1 files changed, 71 insertions, 0 deletions
diff --git a/railties/lib/rails/generators/actions/create_migration.rb b/railties/lib/rails/generators/actions/create_migration.rb
new file mode 100644
index 0000000000..05bc242447
--- /dev/null
+++ b/railties/lib/rails/generators/actions/create_migration.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require "fileutils"
+require "thor/actions"
+
+module Rails
+  module Generators
+    module Actions
+      class CreateMigration < Thor::Actions::CreateFile #:nodoc:
+        def migration_dir
+          File.dirname(@destination)
+        end
+
+        def migration_file_name
+          @base.migration_file_name
+        end
+
+        def identical?
+          exists? && File.binread(existing_migration) == render
+        end
+
+        def revoke!
+          say_destination = exists? ? relative_existing_migration : relative_destination
+          say_status :remove, :red, say_destination
+          return unless exists?
+          ::FileUtils.rm_rf(existing_migration) unless pretend?
+          existing_migration
+        end
+
+        def relative_existing_migration
+          base.relative_to_original_destination_root(existing_migration)
+        end
+
+        def existing_migration
+          @existing_migration ||= begin
+            @base.class.migration_exists?(migration_dir, migration_file_name) ||
+            File.exist?(@destination) && @destination
+          end
+        end
+        alias :exists? :existing_migration
+
+        private
+
+          def on_conflict_behavior # :doc:
+            options = base.options.merge(config)
+            if identical?
+              say_status :identical, :blue, relative_existing_migration
+            elsif options[:force]
+              say_status :remove, :green, relative_existing_migration
+              say_status :create, :green
+              unless pretend?
+                ::FileUtils.rm_rf(existing_migration)
+                yield
+              end
+            elsif options[:skip]
+              say_status :skip, :yellow
+            else
+              say_status :conflict, :red
+              raise Error, "Another migration is already named #{migration_file_name}: " \
+                "#{existing_migration}. Use --force to replace this migration " \
+                "or --skip to ignore conflicted file."
+            end
+          end
+
+          def say_status(status, color, message = relative_destination) # :doc:
+            base.shell.say_status(status, message, color) if config[:verbose]
+          end
+      end
+    end
+  end
+end