Merge branch 'new-diff-notes' into 'master'

New diff notes

Fixes #12732, #14731, #19375, #14783 

Builds on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4110

To do:
- [x] Get it mostly working
- [x] Validate position validity
- [x] Fix: Don’t link to `#`
- [x] Fix: Base ref can be `nil`, potentially, when the MR has an oprhan source branch => Yep, doesn’t work. We need to store a `start_id`
- [x] Optimize: Fewer duplicate `git diff` compares
- [x] Optimize: Pass paths to `PositionTracer#diff` for faster diffs
- [x] Refactor: Use `head_id` in `MergeRequest`/`MergeRequestDiff` instead of `source_sha`
- [x] Refactor: Convert existing array-based diff refs to the DiffRefs model
- [x] Tweak: Use `note_type` in `Autosave` key
- [x] Tweak: Remove `line_code: note.line_code` from `link_to_reply_discussion`
- [x] Update: `SentNotifications` and reply-by-email receiver
- [x] Update: MR diff notification email
- [x] Update: API (MR, Commit note creation and entity)
- [x] Update: GitHub importer
- [x] Address any other TODO comments
- [x] Fix: Suppress "edited 4 minutes ago"
- [x] Write tests
  - [x] `LineMapper`
  - [x] `PositionTracer`
  - [x] `Position`
  - [x] `DiffPositionUpdateService`
  - [x] `DiffNote`
  - [x] `MergeRequests::RefreshService` / `MergeRequest#update_diff_notes_positions`
- [x] Make sure commits with diff notes don't get cleaned up, since this would prevent the diff notes from being rendered (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5062)

Future improvements:
- Display unresolved comments on files outside the diff, if the comment was added when that file _was_ part of the diff
- Allow commenting on sections between hunks, when expanding the diff using `...`
  - (We'd need to generate line code based on Position if we have it, even if it falls outside bounds of diff)
- `diff_hunk` on diff note API entity
- Show diff hunk in notification email
- Resolved line notes would have a boolean, and be inactive through `notes.any? { !active? || resolved? }`
- Multi line notes would store a number of positions, and do the right thing (™) in grouping and then rendering if the first item is multiline? => true
- Image diff notes could store x,y,width,height instead of old_line,new_line for similar grouping. Does it need a reference to say if it's on old or new? These can't have line_codes, clearly. Rendering would be interesting.
- Show commit line comments in the MR diff
- Comment on specific selected words
- Comment on file header
- Unfold top of discussion diff note
- New diff notes API for commits and MRs

/cc @rspeicher

See merge request !4101

16 files changed, 96 insertions, 107 deletions

diff --git a/app/views/projects/commit/show.html.haml b/app/views/projects/commit/show.html.haml
index 401cb4f7e30..d0da2606587 100644
--- a/app/views/projects/commit/show.html.haml
+++ b/app/views/projects/commit/show.html.haml
@@ -7,8 +7,7 @@
   = render "ci_menu"
 - else
   %div.block-connector
-= render "projects/diffs/diffs", diffs: @diffs, project: @project,
-         diff_refs: @diff_refs
+= render "projects/diffs/diffs", diffs: @diffs, project: @project, diff_refs: @commit.diff_refs
 = render "projects/notes/notes_with_form"
 - if can_collaborate_with_project?
   - %w(revert cherry-pick).each do |type|
diff --git a/app/views/projects/diffs/_diffs.html.haml b/app/views/projects/diffs/_diffs.html.haml
index f18bc8c41b3..1975287faee 100644
--- a/app/views/projects/diffs/_diffs.html.haml
+++ b/app/views/projects/diffs/_diffs.html.haml
@@ -2,7 +2,7 @@
 - if diff_view == 'parallel'
   - fluid_layout true
 
-- diff_files = safe_diff_files(diffs, diff_refs)
+- diff_files = safe_diff_files(diffs, diff_refs: diff_refs, repository: project.repository)
 
