Introduce Compare model in the codebase.

This object will manage Gitlab::Git::Compare instances

14 files changed, 82 insertions, 46 deletions

diff --git a/app/controllers/projects/compare_controller.rb b/app/controllers/projects/compare_controller.rb
index 252ddfa429a..7fca5e77f32 100644
--- a/app/controllers/projects/compare_controller.rb
+++ b/app/controllers/projects/compare_controller.rb
@@ -21,7 +21,7 @@ class Projects::CompareController < Projects::ApplicationController
   def diff_for_path
     return render_404 unless @compare
 
-    render_diff_for_path(Compare.decorate(@compare, @project).diff_file_collection(diff_options: diff_options))
+    render_diff_for_path(@compare.diff_file_collection(diff_options: diff_options))
   end
 
   def create
@@ -40,18 +40,12 @@ class Projects::CompareController < Projects::ApplicationController
     @compare = CompareService.new.execute(@project, @head_ref, @project, @start_ref)
 
     if @compare
-      @commits = Commit.decorate(@compare.commits, @project)
+      @commits = @compare.commits
+      @start_commit = @compare.start_commit
+      @commit = @compare.commit
+      @base_commit = @compare.base_commit
 
-      @start_commit = @project.commit(@start_ref)
-      @commit = @project.commit(@head_ref)
-      @base_commit = @project.merge_base_commit(@start_ref, @head_ref)
-
-      diff_refs = Gitlab::Diff::DiffRefs.new(
-        base_sha: @base_commit.try(:sha),
-        start_sha: @start_commit.try(:sha),
-        head_sha: @commit.try(:sha)
-      )
-      @diffs = Compare.decorate(@compare, @project).diff_file_collection(diff_options: diff_options, diff_refs: diff_refs)
+      @diffs = @compare.diff_file_collection(diff_options: diff_options)
 
       @diff_notes_disabled = true
       @grouped_diff_discussions = {}
diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index 39e7d0f6182..20afc6afcb2 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -86,7 +86,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     respond_to do |format|
       format.html { define_discussion_vars }
       format.json do
-        @diffs = @merge_request.diff_file_collection(diff_options) if @merge_request_diff.collected?
+        @diffs = @merge_request.diff_file_collection(diff_options)
 
         render json: { html: view_to_html_string("projects/merge_requests/show/_diffs") }
       end
@@ -157,10 +157,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     @commit = @merge_request.diff_head_commit
     @base_commit = @merge_request.diff_base_commit
     if @merge_request.compare
-      @diffs = Compare.decorate(@merge_request.compare, @project).diff_file_collection(
-        diff_options: diff_options,
-        diff_refs: @merge_request.diff_refs
-      )
+      @diffs = @merge_request.diff_file_collection(diff_options)
     end
     @diff_notes_disabled = true
 
diff --git a/app/models/commit.rb b/app/models/commit.rb
index d22ecb222e5..a339d47f5f3 100644
--- a/app/models/commit.rb
+++ b/app/models/commit.rb
@@ -317,7 +317,7 @@ class Commit
     nil
   end
 
-  def diff_file_collection(diff_options)
+  def diff_file_collection(diff_options = nil)
     Gitlab::Diff::FileCollection::Commit.new(self, diff_options: diff_options)
   end
 
diff --git a/app/models/compare.rb b/app/models/compare.rb
index 6672d1bf059..05c8fbbcc36 100644
--- a/app/models/compare.rb
+++ b/app/models/compare.rb
@@ -1,5 +1,5 @@
 class Compare
-  delegate :commits, :same, :head, :base, to: :@compare
+  delegate :same, :head, :base, to: :@compare
 
   def self.decorate(compare, project)
     if compare.is_a?(Compare)
@@ -14,10 +14,53 @@ class Compare
     @project = project
   end
 
