Merge branch 'refactor-diff-yeild' into 'parallel_diff_refactor'

Refactor diffs

This refactoring done on top of Marin improvements to side-by-side diff.
Main target of this refactoring is to reduce mess and increase test coverage.

1. Use objects:
  * Gitlab::Diff::Line for line change in diff
  * Gitlab::Diff::File for file changes (diff + blob info)
2. Avoid `yield` magic
3. Move logic from views/helper to models/libs
4. Move diff views under separate dir `app/views/projects/diffs`

See merge request !1072

22 files changed, 206 insertions, 204 deletions

diff --git a/app/controllers/projects/edit_tree_controller.rb b/app/controllers/projects/edit_tree_controller.rb
index ca83b21f429..72a41f771c0 100644
--- a/app/controllers/projects/edit_tree_controller.rb
+++ b/app/controllers/projects/edit_tree_controller.rb
@@ -31,7 +31,7 @@ class Projects::EditTreeController < Projects::BaseTreeController
 
     diffy = Diffy::Diff.new(@blob.data, @content, diff: '-U 3',
                             include_diff_info: true)
-    @diff = Gitlab::DiffParser.new(diffy.diff.scan(/.*\n/))
+    @diff_lines = Gitlab::Diff::Parser.new.parse(diffy.diff.scan(/.*\n/))
 
     render layout: false
   end
diff --git a/app/helpers/commits_helper.rb b/app/helpers/commits_helper.rb
index 7d5b9c3238f..90829963e84 100644
--- a/app/helpers/commits_helper.rb
+++ b/app/helpers/commits_helper.rb
@@ -16,87 +16,6 @@ module CommitsHelper
     commit_person_link(commit, options.merge(source: :committer))
   end
 
-  def each_diff_line(diff, index)
-    Gitlab::DiffParser.new(diff.diff.lines.to_a, diff.new_path)
-      .each do |full_line, type, line_code, line_new, line_old|
-        yield(full_line, type, line_code, line_new, line_old)
-      end
-  end
-
-  def parallel_diff_line(diff, index)
-    Gitlab::DiffParser.new(diff.diff.lines.to_a, diff.new_path)
-      .each do |full_line, type, line_code, line_new, line_old, raw_line, next_type, next_line|
-        yield(full_line, type, line_code, line_new, line_old, raw_line, next_type, next_line)
-      end
-  end
-
-  def parallel_diff(diff, index)
-    lines = []
-    skip_next = false
-
-    # Building array of lines
-    #
-    # [left_type, left_line_number, left_line_content, right_line_type, right_line_number, right_line_content]
-    #
-    parallel_diff_line(diff, index) do |full_line, type, line_code, line_new, line_old, raw_line, next_type, next_line|
-      line = [type, line_old, full_line, next_type, line_new]
-      if type == 'match' || type.nil?
-        # line in the right panel is the same as in the left one
-        line = [type, line_old, full_line, type, line_new, full_line]
-        lines.push(line)
-      elsif type == 'old'
-        if next_type == 'new'
-          # Left side has text removed, right side has text added
-          line.push(next_line)
-          lines.push(line)
-          skip_next = true
-        elsif next_type == 'old' || next_type.nil?
-          # Left side has text removed, right side doesn't have any change
-          line.pop # remove the newline
-          line.push(nil) # no line number on the right panel
-          line.push("&nbsp;") # empty line on the right panel
-          lines.push(line)
-        end
-      elsif type == 'new'
-        if skip_next
-          # Change has been already included in previous line so no need to do it again
-          skip_next = false
-          next
-        else
-          # Change is only on the right side, left side has no change
-          line = [nil, nil, "&nbsp;", type, line_new, full_line]
-          lines.push(line)
-        end
-      end
-    end
-    lines
-  end
-
-  def each_diff_line_near(diff, index, expected_line_code)
-    max_number_of_lines = 16
-
-    prev_match_line = nil
-    prev_lines = []
-
-    each_diff_line(diff, index) do |full_line, type, line_code, line_new, line_old|
-      line = [full_line, type, line_code, line_new, line_old]
-      if line_code != expected_line_code
-        if type == "match"
-          prev_lines.clear
-          prev_match_line = line
-        else
-          prev_lines.push(line)
-          prev_lines.shift if prev_lines.length >= max_number_of_lines
-        end
-      else
-        yield(prev_match_line) if !prev_match_line.nil?
-        prev_lines.each { |ln| yield(ln) }
-        yield(line)
-        break
-      end
-    end
-  end
-
   def image_diff_class(diff)
     if diff.deleted_file
       "deleted"
@@ -202,10 +121,6 @@ module CommitsHelper
     end
   end
 
