タグ説明移行 (#422) (#423)

Reviewed-on: #423
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/services/wiki/compatibility_writer.rb

@@ -0,0 +1,33 @@
+module Wiki
+  class CompatibilityWriter
+    def self.create! tag_name:, body:, created_by_user:, message: nil
+      Commit.create_legacy_content!(
+          tag_name:, body:, created_by_user:, message:)
+    end
+
+    def self.update! page:, body:, updated_by_user:, message: nil,
+                     base_revision_id: nil
+      normalised = Commit.normalise_body(body)
+      if normalised.blank?
+        return Commit.legacy_content!(
+            page:, body: normalised, created_user: updated_by_user, message:,
+            base_revision_id:)
+      end
+
+      if base_revision_id.present?
+        current_id = page.wiki_revisions.maximum(:id)
+        if current_id && current_id != base_revision_id.to_i
+          raise Commit::Conflict,
+              "競合が発生してゐます" +
+              "（現在の Id.：#{ current_id }，ベース Id.：#{ base_revision_id }）．"
+        end
+      end
+
+      return if Commit.normalise_body(page.body) == normalised
+
+      Commit.legacy_content!(
+          page:, body: normalised, created_user: updated_by_user, message:,
+          base_revision_id:)
+    end
+  end
+end