-  def diff_file_collection(diff_options:, diff_refs: nil)
+  def commits
+    @commits ||= Commit.decorate(@compare.commits, @project)
+  end
+
+  def start_commit
+    return @start_commit if defined?(@start_commit)
+
+    commit = @compare.base
+    @start_commit = commit ? ::Commit.new(commit, @project) : nil
+  end
+
+  def commit
+    return @commit if defined?(@commit)
+
+    commit = @compare.head
+    @commit = commit ? ::Commit.new(commit, @project) : nil
+  end
+  alias_method :head_commit, :commit
+
+  # Used only on emails_on_push_worker.rb
+  def base_commit=(commit)
+    @base_commit = commit
+  end
+
+  def base_commit
+    return @base_commit if defined?(@base_commit)
+
+    @base_commit = if start_commit && commit
+                     @project.merge_base_commit(start_commit.id, commit.id)
+                   else
+                     nil
+                   end
+  end
+
+  # keyword args until we get ride of diff_refs as argument
+  def diff_file_collection(diff_options:, diff_refs: self.diff_refs)
     Gitlab::Diff::FileCollection::Compare.new(@compare,
       project: @project,
       diff_options: diff_options,
       diff_refs: diff_refs)
   end
+
+  def diff_refs
+    @diff_refs ||= Gitlab::Diff::DiffRefs.new(
+      base_sha:  base_commit.try(:sha),
+      start_sha: start_commit.try(:sha),
+      head_sha: commit.try(:sha)
+    )
+  end
 end
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index abc8bacbe59..62e5573dfdc 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -168,8 +168,12 @@ class MergeRequest < ActiveRecord::Base
     merge_request_diff ? merge_request_diff.diffs(*args) : compare.diffs(*args)
   end
 
-  def diff_file_collection(diff_options)
-    Gitlab::Diff::FileCollection::MergeRequest.new(self, diff_options: diff_options)
+  def diff_file_collection(diff_options = nil)
+    if self.compare
+      self.compare.diff_file_collection(diff_options: diff_options, diff_refs: diff_refs)
+    else
+      Gitlab::Diff::FileCollection::MergeRequest.new(self, diff_options: diff_options)
+    end
   end
 
   def diff_size
diff --git a/app/services/compare_service.rb b/app/services/compare_service.rb
index 149822aa647..bb3aff72b47 100644
--- a/app/services/compare_service.rb
+++ b/app/services/compare_service.rb
@@ -20,10 +20,13 @@ class CompareService
       )
     end
 
-    Gitlab::Git::Compare.new(
+    raw_compare = Gitlab::Git::Compare.new(
       target_project.repository.raw_repository,
       target_branch,
-      source_sha,
+      source_sha
     )
+
+    # REVIEW be sure if it's target_project or source_project
+    Compare.new(raw_compare, target_project)
   end
 end
diff --git a/app/services/merge_requests/build_service.rb b/app/services/merge_requests/build_service.rb
index 7fe57747265..290742f1506 100644
--- a/app/services/merge_requests/build_service.rb
+++ b/app/services/merge_requests/build_service.rb
@@ -34,7 +34,7 @@ module MergeRequests
       # At this point we decide if merge request can be created
       # If we have at least one commit to merge -> creation allowed
       if commits.present?
-        merge_request.compare_commits = Commit.decorate(commits, merge_request.source_project)
+        merge_request.compare_commits = commits
         merge_request.can_be_created = true
         merge_request.compare = compare
       else
diff --git a/app/services/merge_requests/merge_request_diff_cache_service.rb b/app/services/merge_requests/merge_request_diff_cache_service.rb
index 982540ba7f5..8151c24d1b0 100644
--- a/app/services/merge_requests/merge_request_diff_cache_service.rb
+++ b/app/services/merge_requests/merge_request_diff_cache_service.rb
@@ -2,7 +2,7 @@ module MergeRequests
   class MergeRequestDiffCacheService
     def execute(merge_request)
       # Executing the iteration we cache all the highlighted diff information
-      merge_request.diff_file_collection(Gitlab::Diff::FileCollection.default_options).diff_files.to_a
+      merge_request.diff_file_collection.diff_files.to_a
     end
   end
 end
diff --git a/app/views/projects/commit/show.html.haml b/app/views/projects/commit/show.html.haml
index 11b2020f99b..ed44d86a687 100644
--- a/app/views/projects/commit/show.html.haml
+++ b/app/views/projects/commit/show.html.haml
@@ -7,7 +7,7 @@
   = render "ci_menu"
 - else
   %div.block-connector
-= render "projects/diffs/diffs", diff_files: @diffs.diff_files, project: @diffs.project, diff_refs: @diffs.diff_refs
+= render "projects/diffs/diffs", diffs: @diffs
 = render "projects/notes/notes_with_form"
 - if can_collaborate_with_project?
   - %w(revert cherry-pick).each do |type|
diff --git a/app/views/projects/compare/show.html.haml b/app/views/projects/compare/show.html.haml
index eb8a1bd5289..819e9bc15ae 100644
--- a/app/views/projects/compare/show.html.haml
+++ b/app/views/projects/compare/show.html.haml
@@ -8,7 +8,7 @@
 
