import { test, expect } from "bun:test";
import { createRecycleMonitor } from "../src/recycle.ts";

/** Fresh monitor with a small threshold so tests stay readable. */
function monitor(overrides: Partial<Parameters<typeof createRecycleMonitor>[0]> = {}) {
  const recycled: string[] = [];
  const control = createRecycleMonitor({
    threshold: 3,
    idleMs: 1000,
    onRecycle: (reason) => recycled.push(reason),
    ...overrides,
  });
  return { control, recycled };
}

test("stays quiet below the rebuild threshold", () => {
  const { control, recycled } = monitor();

  control.recordRebuild();
  control.recordRebuild();
  control.tick(10_000);

  expect(recycled).toEqual([]);
});

test("recycles once rebuilds pass the threshold and the server goes idle", () => {
  const { control, recycled } = monitor();

  for (let i = 0; i < 3; i++) control.recordRebuild();
  control.recordRequest(0);
  control.tick(1_500);

  expect(recycled.length).toBe(1);
});

test("waits for the idle gap rather than cutting off active work", () => {
  // Recycling mid-request would drop it. The gap is the whole point.
  const { control, recycled } = monitor();

  for (let i = 0; i < 3; i++) control.recordRebuild();
  control.recordRequest(0);
  control.tick(500);
  expect(recycled).toEqual([]);

  control.recordRequest(900);
  control.tick(1_400);
  expect(recycled).toEqual([]);

  control.tick(2_000);
  expect(recycled.length).toBe(1);
});

test("recycles only once even if it keeps being ticked", () => {
  const { control, recycled } = monitor();

  for (let i = 0; i < 5; i++) control.recordRebuild();
  control.recordRequest(0);
  control.tick(5_000);
  control.tick(6_000);
  control.tick(7_000);

  expect(recycled.length).toBe(1);
});

test("a server that never served a request can still recycle", () => {
  const { control, recycled } = monitor();

  for (let i = 0; i < 3; i++) control.recordRebuild();
  control.tick(9_999);

  expect(recycled.length).toBe(1);
});

test("reports how many rebuilds are being retained", () => {
  const { control } = monitor();

  control.recordRebuild();
  control.recordRebuild();

  expect(control.retained()).toBe(2);
});