Implement merge from forks without satellites

app/controllers/projects/merge_requests_controller.rb

@@ -149,7 +149,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     return access_denied! unless @merge_request.can_be_merged_by?(current_user)
 
     if @merge_request.automergeable?
-      AutoMergeWorker.perform_async(@merge_request.id, current_user.id, params)
+      #AutoMergeWorker.perform_async(@merge_request.id, current_user.id, params)
+      @merge_request.automerge!(current_user, params[:commit_message])
       @status = true
     else
       @status = false

app/models/merge_request.rb

@@ -206,11 +206,7 @@ class MergeRequest < ActiveRecord::Base
 
   def check_if_can_be_merged
     can_be_merged =
-      if for_fork?
-        raise 'Implement me'
-      else
-        project.repository.can_be_merged?(source_branch, target_branch)
-      end
+      project.repository.can_be_merged?(source_sha, target_branch)
 
     if can_be_merged
       mark_as_mergeable
@@ -274,14 +270,14 @@ class MergeRequest < ActiveRecord::Base
   #
   # see "git diff"
   def to_diff(current_user)
-    raise 'Implement me'
+    target_project.repository.diff_text(target_branch, source_sha)
   end
 
   # Returns the commit as a series of email patches.
   #
   # see "git format-patch"
   def to_patch(current_user)
-    raise 'Implement me'
+    target_project.repository.format_patch(target_branch, source_sha)
   end
 
   def hook_attrs
@@ -432,4 +428,13 @@ class MergeRequest < ActiveRecord::Base
       "Open"
     end
   end
+
+  def target_sha
+    @target_sha ||= target_project.
+      repository.commit(target_branch).sha
+  end
+
+  def source_sha
+    commits.first.sha
+  end
 end

app/models/merge_request_diff.rb

@@ -160,10 +160,12 @@ class MergeRequestDiff < ActiveRecord::Base
   private
 
   def compare_result
+    source_sha = merge_request.source_project.commit(source_branch).sha
+
     @compare_result ||= CompareService.new.execute(
       merge_request.author,
-      merge_request.source_project,
-      merge_request.source_branch,
+      merge_request.target_project,
+      source_sha,
       merge_request.target_project,
       merge_request.target_branch,
     )

app/models/repository.rb

@@ -422,15 +422,34 @@ class Repository
     }
   end
 
-  def can_be_merged?(source_branch, target_branch)
+  def can_be_merged?(source_sha, target_branch)
     our_commit = rugged.branches[target_branch].target
-    their_commit = rugged.branches[source_branch].target
+    their_commit = rugged.lookup(source_sha)
 
     if our_commit && their_commit
       !rugged.merge_commits(our_commit, their_commit).conflicts?
     end
   end
 
+  def merge(source_sha, target_branch, options = {})
+    our_commit = rugged.branches[target_branch].target
+    their_commit = rugged.lookup(source_sha)
+
+    raise "Invalid merge target" if our_commit.nil?
+    raise "Invalid merge source" if their_commit.nil?
+
+    merge_index = rugged.merge_commits(our_commit, their_commit)
+    return false if merge_index.conflicts?
+
+    actual_options = options.merge(
+      parents: [our_commit, their_commit],
+      tree: merge_index.write_tree(rugged),
+      update_ref: "refs/heads/#{target_branch}"
+    )
+
+    Rugged::Commit.create(rugged, actual_options)
+  end
+
   def search_files(query, ref)
     offset = 2
     args = %W(git grep -i -n --before-context #{offset} --after-context #{offset} #{query} #{ref || root_ref})

app/services/compare_service.rb

+require 'securerandom'
+
 # Compare 2 branches for one repo or between repositories
 # and return Gitlab::CompareResult object that responds to commits and diffs
 class CompareService
@@ -12,7 +14,22 @@ class CompareService
         )
       )
     else
-      raise 'Implement me'
+      random_string = SecureRandom.hex
+      target_project.repository.fetch_ref(
+        source_project.repository.path_to_repo,
+        "refs/heads/#{source_branch}",
+        "refs/tmp/#{random_string}/head"
+      )
+
+      source_sha = source_project.commit(source_branch).sha
+
+      Gitlab::CompareResult.new(
+        Gitlab::Git::Compare.new(
+          target_project.repository.raw_repository,
+          target_branch,
+          source_sha,
+        )
+      )
     end
   end
 end

app/services/merge_requests/auto_merge_service.rb

@@ -31,12 +31,8 @@ module MergeRequests
     end
 
     def merge!
-      if merge_request.for_fork?
-        raise 'Implement me'
-      else
-        if sha = commit
-          after_commit(sha, merge_request.target_branch)
-        end
+      if sha = commit
+        after_commit(sha, merge_request.target_branch)
       end
     end
 
@@ -49,7 +45,7 @@ module MergeRequests
         committer: committer
       }
 
-      repository.merge(merge_request.source_branch, merge_request.target_branch, options)
+      repository.merge(merge_request.source_sha, merge_request.target_branch, options)
     end
 
     def after_commit(sha, branch)

app/views/projects/merge_requests/_new_submit.html.haml

@@ -24,7 +24,7 @@
         = icon('history')
         Commits
         %span.badge= @commits.size
-    %li.diffs-tab
+    %li.diffs-tab.active
       = link_to url_for(params), data: {target: '#diffs', action: 'diffs', toggle: 'tab'} do
         = icon('list-alt')
         Changes
@@ -33,7 +33,7 @@
   .tab-content
     #commits.commits.tab-pane
       = render "projects/commits/commits", project: @project
-    #diffs.diffs.tab-pane
+    #diffs.diffs.tab-pane.active
       - if @diffs.present?
         = render "projects/diffs/diffs", diffs: @diffs, project: @project
       - elsif @commits.size > MergeRequestDiff::COMMITS_SAFE_SIZE