Create a Gitlab::Git submodule for conlict-related files

Rename classes to (hopefully) clearer names while we're doing that.

16 files changed, 294 insertions, 283 deletions

diff --git a/lib/api/commits.rb b/lib/api/commits.rb
index e2d50b4e0a6..6ad97f2deb2 100644
--- a/lib/api/commits.rb
+++ b/lib/api/commits.rb
@@ -186,7 +186,7 @@ module API
 
             lines.each do |line|
               next unless line.new_pos == params[:line] && line.type == params[:line_type]
-              break opts[:line_code] = Gitlab::Git::DiffLineCode.generate(diff.new_path, line.new_pos, line.old_pos)
+              break opts[:line_code] = Gitlab::Git::Conflict::LineCode.generate(diff.new_path, line.new_pos, line.old_pos)
             end
 
             break if opts[:line_code]
diff --git a/lib/api/v3/commits.rb b/lib/api/v3/commits.rb
index 042f4338d53..cbb192d5dfc 100644
--- a/lib/api/v3/commits.rb
+++ b/lib/api/v3/commits.rb
@@ -173,7 +173,7 @@ module API
 
               lines.each do |line|
                 next unless line.new_pos == params[:line] && line.type == params[:line_type]
-                break opts[:line_code] = Gitlab::Git::DiffLineCode.generate(diff.new_path, line.new_pos, line.old_pos)
+                break opts[:line_code] = Gitlab::Git::Conflict::LineCode.generate(diff.new_path, line.new_pos, line.old_pos)
               end
 
               break if opts[:line_code]
diff --git a/lib/github/representation/comment.rb b/lib/github/representation/comment.rb
index b87a11672ed..0cb871630fd 100644
--- a/lib/github/representation/comment.rb
+++ b/lib/github/representation/comment.rb
@@ -23,7 +23,7 @@ module Github
       private
 
       def generate_line_code(line)
-        Gitlab::Git::DiffLineCode.generate(file_path, line.new_pos, line.old_pos)
+        Gitlab::Git::Conflict::LineCode.generate(file_path, line.new_pos, line.old_pos)
       end
 
       def on_diff?
diff --git a/lib/gitlab/bitbucket_import/importer.rb b/lib/gitlab/bitbucket_import/importer.rb
index f613d8e8179..38ba5b97ed0 100644
--- a/lib/gitlab/bitbucket_import/importer.rb
+++ b/lib/gitlab/bitbucket_import/importer.rb
@@ -241,7 +241,7 @@ module Gitlab
       end
 
       def generate_line_code(pr_comment)
-        Gitlab::Git::DiffLineCode.generate(pr_comment.file_path, pr_comment.new_pos, pr_comment.old_pos)
+        Gitlab::Git::Conflict::LineCode.generate(pr_comment.file_path, pr_comment.new_pos, pr_comment.old_pos)
       end
 
       def pull_request_comment_attributes(comment)
diff --git a/lib/gitlab/conflict/file.rb b/lib/gitlab/conflict/file.rb
index 2d8a21f4905..3392388a45f 100644
--- a/lib/gitlab/conflict/file.rb
+++ b/lib/gitlab/conflict/file.rb
@@ -6,7 +6,10 @@ module Gitlab
 
       CONTEXT_LINES = 3
 
-      attr_reader :merge_request, :raw
+      attr_reader :merge_request
+
+      # 'raw' holds the Gitlab::Git::Conflict::File that this instance wraps
+      attr_reader :raw
 
       delegate :type, :content, :their_path, :our_path, :our_mode, :our_blob, :repository, to: :raw
 