 .content-block.oneline-block.files-changed
   .inline-parallel-buttons
@@ -24,7 +24,7 @@
 .files
   - diff_files.each_with_index do |diff_file, index|
     - diff_commit = commit_for_diff(diff_file)
-    - blob = project.repository.blob_for_diff(diff_commit, diff_file)
+    - blob = diff_file.blob(diff_commit)
     - next unless blob
     - blob.load_all_data!(project.repository) unless blob.only_display_raw?
 
diff --git a/app/views/projects/diffs/_file.html.haml b/app/views/projects/diffs/_file.html.haml
index 2395ea3c275..3b758a1ec4e 100644
--- a/app/views/projects/diffs/_file.html.haml
+++ b/app/views/projects/diffs/_file.html.haml
@@ -1,29 +1,8 @@
-.diff-file.file-holder{id: "diff-#{i}", data: diff_file_html_data(project, diff_commit, diff_file)}
+.diff-file.file-holder{id: "diff-#{i}", data: diff_file_html_data(project, diff_file)}
   .file-title{id: "file-path-#{hexdigest(diff_file.file_path)}"}
-    - if diff_file.diff.submodule?
-      %span
-        = icon('archive fw')
-        %span
-          = submodule_link(blob, @commit.id, project.repository)
-    - else
-      = blob_icon blob.mode, blob.name
-
-      = link_to "#diff-#{i}" do
-        - if diff_file.renamed_file
-          - old_path, new_path = mark_inline_diffs(diff_file.old_path, diff_file.new_path)
-          = old_path
-          →
-          = new_path
-        - else
-          %span
-            = diff_file.new_path
-          - if diff_file.deleted_file
-            deleted
-
-      - if diff_file.mode_changed?
-        %small
-          = "#{diff_file.diff.a_mode} → #{diff_file.diff.b_mode}"
+    = render "projects/diffs/file_header", diff_file: diff_file, blob: blob, diff_commit: diff_commit, project: project, url: "#diff-#{i}"
 