-  def diff_file_mode_changed?(diff)
-    diff.a_mode && diff.b_mode && diff.a_mode != diff.b_mode
-  end
-
   def unfold_bottom_class(bottom)
     (bottom) ? 'js-unfold-bottom' : ''
   end
diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index ee4d4fbdff5..6307790d4e7 100644
--- a/app/helpers/diff_helper.rb
+++ b/app/helpers/diff_helper.rb
@@ -1,14 +1,20 @@
 module DiffHelper
-  def safe_diff_files(diffs)
+  def allowed_diff_size
     if diff_hard_limit_enabled?
-      diffs.first(Commit::DIFF_HARD_LIMIT_FILES)
+      Commit::DIFF_HARD_LIMIT_FILES
     else
-      diffs.first(Commit::DIFF_SAFE_FILES)
+      Commit::DIFF_SAFE_FILES
+    end
+  end
+
+  def safe_diff_files(diffs)
+    diffs.first(allowed_diff_size).map do |diff|
+      Gitlab::Diff::File.new(diff)
     end
   end
 
   def show_diff_size_warninig?(diffs)
-    safe_diff_files(diffs).size < diffs.size
+    diffs.size > allowed_diff_size
   end
 
   def diff_hard_limit_enabled?
@@ -19,4 +25,65 @@ module DiffHelper
       false
     end
   end
+
+  def generate_line_code(file_path, line)
+    Gitlab::Diff::LineCode.generate(file_path, line.new_pos, line.old_pos)
+  end
+
+  def parallel_diff(diff_file, index)
+    lines = []
+    skip_next = false
+
+    # Building array of lines
+    #
+    # [left_type, left_line_number, left_line_content, right_line_type, right_line_number, right_line_content]
+    #
+    diff_file.diff_lines.each do |line|
+
+      full_line = line.text
+      type = line.type
+      line_code = generate_line_code(diff_file.file_path, line)
+      line_new = line.new_pos
+      line_old = line.old_pos
+
+      next_line = diff_file.next_line(line.index)
+
+      if next_line
+        next_type = next_line.type
+        next_line = next_line.text
+      end
+
+      line = [type, line_old, full_line, next_type, line_new]
+      if type == 'match' || type.nil?
+        # line in the right panel is the same as in the left one
+        line = [type, line_old, full_line, type, line_new, full_line]
+        lines.push(line)
+      elsif type == 'old'
+        if next_type == 'new'
+          # Left side has text removed, right side has text added
+          line.push(next_line)
+          lines.push(line)
+          skip_next = true
+        elsif next_type == 'old' || next_type.nil?
+          # Left side has text removed, right side doesn't have any change
+          line.pop # remove the newline
+          line.push(nil) # no line number on the right panel
+          line.push("&nbsp;") # empty line on the right panel
+          lines.push(line)
+        end
+      elsif type == 'new'
+        if skip_next
+          # Change has been already included in previous line so no need to do it again
+          skip_next = false
+          next
+        else
+          # Change is only on the right side, left side has no change
+          line = [nil, nil, "&nbsp;", type, line_new, full_line]
+          lines.push(line)
+        end
+      end
+    end
+    lines
+  end
+
 end
diff --git a/app/models/note.rb b/app/models/note.rb
index 7cbab1130ea..fa5fdea4eb0 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -209,9 +209,10 @@ class Note < ActiveRecord::Base
     noteable.diffs.each do |mr_diff|
       next unless mr_diff.new_path == self.diff.new_path
 
-      Gitlab::DiffParser.new(mr_diff.diff.lines.to_a, mr_diff.new_path).
-        each do |full_line, type, line_code, line_new, line_old|
-        if full_line == diff_line
+      lines = Gitlab::Diff::Parser.new.parse(mr_diff.diff.lines.to_a)
+
+      lines.each do |line|
+        if line.text == diff_line
           return true
         end
       end
@@ -232,6 +233,14 @@ class Note < ActiveRecord::Base
     diff.new_path if diff
   end
 
