feat: refactor folder structure (#4498)

* feat: wip refactor folder structure

* Fix

* fix position

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine-metadata/relation-metadata/hooks/before-delete-one-field.hook.ts

@@ -0,0 +1,55 @@
+import {
+  BadRequestException,
+  Injectable,
+  UnauthorizedException,
+} from '@nestjs/common';
+
+import {
+  BeforeDeleteOneHook,
+  DeleteOneInputType,
+} from '@ptc-org/nestjs-query-graphql';
+
+import { RelationMetadataService } from 'src/engine-metadata/relation-metadata/relation-metadata.service';
+
+@Injectable()
+export class BeforeDeleteOneRelation implements BeforeDeleteOneHook<any> {
+  constructor(readonly relationMetadataService: RelationMetadataService) {}
+
+  async run(
+    instance: DeleteOneInputType,
+    context: any,
+  ): Promise<DeleteOneInputType> {
+    const workspaceId = context?.req?.user?.workspace?.id;
+
+    if (!workspaceId) {
+      throw new UnauthorizedException();
+    }
+
+    const relationMetadata =
+      await this.relationMetadataService.findOneWithinWorkspace(workspaceId, {
+        where: {
+          id: instance.id.toString(),
+        },
+      });
+
+    if (!relationMetadata) {
+      throw new BadRequestException('Relation does not exist');
+    }
+
+    if (
+      !relationMetadata.toFieldMetadata.isCustom ||
+      !relationMetadata.fromFieldMetadata.isCustom
+    ) {
+      throw new BadRequestException("Standard Relations can't be deleted");
+    }
+
+    if (
+      relationMetadata.toFieldMetadata.isActive ||
+      relationMetadata.fromFieldMetadata.isActive
+    ) {
+      throw new BadRequestException("Active relations can't be deleted");
+    }
+
+    return instance;
+  }
+}