import { describe, expect, test } from "bun:test";

import { ConcurrencyManager } from "./concurrency";

describe("ConcurrencyManager", () => {
  test("#given limit=2 #when two tasks acquire #then running count is 2", async () => {
    //#given
    const manager = new ConcurrencyManager(2);

    //#when
    await manager.acquire("model:a");
    await manager.acquire("model:a");

    //#then
    expect(manager.getCount("model:a")).toBe(2);
  });

  test("#given limit=2 and two running #when third acquires #then it queues without immediate resolution", async () => {
    //#given
    const manager = new ConcurrencyManager(2);
    await manager.acquire("model:a");
    await manager.acquire("model:a");
    let resolved = false;

    //#when
    const thirdAcquire = manager.acquire("model:a").then(() => {
      resolved = true;
    });
    await Promise.resolve();

    //#then
    expect(manager.getQueueLength("model:a")).toBe(1);
    expect(resolved).toBeFalse();

    manager.release("model:a");
    await thirdAcquire;
    manager.release("model:a");
    manager.release("model:a");
  });

  test("#given limit=2 and queue exists #when one releases #then queued task resolves", async () => {
    //#given
    const manager = new ConcurrencyManager(2);
    await manager.acquire("model:a");
    await manager.acquire("model:a");
    let resolved = false;
    const thirdAcquire = manager.acquire("model:a").then(() => {
      resolved = true;
    });
    await Promise.resolve();
    expect(resolved).toBeFalse();

    //#when
    manager.release("model:a");
    await thirdAcquire;

    //#then
    expect(resolved).toBeTrue();
    expect(manager.getQueueLength("model:a")).toBe(0);
    expect(manager.getCount("model:a")).toBe(2);

    manager.release("model:a");
    manager.release("model:a");
  });
});