+  def file_path
+    if diff.new_path.present?
+      diff.new_path
+    elsif diff.old_path.present?
+      diff.old_path
+    end
+  end
+
   def diff_old_line
     line_code.split('_')[1].to_i
   end
@@ -240,19 +249,49 @@ class Note < ActiveRecord::Base
     line_code.split('_')[2].to_i
   end
 
+  def generate_line_code(line)
+    Gitlab::Diff::LineCode.generate(file_path, line.new_pos, line.old_pos)
+  end
+
   def diff_line
     return @diff_line if @diff_line
 
     if diff
-      Gitlab::DiffParser.new(diff.diff.lines.to_a, diff.new_path)
-        .each do |full_line, type, line_code, line_new, line_old|
-          @diff_line = full_line if line_code == self.line_code
+      diff_lines.each do |line|
+        if generate_line_code(line) == self.line_code
+          @diff_line = line.text
         end
+      end
     end
 
     @diff_line
   end
 
+  def truncated_diff_lines
+    max_number_of_lines = 16
+    prev_match_line = nil
+    prev_lines = []
+
+    diff_lines.each do |line|
+      if generate_line_code(line) != self.line_code
+        if line.type == "match"
+          prev_lines.clear
+          prev_match_line = line
+        else
+          prev_lines.push(line)
+          prev_lines.shift if prev_lines.length >= max_number_of_lines
+        end
+      else
+        prev_lines << line
+        return prev_lines
+      end
+    end
+  end
+
+  def diff_lines
+    @diff_lines ||= Gitlab::Diff::Parser.new.parse(diff.diff.lines.to_a)
+  end
+
   def discussion_id
     @discussion_id ||= Note.build_discussion_id(noteable_type, noteable_id || commit_id, line_code)
   end
diff --git a/app/views/projects/commit/show.html.haml b/app/views/projects/commit/show.html.haml
index 0a15aef6cb7..fc721067ed4 100644
--- a/app/views/projects/commit/show.html.haml
+++ b/app/views/projects/commit/show.html.haml
@@ -1,3 +1,3 @@
 = render "commit_box"
-= render "projects/commits/diffs", diffs: @diffs, project: @project
+= render "projects/diffs/diffs", diffs: @diffs, project: @project
 = render "projects/notes/notes_with_form"
diff --git a/app/views/projects/commits/_diff_file.html.haml b/app/views/projects/commits/_diff_file.html.haml
deleted file mode 100644
index 31208a227ce..00000000000
--- a/app/views/projects/commits/_diff_file.html.haml
+++ /dev/null
@@ -1,48 +0,0 @@
-- file = project.repository.blob_for_diff(@commit, diff)
-- return unless file
-- blob_diff_path = diff_project_blob_path(project,
-  tree_join(@commit.id, diff.new_path))
-.diff-file{id: "diff-#{i}", data: {blob_diff_path: blob_diff_path }}
-  .diff-header{id: "file-path-#{hexdigest(diff.new_path || diff.old_path)}"}
-    - if diff.deleted_file
-      %span= diff.old_path
-
-      .diff-btn-group
-        - if @commit.parent_ids.present?
-          = view_file_btn(@commit.parent_id, diff, project)
-    - else
-      %span= diff.new_path
-      - if diff_file_mode_changed?(diff)
-        %span.file-mode= "#{diff.a_mode} → #{diff.b_mode}"
-
-      .diff-btn-group
-        %label
-          = check_box_tag nil, 1, false, class: "js-toggle-diff-line-wrap"
-          Wrap text
-        &nbsp;
-        = link_to "#", class: "js-toggle-diff-comments btn btn-small" do
-          %i.icon-chevron-down
-          Diff comments
-        &nbsp;
-
-        - if @merge_request && @merge_request.source_project
-          = link_to project_edit_tree_path(@merge_request.source_project, tree_join(@merge_request.source_branch, diff.new_path), from_merge_request_id: @merge_request.id), { class: 'btn btn-small' } do
-            Edit
-          &nbsp;
-
-        = view_file_btn(@commit.id, diff, project)
-
-  .diff-content
-    -# Skipp all non non-supported blobs
-    - return unless file.respond_to?('text?')
-    - if file.text?
-      - if params[:view] == 'parallel'
-        = render "projects/commits/parallel_view", diff: diff, project: project, file: file, index: i
-      - else
-        = render "projects/commits/text_file", diff: diff, index: i
-    - elsif file.image?
-      - old_file = project.repository.prev_blob_for_diff(@commit, diff)
-      = render "projects/commits/image", diff: diff, old_file: old_file, file: file, index: i
-    - else
-      .nothing-here-block No preview for this file type
-
diff --git a/app/views/projects/compare/show.html.haml b/app/views/projects/compare/show.html.haml
index aa79d08509b..45269e662cd 100644
--- a/app/views/projects/compare/show.html.haml
+++ b/app/views/projects/compare/show.html.haml
@@ -18,7 +18,7 @@
     - else
       %ul.well-list= render Commit.decorate(@commits), project: @project
 
