requests/application_controller.rb
new file mode 100644
index 00000000000..5de0f828010
--- /dev/null
+++ b/app/controllers/projects/merge_requests/application_controller.rb
@@ -0,0 +1,48 @@
+class Projects::MergeRequests::ApplicationController < Projects::ApplicationController
+  before_action :check_merge_requests_available!
+  before_action :merge_request
+  before_action :authorize_read_merge_request!
+  before_action :ensure_ref_fetched
+
+  private
+
+  def merge_request
+    @issuable = @merge_request ||= @project.merge_requests.find_by!(iid: params[:id])
+  end
+
+  # Make sure merge requests created before 8.0
+  # have head file in refs/merge-requests/
+  def ensure_ref_fetched
+    @merge_request.ensure_ref_fetched
+  end
+
+  def merge_request_params
+    params.require(:merge_request)
+      .permit(merge_request_params_attributes)
+  end
+
+  def merge_request_params_attributes
+    [
+      :assignee_id,
+      :description,
+      :force_remove_source_branch,
+      :lock_version,
+      :milestone_id,
+      :source_branch,
+      :source_project_id,
+      :state_event,
+      :target_branch,
+      :target_project_id,
+      :task_num,
+      :title,
+
+      label_ids: []
+    ]
+  end
+
+  def set_pipeline_variables
+    @pipelines = @merge_request.all_pipelines
+    @pipeline = @merge_request.head_pipeline
+    @statuses_count = @pipeline.present? ? @pipeline.statuses.relevant.count : 0
+  end
+end
diff --git a/app/controllers/projects/merge_requests/conflicts_controller.rb b/app/controllers/projects/merge_requests/conflicts_controller.rb
new file mode 100644
index 00000000000..a71f23e790d
--- /dev/null
+++ b/app/controllers/projects/merge_requests/conflicts_controller.rb
@@ -0,0 +1,66 @@
+class Projects::MergeRequests::ConflictsController < Projects::MergeRequests::ApplicationController
+  include IssuableActions
+
+  before_action :authorize_can_resolve_conflicts!
+
+  def show
+    respond_to do |format|
+      format.html do
+        labels
+      end
+
+      format.json do
+        if @conflicts_list.can_be_resolved_in_ui?
+          render json: @conflicts_list
+        elsif @merge_request.can_be_merged?
+          render json: {
+            message: 'The merge conflicts for this merge request have already been resolved. Please return to the merge request.',
+            type: 'error'
+          }
+        else
+          render json: {
+            message: 'The merge conflicts for this merge request cannot be resolved through GitLab. Please try to resolve them locally.',
+            type: 'error'
+          }
+        end
+      end
+    end
+  end
+
+  def conflict_for_path
+    return render_404 unless @conflicts_list.can_be_resolved_in_ui?
+
+    file = @conflicts_list.file_for_path(params[:old_path], params[:new_path])
+
+    return render_404 unless file
+
+    render json: file, full_content: true
+  end
+
+  def resolve_conflicts
+    return render_404 unless @conflicts_list.can_be_resolved_in_ui?
+
+    if @merge_request.can_be_merged?
+      render status: :bad_request, json: { message: 'The merge conflicts for this merge request have already been resolved.' }
+      return
+    end
+
+    begin
+      ::MergeRequests::Conflicts::ResolveService
+        .new(merge_request)
+        .execute(current_user, params)
+
+      flash[:notice] = 'All merge conflicts were resolved. The merge request can now be merged.'
+
+      render json: { redirect_to: namespace_project_merge_request_url(@project.namespace, @project, @merge_request, resolved_conflicts: true) }
+    rescue Gitlab::Conflict::ResolutionError => e
+      render status: :bad_request, json: { message: e.message }
+    end
+  end
+
+  def authorize_can_resolve_conflicts!
+    @conflicts_list = ::MergeRequests::Conflicts::ListService.new(@merge_request)
+
+    return render_404 unless @conflicts_list.can_be_resolved_by?(current_user)
+  end
+end
diff --git a/app/controllers/projects/merge_requests/creations_controller.rb b/app/controllers/projects/merge_requests/creations_controller.rb
new file mode 100644
index 00000000000..da058da795e
--- /dev/null
+++ b/app/controllers/projects/merge_requests/creations_controller.rb
@@ -0,0 +1,128 @@
+class Projects::MergeRequests::CreationsController < Projects::MergeRequests::ApplicationController
+  include DiffForPath
+  include DiffHelper
+
+  skip_before_action :merge_request
+  skip_before_action :ensure_ref_fetched
+  before_action :authorize_create_merge_request!
+  before_action :apply_diff_view_cookie!, only: [:diffs, :diff_for_path]
+  before_action :build_merge_request, except: [:create]
+
+  def new
+    define_new_vars
+  end
+
+  def create
+    @target_branches ||= []
+    @merge_request = ::MergeRequests::CreateService.new(project, current_user, merge_request_params).execute
+
+    if @merge_request.valid?
+      redirect_to(merge_request_path(@merge_request))
+    else
+      @source_project = @merge_request.source_project
+      @target_project = @merge_request.target_project
+
+      define_new_vars
+      render action: "new"
+    end
+  end
+
+  def pipelines
+    @pipelines = @merge_request.all_pipelines
+
+    Gitlab::PollingInterval.set_header(response, interval: 10_000)
+
+    render json: {
+      pipelines: PipelineSerializer
+      .new(project: @project, current_user: @current_user)
+      .represent(@pipelines)
+    }
+  end
+
+  def diffs
+    @diffs = if @merge_request.can_be_created
+               @merge_request.diffs(diff_options)
+             else
+               []
+             end
+    @diff_notes_disabled = true
+
+    @environment = @merge_request.environments_for(current_user).last
+
+    render json: { html: view_to_html_string('projects/merge_requests/creations/_diffs', diffs: @diffs, environment: @environment) }
+  end
+
+  def diff_for_path
+    @diffs = @merge_request.diffs(diff_options)
+    @diff_notes_disabled = true
+
+    render_diff_for_path(@diffs)
+  end
+
+  def branch_from
+    # This is always source
+    @source_project = @merge_request.nil? ? @project : @merge_request.source_project
+
+    if params[:ref].present?
+      @ref = params[:ref]
+      @commit = @repository.commit("refs/heads/#{@ref}")
+    end
+
+    render layout: false
+  end
+
+  def branch_to
+    @target_project = selected_target_project
+
+    if params[:ref].present?
+      @ref = params[:ref]
+      @commit = @target_project.commit("refs/heads/#{@ref}")
+    end
+
+    render layout: false
+  end
+
+  def update_branches
+    @target_project = selected_target_project
+    @target_branches = @target_project.repository.branch_names
+
+    render layout: false
+  end
+
+  private
+
+  def build_merge_request
+    params[:merge_request] ||= ActionController::Parameters.new(source_project: @project)
+    @merge_request = ::MergeRequests::BuildService.new(project, current_user, merge_request_params.merge(diff_options: diff_options)).execute
+  end
+
+  def define_new_vars
+    @noteable = @merge_request
+
+    @target_branches = if @merge_request.target_project
+                         @merge_request.target_project.repository.branch_names
+                       else
+                         []
+                       end
+
+    @target_project = @merge_request.target_project
+    @source_project = @merge_request.source_project
+    @commits = @merge_request.compare_commits.reverse
+    @commit = @merge_request.diff_head_commit
+
+    @note_counts = Note.where(commit_id: @commits.map(&:id))
+      .group(:commit_id).count
+
+    @labels = LabelsFinder.new(current_user, project_id: @project.id).execute
+
+    set_pipeline_variables
+  end
+
+  def selected_target_project
+    if @project.id.to_s == params[:target_project_id] || @project.forked_project_link.nil?
+      @project
+    else
+      @project.forked_project_link.forked_from_project
+    end
+  end
+end
diff --git a/app/controllers/projects/merge_requests/diffs_controller.rb b/app/controllers/projects/merge_requests/diffs_controller.rb
new file mode 100644
index 00000000000..330b7df4541
--- /dev/null
+++ b/app/controllers/projects/merge_requests/diffs_controller.rb
@@ -0,0 +1,66 @@
+class Projects::MergeRequests::DiffsController < Projects::MergeRequests::ApplicationController
+  include DiffForPath
+  include DiffHelper
+  include RendersNotes
+
+  before_action :apply_diff_view_cookie!
+  before_action :define_diff_vars
+  before_action :define_diff_comment_vars
+
+  def show
+    @environment = @merge_request.environments_for(current_user).last
+
+    render json: { html: view_to_html_string("projects/merge_requests/diffs/_diffs") }
+  end
+
+  def diff_for_path
+    render_diff_for_path(@diffs)
+  end
+
+  private
+
+  def define_diff_vars
+    @merge_request_diff =
+      if params[:diff_id]
+        @merge_request.merge_request_diffs.viewable.find(params[:diff_id])
+      else
+        @merge_request.merge_request_diff
+      end
+
+    @merge_request_diffs = @merge_request.merge_request_diffs.viewable.select_without_diff
+    @comparable_diffs = @merge_request_diffs.select { |diff| diff.id < @merge_request_diff.id }
+
+    if params[:start_sha].present?
+      @start_sha = params[:start_sha]
+      @start_version = @comparable_diffs.find { |diff| diff.head_commit_sha == @start_sha }
+
+      unless @start_version
+        @start_sha = @merge_request_diff.head_commit_sha
+        @start_version = @merge_request_diff
+      end
+    end
+
+    @compare =
+      if @start_sha
+        @merge_request_diff.compare_with(@start_sha)
+      else
+        @merge_request_diff
+      end
+
+    @diffs = @compare.diffs(diff_options)
+  end
+
+  def define_diff_comment_vars
+    @new_diff_note_attrs = {
+      noteable_type: 'MergeRequest',
+      noteable_id: @merge_request.id
+    }
+
+    @diff_notes_disabled = false
+
+    @use_legacy_diff_notes = !@merge_request.has_complete_diff_refs?
+
+    @grouped_diff_discussions = @merge_request.grouped_diff_discussions(@compare.diff_refs)
+    @notes = prepare_notes_for_rendering(@grouped_diff_discussions.values.flatten.flat_map(&:notes))
+  end
+end
diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index 879ff6d393e..04f8e95aa09 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -1,38 +1,17 @@
-class Projects::MergeRequestsController < Projects::ApplicationController
+class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationController
   include ToggleSubscriptionAction
-  include DiffForPath
-  include DiffHelper
   include IssuableActions
   include RendersNotes
   include ToggleAwardEmoji
   include IssuableCollections
 
