import { describe, expect, test } from 'vitest';

import {
  createRequestSequencer,
  isNearBottom,
  NEAR_BOTTOM_THRESHOLD,
  RECOVERY_THRESHOLD,
  shouldShowRecovery,
} from '@/components/agent-workspace/workspace-helpers';

describe('createRequestSequencer', () => {
  test('only the latest issued token is considered current', () => {
    const sequencer = createRequestSequencer();
    const first = sequencer.next();
    const second = sequencer.next();

    // Simulate the first (slower) request resolving after the second: it is
    // stale and must be dropped.
    expect(sequencer.isLatest(first)).toBe(false);
    // The newest request wins.
    expect(sequencer.isLatest(second)).toBe(true);
  });

  test('a fresh request supersedes a previously latest one', () => {
    const sequencer = createRequestSequencer();
    const token = sequencer.next();
    expect(sequencer.isLatest(token)).toBe(true);
    sequencer.next();
    expect(sequencer.isLatest(token)).toBe(false);
  });
});

describe('shouldShowRecovery', () => {
  test('defaults to a threshold of 3 consecutive failures', () => {
    expect(RECOVERY_THRESHOLD).toBe(3);
    expect(shouldShowRecovery(0)).toBe(false);
    expect(shouldShowRecovery(1)).toBe(false);
    expect(shouldShowRecovery(2)).toBe(false);
    expect(shouldShowRecovery(3)).toBe(true);
    expect(shouldShowRecovery(4)).toBe(true);
  });

  test('honours a custom threshold', () => {
    expect(shouldShowRecovery(1, 2)).toBe(false);
    expect(shouldShowRecovery(2, 2)).toBe(true);
  });
});

describe('isNearBottom', () => {
  test('true when within the threshold band of the bottom', () => {
    expect(
      isNearBottom({ scrollHeight: 1000, scrollTop: 940, clientHeight: 100 }),
    ).toBe(true);
  });

  test('false when scrolled up beyond the threshold', () => {
    expect(
      isNearBottom({ scrollHeight: 1000, scrollTop: 200, clientHeight: 100 }),
    ).toBe(false);
  });

  test('uses NEAR_BOTTOM_THRESHOLD as the default band', () => {
    expect(NEAR_BOTTOM_THRESHOLD).toBe(80);
    // Exactly at the threshold is not "near" (strict less-than).
    expect(
      isNearBottom({ scrollHeight: 1000, scrollTop: 820, clientHeight: 100 }),
    ).toBe(false);
    expect(
      isNearBottom({ scrollHeight: 1000, scrollTop: 821, clientHeight: 100 }),
    ).toBe(true);
  });
});