-  = render "projects/commits/diffs", diffs: @diffs, project: @project
+  = render "projects/diffs/diffs", diffs: @diffs, project: @project
 
 - else
   .light-well
diff --git a/app/views/projects/commits/_diffs.html.haml b/app/views/projects/diffs/_diffs.html.haml
index 17efa8debe1..49b3dc6941a 100644
--- a/app/views/projects/commits/_diffs.html.haml
+++ b/app/views/projects/diffs/_diffs.html.haml
@@ -1,6 +1,6 @@
 .row
   .col-md-8
-    = render 'projects/commits/diff_stats', diffs: diffs
+    = render 'projects/diffs/stats', diffs: diffs
   .col-md-4
     %ul.nav.nav-tabs
       %li.pull-right{class: params[:view] == 'parallel' ? 'active' : ''}
@@ -11,12 +11,13 @@
         - params_copy[:view] = 'inline'
         = link_to "Inline Diff", url_for(params_copy), {id: "commit-diff-viewtype"}
 
+
 - if show_diff_size_warninig?(diffs)
-  = render 'projects/commits/diff_warning', diffs: diffs
+  = render 'projects/diffs/warning', diffs: diffs
 
 .files
-  - safe_diff_files(diffs).each_with_index do |diff, i|
-    = render 'projects/commits/diff_file', diff: diff, i: i, project: project
+  - safe_diff_files(diffs).each_with_index do |diff_file, index|
+    = render 'projects/diffs/file', diff_file: diff_file, i: index, project: project
 
 - if @diff_timeout
   .alert.alert-danger
diff --git a/app/views/projects/diffs/_file.html.haml b/app/views/projects/diffs/_file.html.haml
new file mode 100644
index 00000000000..be0301e75f8
--- /dev/null
+++ b/app/views/projects/diffs/_file.html.haml
@@ -0,0 +1,47 @@
+- blob = project.repository.blob_for_diff(@commit, diff_file.diff)
+- return unless blob
+- blob_diff_path = diff_project_blob_path(project, tree_join(@commit.id, diff_file.file_path))
+.diff-file{id: "diff-#{i}", data: {blob_diff_path: blob_diff_path }}
+  .diff-header{id: "file-path-#{hexdigest(diff_file.new_path || diff_file.old_path)}"}
+    - if diff_file.deleted_file
+      %span= diff_file.old_path
+
+      .diff-btn-group
+        - if @commit.parent_ids.present?
+          = view_file_btn(@commit.parent_id, diff_file, project)
+    - else
+      %span= diff_file.new_path
+      - if diff_file.mode_changed?
+        %span.file-mode= "#{diff.a_mode} → #{diff.b_mode}"
+
+      .diff-btn-group
+        %label
+          = check_box_tag nil, 1, false, class: "js-toggle-diff-line-wrap"
+          Wrap text
+        &nbsp;
+        = link_to "#", class: "js-toggle-diff-comments btn btn-small" do
+          %i.icon-chevron-down
+          Diff comments
+        &nbsp;
+
+        - if @merge_request && @merge_request.source_project
+          = link_to project_edit_tree_path(@merge_request.source_project, tree_join(@merge_request.source_branch, diff_file.new_path), from_merge_request_id: @merge_request.id), { class: 'btn btn-small' } do
+            Edit
+          &nbsp;
+
+        = view_file_btn(@commit.id, diff_file, project)
+
+  .diff-content
+    -# Skipp all non non-supported blobs
+    - return unless blob.respond_to?('text?')
+    - if blob.text?
+      - if params[: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.image?
+      - old_file = project.repository.prev_blob_for_diff(@commit, diff_file)
+      = render "projects/diffs/image", diff_file: diff_file, old_file: old_file, file: blob, index: i
+    - else
+      .nothing-here-block No preview for this file type
+
diff --git a/app/views/projects/commits/_image.html.haml b/app/views/projects/diffs/_image.html.haml
index 6d9ef5964d9..900646dd0a4 100644
--- a/app/views/projects/commits/_image.html.haml
+++ b/app/views/projects/diffs/_image.html.haml
@@ -1,3 +1,4 @@
+- diff = diff_file.diff
 - if diff.renamed_file || diff.new_file || diff.deleted_file
   .image
     %span.wrap
diff --git a/app/views/projects/commits/diffs/_match_line.html.haml b/app/views/projects/diffs/_match_line.html.haml
index 4ebe3379733..4ebe3379733 100644
--- a/app/views/projects/commits/diffs/_match_line.html.haml
+++ b/app/views/projects/diffs/_match_line.html.haml
diff --git a/app/views/projects/commits/diffs/_match_line_parallel.html.haml b/app/views/projects/diffs/_match_line_parallel.html.haml
index 815df16aa4a..815df16aa4a 100644
--- a/app/views/projects/commits/diffs/_match_line_parallel.html.haml
+++ b/app/views/projects/diffs/_match_line_parallel.html.haml
diff --git a/app/views/projects/commits/_parallel_view.html.haml b/app/views/projects/diffs/_parallel_view.html.haml
index dec417bb21f..e7c0a5a8e58 100644
--- a/app/views/projects/commits/_parallel_view.html.haml
+++ b/app/views/projects/diffs/_parallel_view.html.haml
@@ -1,7 +1,7 @@
 / Side-by-side diff view
 %div.text-file
   %table
-    - parallel_diff(diff, index).each do |line|
+    - parallel_diff(diff_file, index).each do |line|
       - type_left = line[0]
       - line_number_left = line[1]
       - line_content_left = line[2]
@@ -11,7 +11,7 @@
 