+    - unless diff_file.submodule?
       .file-actions.hidden-xs
         - if blob_text_viewable?(blob)
           = link_to '#', class: 'js-toggle-diff-comments btn active has-tooltip btn-file-option', title: "Toggle comments for this file" do
@@ -42,17 +21,23 @@
     - return unless blob.respond_to?(:text?)
     - if diff_file.too_large?
       .nothing-here-block This diff could not be displayed because it is too large.
-    - elsif blob_text_viewable?(blob) && !project.repository.diffable?(blob)
-      .nothing-here-block This diff was suppressed by a .gitattributes entry.
-    - elsif blob_text_viewable?(blob)
-      - if diff_view == 'parallel'
-        = render "projects/diffs/parallel_view", diff_file: diff_file, project: project, blob: blob, index: i
-      - else
-        = render "projects/diffs/text_file", diff_file: diff_file, index: i
     - elsif blob.only_display_raw?
       .nothing-here-block This file is too large to display.
+    - elsif blob_text_viewable?(blob)
+      - if !project.repository.diffable?(blob)
+        .nothing-here-block This diff was suppressed by a .gitattributes entry.
+      - elsif diff_file.diff_lines.length > 0
+        - if diff_view == 'parallel'
+          = render "projects/diffs/parallel_view", diff_file: diff_file, project: project, blob: blob, index: i
+        - else
+          = render "projects/diffs/text_file", diff_file: diff_file, index: i
+      - else
+        - if diff_file.mode_changed?
+          .nothing-here-block File mode changed
+        - elsif diff_file.renamed_file
+          .nothing-here-block File moved
     - elsif blob.image?
-      - old_file = project.repository.prev_blob_for_diff(diff_commit, diff_file)
-      = render "projects/diffs/image", diff_file: diff_file, old_file: old_file, file: blob, index: i, diff_refs: diff_refs
+      - old_blob = diff_file.old_blob(diff_commit)
+      = render "projects/diffs/image", diff_file: diff_file, old_file: old_blob, file: blob, index: i
     - else
       .nothing-here-block No preview for this file type
diff --git a/app/views/projects/diffs/_file_header.html.haml b/app/views/projects/diffs/_file_header.html.haml
new file mode 100644
index 00000000000..95a2772fd0b
--- /dev/null
+++ b/app/views/projects/diffs/_file_header.html.haml
@@ -0,0 +1,25 @@
+- if defined?(blob) && blob && diff_file.submodule?
+  %span
+    = icon('archive fw')
+    %span
+      = submodule_link(blob, diff_commit.id, project.repository)
+- else
+  = conditional_link_to url.present?, url do
+    = blob_icon diff_file.b_mode, diff_file.file_path
+
+    - if diff_file.renamed_file
+      - old_path, new_path = mark_inline_diffs(diff_file.old_path, diff_file.new_path)
+      %strong
+        = old_path
+      →
+      %strong
+        = new_path
+    - else
+      %strong
+        = diff_file.new_path
+      - if diff_file.deleted_file
+        deleted
+
+  - if diff_file.mode_changed?
+    %small
+      = "#{diff_file.a_mode} → #{diff_file.b_mode}"
diff --git a/app/views/projects/diffs/_image.html.haml b/app/views/projects/diffs/_image.html.haml
index 2731219ccad..9ec6a7aa5cd 100644
--- a/app/views/projects/diffs/_image.html.haml
+++ b/app/views/projects/diffs/_image.html.haml
@@ -1,9 +1,8 @@
 - diff = diff_file.diff
-- file_raw_path = namespace_project_raw_path(@project.namespace, @project, tree_join(@commit.id, diff.new_path))
+- file_raw_path = namespace_project_raw_path(@project.namespace, @project, tree_join(diff_file.new_ref, diff.new_path))
 // diff_refs will be nil for orphaned commits (e.g. first commit in repo)
-- if diff_refs
-  - old_commit_id = diff_refs.first.id
-  - old_file_raw_path = namespace_project_raw_path(@project.namespace, @project, tree_join(old_commit_id, diff.old_path))
+- if diff_file.old_ref
+  - old_file_raw_path = namespace_project_raw_path(@project.namespace, @project, tree_join(diff_file.old_ref, diff.old_path))
 
