[PM-5606] Add reactive generator service (#7446)

libs/common/src/tools/generator/abstractions/generator-strategy.abstraction.ts

@@ -0,0 +1,32 @@
+import { PolicyType } from "../../../admin-console/enums";
+// FIXME: use index.ts imports once policy abstractions and models
+// implement ADR-0002
+import { Policy as AdminPolicy } from "../../../admin-console/models/domain/policy";
+import { KeyDefinition } from "../../../platform/state";
+
+import { PolicyEvaluator } from "./policy-evaluator.abstraction";
+
+/** Tailors the generator service to generate a specific kind of credentials */
+export abstract class GeneratorStrategy<Options, Policy> {
+  /** The key used when storing credentials on disk. */
+  disk: KeyDefinition<Options>;
+
+  /** Identifies the policy enforced by the generator. */
+  policy: PolicyType;
+
+  /** Length of time in milliseconds to cache the evaluator */
+  cache_ms: number;
+
+  /** Creates an evaluator from a generator policy.
+   * @param policy The policy being evaluated.
+   * @returns the policy evaluator.
+   * @throws when the policy's type does not match the generator's policy type.
+   */
+  evaluator: (policy: AdminPolicy) => PolicyEvaluator<Policy, Options>;
+
+  /** Generates credentials from the given options.
+   * @param options The options used to generate the credentials.
+   * @returns a promise that resolves to the generated credentials.
+   */
+  generate: (options: Options) => Promise<string>;
+}