       %tr.line_holder.parallel
         - if type_left == 'match'
-          = render "projects/commits/diffs/match_line_parallel", { line: line_content_left,
+          = render "projects/diffs/match_line_parallel", { line: line_content_left,
           line_old: line_number_left, line_new: line_number_right }
         - elsif type_left ==  'old' || type_left.nil?
           %td.old_line{class: "#{type_left}"}
@@ -21,6 +21,6 @@
             = link_to raw(line_number_right)
             %td.line_content.parallel{class: "noteable_line #{type_right == 'new' ? 'new' : nil}"}= raw line_content_right
 
-- if diff.diff.blank? && diff_file_mode_changed?(diff)
+- if diff_file.diff.diff.blank? && diff_file.mode_changed?
   .file-mode-changed
     File mode changed
diff --git a/app/views/projects/commits/_diff_stats.html.haml b/app/views/projects/diffs/_stats.html.haml
index 8ef7cc6e086..8ef7cc6e086 100644
--- a/app/views/projects/commits/_diff_stats.html.haml
+++ b/app/views/projects/diffs/_stats.html.haml
diff --git a/app/views/projects/commits/_text_file.html.haml b/app/views/projects/diffs/_text_file.html.haml
index 756481c1b21..b1c987563f1 100644
--- a/app/views/projects/commits/_text_file.html.haml
+++ b/app/views/projects/diffs/_text_file.html.haml
@@ -1,33 +1,36 @@
-- too_big = diff.diff.lines.count > Commit::DIFF_SAFE_LINES
+- too_big = diff_file.diff_lines.count > Commit::DIFF_SAFE_LINES
 - if too_big
   %a.supp_diff_link Changes suppressed. Click to show
 
 %table.text-file{class: "#{'hide' if too_big}"}
   - last_line = 0
-  - each_diff_line(diff, index) do |line, type, line_code, line_new, line_old, raw_line|
-    - last_line = line_new
+  - diff_file.diff_lines.each_with_index do |line, index|
+    - type = line.type
+    - last_line = line.new_pos
+    - line_code = generate_line_code(diff_file.file_path, line)
+    - line_old = line.old_pos
     %tr.line_holder{ id: line_code, class: "#{type}" }
       - if type == "match"
-        = render "projects/commits/diffs/match_line", {line: line,
-          line_old: line_old, line_new: line_new, bottom: false}
+        = render "projects/diffs/match_line", {line: line.text,
+          line_old: line_old, line_new: line.new_pos, bottom: false}
       - else
         %td.old_line
           = link_to raw(type == "new" ? "&nbsp;" : line_old), "##{line_code}", id: line_code
           - if @comments_allowed
             = link_to_new_diff_note(line_code)
-        %td.new_line{data: {linenumber: line_new}}
-          = link_to raw(type == "old" ? "&nbsp;" : line_new) , "##{line_code}", id: line_code
-        %td.line_content{class: "noteable_line #{type} #{line_code}", "line_code" => line_code}= raw diff_line_content(line)
+        %td.new_line{data: {linenumber: line.new_pos}}
+          = link_to raw(type == "old" ? "&nbsp;" : line.new_pos) , "##{line_code}", id: line_code
+        %td.line_content{class: "noteable_line #{type} #{line_code}", "line_code" => line_code}= raw diff_line_content(line.text)
 