@@ -107,7 +110,7 @@ module Gitlab
       end
 
       def line_code(line)
-        Gitlab::Git::DiffLineCode.generate(our_path, line.new_pos, line.old_pos)
+        Gitlab::Git::Conflict::LineCode.generate(our_path, line.new_pos, line.old_pos)
       end
 
       def create_match_line(line)
diff --git a/lib/gitlab/conflict/file_collection.rb b/lib/gitlab/conflict/file_collection.rb
index 573a953b2aa..fb28e80ff73 100644
--- a/lib/gitlab/conflict/file_collection.rb
+++ b/lib/gitlab/conflict/file_collection.rb
@@ -1,14 +1,14 @@
 module Gitlab
   module Conflict
     class FileCollection
-      attr_reader :merge_request, :merge
+      attr_reader :merge_request, :resolver
 
       def initialize(merge_request)
         source_repo = merge_request.source_project.repository.raw
         our_commit = merge_request.source_branch_head.raw
         their_commit = merge_request.target_branch_head.raw
         target_repo = merge_request.target_project.repository.raw
-        @merge = Gitlab::Git::Merge.new(source_repo, our_commit, target_repo, their_commit)
+        @resolver = Gitlab::Git::Conflict::Resolver.new(source_repo, our_commit, target_repo, their_commit)
         @merge_request = merge_request
       end
 
@@ -18,11 +18,11 @@ module Gitlab
           target_branch: merge_request.target_branch,
           commit_message: commit_message || default_commit_message
         }
-        merge.resolve_conflicts(user, files, args)
+        resolver.resolve_conflicts(user, files, args)
       end
 
       def files
-        @files ||= merge.conflicts.map do |conflict_file|
+        @files ||= resolver.conflicts.map do |conflict_file|
           Gitlab::Conflict::File.new(conflict_file, merge_request: merge_request)
         end
       end
diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index bc2c25c9cb6..3f8d2041c29 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -49,7 +49,7 @@ module Gitlab
       def line_code(line)
         return if line.meta?
 
-        Gitlab::Git::DiffLineCode.generate(file_path, line.new_pos, line.old_pos)
+        Gitlab::Git::Conflict::LineCode.generate(file_path, line.new_pos, line.old_pos)
       end
 