-  before_action :check_merge_requests_available!
-  before_action :merge_request, only: [
-    :edit, :update, :show, :diffs, :commits, :conflicts, :conflict_for_path, :pipelines, :merge,
-    :pipeline_status, :ci_environments_status, :toggle_subscription, :cancel_merge_when_pipeline_succeeds, :remove_wip, :resolve_conflicts, :assign_related_issues, :commit_change_content
-  ]
-  before_action :validates_merge_request, only: [:show, :diffs, :commits, :pipelines]
-  before_action :define_show_vars, only: [:diffs, :commits, :conflicts, :conflict_for_path, :builds, :pipelines]
-  before_action :ensure_ref_fetched, only: [:show, :diffs, :commits, :builds, :conflicts, :conflict_for_path, :pipelines]
-  before_action :close_merge_request_without_source_project, only: [:show, :diffs, :commits, :builds, :pipelines]
-  before_action :check_if_can_be_merged, only: :show
-  before_action :apply_diff_view_cookie!, only: [:new_diffs]
-  before_action :build_merge_request, only: [:new, :new_diffs]
-
-  # Allow read any merge_request
-  before_action :authorize_read_merge_request!
-
-  # Allow write(create) merge_request
-  before_action :authorize_create_merge_request!, only: [:new, :create]
-
-  # Allow modify merge_request
+  skip_before_action :merge_request, only: [:index, :bulk_update]
+  skip_before_action :ensure_ref_fetched, only: [:index, :bulk_update]
+
   before_action :authorize_update_merge_request!, only: [:close, :edit, :update, :remove_wip, :sort]
 
   before_action :authenticate_user!, only: [:assign_related_issues]
 
-  before_action :authorize_can_resolve_conflicts!, only: [:conflicts, :conflict_for_path, :resolve_conflicts]
-
   def index
     @collection_type    = "MergeRequest"
     @merge_requests     = merge_requests_collection
@@ -72,10 +51,30 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   end
 
   def show
+    validates_merge_request
+    ensure_ref_fetched
+    close_merge_request_without_source_project
+    check_if_can_be_merged
+
     respond_to do |format|
       format.html do
-        define_discussion_vars
-        define_show_vars
+        # Build a note object for comment form
+        @note = @project.notes.new(noteable: @merge_request)
+
+        @discussions = @merge_request.discussions
+        @notes = prepare_notes_for_rendering(@discussions.flat_map(&:notes))
+
+        @noteable = @merge_request
+        @commits_count = @merge_request.commits_count
+
+        if @merge_request.locked_long_ago?
+          @merge_request.unlock_mr
+          @merge_request.close
+        end
+
+        labels
+
+        set_pipeline_variables
       end
 
       format.json do
@@ -98,198 +97,40 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     end
   end
 
-  def diffs
-    apply_diff_view_cookie!
-
-    respond_to do |format|
-      format.html { define_discussion_vars }
-      format.json do
-        define_diff_vars
-        define_diff_comment_vars
-
-        @environment = @merge_request.environments_for(current_user).last
-
-        render json: { html: view_to_html_string("projects/merge_requests/show/_diffs") }
-      end
-    end
-  end
-
-  # With an ID param, loads the MR at that ID. Otherwise, accepts the same params as #new
-  # and uses that (unsaved) MR.
-  #
-  def diff_for_path
-    if params[:id]
-      merge_request
-      define_diff_vars
-      define_diff_comment_vars
-    else
-      build_merge_request
-      @compare = @merge_request
-      @diffs = @compare.diffs(diff_options)
-      @diff_notes_disabled = true
-    end
-
-    render_diff_for_path(@diffs)
-  end
-
   def commits
-    respond_to do |format|
-      format.html do
-        define_discussion_vars
-
-        render 'show'
-      end
-      format.json do
-        # Get commits from repository
-        # or from cache if already merged
-        @commits = @merge_request.commits
-        @note_counts = Note.where(commit_id: @commits.map(&:id))
-          .group(:commit_id).count
-
-        render json: { html: view_to_html_string('projects/merge_requests/show/_commits') }
-      end
-    end
-  end
-
-  def conflicts
-    respond_to do |format|
-      format.html { define_discussion_vars }
-
-      format.json do
-        if @conflicts_list.can_be_resolved_in_ui?
-          render json: @conflicts_list
-        elsif @merge_request.can_be_merged?
-          render json: {
-            message: 'The merge conflicts for this merge request have already been resolved. Please return to the merge request.',
-            type: 'error'
-          }
-        else
-          render json: {
-            message: 'The merge conflicts for this merge request cannot be resolved through GitLab. Please try to resolve them locally.',
-            type: 'error'
-          }
-        end
-      end
-    end
-  end
-
-  def conflict_for_path
-    return render_404 unless @conflicts_list.can_be_resolved_in_ui?
-
-    file = @conflicts_list.file_for_path(params[:old_path], params[:new_path])
-
-    return render_404 unless file
-
-    render json: file, full_content: true
-  end
-
-  def resolve_conflicts
-    return render_404 unless @conflicts_list.can_be_resolved_in_ui?
-
-    if @merge_request.can_be_merged?
-      render status: :bad_request, json: { message: 'The merge conflicts for this merge request have already been resolved.' }
-      return
-    end
-
-    begin
-      MergeRequests::Conflicts::ResolveService
-        .new(merge_request)
-        .execute(current_user, params)
-
-      flash[:notice] = 'All merge conflicts were resolved. The merge request can now be merged.'
+    # Get commits from repository
+    # or from cache if already merged
+    @commits = @merge_request.commits
+    @note_counts = Note.where(commit_id: @commits.map(&:id))
+      .group(:commit_id).count
 
