Merge branch 'parallel_diff_refactor' into 'master'

Parallel diff refactor

Refactor side-by-side diff to remove code duplication.

Base the side-by-side diff on inline diff code.

In first iteration:

1. commenting on the side-by-side diff is not possible
1. no expanding of the surrounding code

See merge request !1066

2 files changed, 83 insertions, 129 deletions

diff --git a/app/helpers/commits_helper.rb b/app/helpers/commits_helper.rb
index f61aa259154..cab2984a4c4 100644
--- a/app/helpers/commits_helper.rb
+++ b/app/helpers/commits_helper.rb
@@ -16,38 +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 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"
@@ -63,14 +31,6 @@ module CommitsHelper
     escape_javascript(render "projects/commits/#{template}", commit: commit, project: project) unless commit.nil?
   end
 
-  def diff_line_content(line)
-    if line.blank?
-      "  "
-    else
-      line
-    end
-  end
-
   # Breadcrumb links for a Project and, if applicable, a tree path
   def commits_breadcrumbs
     return unless @project && @ref
@@ -105,82 +65,6 @@ module CommitsHelper
     branches.sort.map { |branch| link_to(branch, project_tree_path(project, branch)) }.join(", ").html_safe
   end
 
-  def parallel_diff_lines(project, commit, diff, file)
-    old_file = project.repository.blob_at(commit.parent_id, diff.old_path) if commit.parent_id
-    deleted_lines = {}
-    added_lines = {}
-    each_diff_line(diff, 0) do |line, type, line_code, line_new, line_old|
-      if type == "old"
-        deleted_lines[line_old] = { line_code: line_code, type: type, line: line }
-      elsif type == "new"
-        added_lines[line_new]   = { line_code: line_code, type: type, line: line }
-      end
-    end
-    max_length = old_file ? [old_file.loc, file.loc].max : file.loc
-
-    offset1 = 0
-    offset2 = 0
-    old_lines = []
-    new_lines = []
-
-    max_length.times do |line_index|
-      line_index1 = line_index - offset1
-      line_index2 = line_index - offset2
-      deleted_line = deleted_lines[line_index1 + 1]
-      added_line = added_lines[line_index2 + 1]
-      old_line = old_file.lines[line_index1] if old_file
-      new_line = file.lines[line_index2]
-
-      if deleted_line && added_line
-      elsif deleted_line
-        new_line = nil
-        offset2 += 1
-      elsif added_line
-        old_line = nil
-        offset1 += 1
-      end
-
-      old_lines[line_index] = DiffLine.new
-      new_lines[line_index] = DiffLine.new
-
-      # old
-      if line_index == 0 && diff.new_file
-        old_lines[line_index].type = :file_created
-        old_lines[line_index].content = 'File was created'
-      elsif deleted_line
-        old_lines[line_index].type = :deleted
-        old_lines[line_index].content = old_line
-        old_lines[line_index].num = line_index1 + 1
-        old_lines[line_index].code = deleted_line[:line_code]
-      elsif old_line
-        old_lines[line_index].type = :no_change
-        old_lines[line_index].content = old_line
-        old_lines[line_index].num = line_index1 + 1
-      else
-        old_lines[line_index].type = :added
-      end
-
-      # new
-      if line_index == 0 && diff.deleted_file
-        new_lines[line_index].type = :file_deleted
-        new_lines[line_index].content = "File was deleted"
-      elsif added_line
-        new_lines[line_index].type = :added
-        new_lines[line_index].num = line_index2 + 1
-        new_lines[line_index].content = new_line
-        new_lines[line_index].code = added_line[:line_code]
-      elsif new_line
-        new_lines[line_index].type = :no_change
-        new_lines[line_index].num = line_index2 + 1
-        new_lines[line_index].content = new_line
-      else
-        new_lines[line_index].type = :deleted
-      end
-    end
-
-    return old_lines, new_lines
-  end
-
   def link_to_browse_code(project, commit)
     if current_controller?(:projects, :commits)
       if @repo.blob_at(commit.id, @path)
@@ -229,14 +113,6 @@ 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
-
   def view_file_btn(commit_sha, diff, project)
     link_to project_blob_path(project, tree_join(commit_sha, diff.new_path)),
             class: 'btn btn-small view-file js-view-file' do
diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index ee4d4fbdff5..afe7447d4e2 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
+  def show_diff_size_warning?(diffs)
+    diffs.size > allowed_diff_size
   end
 
   def diff_hard_limit_enabled?
@@ -19,4 +25,76 @@ 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, line_code, 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, line_code, 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, line_code, 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;", line_code, type, line_new, full_line]
+          lines.push(line)
+        end
+      end
+    end
+    lines
+  end
+
+  def unfold_bottom_class(bottom)
+    (bottom) ? 'js-unfold-bottom' : ''
+  end
+
+  def diff_line_content(line)
+    if line.blank?
+      " &nbsp;"
+    else
+      line
+    end
+  end
 end