       def line_for_line_code(code)
diff --git a/lib/gitlab/git/conflict/file.rb b/lib/gitlab/git/conflict/file.rb
new file mode 100644
index 00000000000..b2bc653904d
--- /dev/null
+++ b/lib/gitlab/git/conflict/file.rb
@@ -0,0 +1,86 @@
+module Gitlab
+  module Git
+    module Conflict
+      class File
+        attr_reader :content, :their_path, :our_path, :our_mode, :repository
+
+        def initialize(repository, commit_oid, conflict, content)
+          @repository = repository
+          @commit_oid = commit_oid
+          @their_path = conflict[:theirs][:path]
+          @our_path = conflict[:ours][:path]
+          @our_mode = conflict[:ours][:mode]
+          @content = content
+        end
+
+        def lines
+          return @lines if defined?(@lines)
+
+          begin
+            @type = 'text'
+            @lines = Gitlab::Git::Conflict::Parser.parse(content,
+                                                      our_path: our_path,
+                                                      their_path: their_path)
+          rescue Gitlab::Git::Conflict::Parser::ParserError
+            @type = 'text-editor'
+            @lines = nil
+          end
+        end
+
+        def type
+          lines unless @type
+
+          @type.inquiry
+        end
+
+        def our_blob
+          # REFACTOR NOTE: the source of `commit_oid` used to be
+          # `merge_request.diff_refs.head_sha`. Instead of passing this value
+          # around the new lib structure, I decided to use `@commit_oid` which is
+          # equivalent to `merge_request.source_branch_head.raw.rugged_commit.oid`.
+          # That is what `merge_request.diff_refs.head_sha` is equivalent to when
+          # `merge_request` is not persisted (see `MergeRequest#diff_head_commit`).
+          # I think using the same oid is more consistent anyways, but if Conflicts
+          # start breaking, the change described above is a good place to look at.
+          @our_blob ||= repository.blob_at(@commit_oid, our_path)
+        end
+
+        def line_code(line)
+          Gitlab::Git::Conflict::LineCode.generate(our_path, line[:line_new], line[:line_old])
+        end
+
+        def resolve_lines(resolution)
+          section_id = nil
+
+          lines.map do |line|
+            unless line[:type]
+              section_id = nil
+              next line
+            end
+
+            section_id ||= line_code(line)
+
+            case resolution[section_id]
+            when 'head'
+              next unless line[:type] == 'new'
+            when 'origin'
+              next unless line[:type] == 'old'
+            else
+              raise Gitlab::Git::Conflict::Resolver::ResolutionError, "Missing resolution for section ID: #{section_id}"
+            end
+
+            line
+          end.compact
+        end
+
+        def resolve_content(resolution)
+          if resolution == content
+            raise Gitlab::Git::Conflict::Resolver::ResolutionError, "Resolved content has no changes for file #{our_path}"
+          end
+
+          resolution
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/conflict/line_code.rb b/lib/gitlab/git/conflict/line_code.rb
new file mode 100644
index 00000000000..bdbb4c9cb83
--- /dev/null
+++ b/lib/gitlab/git/conflict/line_code.rb
@@ -0,0 +1,11 @@
+module Gitlab
+  module Git
+    module Conflict
+      class LineCode
+        def self.generate(file_path, new_line_position, old_line_position)
+          "#{Digest::SHA1.hexdigest(file_path)}_#{old_line_position}_#{new_line_position}"
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/conflict/parser.rb b/lib/gitlab/git/conflict/parser.rb
new file mode 100644
index 00000000000..3effa9d2d31
--- /dev/null
+++ b/lib/gitlab/git/conflict/parser.rb
@@ -0,0 +1,91 @@
+module Gitlab
+  module Git
+    module Conflict
+      class Parser
+        UnresolvableError = Class.new(StandardError)
+        UnmergeableFile = Class.new(UnresolvableError)
+        UnsupportedEncoding = Class.new(UnresolvableError)
+
+        # Recoverable errors - the conflict can be resolved in an editor, but not with
+        # sections.
+        ParserError = Class.new(StandardError)
+        UnexpectedDelimiter = Class.new(ParserError)
+        MissingEndDelimiter = Class.new(ParserError)
+
+        class << self
+          def parse(text, our_path:, their_path:, parent_file: nil)
+            validate_text!(text)
+
+            line_obj_index = 0
+            line_old = 1
+            line_new = 1
+            type = nil
+            lines = []
+            conflict_start = "<<<<<<< #{our_path}"
+            conflict_middle = '======='
+            conflict_end = ">>>>>>> #{their_path}"
+
+            text.each_line.map do |line|
+              full_line = line.delete("\n")
+
+              if full_line == conflict_start
+                validate_delimiter!(type.nil?)
+
+                type = 'new'
+              elsif full_line == conflict_middle
+                validate_delimiter!(type == 'new')
+
+                type = 'old'