-      render json: { redirect_to: namespace_project_merge_request_url(@project.namespace, @project, @merge_request, resolved_conflicts: true) }
-    rescue Gitlab::Conflict::ResolutionError => e
-      render status: :bad_request, json: { message: e.message }
-    end
+    render json: { html: view_to_html_string('projects/merge_requests/_commits') }
   end
 
   def pipelines
     @pipelines = @merge_request.all_pipelines
 
-    respond_to do |format|
-      format.html do
-        define_discussion_vars
-
-        render 'show'
-      end
-
-      format.json do
-        Gitlab::PollingInterval.set_header(response, interval: 10_000)
+    Gitlab::PollingInterval.set_header(response, interval: 10_000)
 
-        render json: PipelineSerializer
-          .new(project: @project, current_user: @current_user)
-          .represent(@pipelines)
-      end
-    end
-  end
-
-  def new
-    respond_to do |format|
-      format.html { define_new_vars }
-      format.json do
-        define_pipelines_vars
-
-        Gitlab::PollingInterval.set_header(response, interval: 10_000)
-
-        render json: {
-          pipelines: PipelineSerializer
-          .new(project: @project, current_user: @current_user)
-          .represent(@pipelines)
-        }
-      end
-    end
-  end
-
-  def new_diffs
-    respond_to do |format|
-      format.html do
-        define_new_vars
-        @show_changes_tab = true
-        render "new"
-      end
-      format.json do
-        @diffs = if @merge_request.can_be_created
-                   @merge_request.diffs(diff_options)
-                 else
-                   []
-                 end
-        @diff_notes_disabled = true
-
-        @environment = @merge_request.environments_for(current_user).last
-
-        render json: { html: view_to_html_string('projects/merge_requests/_new_diffs', diffs: @diffs, environment: @environment) }
-      end
-    end
-  end
-
-  def create
-    @target_branches ||= []
-    @merge_request = MergeRequests::CreateService.new(project, current_user, merge_request_params).execute
-
-    if @merge_request.valid?
-      redirect_to(merge_request_path(@merge_request))
-    else
-      @source_project = @merge_request.source_project
-      @target_project = @merge_request.target_project
-      render action: "new"
-    end
+    render json: PipelineSerializer
+      .new(project: @project, current_user: @current_user)
+      .represent(@pipelines)
   end
 
   def edit
-    @source_project = @merge_request.source_project
-    @target_project = @merge_request.target_project
-    @target_branches = @merge_request.target_project.repository.branch_names
+    define_edit_vars
   end
 
   def update
-    @merge_request = MergeRequests::UpdateService.new(project, current_user, merge_request_params).execute(@merge_request)
+    @merge_request = ::MergeRequests::UpdateService.new(project, current_user, merge_request_params).execute(@merge_request)
 
     respond_to do |format|
       format.html do
         if @merge_request.valid?
           redirect_to([@merge_request.target_project.namespace.becomes(Namespace), @merge_request.target_project, @merge_request])
         else
+          define_edit_vars
+
           render :edit
         end
       end
@@ -299,11 +140,13 @@ class Projects::MergeRequestsController < Projects::ApplicationController
       end
     end
   rescue ActiveRecord::StaleObjectError
+    define_edit_vars if request.format.html?
+
     render_conflict_response
   end
 
   def remove_wip
-    @merge_request = MergeRequests::UpdateService
+    @merge_request = ::MergeRequests::UpdateService
       .new(project, current_user, wip_event: 'unwip')
       .execute(@merge_request)
 
@@ -319,7 +162,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
       return access_denied!
     end
 
-    MergeRequests::MergeWhenPipelineSucceedsService
+    ::MergeRequests::MergeWhenPipelineSucceedsService
       .new(@project, current_user)
       .cancel(@merge_request)
 
@@ -338,53 +181,19 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     end
   end
 
-  def branch_from
-    # This is always source
-    @source_project = @merge_request.nil? ? @project : @merge_request.source_project
-
-    if params[:ref].present?
-      @ref = params[:ref]
-      @commit = @repository.commit("refs/heads/#{@ref}")
-    end
-
-    render layout: false
-  end
-
-  def branch_to
-    @target_project = selected_target_project
-
-    if params[:ref].present?
-      @ref = params[:ref]
-      @commit = @target_project.commit("refs/heads/#{@ref}")
-    end
-
-    render layout: false
-  end
-
-  def update_branches
-    @target_project = selected_target_project
-    @target_branches = @target_project.repository.branch_names
-
-    render layout: false
-  end
-
   def assign_related_issues
-    result = MergeRequests::AssignIssuesService.new(project, current_user, merge_request: @merge_request).execute
+    result = ::MergeRequests::AssignIssuesService.new(project, current_user, merge_request: @merge_request).execute
 
-    respond_to do |format|
-      format.html do
-        case result[:count]
-        when 0
-          flash[:error] = "Failed to assign you issues related to the merge request"
-        when 1
-          flash[:notice] = "1 issue has been assigned to you"
-        else
-          flash[:notice] = "#{result[:count]} issues have been assigned to you"
-        end
-
-        redirect_to(merge_request_path(@merge_request))
-      end
+    case result[:count]
+    when 0
+      flash[:error] = "Failed to assign you issues related to the merge request"
+    when 1
+      flash[:notice] = "1 issue has been assigned to you"
+    else
+      flash[:notice] = "#{result[:count]} issues have been assigned to you"
     end
+
+    redirect_to(merge_request_path(@merge_request))
   end
 
   def pipeline_status
@@ -432,17 +241,6 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
   protected
 
-  def selected_target_project
-    if @project.id.to_s == params[:target_project_id] || @project.forked_project_link.nil?
-      @project
-    else
-      @project.forked_project_link.forked_from_project
-    end
-  end
-
-  def merge_request
-    @issuable = @merge_request ||= @project.merge_requests.find_by!(iid: params[:id])
-  end
   alias_method :subscribable_resource, :merge_request
   alias_method :issuable, :merge_request
   alias_method :awardable, :merge_request
@@ -455,12 +253,6 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     return render_404 unless can?(current_user, :admin_merge_request, @merge_request)
   end
 
-  def authorize_can_resolve_conflicts!
-    @conflicts_list = MergeRequests::Conflicts::ListService.new(@merge_request)
-
-    return render_404 unless @conflicts_list.can_be_resolved_by?(current_user)
-  end
-
   def validates_merge_request
     # Show git not found page
     # if there is no saved commits between source & target branch
@@ -470,133 +262,11 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     end
   end
 