     - if @reply_allowed
       - comments = @line_notes.select { |n| n.line_code == line_code }.sort_by(&:created_at)
       - unless comments.empty?
-        = render "projects/notes/diff_notes_with_reply", notes: comments, line: line
+        = render "projects/notes/diff_notes_with_reply", notes: comments, line: line.text
 
   - if last_line > 0
-    = render "projects/commits/diffs/match_line", {line: "",
+    = render "projects/diffs/match_line", {line: "",
       line_old: last_line, line_new: last_line, bottom: true}
 
-- if diff.diff.blank? && diff_file_mode_changed?(diff)
+- if diff_file.diff.blank? && diff_file.mode_changed?
   .file-mode-changed
     File mode changed
diff --git a/app/views/projects/commits/_diff_warning.html.haml b/app/views/projects/diffs/_warning.html.haml
index 05d516efa11..86ed6bbeaa2 100644
--- a/app/views/projects/commits/_diff_warning.html.haml
+++ b/app/views/projects/diffs/_warning.html.haml
@@ -14,6 +14,6 @@
           = link_to "Email patch", project_merge_request_path(@project, @merge_request, format: :patch), class: "btn btn-warning btn-small"
   %p
     To preserve performance only
-    %strong #{safe_diff_files(diffs).size} of #{diffs.size}
+    %strong #{allowed_diff_size} of #{diffs.size}
     files displayed.
 
diff --git a/app/views/projects/edit_tree/_diff.html.haml b/app/views/projects/edit_tree/_diff.html.haml
deleted file mode 100644
index cf044feb9a4..00000000000
--- a/app/views/projects/edit_tree/_diff.html.haml
+++ /dev/null
@@ -1,13 +0,0 @@
-%table.text-file
-  - each_diff_line(diff, 1) do |line, type, line_code, line_new, line_old, raw_line|
-    %tr.line_holder{ id: line_code, class: "#{type}" }
-      - if type == "match"
-        %td.old_line= "..."
-        %td.new_line= "..."
-        %td.line_content.matched= line
-      - else
-        %td.old_line
-          = link_to raw(type == "new" ? "&nbsp;" : line_old), "##{line_code}", id: line_code
-        %td.new_line= link_to raw(type == "old" ? "&nbsp;" : line_new) , "##{line_code}", id: line_code
-        %td.line_content{class: "noteable_line #{type} #{line_code}", "line_code" => line_code}= raw diff_line_content(line)
-
diff --git a/app/views/projects/edit_tree/preview.html.haml b/app/views/projects/edit_tree/preview.html.haml
index 87ce5dc31d3..e7c3460ad78 100644
--- a/app/views/projects/edit_tree/preview.html.haml
+++ b/app/views/projects/edit_tree/preview.html.haml
@@ -9,18 +9,17 @@
         = raw render_markup(@blob.name, @content)
     - else
       .file-content.code
-        - unless @diff.empty?
+        - unless @diff_lines.empty?
           %table.text-file
-            - @diff.each do |line, type, line_code, line_new, line_old, raw_line|
-              %tr.line_holder{ id: line_code, class: "#{type}" }
-                - if type == "match"
+            - @diff_lines.each do |line|
+              %tr.line_holder{ class: "#{line.type}" }
+                - if line.type == "match"
                   %td.old_line= "..."
                   %td.new_line= "..."
-                  %td.line_content.matched= line
+                  %td.line_content.matched= line.text
                 - else
                   %td.old_line
-                    = link_to raw(type == "new" ? "&nbsp;" : line_old), "##{line_code}", id: line_code
-                  %td.new_line= link_to raw(type == "old" ? "&nbsp;" : line_new) , "##{line_code}", id: line_code
-                  %td.line_content{class: "noteable_line #{type} #{line_code}", "line_code" => line_code}= raw diff_line_content(line)
+                  %td.new_line
+                  %td.line_content{class: "#{line.type}"}= raw diff_line_content(line.text)
         - else
           .nothing-here-block No changes.
diff --git a/app/views/projects/merge_requests/_new_submit.html.haml b/app/views/projects/merge_requests/_new_submit.html.haml
index dc3f9d592f6..e013fd6d1ce 100644
--- a/app/views/projects/merge_requests/_new_submit.html.haml
+++ b/app/views/projects/merge_requests/_new_submit.html.haml
@@ -75,7 +75,7 @@
 
