1 files changed, 99 insertions, 0 deletions
diff --git a/app/services/import_csv/base_service.rb b/app/services/import_csv/base_service.rb
new file mode 100644
index 00000000000..feb76425fb4
--- /dev/null
+++ b/app/services/import_csv/base_service.rb
@@ -0,0 +1,99 @@
+# frozen_string_literal: true
+
+module ImportCsv
+  class BaseService
+    def initialize(user, project, csv_io)
+      @user = user
+      @project = project
+      @csv_io = csv_io
+      @results = { success: 0, error_lines: [], parse_error: false }
+    end
+
+    def execute
+      process_csv
+      email_results_to_user
+
+      results
+    end
+
+    def email_results_to_user
+      raise NotImplementedError
+    end
+
+    private
+
+    attr_reader :user, :project, :csv_io, :results
+
+    def attributes_for(row)
+      raise NotImplementedError
+    end
+
+    def validate_headers_presence!(headers)
+      raise NotImplementedError
+    end
+
+    def create_object_class
+      raise NotImplementedError
+    end
+
+    def process_csv
+      with_csv_lines.each do |row, line_no|
+        attributes = attributes_for(row)
+
+        if create_object(attributes)&.persisted?
+          results[:success] += 1
+        else
+          results[:error_lines].push(line_no)
+        end
+      end
+    rescue ArgumentError, CSV::MalformedCSVError
+      results[:parse_error] = true
+    end
+
+    def with_csv_lines
+      csv_data = @csv_io.open(&:read).force_encoding(Encoding::UTF_8)
+      validate_headers_presence!(csv_data.lines.first)
+
+      CSV.new(
+        csv_data,
+        col_sep: detect_col_sep(csv_data.lines.first),
+        headers: true,
+        header_converters: :symbol
+      ).each.with_index(2)
+    end
+
+    def detect_col_sep(header)
+      if header.include?(",")
+        ","
+      elsif header.include?(";")
+        ";"
+      elsif header.include?("\t")
+        "\t"
+      else
+        raise CSV::MalformedCSVError.new('Invalid CSV format', 1)
+      end
+    end
+
+    def create_object(attributes)
+      # NOTE: CSV imports are performed by workers, so we do not have a request context in order
+      # to create a SpamParams object to pass to the issuable create service.
+      spam_params = nil
+
+      # default_params can be extracted into a method if we need
+      # to support creation of objects that belongs to groups.
+      default_params = { container: project,
+                         current_user: user,
+                         params: attributes,
+                         spam_params: spam_params }
+
+      create_service = create_object_class.new(**default_params.merge(extra_create_service_params))
+
+      create_service.execute_without_rate_limiting
+    end
+
+    # Overidden in subclasses to support specific parameters
+    def extra_create_service_params
+      {}
+    end
+  end
+end