import { afterEach, describe, expect, it, vi } from 'vitest';
import type { Instance, InstancePage } from '@multi-simadmin/contracts';

import type { InstanceService } from '../instances/instance-service.js';
import type { ConnectionProbe } from './connection-probe.js';
import type { ConnectionSettingsService } from './connection-settings-service.js';
import { FleetHeartbeatCoordinator } from './fleet-heartbeat.js';

function instance(id: string): Instance {
  return {
    id,
    name: id,
    origin: `http://10.0.0.1:3000`,
    authMode: 'none',
    configRevision: 1,
    createdAt: '2026-09-05T00:00:00.000Z',
    updatedAt: '2026-09-05T00:00:00.000Z',
  } as unknown as Instance;
}

function page(items: readonly Instance[], pageSize: number): InstancePage {
  return { items: [...items], page: { page: 1, pageSize, total: items.length } };
}

function coordinator(options: {
  readonly pages: ReadonlyMap<number, readonly Instance[]>;
  readonly pageSize: number;
  readonly probe?: (id: string) => Promise<void>;
  readonly heartbeatMs?: number;
  readonly concurrency?: number;
}) {
  const listed: string[] = [];
  const instances = {
    async list(query: { page?: number; pageSize?: number }) {
      const pageSize = options.pageSize;
      const current = query.page ?? 1;
      listed.push(String(current));
      return page(options.pages.get(current) ?? [], pageSize);
    },
  } as unknown as InstanceService;
  const probed: string[] = [];
  const probe = {
    async test(id: string) {
      probed.push(id);
      await options.probe?.(id);
      return { instanceId: id, authenticated: true, checkedAt: '2026-09-05T00:00:00.000Z' };
    },
  } as unknown as ConnectionProbe;
  const settings = {
    heartbeatMs: options.heartbeatMs ?? 30_000,
  } as unknown as ConnectionSettingsService;
  const beat = new FleetHeartbeatCoordinator({
    instances,
    probe,
    settings,
    pageSize: options.pageSize,
    now: () => new Date('2026-09-05T00:00:00.000Z'),
    ...(options.concurrency === undefined ? {} : { concurrency: options.concurrency }),
  });
  return { beat, listed, probed };
}

afterEach(() => {
  vi.useRealTimers();
});

describe('FleetHeartbeatCoordinator', () => {
  it('probes every instance once across pages', async () => {
    const { beat, listed, probed } = coordinator({
      pageSize: 2,
      pages: new Map([
        [1, [instance('a'), instance('b')]],
        [2, [instance('c')]],
      ]),
    });
    await expect(beat.runOnce()).resolves.toEqual({
      probed: 3,
      failed: 0,
      startedAt: '2026-09-05T00:00:00.000Z',
      finishedAt: '2026-09-05T00:00:00.000Z',
    });
    expect(listed).toEqual(['1', '2']);
    expect([...probed].sort()).toEqual(['a', 'b', 'c']);
  });

  it('stops paging on a short page and probes a duplicated id once', async () => {
    const { beat, listed, probed } = coordinator({
      pageSize: 2,
      pages: new Map([[1, [instance('a'), instance('a')]]]),
    });
    await beat.runOnce();
    expect(listed).toEqual(['1', '2']);
    expect(probed).toEqual(['a']);
  });

  it('counts a failing device without abandoning the rest of the fleet', async () => {
    const { beat } = coordinator({
      pageSize: 10,
      concurrency: 1,
      pages: new Map([[1, [instance('a'), instance('b'), instance('c')]]]),
      probe: async (id) => {
        if (id === 'b') throw new Error('ECONNREFUSED');
      },
    });
    await expect(beat.runOnce()).resolves.toMatchObject({ probed: 2, failed: 1 });
  });

  it('shares one pass between concurrent refresh requests', async () => {
    let release: (() => void) | undefined;
    const gate = new Promise<void>((resolve) => {
      release = resolve;
    });
    const { beat, probed } = coordinator({
      pageSize: 10,
      concurrency: 1,
      pages: new Map([[1, [instance('a')]]]),
      probe: () => gate,
    });
    const first = beat.runOnce();
    const second = beat.runOnce();
    release?.();
    await Promise.all([first, second]);
    expect(probed).toEqual(['a']);
  });

  it('runs a beat on the configured cadence and stops cleanly', async () => {
    vi.useFakeTimers();
    const { beat, probed } = coordinator({
      pageSize: 10,
      pages: new Map([[1, [instance('a')]]]),
      heartbeatMs: 5_000,
    });
    beat.start();
    beat.start();
    await vi.advanceTimersByTimeAsync(5_000);
    expect(probed).toEqual(['a']);
    await vi.advanceTimersByTimeAsync(5_000);
    expect(probed).toEqual(['a', 'a']);
    beat.stop();
    await vi.advanceTimersByTimeAsync(60_000);
    expect(probed).toHaveLength(2);
  });

  it('refuses an unusable worker or page size', () => {
    const base = {
      instances: {} as unknown as InstanceService,
      probe: {} as unknown as ConnectionProbe,
      settings: {} as unknown as ConnectionSettingsService,
    };
    expect(() => new FleetHeartbeatCoordinator({ ...base, concurrency: 0 })).toThrow(RangeError);
    expect(() => new FleetHeartbeatCoordinator({ ...base, concurrency: 17 })).toThrow(RangeError);
    expect(() => new FleetHeartbeatCoordinator({ ...base, pageSize: 0 })).toThrow(RangeError);
    expect(() => new FleetHeartbeatCoordinator({ ...base, pageSize: 101 })).toThrow(RangeError);
  });
});