   %h4 Changes
   - if @diffs.present?
-    = render "projects/commits/diffs", diffs: @diffs, project: @project
+    = render "projects/diffs/diffs", diffs: @diffs, project: @project
   - elsif @commits.size > MergeRequestDiff::COMMITS_SAFE_SIZE
     .bs-callout.bs-callout-danger
       %h4 This comparison includes more than #{MergeRequestDiff::COMMITS_SAFE_SIZE} commits.
diff --git a/app/views/projects/merge_requests/show/_diffs.html.haml b/app/views/projects/merge_requests/show/_diffs.html.haml
index eb63b68106e..d361c5f579a 100644
--- a/app/views/projects/merge_requests/show/_diffs.html.haml
+++ b/app/views/projects/merge_requests/show/_diffs.html.haml
@@ -1,5 +1,5 @@
 - if @merge_request_diff.collected?
-  = render "projects/commits/diffs", diffs: @merge_request.diffs, project: @merge_request.source_project
+  = render "projects/diffs/diffs", diffs: @merge_request.diffs, project: @merge_request.source_project
 - elsif @merge_request_diff.empty?
   .nothing-here-block Nothing to merge from #{@merge_request.source_branch} into #{@merge_request.target_branch}
 - else
diff --git a/app/views/projects/notes/_diff_note_link.html.haml b/app/views/projects/notes/_diff_note_link.html.haml
deleted file mode 100644
index 377c926a204..00000000000
--- a/app/views/projects/notes/_diff_note_link.html.haml
+++ /dev/null
@@ -1,10 +0,0 @@
-- note = @project.notes.new(@comments_target.merge({ line_code: line_code }))
-= link_to "",
-          "javascript:;",
-          class: "add-diff-note js-add-diff-note-button",
-          data: { noteable_type: note.noteable_type,
-                  noteable_id:   note.noteable_id,
-                  commit_id:     note.commit_id,
-                  line_code:     note.line_code,
-                  discussion_id: note.discussion_id },
-          title: "Add a comment to this line"
diff --git a/app/views/projects/notes/discussions/_diff.html.haml b/app/views/projects/notes/discussions/_diff.html.haml
index 26c5494f466..da71220af17 100644
--- a/app/views/projects/notes/discussions/_diff.html.haml
+++ b/app/views/projects/notes/discussions/_diff.html.haml
@@ -11,16 +11,17 @@
       %br/
     .diff-content
       %table
-        - each_diff_line_near(diff, note.diff_file_index, note.line_code) do |line, type, line_code, line_new, line_old|
+        - note.truncated_diff_lines.each do |line|
+          - line_code = generate_line_code(note.file_path, line)
           %tr.line_holder{ id: line_code }
-            - if type == "match"
+            - if line.type == "match"
               %td.old_line= "..."
               %td.new_line= "..."
-              %td.line_content.matched= line
+              %td.line_content.matched= line.text
             - else
-              %td.old_line= raw(type == "new" ? "&nbsp;" : line_old)
-              %td.new_line= raw(type == "old" ? "&nbsp;" : line_new)
-              %td.line_content{class: "noteable_line #{type} #{line_code}", "line_code" => line_code}= raw "#{line} &nbsp;"
+              %td.old_line= raw(line.type == "new" ? "&nbsp;" : line.old_pos)
+              %td.new_line= raw(line.type == "old" ? "&nbsp;" : line.new_pos)
+              %td.line_content{class: "noteable_line #{line.type} #{line_code}", "line_code" => line_code}= raw "#{line.text} &nbsp;"
 
               - if line_code == note.line_code
                 = render "projects/notes/diff_notes_with_reply", notes: discussion_notes