-  def define_show_vars
-    @noteable = @merge_request
-    @commits_count = @merge_request.commits_count
-
-    if @merge_request.locked_long_ago?
-      @merge_request.unlock_mr
-      @merge_request.close
-    end
-
-    labels
-    define_pipelines_vars
-  end
-
-  # Discussion tab data is rendered on html responses of actions
-  # :show, :diff, :commits, :builds. but not when request the data through AJAX
-  def define_discussion_vars
-    # Build a note object for comment form
-    @note = @project.notes.new(noteable: @merge_request)
-
-    @discussions = @merge_request.discussions
-    @notes = prepare_notes_for_rendering(@discussions.flat_map(&:notes))
-  end
-
-  def define_diff_vars
-    @merge_request_diff =
-      if params[:diff_id]
-        @merge_request.merge_request_diffs.viewable.find(params[:diff_id])
-      else
-        @merge_request.merge_request_diff
-      end
-
-    @merge_request_diffs = @merge_request.merge_request_diffs.viewable.select_without_diff
-    @comparable_diffs = @merge_request_diffs.select { |diff| diff.id < @merge_request_diff.id }
-
-    if params[:start_sha].present?
-      @start_sha = params[:start_sha]
-      @start_version = @comparable_diffs.find { |diff| diff.head_commit_sha == @start_sha }
-
-      unless @start_version
-        @start_sha = @merge_request_diff.head_commit_sha
-        @start_version = @merge_request_diff
-      end
-    end
-
-    @compare =
-      if @start_sha
-        @merge_request_diff.compare_with(@start_sha)
-      else
-        @merge_request_diff
-      end
-
-    @diffs = @compare.diffs(diff_options)
-  end
-
-  def define_diff_comment_vars
-    @new_diff_note_attrs = {
-      noteable_type: 'MergeRequest',
-      noteable_id: @merge_request.id
-    }
-
-    @diff_notes_disabled = false
-
-    @use_legacy_diff_notes = !@merge_request.has_complete_diff_refs?
-
-    @grouped_diff_discussions = @merge_request.grouped_diff_discussions(@compare.diff_refs)
-    @notes = prepare_notes_for_rendering(@grouped_diff_discussions.values.flatten.flat_map(&:notes))
-  end
-
-  def define_pipelines_vars
-    @pipelines = @merge_request.all_pipelines
-    @pipeline = @merge_request.head_pipeline
-    @statuses_count = @pipeline.present? ? @pipeline.statuses.relevant.count : 0
-  end
-
-  def define_new_vars
-    @noteable = @merge_request
-
-    @target_branches = if @merge_request.target_project
-                         @merge_request.target_project.repository.branch_names
-                       else
-                         []
-                       end
-
-    @target_project = merge_request.target_project
-    @source_project = merge_request.source_project
-    @commits = @merge_request.compare_commits.reverse
-    @commit = @merge_request.diff_head_commit
-
-    @note_counts = Note.where(commit_id: @commits.map(&:id))
-      .group(:commit_id).count
-
-    @labels = LabelsFinder.new(current_user, project_id: @project.id).execute
-
-    @show_changes_tab = params[:show_changes].present?
-
-    define_pipelines_vars
-  end
-
   def invalid_mr
     # Render special view for MR with removed target branch
     render 'invalid'
   end
 
-  def merge_request_params
-    params.require(:merge_request)
-      .permit(merge_request_params_attributes)
-  end
-
-  def merge_request_params_attributes
-    [
-      :assignee_id,
-      :description,
-      :force_remove_source_branch,
-      :lock_version,
-      :milestone_id,
-      :source_branch,
-      :source_project_id,
-      :state_event,
-      :target_branch,
-      :target_project_id,
-      :task_num,
-      :title,
-
-      label_ids: []
-    ]
-  end
-
   def merge_params
     params.permit(merge_params_attributes)
   end
@@ -605,22 +275,11 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     [:should_remove_source_branch, :commit_message]
   end
 
-  # Make sure merge requests created before 8.0
-  # have head file in refs/merge-requests/
-  def ensure_ref_fetched
-    @merge_request.ensure_ref_fetched
-  end
-
   def merge_when_pipeline_succeeds_active?
     params[:merge_when_pipeline_succeeds].present? &&
       @merge_request.head_pipeline && @merge_request.head_pipeline.active?
   end
 
-  def build_merge_request
-    params[:merge_request] ||= ActionController::Parameters.new(source_project: @project)
-    @merge_request = MergeRequests::BuildService.new(project, current_user, merge_request_params.merge(diff_options: diff_options)).execute
-  end
-
   def close_merge_request_without_source_project
     if !@merge_request.source_project && @merge_request.open?
       @merge_request.close
@@ -648,7 +307,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
       return :failed unless @merge_request.head_pipeline
 
       if @merge_request.head_pipeline.active?
-        MergeRequests::MergeWhenPipelineSucceedsService
+        ::MergeRequests::MergeWhenPipelineSucceedsService
           .new(@project, current_user, merge_params)
           .execute(@merge_request)
 
@@ -672,4 +331,10 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   def serializer
     MergeRequestSerializer.new(current_user: current_user, project: merge_request.project)
   end
+
+  def define_edit_vars
+    @source_project = @merge_request.source_project
+    @target_project = @merge_request.target_project
+    @target_branches = @merge_request.target_project.repository.branch_names
+  end
 end
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index dc7ff78f3df..7be8e3b96cf 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -131,10 +131,7 @@ module ApplicationHelper
   end
 
   def body_data_page
-    path = controller.controller_path.split('/')
-    namespace = path.first if path.second
-
-    [namespace, controller.controller_name, controller.action_name].compact.join(':')
+    [*controller.controller_path.split('/'), controller.action_name].compact.join(':')
   end
 
   # shortcut for gitlab config
diff --git a/app/helpers/blob_helper.rb b/app/helpers/blob_helper.rb
index 3efa7c36057..ee36617ba9a 100644
--- a/app/helpers/blob_helper.rb
+++ b/app/helpers/blob_helper.rb
@@ -284,7 +284,7 @@ module BlobHelper
 
     merge_project = can?(current_user, :create_merge_request, project) ? project : (current_user && current_user.fork_of(project))
     if merge_project
-      options << link_to("create a merge request", new_namespace_project_merge_request_path(project.namespace, project))
+      options << link_to("create a merge request", namespace_project_new_merge_request_path(project.namespace, project))
     end
 
     options
diff --git a/app/helpers/compare_helper.rb b/app/helpers/compare_helper.rb
index 2aa0449c46e..424ded2b69d 100644
--- a/app/helpers/compare_helper.rb
+++ b/app/helpers/compare_helper.rb
@@ -9,7 +9,7 @@ module CompareHelper
   end
 
   def create_mr_path(from = params[:from], to = params[:to], project = @project)
-    new_namespace_project_merge_request_path(
+    namespace_project_new_merge_request_path(
       project.namespace,
       project,
       merge_request: {
diff --git a/app/helpers/merge_requests_helper.rb b/app/helpers/merge_requests_helper.rb
index 39d30631646..54d6f86fa11 100644
--- a/app/helpers/merge_requests_helper.rb
+++ b/app/helpers/merge_requests_helper.rb
@@ -1,7 +1,7 @@
 module MergeRequestsHelper
   def new_mr_path_from_push_event(event)
     target_project = event.project.default_merge_request_target
-    new_namespace_project_merge_request_path(
+    namespace_project_new_merge_request_path(
       event.project.namespace,
       event.project,
       new_mr_from_push_event(event, target_project)
@@ -48,7 +48,7 @@ module MergeRequestsHelper
   end
 
   def mr_change_branches_path(merge_request)
-    new_namespace_project_merge_request_path(
+    namespace_project_new_merge_request_path(
       @project.namespace, @project,
       merge_request: {
         source_project_id: merge_request.source_project_id,
diff --git a/app/helpers/nav_helper.rb b/app/helpers/nav_helper.rb
index 833d3c36b28..e589ed4e56d 100644
--- a/app/helpers/nav_helper.rb
+++ b/app/helpers/nav_helper.rb
@@ -1,11 +1,7 @@
 module NavHelper
   def page_gutter_class
     if current_path?('merge_requests#show') ||
-        current_path?('merge_requests#diffs') ||
-        current_path?('merge_requests#commits') ||
-        current_path?('merge_requests#builds') ||
-        current_path?('merge_requests#conflicts') ||
-        current_path?('merge_requests#pipelines') ||
+        current_path?('projects/merge_requests/conflicts#show') ||
         current_path?('issues#show') ||
         current_path?('milestones#show')
       if cookies[:collapsed_gutter] == 'true'
diff --git a/app/services/merge_requests/get_urls_service.rb b/app/services/merge_requests/get_urls_service.rb
index f00a33969a8..5dd40e07c0d 100644
--- a/app/services/merge_requests/get_urls_service.rb
+++ b/app/services/merge_requests/get_urls_service.rb
@@ -49,7 +49,7 @@ module MergeRequests
 
     def url_for_new_merge_request(branch_name)
       merge_request_params = { source_branch: branch_name }
-      url = Gitlab::Routing.url_helpers.new_namespace_project_merge_request_url(project.namespace, project, merge_request: merge_request_params)
+      url = Gitlab::Routing.url_helpers.namespace_project_new_merge_request_url(project.namespace, project, merge_request: merge_request_params)
       { branch_name: branch_name, url: url, new_merge_request: true }
     end
 
diff --git a/app/services/projects/unlink_fork_service.rb b/app/services/projects/unlink_fork_service.rb
index 315c3e16292..f385e426827 100644
--- a/app/services/projects/unlink_fork_service.rb
+++ b/app/services/projects/unlink_fork_service.rb
@@ -10,7 +10,7 @@ module Projects
       merge_requests = @project.forked_from_project.merge_requests.opened.from_project(@project)
 
       merge_requests.each do |mr|
-        MergeRequests::CloseService.new(@project, @current_user).execute(mr)
+        ::MergeRequests::CloseService.new(@project, @current_user).execute(mr)
       end
 
