/**
 * Pure-function unit tests for recommender logic — no DB, no HTTP.
 * These can import directly from the module without any mocking.
 */
import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
import { inferReward, dueAgeDays, pickPromptVersion } from '../recommender.js';
import { config } from '../../config.js';

describe('inferReward', () => {
  it('dismiss → -1', () => expect(inferReward('dismiss', null)).toBe(-1.0));
  it('snooze → +0.1', () => expect(inferReward('snooze', null)).toBe(0.1));
  it('helpful → +0.5', () => expect(inferReward('helpful', null)).toBe(0.5));
  it('not_helpful → -0.5', () => expect(inferReward('not_helpful', null)).toBe(-0.5));
  it('done with null dwell → +0.5', () => expect(inferReward('done', null)).toBe(0.5));
  it('done < 15s (reflex) → -0.3', () => expect(inferReward('done', 5_000)).toBe(-0.3));
  it('done 15s–2min (magic) → +1.0', () => expect(inferReward('done', 60_000)).toBe(1.0));
  it('done 2–10min (good) → +0.6', () => expect(inferReward('done', 300_000)).toBe(0.6));
  it('done > 10min (eventual) → +0.3', () => expect(inferReward('done', 700_000)).toBe(0.3));
  it('done exactly 15s (boundary) → magic zone', () => expect(inferReward('done', 15_000)).toBe(1.0));
  it('done exactly 2min (boundary) → good zone', () => expect(inferReward('done', 120_000)).toBe(0.6));
});

describe('dueAgeDays', () => {
  it('null due → 0', () => expect(dueAgeDays(null)).toBe(0));
  it('empty object → 0', () => expect(dueAgeDays({})).toBe(0));
  it('future date → 0 (clamped)', () => {
    const future = new Date(Date.now() + 86_400_000).toISOString();
    expect(dueAgeDays({ datetime: future })).toBe(0);
  });
  it('past date → positive age', () => {
    const twoDaysAgo = new Date(Date.now() - 2 * 86_400_000).toISOString();
    const age = dueAgeDays({ datetime: twoDaysAgo });
    expect(age).toBeGreaterThan(1.9);
    expect(age).toBeLessThan(2.1);
  });
  it('date-only field used when datetime absent', () => {
    const yesterday = new Date(Date.now() - 86_400_000).toISOString().slice(0, 10);
    expect(dueAgeDays({ date: yesterday })).toBeGreaterThan(0);
  });
});

describe('pickPromptVersion', () => {
  // Save + restore the original env-driven config field across tests.
  let original: string;
  beforeEach(() => { original = config.TIP_PROMPT_VERSION; });
  afterEach(() => { (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = original; });

  it('empty config → null (let ml/serving pick its default)', () => {
    (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = '';
    expect(pickPromptVersion()).toBeNull();
  });

  it('whitespace-only config → null', () => {
    (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = '  ';
    expect(pickPromptVersion()).toBeNull();
  });

  it('single value → that value', () => {
    (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = 'v2-mentor';
    expect(pickPromptVersion()).toBe('v2-mentor');
  });

  it('comma-separated → uniformly samples from the set', () => {
    (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = 'v1,v2-mentor,v3-few-shot';
    const seen = new Set<string>();
    // With 100 trials, the chance of missing any of 3 buckets is (2/3)^100 ≈ 0 — test is reliable.
    for (let i = 0; i < 100; i++) {
      const picked = pickPromptVersion();
      expect(picked).not.toBeNull();
      seen.add(picked!);
    }
    expect(seen).toEqual(new Set(['v1', 'v2-mentor', 'v3-few-shot']));
  });

  it('trims whitespace around comma-separated entries', () => {
    (config as { TIP_PROMPT_VERSION: string }).TIP_PROMPT_VERSION = ' v1 , v2-mentor ';
    for (let i = 0; i < 20; i++) {
      const picked = pickPromptVersion()!;
      expect(['v1', 'v2-mentor']).toContain(picked);
    }
  });
});