+              elsif full_line == conflict_end
+                validate_delimiter!(type == 'old')
+
+                type = nil
+              elsif line[0] == '\\'
+                type = 'nonewline'
+                lines << {
+                  full_line: full_line,
+                  type: type,
+                  line_obj_index: line_obj_index,
+                  line_old: line_old,
+                  line_new: line_new
+                }
+              else
+                lines << {
+                  full_line: full_line,
+                  type: type,
+                  line_obj_index: line_obj_index,
+                  line_old: line_old,
+                  line_new: line_new
+                }
+
+                line_old += 1 if type != 'new'
+                line_new += 1 if type != 'old'
+
+                line_obj_index += 1
+              end
+            end
+
+            raise MissingEndDelimiter unless type.nil?
+
+            lines
+          end
+
+          private
+
+          def validate_text!(text)
+            raise UnmergeableFile if text.blank? # Typically a binary file
+            raise UnmergeableFile if text.length > 200.kilobytes
+
+            text.force_encoding('UTF-8')
+
+            raise UnsupportedEncoding unless text.valid_encoding?
+          end
+
+          def validate_delimiter!(condition)
+            raise UnexpectedDelimiter unless condition
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/conflict/resolver.rb b/lib/gitlab/git/conflict/resolver.rb
new file mode 100644
index 00000000000..df509c5f4ce
--- /dev/null
+++ b/lib/gitlab/git/conflict/resolver.rb
@@ -0,0 +1,91 @@
+module Gitlab
+  module Git
+    module Conflict
+      class Resolver
+        ConflictSideMissing = Class.new(StandardError)
+        ResolutionError = Class.new(StandardError)
+
+        def initialize(repository, our_commit, target_repository, their_commit)
+          @repository = repository
+          @our_commit = our_commit.rugged_commit
+          @target_repository = target_repository
+          @their_commit = their_commit.rugged_commit
+        end
+
+        def conflicts
+          @conflicts ||= begin
+            target_index = @target_repository.rugged.merge_commits(@our_commit, @their_commit)
+
+            # We don't need to do `with_repo_branch_commit` here, because the target
+            # project always fetches source refs when creating merge request diffs.
+            target_index.conflicts.map do |conflict|
+              raise ConflictSideMissing unless conflict[:theirs] && conflict[:ours]
+
+              Gitlab::Git::Conflict::File.new(
+                @target_repository,
+                @our_commit.oid,
+                conflict,
+                target_index.merge_file(conflict[:ours][:path])[:data]
+              )
+            end
+          end
+        end
+
+        def resolve_conflicts(user, files, source_branch:, target_branch:, commit_message:)
+          @repository.with_repo_branch_commit(@target_repository, target_branch) do
+            files.each do |file_params|
+              conflict_file = conflict_for_path(file_params[:old_path], file_params[:new_path])
+
+              write_resolved_file_to_index(conflict_file, file_params)
+            end
+
+            unless index.conflicts.empty?
+              missing_files = index.conflicts.map { |file| file[:ours][:path] }
+
+              raise ResolutionError, "Missing resolutions for the following files: #{missing_files.join(', ')}"
+            end
+
+            commit_params = {
+              message: commit_message,
+              parents: [@our_commit, @their_commit].map(&:oid)
+            }
+
+            @repository.commit_index(user, source_branch, index, commit_params)
+          end
+        end
+
+        def conflict_for_path(old_path, new_path)
+          conflicts.find do |conflict|
+            conflict.their_path == old_path && conflict.our_path == new_path
+          end
+        end
+
+        private
+
+        # We can only write when getting the merge index from the source
+        # project, because we will write to that project. We don't use this all
+        # the time because this fetches a ref into the source project, which
+        # isn't needed for reading.
+        def index
+          @index ||= @repository.rugged.merge_commits(@our_commit, @their_commit)
+        end
+
+        def write_resolved_file_to_index(file, params)
+          if params[:sections]
+            resolved_lines = file.resolve_lines(params[:sections])
+            new_file = resolved_lines.map { |line| line[:full_line] }.join("\n")
+
+            new_file << "\n" if file.our_blob.data.ends_with?("\n")
+          elsif params[:content]
+            new_file = file.resolve_content(params[:content])
+          end
+
+          our_path = file.our_path
+
+          index.add(path: our_path, oid: @repository.rugged.write(new_file, :blob), mode: file.our_mode)
+          index.conflict_remove(our_path)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/git/conflict_file.rb b/lib/gitlab/git/conflict_file.rb
