feat(utils/env-manager): adds environment variables manager

package.json

@@ -126,6 +126,7 @@
     "js-yaml": "^3.13.1",
     "loglevel": "^1.6.1",
     "manage-path": "^2.0.0",
+    "path-key": "^3.1.0",
     "pify": "^4.0.1",
     "promist": "^0.5.3",
     "prompts": "^2.0.4",

src/utils/env-manager.ts

@@ -0,0 +1,37 @@
+import pathKey from 'path-key';
+import alter from 'manage-path';
+import { IOfType } from '~/types';
+
+export default class EnvManager {
+  private key: string;
+  private env: IOfType<string | undefined>;
+  private initial: IOfType<string | undefined>;
+  private assigned: IOfType<string | undefined>;
+  public constructor(env: IOfType<string | undefined>) {
+    this.key = pathKey({ env });
+    this.env = env;
+    this.initial = Object.assign({}, env);
+    this.assigned = {};
+  }
+  public assign(env: IOfType<string | undefined>): void {
+    Object.assign(this.env, env);
+    Object.assign(this.assigned, env);
+  }
+  public addPaths(paths: string[]): void {
+    const env = { [this.key]: this.env[this.key] };
+    alter(env).unshift(paths);
+    this.assign(env);
+  }
+  public restore(): void {
+    const toRestore = Object.keys(this.assigned).reduce(
+      (acc: IOfType<string | undefined>, key) => {
+        if (this.env[key] === this.assigned[key]) acc[key] = this.initial[key];
+        return acc;
+      },
+      {}
+    );
+
+    Object.assign(this.env, toRestore);
+    this.assigned = {};
+  }
+}