       @project.forked_project_link.destroy
diff --git a/app/views/layouts/header/_new_dropdown.haml b/app/views/layouts/header/_new_dropdown.haml
index 9ff1164f2ee..4d41579168c 100644
--- a/app/views/layouts/header/_new_dropdown.haml
+++ b/app/views/layouts/header/_new_dropdown.haml
@@ -33,7 +33,7 @@
               = link_to 'New issue', new_namespace_project_issue_path(@project.namespace, @project)
           - if merge_project
             %li
-              = link_to 'New merge request', new_namespace_project_merge_request_path(merge_project.namespace, merge_project)
+              = link_to 'New merge request', namespace_project_new_merge_request_path(merge_project.namespace, merge_project)
           - if create_project_snippet
             %li.header-new-project-snippet
               = link_to 'New snippet', new_namespace_project_snippet_path(@project.namespace, @project)
diff --git a/app/views/layouts/nav/_project.html.haml b/app/views/layouts/nav/_project.html.haml
index 29658da7792..68024d782a6 100644
--- a/app/views/layouts/nav/_project.html.haml
+++ b/app/views/layouts/nav/_project.html.haml
@@ -31,7 +31,9 @@
               %span.badge.count.issue_counter= number_with_delimiter(IssuesFinder.new(current_user, project_id: @project.id).execute.opened.count)
 
     - if project_nav_tab? :merge_requests
-      = nav_link(controller: @project.default_issues_tracker? ? :merge_requests : [:merge_requests, :labels, :milestones]) do
+      - controllers = [:merge_requests, 'projects/merge_requests/conflicts']
+      - controllers.push(:merge_requests, :labels, :milestones) unless @project.default_issues_tracker?
+      = nav_link(controller: controllers) do
         = link_to namespace_project_merge_requests_path(@project.namespace, @project), title: 'Merge Requests', class: 'shortcuts-merge_requests' do
           %span
             Merge Requests
diff --git a/app/views/projects/buttons/_dropdown.html.haml b/app/views/projects/buttons/_dropdown.html.haml
index 960b57a8008..aa1a533b5cb 100644
--- a/app/views/projects/buttons/_dropdown.html.haml
+++ b/app/views/projects/buttons/_dropdown.html.haml
@@ -16,7 +16,7 @@
 
       - if merge_project
         %li
-          = link_to new_namespace_project_merge_request_path(merge_project.namespace, merge_project) do
+          = link_to namespace_project_new_merge_request_path(merge_project.namespace, merge_project) do
             = icon('tasks fw')
             #{ _('New merge request') }
 
diff --git a/app/views/projects/commits/_commits.html.haml b/app/views/projects/commits/_commits.html.haml
index 93fd0789c11..cf8dffc8957 100644
--- a/app/views/projects/commits/_commits.html.haml
+++ b/app/views/projects/commits/_commits.html.haml
@@ -8,7 +8,7 @@
 
   %li.commits-row{ data: { day: day } }
     %ul.content-list.commit-list
-      = render commits, project: project, ref: ref
+      = render partial: 'projects/commits/commit', collection: commits, locals: { project: project, ref: ref }
 
