Start of MR confict resolver service

app/models/merge_request.rb

@@ -321,6 +321,18 @@ class MergeRequest < ActiveRecord::Base
     end
   end
+  def conflicts?
+    project.repository.conflicts?(diff_head_sha, target_branch)
+  end
+
+  def conflicts
+    project.repository.conflicts(diff_head_sha, target_branch)
+  end
+
+  def conflict_diff(conflict)
+    project.repository.conflict_diff(diff_head_sha, target_branch, conflict[:ancestor][:path])
+  end
+
   def merge_event
     @merge_event ||= target_project.events.where(target_id: self.id, target_type: "MergeRequest", action: Event::MERGED).last
   end

app/models/repository.rb

@@ -637,11 +637,11 @@ class Repository
   def contributors
     commits = self.commits(nil, limit: 2000, offset: 0, skip_merges: true)
-    commits.group_by(&:author_email).map do |email, commits|
+    commits.group_by(&:author_email).map do |author_email, author_commits|
       contributor = Gitlab::Contributor.new
-      contributor.email = email
-      commits.each do |commit|
+      contributor.email = author_email
+      author_commits.each do |commit|
         if contributor.name.blank?
           contributor.name = commit.author_name
         end
@@ -769,6 +769,39 @@ class Repository
     end
   end
+  def conflicts?(source_sha, target_branch)
+    our_commit = rugged.branches[target_branch].target
+    their_commit = rugged.lookup(source_sha)
+
+    if our_commit && their_commit
+      rugged.merge_commits(our_commit, their_commit).conflicts?
+    else
+      false
+    end
+  end
+
+  def conflicts(source_sha, target_branch)
+    our_commit = rugged.branches[target_branch].target
+    their_commit = rugged.lookup(source_sha)
+
+    if our_commit && their_commit
+      rugged.merge_commits(our_commit, their_commit).conflicts
+    else
+      []
+    end
+  end
+
+  def conflict_diff(source_sha, target_branch, path)
+    our_commit = rugged.branches[target_branch].target
+    their_commit = rugged.lookup(source_sha)
+
+    if our_commit && their_commit && path
+      rugged.diff(our_commit, their_commit, { paths: [path], context_lines: 3 })
+    else
+      []
+    end
+  end
+
   def merge(user, source_sha, target_branch, options = {})
     our_commit = rugged.branches[target_branch].target
     their_commit = rugged.lookup(source_sha)

app/services/merge_requests/conflicts/formatter_service.rb

+module MergeRequests
+  module Conflicts
+    class FormatterService
+      attr_accessor :rugged_input
+
+      def initialize(rugged_input)
+        @rugged_input = rugged_input
+      end
+
+      def format_from_rugged
+        # TODO: format!
+        @rugged_input
+      end
+    end
+  end
+end

app/services/merge_requests/conflicts/resolver_service.rb

+module MergeRequests
+  module Conflicts
+    class ResolverService
+      attr_accessor :merge_request
+
+      def initialize(merge_request)
+        @merge_request = merge_request
+      end
+
+      def conflicts
+        return [] unless @merge_request.conflicts?
+
+        diff_lines = []
+
+        @merge_request.conflicts.each do |c|
+          diff_lines.push(
+            Gitlab::Diff::Parser.new.parse(
+              @merge_request.conflict_diff(c).each_line.collect { |el| el.content }
+            ).to_a
+          )
+        end
+
+        diff_lines
+      end
+    end
+  end
+end