[PM-5972] add subaddress generator strategy (#7897)

libs/common/src/tools/generator/username/subaddress-generator-strategy.ts

@@ -0,0 +1,56 @@
+import { PolicyType } from "../../../admin-console/enums";
+import { Policy } from "../../../admin-console/models/domain/policy";
+import { GeneratorStrategy } from "../abstractions";
+import { DefaultPolicyEvaluator } from "../default-policy-evaluator";
+import { SUBADDRESS_SETTINGS } from "../key-definitions";
+import { NoPolicy } from "../no-policy";
+
+import { SubaddressGenerationOptions } from "./subaddress-generator-options";
+import { UsernameGenerationServiceAbstraction } from "./username-generation.service.abstraction";
+
+const ONE_MINUTE = 60 * 1000;
+
+/** Strategy for creating an email subaddress */
+export class SubaddressGeneratorStrategy
+  implements GeneratorStrategy<SubaddressGenerationOptions, NoPolicy>
+{
+  /** Instantiates the generation strategy
+   *  @param usernameService generates an email subaddress from an email address
+   */
+  constructor(private usernameService: UsernameGenerationServiceAbstraction) {}
+
+  /** {@link GeneratorStrategy.disk} */
+  get disk() {
+    return SUBADDRESS_SETTINGS;
+  }
+
+  /** {@link GeneratorStrategy.policy} */
+  get policy() {
+    // Uses password generator since there aren't policies
+    // specific to usernames.
+    return PolicyType.PasswordGenerator;
+  }
+
+  /** {@link GeneratorStrategy.cache_ms} */
+  get cache_ms() {
+    return ONE_MINUTE;
+  }
+
+  /** {@link GeneratorStrategy.evaluator} */
+  evaluator(policy: Policy) {
+    if (policy.type !== this.policy) {
+      const details = `Expected: ${this.policy}. Received: ${policy.type}`;
+      throw Error("Mismatched policy type. " + details);
+    }
+
+    return new DefaultPolicyEvaluator<SubaddressGenerationOptions>();
+  }
+
+  /** {@link GeneratorStrategy.generate} */
+  generate(options: SubaddressGenerationOptions) {
+    return this.usernameService.generateSubaddress({
+      subaddressEmail: options.email,
+      subaddressType: options.type,
+    });
+  }
+}