 - if hidden > 0
   %li.alert.alert-warning
diff --git a/app/views/projects/diffs/_diffs.html.haml b/app/views/projects/diffs/_diffs.html.haml
index d538c4c86c8..f9385459a66 100644
--- a/app/views/projects/diffs/_diffs.html.haml
+++ b/app/views/projects/diffs/_diffs.html.haml
@@ -10,7 +10,7 @@
     - if show_whitespace_toggle
       - if current_controller?(:commit)
         = commit_diff_whitespace_link(diffs.project, @commit, class: 'hidden-xs')
-      - elsif current_controller?(:merge_requests)
+      - elsif current_controller?('projects/merge_requests/diffs')
         = diff_merge_request_whitespace_link(diffs.project, @merge_request, class: 'hidden-xs')
       - elsif current_controller?(:compare)
         = diff_compare_whitespace_link(diffs.project, params[:from], params[:to], class: 'hidden-xs')
diff --git a/app/views/projects/diffs/_warning.html.haml b/app/views/projects/diffs/_warning.html.haml
index 295a1b62535..402c18c447e 100644
--- a/app/views/projects/diffs/_warning.html.haml
+++ b/app/views/projects/diffs/_warning.html.haml
@@ -2,13 +2,12 @@
   %h4
     Too many changes to show.
     .pull-right
-      - if current_controller?(:commit) or current_controller?(:merge_requests)
-        - if current_controller?(:commit)
-          = link_to "Plain diff", namespace_project_commit_path(@project.namespace, @project, @commit, format: :diff), class: "btn btn-sm"
-          = link_to "Email patch", namespace_project_commit_path(@project.namespace, @project, @commit, format: :patch), class: "btn btn-sm"
-        - elsif @merge_request && @merge_request.persisted?
-          = link_to "Plain diff", merge_request_path(@merge_request, format: :diff), class: "btn btn-sm"
-          = link_to "Email patch", merge_request_path(@merge_request, format: :patch), class: "btn btn-sm"
+      - if current_controller?(:commit)
+        = link_to "Plain diff", namespace_project_commit_path(@project.namespace, @project, @commit, format: :diff), class: "btn btn-sm"
+        = link_to "Email patch", namespace_project_commit_path(@project.namespace, @project, @commit, format: :patch), class: "btn btn-sm"
+      - elsif current_controller?('projects/merge_requests/diffs') && @merge_request&.persisted?
+        = link_to "Plain diff", merge_request_path(@merge_request, format: :diff), class: "btn btn-sm"
+        = link_to "Email patch", merge_request_path(@merge_request, format: :patch), class: "btn btn-sm"
   %p
     To preserve performance only
     %strong #{diff_files.size} of #{diff_files.real_size}
diff --git a/app/views/projects/merge_requests/show/_commits.html.haml b/app/views/projects/merge_requests/_commits.html.haml
index 11793919ff7..11793919ff7 100644
--- a/app/views/projects/merge_requests/show/_commits.html.haml
+++ b/app/views/projects/merge_requests/_commits.html.haml
diff --git a/app/views/projects/merge_requests/show/_how_to_merge.html.haml b/app/views/projects/merge_requests/_how_to_merge.html.haml
index 766cb272bec..766cb272bec 100644
--- a/app/views/projects/merge_requests/show/_how_to_merge.html.haml
+++ b/app/views/projects/merge_requests/_how_to_merge.html.haml
diff --git a/app/views/projects/merge_requests/show/_mr_box.html.haml b/app/views/projects/merge_requests/_mr_box.html.haml
index 8a390cf8700..8a390cf8700 100644
--- a/app/views/projects/merge_requests/show/_mr_box.html.haml
+++ b/app/views/projects/merge_requests/_mr_box.html.haml
diff --git a/app/views/projects/merge_requests/show/_mr_title.html.haml b/app/views/projects/merge_requests/_mr_title.html.haml
index d9428b8562e..d9428b8562e 100644
--- a/app/views/projects/merge_requests/show/_mr_title.html.haml
+++ b/app/views/projects/merge_requests/_mr_title.html.haml
diff --git a/app/views/projects/merge_requests/show/_pipelines.html.haml b/app/views/projects/merge_requests/_pipelines.html.haml
index 2f1dbe87619..2f1dbe87619 100644
--- a/app/views/projects/merge_requests/show/_pipelines.html.haml
+++ b/app/views/projects/merge_requests/_pipelines.html.haml
diff --git a/app/views/projects/merge_requests/_show.html.haml b/app/views/projects/merge_requests/_show.html.haml
deleted file mode 100644
index 75120409bb3..00000000000
--- a/app/views/projects/merge_requests/_show.html.haml
+++ /dev/null
@@ -1,97 +0,0 @@
-- @content_class = "limit-container-width" unless fluid_layout
-- page_title "#{@merge_request.title} (#{@merge_request.to_reference})", "Merge Requests"
-- page_description @merge_request.description
-- page_card_attributes @merge_request.card_attributes
-- content_for :page_specific_javascripts do
-  = page_specific_javascript_bundle_tag('common_vue')
-  = page_specific_javascript_bundle_tag('diff_notes')
-
-.merge-request{ 'data-url' => merge_request_path(@merge_request, format: :json), 'data-project-path' => project_path(@merge_request.project) }
-  = render "projects/merge_requests/show/mr_title"
-
-  .merge-request-details.issuable-details{ data: { id: @merge_request.project.id } }
-    = render "projects/merge_requests/show/mr_box"
-
-    - if @merge_request.source_branch_exists?
-      = render "projects/merge_requests/show/how_to_merge"
-
-    :javascript
-      window.gl.mrWidgetData = #{serialize_issuable(@merge_request)}
-
-    #js-vue-mr-widget.mr-widget
-
-    - content_for :page_specific_javascripts do
-      = webpack_bundle_tag 'common_vue'
-      = webpack_bundle_tag 'vue_merge_request_widget'
-
-    .content-block.content-block-small.emoji-list-container
-      = render 'award_emoji/awards_block', awardable: @merge_request, inline: true
-
-    .merge-request-tabs-holder{ class: ("js-tabs-affix" unless ENV['RAILS_ENV'] == 'test') }
-      .merge-request-tabs-container
-        .scrolling-tabs-container.inner-page-scroll-tabs.is-smaller
-          .fade-left= icon('angle-left')
-          .fade-right= icon('angle-right')
-          .nav-links.scrolling-tabs
-            %ul.merge-request-tabs
-              %li.notes-tab
-                = link_to namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#notes', action: 'notes', toggle: 'tab' } do
-                  Discussion
-                  %span.badge= @merge_request.related_notes.user.count
-              - if @merge_request.source_project
-                %li.commits-tab
-                  = link_to commits_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#commits', action: 'commits', toggle: 'tab' } do
-                    Commits
-                    %span.badge= @commits_count
-              - if @pipelines.any?
-                %li.pipelines-tab
-                  = link_to pipelines_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: '#pipelines', action: 'pipelines', toggle: 'tab' } do
-                    Pipelines
-                    %span.badge= @pipelines.size
-              %li.diffs-tab
-                = link_to diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#diffs', action: 'diffs', toggle: 'tab' } do
-                  Changes
-                  %span.badge= @merge_request.diff_size
-        #resolve-count-app.line-resolve-all-container.prepend-top-10{ "v-cloak" => true }
-          %resolve-count{ "inline-template" => true, ":logged-out" => "#{current_user.nil?}" }
-            %div
-              .line-resolve-all{ "v-show" => "discussionCount > 0",
-                ":class" => "{ 'has-next-btn': !loggedOut && resolvedDiscussionCount !== discussionCount }" }
-                %span.line-resolve-btn.is-disabled{ type: "button",
-                    ":class" => "{ 'is-active': resolvedDiscussionCount === discussionCount }" }
-                  = render "shared/icons/icon_status_success.svg"
-                %span.line-resolve-text
-                  {{ resolvedDiscussionCount }}/{{ discussionCount }} {{ resolvedCountText }} resolved
-              = render "discussions/new_issue_for_all_discussions", merge_request: @merge_request
-              = render "discussions/jump_to_next"
-
-    .tab-content#diff-notes-app
-      #notes.notes.tab-pane.voting_notes
-        .row
-          %section.col-md-12
-            .issuable-discussion
-              = render "projects/merge_requests/discussion"
-
-      #commits.commits.tab-pane
-        -# This tab is always loaded via AJAX
-      #pipelines.pipelines.tab-pane
-        - if @pipelines.any?
-          = render 'projects/commit/pipelines_list', disable_initialization: true, endpoint: pipelines_namespace_project_merge_request_path(@project.namespace, @project, @merge_request)
-      #diffs.diffs.tab-pane
-        -# This tab is always loaded via AJAX
-
-    .mr-loading-status
-      = spinner
-
-= render 'shared/issuable/sidebar', issuable: @merge_request
-- if @merge_request.can_be_reverted?(current_user)
-  = render "projects/commit/change", type: 'revert', commit: @merge_request.merge_commit, title: @merge_request.title
-- if @merge_request.can_be_cherry_picked?
-  = render "projects/commit/change", type: 'cherry-pick', commit: @merge_request.merge_commit, title: @merge_request.title
-
-:javascript
-  $(function () {
-    window.mergeRequest = new MergeRequest({
-      action: "#{controller.action_name}"
-    });
-  });
diff --git a/app/views/projects/merge_requests/conflicts.html.haml b/app/views/projects/merge_requests/conflicts.html.haml
index 51d59280be8..f016b9c13b3 100644
--- a/app/views/projects/merge_requests/conflicts.html.haml
+++ b/app/views/projects/merge_requests/conflicts.html.haml
@@ -3,10 +3,10 @@
   = page_specific_javascript_bundle_tag('common_vue')
   = page_specific_javascript_bundle_tag('merge_conflicts')
   = page_specific_javascript_tag('lib/ace.js')
-= render "projects/merge_requests/show/mr_title"
+= render "projects/merge_requests/mr_title"
 
 .merge-request-details.issuable-details
-  = render "projects/merge_requests/show/mr_box"
+  = render "projects/merge_requests/mr_box"
 
