feat(): multiple instances support

lib/services/base-explorer.service.ts

@@ -0,0 +1,59 @@
+import { InstanceWrapper } from '@nestjs/core/injector/instance-wrapper';
+import { Module } from '@nestjs/core/injector/module';
+import { flattenDeep, groupBy, identity, isEmpty, mapValues } from 'lodash';
+import { UpdateMetadata } from '../interfaces';
+
+export class BaseExplorerService {
+  getModules(
+    modulesContainer: Map<string, Module>,
+    include: Function[],
+  ): Module[] {
+    if (!include || isEmpty(include)) {
+      return [...modulesContainer.values()];
+    }
+    const whitelisted = this.includeWhitelisted(modulesContainer, include);
+    return whitelisted;
+  }
+
+  includeWhitelisted(
+    modulesContainer: Map<string, Module>,
+    include: Function[],
+  ): Module[] {
+    const modules = [...modulesContainer.values()];
+    return modules.filter(({ metatype }) =>
+      include.some((item) => item === metatype),
+    );
+  }
+
+  flatMap<T = UpdateMetadata>(
+    modules: Module[],
+    callback: (instance: InstanceWrapper, moduleRef: Module) => T | T[],
+  ): T[] {
+    const invokeMap = () => {
+      return modules.map((moduleRef) => {
+        const providers = [...moduleRef.providers.values()];
+        return providers.map((wrapper) => callback(wrapper, moduleRef));
+      });
+    };
+    return flattenDeep(invokeMap()).filter(identity);
+  }
+
+  groupMetadata(resolvers: UpdateMetadata[]) {
+    const groupByType = groupBy(
+      resolvers,
+      (metadata: UpdateMetadata) => metadata.type,
+    );
+    const groupedMetadata = mapValues(
+      groupByType,
+      (resolversArr: UpdateMetadata[]) =>
+        resolversArr.reduce(
+          (prev, curr) => ({
+            ...prev,
+            [curr.name]: curr.callback,
+          }),
+          {},
+        ),
+    );
+    return groupedMetadata;
+  }
+}