deleted file mode 100644
index 95a1a9bbe5b..00000000000
--- a/lib/gitlab/git/conflict_file.rb
+++ /dev/null
@@ -1,84 +0,0 @@
-module Gitlab
-  module Git
-    class ConflictFile
-      attr_reader :content, :their_path, :our_path, :our_mode, :repository
-
-      def initialize(repository, commit_oid, conflict, content)
-        @repository = repository
-        @commit_oid = commit_oid
-        @their_path = conflict[:theirs][:path]
-        @our_path = conflict[:ours][:path]
-        @our_mode = conflict[:ours][:mode]
-        @content = content
-      end
-
-      def lines
-        return @lines if defined?(@lines)
-
-        begin
-          @type = 'text'
-          @lines = Gitlab::Git::ConflictParser.parse(content,
-                                                     our_path: our_path,
-                                                     their_path: their_path)
-        rescue Gitlab::Git::ConflictParser::ParserError
-          @type = 'text-editor'
-          @lines = nil
-        end
-      end
-
-      def type
-        lines unless @type
-
-        @type.inquiry
-      end
-
-      def our_blob
-        # REFACTOR NOTE: the source of `commit_oid` used to be
-        # `merge_request.diff_refs.head_sha`. Instead of passing this value
-        # around the new lib structure, I decided to use `@commit_oid` which is
-        # equivalent to `merge_request.source_branch_head.raw.rugged_commit.oid`.
-        # That is what `merge_request.diff_refs.head_sha` is equivalent to when
-        # `merge_request` is not persisted (see `MergeRequest#diff_head_commit`).
-        # I think using the same oid is more consistent anyways, but if Conflicts
-        # start breaking, the change described above is a good place to look at.
-        @our_blob ||= repository.blob_at(@commit_oid, our_path)
-      end
-
-      def line_code(line)
-        Gitlab::Git::DiffLineCode.generate(our_path, line[:line_new], line[:line_old])
-      end
-
-      def resolve_lines(resolution)
-        section_id = nil
-
-        lines.map do |line|
-          unless line[:type]
-            section_id = nil
-            next line
-          end
-
-          section_id ||= line_code(line)
-
-          case resolution[section_id]
-          when 'head'
-            next unless line[:type] == 'new'
-          when 'origin'
-            next unless line[:type] == 'old'
-          else
-            raise Gitlab::Git::Merge::ResolutionError, "Missing resolution for section ID: #{section_id}"
-          end
-
-          line
-        end.compact
-      end
-
-      def resolve_content(resolution)
-        if resolution == content
-          raise Gitlab::Git::Merge::ResolutionError, "Resolved content has no changes for file #{our_path}"
-        end
-
-        resolution
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/git/conflict_parser.rb b/lib/gitlab/git/conflict_parser.rb
deleted file mode 100644
index 90b03848aee..00000000000
--- a/lib/gitlab/git/conflict_parser.rb
+++ /dev/null
@@ -1,89 +0,0 @@
-module Gitlab
-  module Git
-    class ConflictParser
-      UnresolvableError = Class.new(StandardError)
-      UnmergeableFile = Class.new(UnresolvableError)
-      UnsupportedEncoding = Class.new(UnresolvableError)
-
-      # Recoverable errors - the conflict can be resolved in an editor, but not with
-      # sections.
-      ParserError = Class.new(StandardError)
-      UnexpectedDelimiter = Class.new(ParserError)
-      MissingEndDelimiter = Class.new(ParserError)
-
-      class << self
-        def parse(text, our_path:, their_path:, parent_file: nil)
-          validate_text!(text)
-
-          line_obj_index = 0
-          line_old = 1
-          line_new = 1
-          type = nil
-          lines = []
-          conflict_start = "<<<<<<< #{our_path}"
-          conflict_middle = '======='
-          conflict_end = ">>>>>>> #{their_path}"
-
-          text.each_line.map do |line|
-            full_line = line.delete("\n")
-
-            if full_line == conflict_start
-              validate_delimiter!(type.nil?)
-
-              type = 'new'
-            elsif full_line == conflict_middle
-              validate_delimiter!(type == 'new')
-
-              type = 'old'
-            elsif full_line == conflict_end
-              validate_delimiter!(type == 'old')
-
-              type = nil
-            elsif line[0] == '\\'
-              type = 'nonewline'
-              lines << {
-                full_line: full_line,
-                type: type,
-                line_obj_index: line_obj_index,
-                line_old: line_old,
-                line_new: line_new
-              }
-            else
-              lines << {
-                full_line: full_line,
-                type: type,
-                line_obj_index: line_obj_index,
-                line_old: line_old,
-                line_new: line_new
-              }
-
-              line_old += 1 if type != 'new'
-              line_new += 1 if type != 'old'