 = render 'shared/issuable/sidebar', issuable: @merge_request
 
diff --git a/app/views/projects/merge_requests/conflicts/show.html.haml b/app/views/projects/merge_requests/conflicts/show.html.haml
new file mode 100644
index 00000000000..f016b9c13b3
--- /dev/null
+++ b/app/views/projects/merge_requests/conflicts/show.html.haml
@@ -0,0 +1,38 @@
+- page_title "Merge Conflicts", "#{@merge_request.title} (#{@merge_request.to_reference}", "Merge Requests"
+- content_for :page_specific_javascripts do
+  = page_specific_javascript_bundle_tag('common_vue')
+  = page_specific_javascript_bundle_tag('merge_conflicts')
+  = page_specific_javascript_tag('lib/ace.js')
+= render "projects/merge_requests/mr_title"
+
+.merge-request-details.issuable-details
+  = render "projects/merge_requests/mr_box"
+
+= render 'shared/issuable/sidebar', issuable: @merge_request
+
+#conflicts{ "v-cloak" => "true", data: { conflicts_path: conflicts_namespace_project_merge_request_path(@merge_request.project.namespace, @merge_request.project, @merge_request, format: :json),
+    resolve_conflicts_path: resolve_conflicts_namespace_project_merge_request_path(@merge_request.project.namespace, @merge_request.project, @merge_request) } }
+  .loading{ "v-if" => "isLoading" }
+    %i.fa.fa-spinner.fa-spin
+
+  .nothing-here-block{ "v-if" => "hasError" }
+    {{conflictsData.errorMessage}}
+
+  = render partial: "projects/merge_requests/conflicts/commit_stats"
+
+  .files-wrapper{ "v-if" => "!isLoading && !hasError" }
+    .files
+      .diff-file.file-holder.conflict{ "v-for" => "file in conflictsData.files" }
+        .js-file-title.file-title
+          %i.fa.fa-fw{ ":class" => "file.iconClass" }
+          %strong {{file.filePath}}
+          = render partial: 'projects/merge_requests/conflicts/file_actions'
+        .diff-content.diff-wrap-lines
+          .diff-wrap-lines.code.file-content.js-syntax-highlight{ "v-show" => "!isParallel && file.resolveMode === 'interactive' && file.type === 'text'" }
+            = render partial: "projects/merge_requests/conflicts/components/inline_conflict_lines"
+          .diff-wrap-lines.code.file-content.js-syntax-highlight{ "v-show" => "isParallel && file.resolveMode === 'interactive' && file.type === 'text'" }
+            %parallel-conflict-lines{ ":file" => "file" }
+          %div{ "v-show" => "file.resolveMode === 'edit' ||  file.type === 'text-editor'" }
+            = render partial: "projects/merge_requests/conflicts/components/diff_file_editor"
+
+    = render partial: "projects/merge_requests/conflicts/submit_form"
diff --git a/app/views/projects/merge_requests/_new_diffs.html.haml b/app/views/projects/merge_requests/creations/_diffs.html.haml
index 627fc4e9671..627fc4e9671 100644
--- a/app/views/projects/merge_requests/_new_diffs.html.haml
+++ b/app/views/projects/merge_requests/creations/_diffs.html.haml
diff --git a/app/views/projects/merge_requests/_new_compare.html.haml b/app/views/projects/merge_requests/creations/_new_compare.html.haml
index 0f37abb579c..7cda326afef 100644
--- a/app/views/projects/merge_requests/_new_compare.html.haml
+++ b/app/views/projects/merge_requests/creations/_new_compare.html.haml
@@ -1,7 +1,7 @@
 %h3.page-title
   New Merge Request
 
-= form_for [@project.namespace.becomes(Namespace), @project, @merge_request], url: new_namespace_project_merge_request_path(@project.namespace, @project), method: :get, html: { class: "merge-request-form form-inline js-requires-input" } do |f|
+= form_for [@project.namespace.becomes(Namespace), @project, @merge_request], url: namespace_project_new_merge_request_path(@project.namespace, @project), method: :get, html: { class: "merge-request-form form-inline js-requires-input" } do |f|
   .hide.alert.alert-danger.mr-compare-errors
   .merge-request-branches.row
     .col-md-6
@@ -69,7 +69,7 @@
 
 :javascript
   new Compare({
-    targetProjectUrl: "#{update_branches_namespace_project_merge_requests_path(@source_project.namespace, @source_project)}",
-    sourceBranchUrl: "#{branch_from_namespace_project_merge_requests_path(@source_project.namespace, @source_project)}",
-    targetBranchUrl: "#{branch_to_namespace_project_merge_requests_path(@source_project.namespace, @source_project)}"
+    targetProjectUrl: "#{namespace_project_new_merge_request_update_branches_path(@source_project.namespace, @source_project)}",
+    sourceBranchUrl: "#{namespace_project_new_merge_request_branch_from_path(@source_project.namespace, @source_project)}",
+    targetBranchUrl: "#{namespace_project_new_merge_request_branch_to_path(@source_project.namespace, @source_project)}"
   });
diff --git a/app/views/projects/merge_requests/_new_submit.html.haml b/app/views/projects/merge_requests/creations/_new_submit.html.haml
index e3ecbee5490..c72dd1d8e29 100644
--- a/app/views/projects/merge_requests/_new_submit.html.haml
+++ b/app/views/projects/merge_requests/creations/_new_submit.html.haml
@@ -31,28 +31,27 @@
           %span.badge= @commits.size
       - if @pipelines.any?
         %li.builds-tab
-          = link_to url_for(params), data: {target: 'div#pipelines', action: 'pipelines', toggle: 'tab'} do
+          = link_to url_for(params.merge(action: 'pipelines')), data: {target: 'div#pipelines', action: 'pipelines', toggle: 'tab'} do
             Pipelines
             %span.badge= @pipelines.size
       %li.diffs-tab
-        = link_to url_for(params.merge(action: 'new_diffs')), data: {target: 'div#diffs', action: 'new/diffs', toggle: 'tab'} do
+        = link_to url_for(params.merge(action: 'diffs')), data: {target: 'div#diffs', action: 'diffs', toggle: 'tab'} do
           Changes
           %span.badge= @merge_request.diff_size
 
     .tab-content
       #commits.commits.tab-pane.active
-        = render "projects/merge_requests/show/commits"
+        = render "projects/merge_requests/commits"
       #diffs.diffs.tab-pane
         -# This tab is always loaded via AJAX
       - if @pipelines.any?
         #pipelines.pipelines.tab-pane
-          = render 'projects/merge_requests/show/pipelines', endpoint: url_for(params.merge(format: :json)), disable_initialization: true
+          = render 'projects/merge_requests/pipelines', endpoint: url_for(params.merge(action: 'pipelines', format: :json)), disable_initialization: true
 
   .mr-loading-status
     = spinner
 
 :javascript
   var merge_request = new MergeRequest({
-    action: "#{(@show_changes_tab ? 'new/diffs' : 'new')}",
-    setUrl: false,
+    action: "#{j params[:tab].presence || 'new'}",
   });
diff --git a/app/views/projects/merge_requests/branch_from.html.haml b/app/views/projects/merge_requests/creations/branch_from.html.haml
index 3837c4b388d..3837c4b388d 100644
--- a/app/views/projects/merge_requests/branch_from.html.haml
+++ b/app/views/projects/merge_requests/creations/branch_from.html.haml
diff --git a/app/views/projects/merge_requests/branch_to.html.haml b/app/views/projects/merge_requests/creations/branch_to.html.haml
index d69b71790a0..d69b71790a0 100644
--- a/app/views/projects/merge_requests/branch_to.html.haml
+++ b/app/views/projects/merge_requests/creations/branch_to.html.haml
diff --git a/app/views/projects/merge_requests/new.html.haml b/app/views/projects/merge_requests/creations/new.html.haml
index 2e798ce780a..2e798ce780a 100644
--- a/app/views/projects/merge_requests/new.html.haml
+++ b/app/views/projects/merge_requests/creations/new.html.haml
diff --git a/app/views/projects/merge_requests/update_branches.html.haml b/app/views/projects/merge_requests/creations/update_branches.html.haml
index 64482973a89..64482973a89 100644
--- a/app/views/projects/merge_requests/update_branches.html.haml
+++ b/app/views/projects/merge_requests/creations/update_branches.html.haml
diff --git a/app/views/projects/merge_requests/diffs.html.haml b/app/views/projects/merge_requests/diffs.html.haml
deleted file mode 100644
index 2a5b8b1441e..00000000000
--- a/app/views/projects/merge_requests/diffs.html.haml
+++ /dev/null
@@ -1 +0,0 @@
-= render "show"
diff --git a/app/views/projects/merge_requests/show/_diffs.html.haml b/app/views/projects/merge_requests/diffs/_diffs.html.haml
index 7f0913ea516..fb31e2fef00 100644
--- a/app/views/projects/merge_requests/show/_diffs.html.haml
+++ b/app/views/projects/merge_requests/diffs/_diffs.html.haml
@@ -1,5 +1,5 @@
 - if @merge_request_diff.collected? || @merge_request_diff.overflow?
-  = render 'projects/merge_requests/show/versions'
+  = render 'projects/merge_requests/diffs/versions'
   = render "projects/diffs/diffs", diffs: @diffs, environment: @environment
 - elsif @merge_request_diff.empty?
   .nothing-here-block Nothing to merge from #{@merge_request.source_branch} into #{@merge_request.target_branch}
diff --git a/app/views/projects/merge_requests/show/_versions.html.haml b/app/views/projects/merge_requests/diffs/_versions.html.haml
index 0999b95c9c9..0999b95c9c9 100644
--- a/app/views/projects/merge_requests/show/_versions.html.haml
+++ b/app/views/projects/merge_requests/diffs/_versions.html.haml
diff --git a/app/views/projects/merge_requests/index.html.haml b/app/views/projects/merge_requests/index.html.haml
index 6d75a9f34a3..86996e488a1 100644
--- a/app/views/projects/merge_requests/index.html.haml
+++ b/app/views/projects/merge_requests/index.html.haml
@@ -22,7 +22,7 @@
           = button_tag "Edit Merge Requests", class: "btn js-bulk-update-toggle"
         - merge_project = can?(current_user, :create_merge_request, @project) ? @project : (current_user && current_user.fork_of(@project))
         - if merge_project
-          = link_to new_namespace_project_merge_request_path(merge_project.namespace, merge_project), class: "btn btn-new", title: "New merge request" do
+          = link_to namespace_project_new_merge_request_path(merge_project.namespace, merge_project), class: "btn btn-new", title: "New merge request" do
             New merge request
 