 - if diff.renamed_file || diff.new_file || diff.deleted_file
   .image
@@ -16,7 +15,7 @@
     %div.two-up.view
       %span.wrap
         .frame.deleted
-          %a{href: namespace_project_blob_path(@project.namespace, @project, tree_join(old_commit_id, diff.old_path))}
+          %a{href: namespace_project_blob_path(@project.namespace, @project, tree_join(diff_file.old_ref, diff.old_path))}
             %img{src: old_file_raw_path}
         %p.image-info.hide
           %span.meta-filesize= "#{number_to_human_size old_file.size}"
@@ -28,7 +27,7 @@
           %span.meta-height
       %span.wrap
         .frame.added
-          %a{href: namespace_project_blob_path(@project.namespace, @project, tree_join(@commit.id, diff.new_path))}
+          %a{href: namespace_project_blob_path(@project.namespace, @project, tree_join(diff_file.new_ref, diff.new_path))}
             %img{src: file_raw_path}
         %p.image-info.hide
           %span.meta-filesize= "#{number_to_human_size file.size}"
diff --git a/app/views/projects/diffs/_line.html.haml b/app/views/projects/diffs/_line.html.haml
index f1577e8a47b..22cad00240a 100644
--- a/app/views/projects/diffs/_line.html.haml
+++ b/app/views/projects/diffs/_line.html.haml
@@ -1,3 +1,6 @@
+- plain = local_assigns.fetch(:plain, false)
+- line_code = diff_file.line_code(line)
+- position = diff_file.position(line)
 - type = line.type
 %tr.line_holder{ id: line_code, class: type }
   - case type
@@ -9,18 +12,19 @@
     %td.new_line.diff-line-num
     %td.line_content.match= line.text
   - else
-    %td.old_line.diff-line-num{ class: type, data: { linenumber: line.new_pos } }
+    %td.old_line.diff-line-num{ class: type, data: { linenumber: line.old_pos } }
       - link_text = type == "new" ? " ".html_safe : line.old_pos
-      - if defined?(plain) && plain
+      - if plain
         = link_text
       - else
         = link_to "", "##{line_code}", id: line_code, data: { linenumber: link_text }
-      - if !@diff_notes_disabled && can?(current_user, :create_note, @project)
-        = link_to_new_diff_note(line_code)
+
+      - if !plain && !@diff_notes_disabled && can?(current_user, :create_note, @project)
+        = link_to_new_diff_note(line_code, position)
     %td.new_line.diff-line-num{ class: type, data: { linenumber: line.new_pos } }
       - link_text = type == "old" ? " ".html_safe : line.new_pos
-      - if defined?(plain) && plain
+      - if plain
         = link_text
       - else
         = link_to "", "##{line_code}", id: line_code, data: { linenumber: link_text }
-    %td.line_content{ class: ['noteable_line', type, line_code], data: { line_code: line_code } }= diff_line_content(line.text, type)
+    %td.line_content.noteable_line{ class: [type, line_code], data: { line_code: line_code, position: position.to_json } }= diff_line_content(line.text, type)
diff --git a/app/views/projects/diffs/_parallel_view.html.haml b/app/views/projects/diffs/_parallel_view.html.haml
index 4ecc9528bd2..51f207dce94 100644
--- a/app/views/projects/diffs/_parallel_view.html.haml
+++ b/app/views/projects/diffs/_parallel_view.html.haml
@@ -14,30 +14,28 @@
           %td.new_line.diff-line-num
           %td.line_content.parallel.match= left[:text]
         - else
-          %td.old_line.diff-line-num{id: left[:line_code], class: "#{left[:type]} #{'empty-cell' if !left[:number]}"}
+          %td.old_line.diff-line-num{id: left[:line_code], class: [left[:type], ('empty-cell' unless left[:number])]}
             = link_to raw(left[:number]), "##{left[:line_code]}", id: left[:line_code]
             - if !@diff_notes_disabled && can?(current_user, :create_note, @project)
-              = link_to_new_diff_note(left[:line_code], 'old')
-          %td.line_content{class: "parallel noteable_line #{left[:type]} #{left[:line_code]} #{'empty-cell' if left[:text].empty?}", data: { line_code: left[:line_code] }}= diff_line_content(left[:text])
+              = link_to_new_diff_note(left[:line_code], left[:position], 'old')
+          %td.line_content.parallel.noteable_line{class: [left[:type], left[:line_code], ('empty-cell' if left[:text].empty?)], data: { line_code: left[:line_code], position: left[:position].to_json }}= diff_line_content(left[:text])
 
           - if right[:type] == 'new'
             - new_line_class = 'new'
             - new_line_code = right[:line_code]
+            - new_position = right[:position]
           - else
             - new_line_class = nil
             - new_line_code = left[:line_code]
+            - new_position = left[:position]
 
-          %td.new_line.diff-line-num{id: new_line_code, class: "#{new_line_class} #{'empty-cell' if !right[:number]}", data: { linenumber: right[:number] }}
+          %td.new_line.diff-line-num{id: new_line_code, class: [new_line_class, ('empty-cell' unless right[:number])], data: { linenumber: right[:number] }}
             = link_to raw(right[:number]), "##{new_line_code}", id: new_line_code
             - if !@diff_notes_disabled && can?(current_user, :create_note, @project)
-              = link_to_new_diff_note(new_line_code, 'new')
-          %td.line_content.parallel{class: "noteable_line #{new_line_class} #{new_line_code} #{'empty-cell' if right[:text].empty?}", data: { line_code: new_line_code }}= diff_line_content(right[:text])
+              = link_to_new_diff_note(new_line_code, new_position, 'new')
+          %td.line_content.parallel.noteable_line{class: [new_line_class, new_line_code, ('empty-cell' if right[:text].empty?)], data: { line_code: new_line_code, position: new_position.to_json }}= diff_line_content(right[:text])
 