   - if @commits.present?
     = render "projects/commits/commit_list"
-    = render "projects/diffs/diffs", diff_files: @diffs.diff_files, project: @diffs.project, diff_refs: @diffs.diff_refs
+    = render "projects/diffs/diffs", diffs: @diffs
   - else
     .light-well
       .center
diff --git a/app/views/projects/diffs/_diffs.html.haml b/app/views/projects/diffs/_diffs.html.haml
index 45895a9a3de..35fdf7d5278 100644
--- a/app/views/projects/diffs/_diffs.html.haml
+++ b/app/views/projects/diffs/_diffs.html.haml
@@ -1,4 +1,5 @@
 - show_whitespace_toggle = local_assigns.fetch(:show_whitespace_toggle, true)
+- diff_files = diffs.diff_files
 - if diff_view == 'parallel'
   - fluid_layout true
 
@@ -26,7 +27,7 @@
     - diff_commit = commit_for_diff(diff_file)
     - blob = diff_file.blob(diff_commit)
     - next unless blob
-    - blob.load_all_data!(project.repository) unless blob.only_display_raw?
+    - blob.load_all_data!(@project.repository) unless blob.only_display_raw?
 
-    = render 'projects/diffs/file', i: index, project: project,
-      diff_file: diff_file, diff_commit: diff_commit, blob: blob, diff_refs: diff_refs
+    = render 'projects/diffs/file', i: index, project: @project,
+      diff_file: diff_file, diff_commit: diff_commit, blob: blob, diff_refs: diffs.diff_refs
diff --git a/app/views/projects/merge_requests/_new_submit.html.haml b/app/views/projects/merge_requests/_new_submit.html.haml
index cb2b623691c..598bd743676 100644
--- a/app/views/projects/merge_requests/_new_submit.html.haml
+++ b/app/views/projects/merge_requests/_new_submit.html.haml
@@ -42,7 +42,7 @@
           %h4 This comparison includes more than #{MergeRequestDiff::COMMITS_SAFE_SIZE} commits.
           %p To preserve performance the line changes are not shown.
       - else
-        = render "projects/diffs/diffs", diff_files: @diffs.diff_files, project: @diffs.project, diff_refs: @merge_request.diff_refs, show_whitespace_toggle: false
+        = render "projects/diffs/diffs", diffs: @diffs, show_whitespace_toggle: false
     - if @pipeline
       #builds.builds.tab-pane
         = render "projects/merge_requests/show/builds"
diff --git a/app/views/projects/merge_requests/show/_diffs.html.haml b/app/views/projects/merge_requests/show/_diffs.html.haml
index 5b842dd9280..c6d2567af35 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/diffs/diffs", diff_files: @diffs.diff_files,
+  = render "projects/diffs/diffs", diffs: @diffs,
     diff_refs: @diffs.diff_refs, project: @diffs.project
 - 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/workers/emails_on_push_worker.rb b/app/workers/emails_on_push_worker.rb
index 0b6a01a3200..0b63913cfd1 100644
--- a/app/workers/emails_on_push_worker.rb
+++ b/app/workers/emails_on_push_worker.rb
@@ -33,25 +33,19 @@ class EmailsOnPushWorker
     reverse_compare = false
 
     if action == :push
-      merge_base_sha = project.merge_base_commit(before_sha, after_sha).try(:sha)
+      base_commit = project.merge_base_commit(before_sha, after_sha)
       compare = Gitlab::Git::Compare.new(project.repository.raw_repository, before_sha, after_sha)
-
-      diff_refs = Gitlab::Diff::DiffRefs.new(
-        base_sha: merge_base_sha,
-        start_sha: before_sha,
-        head_sha: after_sha
-      )
+      compare = Compare.decorate(compare, project)
+      compare.base_commit = base_commit
+      diff_refs = compare.diff_refs
 
       return false if compare.same
 
       if compare.commits.empty?
         compare = Gitlab::Git::Compare.new(project.repository.raw_repository, after_sha, before_sha)
-
-        diff_refs = Gitlab::Diff::DiffRefs.new(
-          base_sha: merge_base_sha,
-          start_sha: after_sha,
-          head_sha: before_sha
-        )
+        compare = Compare.decorate(compare, project)
+        compare.base_commit = base_commit
+        diff_refs = compare.diff_refs
 
         reverse_compare = true