     = render 'shared/issuable/search_bar', type: :merge_requests
@@ -33,4 +33,4 @@
     .merge-requests-holder
       = render 'merge_requests'
 - else
-  = render 'shared/empty_states/merge_requests', button_path: new_namespace_project_merge_request_path(@project.namespace, @project)
+  = render 'shared/empty_states/merge_requests', button_path: namespace_project_new_merge_request_path(@project.namespace, @project)
diff --git a/app/views/projects/merge_requests/invalid.html.haml b/app/views/projects/merge_requests/invalid.html.haml
index a00d3128ffe..6df19d6438b 100644
--- a/app/views/projects/merge_requests/invalid.html.haml
+++ b/app/views/projects/merge_requests/invalid.html.haml
@@ -1,8 +1,8 @@
 - page_title "#{@merge_request.title} (#{@merge_request.to_reference}", "Merge Requests"
 
 .merge-request
-  = render "projects/merge_requests/show/mr_title"
-  = render "projects/merge_requests/show/mr_box"
+  = render "projects/merge_requests/mr_title"
+  = render "projects/merge_requests/mr_box"
 
   .alert.alert-danger
     %p
diff --git a/app/views/projects/merge_requests/show.html.haml b/app/views/projects/merge_requests/show.html.haml
index 2a5b8b1441e..dbbf1bde088 100644
--- a/app/views/projects/merge_requests/show.html.haml
+++ b/app/views/projects/merge_requests/show.html.haml
@@ -1 +1,97 @@
-= render "show"
+- @content_class = "limit-container-width" unless fluid_layout
+- page_title "#{@merge_request.title} (#{@merge_request.to_reference})", "Merge Requests"
+- page_description @merge_request.description
+- page_card_attributes @merge_request.card_attributes
+- content_for :page_specific_javascripts do
+  = page_specific_javascript_bundle_tag('common_vue')
+  = page_specific_javascript_bundle_tag('diff_notes')
+
+.merge-request{ 'data-url' => merge_request_path(@merge_request, format: :json), 'data-project-path' => project_path(@merge_request.project) }
+  = render "projects/merge_requests/mr_title"
+
+  .merge-request-details.issuable-details{ data: { id: @merge_request.project.id } }
+    = render "projects/merge_requests/mr_box"
+
+    - if @merge_request.source_branch_exists?
+      = render "projects/merge_requests/how_to_merge"
+
+    :javascript
+      window.gl.mrWidgetData = #{serialize_issuable(@merge_request)}
+
+    #js-vue-mr-widget.mr-widget
+
+    - content_for :page_specific_javascripts do
+      = webpack_bundle_tag 'common_vue'
+      = webpack_bundle_tag 'vue_merge_request_widget'
+
+    .content-block.content-block-small.emoji-list-container
+      = render 'award_emoji/awards_block', awardable: @merge_request, inline: true
+
+    .merge-request-tabs-holder{ class: ("js-tabs-affix" unless ENV['RAILS_ENV'] == 'test') }
+      .merge-request-tabs-container
+        .scrolling-tabs-container.inner-page-scroll-tabs.is-smaller
+          .fade-left= icon('angle-left')
+          .fade-right= icon('angle-right')
+          .nav-links.scrolling-tabs
+            %ul.merge-request-tabs
+              %li.notes-tab
+                = link_to namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#notes', action: 'show', toggle: 'tab' } do
+                  Discussion
+                  %span.badge= @merge_request.related_notes.user.count
+              - if @merge_request.source_project
+                %li.commits-tab
+                  = link_to commits_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#commits', action: 'commits', toggle: 'tab' } do
+                    Commits
+                    %span.badge= @commits_count
+              - if @pipelines.any?
+                %li.pipelines-tab
+                  = link_to pipelines_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: '#pipelines', action: 'pipelines', toggle: 'tab' } do
+                    Pipelines
+                    %span.badge= @pipelines.size
+              %li.diffs-tab
+                = link_to diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: { target: 'div#diffs', action: 'diffs', toggle: 'tab' } do
+                  Changes
+                  %span.badge= @merge_request.diff_size
+        #resolve-count-app.line-resolve-all-container.prepend-top-10{ "v-cloak" => true }
+          %resolve-count{ "inline-template" => true, ":logged-out" => "#{current_user.nil?}" }
+            %div
+              .line-resolve-all{ "v-show" => "discussionCount > 0",
+                ":class" => "{ 'has-next-btn': !loggedOut && resolvedDiscussionCount !== discussionCount }" }
+                %span.line-resolve-btn.is-disabled{ type: "button",
+                    ":class" => "{ 'is-active': resolvedDiscussionCount === discussionCount }" }
+                  = render "shared/icons/icon_status_success.svg"
+                %span.line-resolve-text
+                  {{ resolvedDiscussionCount }}/{{ discussionCount }} {{ resolvedCountText }} resolved
+              = render "discussions/new_issue_for_all_discussions", merge_request: @merge_request
+              = render "discussions/jump_to_next"
+
+    .tab-content#diff-notes-app
+      #notes.notes.tab-pane.voting_notes
+        .row
+          %section.col-md-12
+            .issuable-discussion
+              = render "projects/merge_requests/discussion"
+
+      #commits.commits.tab-pane
+        -# This tab is always loaded via AJAX
+      #pipelines.pipelines.tab-pane
+        - if @pipelines.any?
+          = render 'projects/commit/pipelines_list', disable_initialization: true, endpoint: pipelines_namespace_project_merge_request_path(@project.namespace, @project, @merge_request)
+      #diffs.diffs.tab-pane
+        -# This tab is always loaded via AJAX
+
+    .mr-loading-status
+      = spinner
+
+= render 'shared/issuable/sidebar', issuable: @merge_request
+- if @merge_request.can_be_reverted?(current_user)
+  = render "projects/commit/change", type: 'revert', commit: @merge_request.merge_commit, title: @merge_request.title
+- if @merge_request.can_be_cherry_picked?
+  = render "projects/commit/change", type: 'cherry-pick', commit: @merge_request.merge_commit, title: @merge_request.title
+
+:javascript
+  $(function () {
+    window.mergeRequest = new MergeRequest({
+      action: "#{j params[:tab].presence || 'show'}",
+    });
+  });
diff --git a/app/workers/expire_pipeline_cache_worker.rb b/app/workers/expire_pipeline_cache_worker.rb
index d760f5b140f..92e622285de 100644
--- a/app/workers/expire_pipeline_cache_worker.rb
+++ b/app/workers/expire_pipeline_cache_worker.rb
@@ -46,7 +46,7 @@ class ExpirePipelineCacheWorker
   end
 
   def new_merge_request_pipelines_path(project)
-    Gitlab::Routing.url_helpers.new_namespace_project_merge_request_path(
+    Gitlab::Routing.url_helpers.namespace_project_new_merge_request_path(
       project.namespace,
       project,
       format: :json)