       - unless @diff_notes_disabled
         - notes_left, notes_right = organize_comments(left, right)
         - if notes_left.present? || notes_right.present?
           = render "projects/notes/diff_notes_with_reply_parallel", notes_left: notes_left, notes_right: notes_right
-
-- if diff_file.diff.diff.blank? && diff_file.mode_changed?
-  .file-mode-changed
-    File mode changed
diff --git a/app/views/projects/diffs/_text_file.html.haml b/app/views/projects/diffs/_text_file.html.haml
index 068593a7dd1..192093d1273 100644
--- a/app/views/projects/diffs/_text_file.html.haml
+++ b/app/views/projects/diffs/_text_file.html.haml
@@ -4,22 +4,17 @@
     %a.show-suppressed-diff.js-show-suppressed-diff Changes suppressed. Click to show.
 
 %table.text-file.code.js-syntax-highlight{ class: too_big ? 'hide' : '' }
-
   - last_line = 0
-  - diff_file.highlighted_diff_lines.each_with_index do |line, index|
-    - line_code = generate_line_code(diff_file.file_path, line)
+  - diff_file.highlighted_diff_lines.each do |line|
     - last_line = line.new_pos
-    = render "projects/diffs/line", {line: line, diff_file: diff_file, line_code: line_code}
+    = render "projects/diffs/line", line: line, diff_file: diff_file
 
     - unless @diff_notes_disabled
-      - diff_notes = @grouped_diff_notes[line_code]
+      - line_code = diff_file.line_code(line)
+      - diff_notes = @grouped_diff_notes[line_code] if line_code
       - if diff_notes
         = render "projects/notes/diff_notes_with_reply", notes: diff_notes
 
   - if last_line > 0
     = render "projects/diffs/match_line", { line: "",
       line_old: last_line, line_new: last_line, bottom: true, new_file: diff_file.new_file }
-
-- if diff_file.diff.blank? && diff_file.mode_changed?
-  .file-mode-changed
-    File mode changed
diff --git a/app/views/projects/merge_requests/widget/_heading.html.haml b/app/views/projects/merge_requests/widget/_heading.html.haml
index 08a38d283d2..489c632ae22 100644
--- a/app/views/projects/merge_requests/widget/_heading.html.haml
+++ b/app/views/projects/merge_requests/widget/_heading.html.haml
@@ -7,7 +7,7 @@
           CI build
           = ci_label_for_status(status)
         for
-        - commit = @merge_request.last_commit
+        - commit = @merge_request.diff_head_commit
         = succeed "." do
           = link_to @pipeline.short_sha, namespace_project_commit_path(@merge_request.source_project.namespace, @merge_request.source_project, @pipeline.sha), class: "monospace"
         %span.ci-coverage
@@ -24,7 +24,7 @@
           CI build
           = ci_label_for_status(status)
         for
-        - commit = @merge_request.last_commit
+        - commit = @merge_request.diff_head_commit
         = succeed "." do
           = link_to commit.short_id, namespace_project_commit_path(@merge_request.source_project.namespace, @merge_request.source_project, commit), class: "monospace"
         %span.ci-coverage
@@ -33,12 +33,12 @@
 
     .ci_widget
       = icon("spinner spin")
-      Checking CI status for #{@merge_request.last_commit_short_sha}…
+      Checking CI status for #{@merge_request.diff_head_commit.short_id}…
 
     .ci_widget.ci-not_found{style: "display:none"}
       = icon("times-circle")
-      Could not find CI status for #{@merge_request.last_commit_short_sha}.
+      Could not find CI status for #{@merge_request.diff_head_commit.short_id}.
 