-
-              line_obj_index += 1
-            end
-          end
-
-          raise MissingEndDelimiter unless type.nil?
-
-          lines
-        end
-
-        private
-
-        def validate_text!(text)
-          raise UnmergeableFile if text.blank? # Typically a binary file
-          raise UnmergeableFile if text.length > 200.kilobytes
-
-          text.force_encoding('UTF-8')
-
-          raise UnsupportedEncoding unless text.valid_encoding?
-        end
-
-        def validate_delimiter!(condition)
-          raise UnexpectedDelimiter unless condition
-        end
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/git/diff_line_code.rb b/lib/gitlab/git/diff_line_code.rb
deleted file mode 100644
index aab963ba928..00000000000
--- a/lib/gitlab/git/diff_line_code.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-module Gitlab
-  module Git
-    class DiffLineCode
-      def self.generate(file_path, new_line_position, old_line_position)
-        "#{Digest::SHA1.hexdigest(file_path)}_#{old_line_position}_#{new_line_position}"
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/git/merge.rb b/lib/gitlab/git/merge.rb
deleted file mode 100644
index 3a0205c17f4..00000000000
--- a/lib/gitlab/git/merge.rb
+++ /dev/null
@@ -1,89 +0,0 @@
-module Gitlab
-  module Git
-    class Merge
-      ConflictSideMissing = Class.new(StandardError)
-      ResolutionError = Class.new(StandardError)
-
-      def initialize(repository, our_commit, target_repository, their_commit)
-        @repository = repository
-        @our_commit = our_commit.rugged_commit
-        @target_repository = target_repository
-        @their_commit = their_commit.rugged_commit
-      end
-
-      def conflicts
-        @conflicts ||= begin
-          target_index = @target_repository.rugged.merge_commits(@our_commit, @their_commit)
-
-          # We don't need to do `with_repo_branch_commit` here, because the target
-          # project always fetches source refs when creating merge request diffs.
-          target_index.conflicts.map do |conflict|
-            raise ConflictSideMissing unless conflict[:theirs] && conflict[:ours]
-
-            Gitlab::Git::ConflictFile.new(
-              @target_repository,
-              @our_commit.oid,
-              conflict,
-              target_index.merge_file(conflict[:ours][:path])[:data]
-            )
-          end
-        end
-      end
-
-      def resolve_conflicts(user, files, source_branch:, target_branch:, commit_message:)
-        @repository.with_repo_branch_commit(@target_repository, target_branch) do
-          files.each do |file_params|
-            conflict_file = conflict_for_path(file_params[:old_path], file_params[:new_path])
-
-            write_resolved_file_to_index(conflict_file, file_params)
-          end
-
-          unless index.conflicts.empty?
-            missing_files = index.conflicts.map { |file| file[:ours][:path] }
-
-            raise ResolutionError, "Missing resolutions for the following files: #{missing_files.join(', ')}"
-          end
-
-          commit_params = {
-            message: commit_message,
-            parents: [@our_commit, @their_commit].map(&:oid)
-          }
-
-          @repository.commit_index(user, source_branch, index, commit_params)
-        end
-      end
-
-      def conflict_for_path(old_path, new_path)
-        conflicts.find do |conflict|
-          conflict.their_path == old_path && conflict.our_path == new_path
-        end
-      end
-
-      private
-
-      # We can only write when getting the merge index from the source
-      # project, because we will write to that project. We don't use this all
-      # the time because this fetches a ref into the source project, which
-      # isn't needed for reading.
-      def index
-        @index ||= @repository.rugged.merge_commits(@our_commit, @their_commit)
-      end
-
-      def write_resolved_file_to_index(file, params)
-        if params[:sections]
-          resolved_lines = file.resolve_lines(params[:sections])
-          new_file = resolved_lines.map { |line| line[:full_line] }.join("\n")
-
-          new_file << "\n" if file.our_blob.data.ends_with?("\n")
-        elsif params[:content]
-          new_file = file.resolve_content(params[:content])
-        end
-
-        our_path = file.our_path
-
-        index.add(path: our_path, oid: @repository.rugged.write(new_file, :blob), mode: file.our_mode)
-        index.conflict_remove(our_path)
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/github_import/comment_formatter.rb b/lib/gitlab/github_import/comment_formatter.rb
index 6490cd7002d..f8757507b78 100644
--- a/lib/gitlab/github_import/comment_formatter.rb
+++ b/lib/gitlab/github_import/comment_formatter.rb
@@ -38,7 +38,7 @@ module Gitlab
       end
 
       def generate_line_code(line)
-        Gitlab::Git::DiffLineCode.generate(file_path, line.new_pos, line.old_pos)
+        Gitlab::Git::Conflict::LineCode.generate(file_path, line.new_pos, line.old_pos)
       end
 
       def on_diff?