1 files changed, 30 insertions, 51 deletions

diff --git a/lib/gitlab/import_export/config.rb b/lib/gitlab/import_export/config.rb
index f6cd4eb5e0c..6f4919ead4e 100644
--- a/lib/gitlab/import_export/config.rb
+++ b/lib/gitlab/import_export/config.rb
@@ -3,70 +3,49 @@
 module Gitlab
   module ImportExport
     class Config
+      def initialize
+        @hash = parse_yaml
+        @hash.deep_symbolize_keys!
+        @ee_hash = @hash.delete(:ee) || {}
+
+        @hash[:tree] = normalize_tree(@hash[:tree])
+        @ee_hash[:tree] = normalize_tree(@ee_hash[:tree] || {})
+      end
+
       # Returns a Hash of the YAML file, including EE specific data if EE is
       # used.
       def to_h
-        hash = parse_yaml
-        ee_hash = hash['ee']
-
-        if merge? && ee_hash
-          ee_hash.each do |key, value|
-            if key == 'project_tree'
-              merge_project_tree(value, hash[key])
-            else
-              merge_attributes_list(value, hash[key])
-            end
-          end
+        if merge_ee?
+          deep_merge(@hash, @ee_hash)
+        else
+          @hash
         end
-
-        # We don't want to expose this section after this point, as it is no
-        # longer needed.
-        hash.delete('ee')
-
-        hash
       end
 
-      # Merges a project relationships tree into the target tree.
-      #
-      # @param [Array<Hash|Symbol>] source_values
-      # @param [Array<Hash|Symbol>] target_values
-      def merge_project_tree(source_values, target_values)
-        source_values.each do |value|
-          if value.is_a?(Hash)
-            # Examples:
-            #
-            # { 'project_tree' => [{ 'labels' => [...] }] }
-            # { 'notes' => [:author, { 'events' => [:push_event_payload] }] }
-            value.each do |key, val|
-              target = target_values
-                .find { |h| h.is_a?(Hash) && h[key] }
+      private
 
-              if target
-                merge_project_tree(val, target[key])
-              else
-                target_values << { key => val.dup }
-              end
-            end
-          else
-            # Example: :priorities, :author, etc
-            target_values << value
-          end
+      def deep_merge(hash_a, hash_b)
+        hash_a.deep_merge(hash_b) do |_, this_val, other_val|
+          this_val.to_a + other_val.to_a
         end
       end
 
-      # Merges a Hash containing a flat list of attributes, such as the entries
-      # in a `excluded_attributes` section.
-      #
-      # @param [Hash] source_values
-      # @param [Hash] target_values
-      def merge_attributes_list(source_values, target_values)
-        source_values.each do |key, values|
-          target_values[key] ||= []
-          target_values[key].concat(values)
+      def normalize_tree(item)
+        case item
+        when Array
+          item.reduce({}) do |hash, subitem|
+            hash.merge!(normalize_tree(subitem))
+          end
+        when Hash
+          item.transform_values(&method(:normalize_tree))
+        when Symbol
+          { item => {} }
+        else
+          raise ArgumentError, "#{item} needs to be Array, Hash, Symbol or NilClass"
         end
       end
 
-      def merge?
+      def merge_ee?
         Gitlab.ee?
       end