     .ci_widget.ci-error{style: "display:none"}
       = icon("times-circle")
-      Could not connect to the CI server. Please check your settings and try again.
\ No newline at end of file
+      Could not connect to the CI server. Please check your settings and try again.
diff --git a/app/views/projects/merge_requests/widget/open/_accept.html.haml b/app/views/projects/merge_requests/widget/open/_accept.html.haml
index 941513febbd..bf2e76f0083 100644
--- a/app/views/projects/merge_requests/widget/open/_accept.html.haml
+++ b/app/views/projects/merge_requests/widget/open/_accept.html.haml
@@ -2,7 +2,7 @@
 
 = form_for [:merge, @project.namespace.becomes(Namespace), @project, @merge_request], remote: true, method: :post, html: { class: 'accept-mr-form js-quick-submit js-requires-input' } do |f|
   = hidden_field_tag :authenticity_token, form_authenticity_token
-  = hidden_field_tag :sha, @merge_request.source_sha
+  = hidden_field_tag :sha, @merge_request.diff_head_sha
   .accept-merge-holder.clearfix.js-toggle-container
     .clearfix
       .accept-action
diff --git a/app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml b/app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml
index ad898ff153b..2b6b5e05e86 100644
--- a/app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml
+++ b/app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml
@@ -16,7 +16,7 @@
   - if remove_source_branch_button || user_can_cancel_automatic_merge
     .clearfix.prepend-top-10
       - if remove_source_branch_button
-        = link_to merge_namespace_project_merge_request_path(@merge_request.target_project.namespace, @merge_request.target_project, @merge_request, merge_when_build_succeeds: true, should_remove_source_branch: true, sha: @merge_request.source_sha), remote: true, method: :post, class: "btn btn-grouped btn-primary btn-sm remove_source_branch" do
+        = link_to merge_namespace_project_merge_request_path(@merge_request.target_project.namespace, @merge_request.target_project, @merge_request, merge_when_build_succeeds: true, should_remove_source_branch: true, sha: @merge_request.diff_head_sha), remote: true, method: :post, class: "btn btn-grouped btn-primary btn-sm remove_source_branch" do
           = icon('times')
           Remove Source Branch When Merged
 
diff --git a/app/views/projects/notes/_diff_notes_with_reply.html.haml b/app/views/projects/notes/_diff_notes_with_reply.html.haml
index 8144c1ba49e..ec6c4938efc 100644
--- a/app/views/projects/notes/_diff_notes_with_reply.html.haml
+++ b/app/views/projects/notes/_diff_notes_with_reply.html.haml
@@ -4,5 +4,4 @@
   %td.notes_content
     %ul.notes{ data: { discussion_id: note.discussion_id } }
       = render partial: "projects/notes/note", collection: notes, as: :note
-    .discussion-reply-holder
-      = link_to_reply_discussion(note)
+    = link_to_reply_discussion(note)
diff --git a/app/views/projects/notes/_diff_notes_with_reply_parallel.html.haml b/app/views/projects/notes/_diff_notes_with_reply_parallel.html.haml
index 45986b0d1e8..e50a4f86d03 100644
--- a/app/views/projects/notes/_diff_notes_with_reply_parallel.html.haml
+++ b/app/views/projects/notes/_diff_notes_with_reply_parallel.html.haml
@@ -8,8 +8,7 @@
       %ul.notes{ data: { discussion_id: note_left.discussion_id } }
         = render partial: "projects/notes/note", collection: notes_left, as: :note
 
-      .discussion-reply-holder
-        = link_to_reply_discussion(note_left, 'old')
+      = link_to_reply_discussion(note_left, 'old')
   - else
     %td.notes_line.old= ""
     %td.notes_content.parallel.old= ""
@@ -20,8 +19,7 @@
       %ul.notes{ data: { discussion_id: note_right.discussion_id } }
         = render partial: "projects/notes/note", collection: notes_right, as: :note
 
-      .discussion-reply-holder
-        = link_to_reply_discussion(note_right, 'new')
+      = link_to_reply_discussion(note_right, 'new')
   - else
     %td.notes_line.new= ""
     %td.notes_content.parallel.new= ""
diff --git a/app/views/projects/notes/_form.html.haml b/app/views/projects/notes/_form.html.haml
index 03b3f6935d1..7c61ba750fe 100644
--- a/app/views/projects/notes/_form.html.haml
+++ b/app/views/projects/notes/_form.html.haml
@@ -7,6 +7,7 @@
   = f.hidden_field :noteable_id
   = f.hidden_field :noteable_type
   = f.hidden_field :type
+  = f.hidden_field :position
 
   = render layout: 'projects/md_preview', locals: { preview_class: "md-preview", referenced_users: true } do
     = render 'projects/zen', f: f, attr: :note, classes: 'note-textarea js-note-text', placeholder: "Write a comment or drag your files here..."
diff --git a/app/views/projects/notes/discussions/_diff_with_notes.html.haml b/app/views/projects/notes/discussions/_diff_with_notes.html.haml
index 6401245bf73..4a69b8f8840 100644
--- a/app/views/projects/notes/discussions/_diff_with_notes.html.haml
+++ b/app/views/projects/notes/discussions/_diff_with_notes.html.haml
@@ -1,30 +1,17 @@
 - note = discussion_notes.first
-- diff = note.diff
-- return unless diff
+- diff_file = note.diff_file
+- return unless diff_file
+
+- blob = note.blob
+
+.diff-file.file-holder
+  .file-title
+    = render "projects/diffs/file_header", diff_file: diff_file, blob: blob, diff_commit: diff_file.content_commit, project: note.project, url: diff_note_path(note)
 
-.diff-file
-  .diff-header
-    %span
-      - if diff.deleted_file
-        = diff.old_path
-      - else
-        = diff.new_path
-        - if diff.a_mode && diff.b_mode && diff.a_mode != diff.b_mode
-          %span.file-mode= "#{diff.a_mode} → #{diff.b_mode}"
   .diff-content.code.js-syntax-highlight
     %table
       - note.truncated_diff_lines.each do |line|
-        - type = line.type
-        - line_code = generate_line_code(note.diff_file_path, line)
-        %tr.line_holder{ id: line_code, class: "#{type}" }
-          - if type == "match"
-            %td.old_line.diff-line-num= "..."
-            %td.new_line.diff-line-num= "..."
-            %td.line_content.match= line.text
-          - else
-            %td.old_line.diff-line-num{ data: { linenumber: type == "new" ? " ".html_safe : line.old_pos } }
-            %td.new_line.diff-line-num{ data: { linenumber: type == "old" ? " ".html_safe : line.new_pos } }
-            %td.line_content{ class: ['noteable_line', type, line_code], line_code: line_code }= diff_line_content(line.text, type)
+        = render "projects/diffs/line", line: line, diff_file: diff_file, plain: true
 
-            - if line_code == note.line_code
-              = render "projects/notes/diff_notes_with_reply", notes: discussion_notes
+        - if note.for_line?(line)
+          = render "projects/notes/diff_notes_with_reply", notes: discussion_notes
diff --git a/app/views/projects/notes/discussions/_notes.html.haml b/app/views/projects/notes/discussions/_notes.html.haml
index e598e3c7c63..a785149549d 100644
--- a/app/views/projects/notes/discussions/_notes.html.haml
+++ b/app/views/projects/notes/discussions/_notes.html.haml
@@ -3,5 +3,4 @@
   .notes{ data: { discussion_id: note.discussion_id } }
     %ul.notes.timeline
       = render partial: "projects/notes/note", collection: discussion_notes, as: :note
-  .discussion-reply-holder
-    = link_to_reply_discussion(note)
+  = link_to_reply_discussion(note)