import { describe, expect, it } from 'vitest';
import { detectRecencyIntent } from '../recency';

// Fixed "now" so the month-name branch is deterministic: 2026-08-07.
const NOW = new Date('2026-08-07T10:00:00.000Z');

describe('detectRecencyIntent', () => {
  it('recognises the two questions that actually failed against a populated index', () => {
    // Both were asked by a real user and both returned nothing useful, because
    // bm25 matched the WORDS "last"/"July" rather than the dates.
    expect(detectRecencyIntent('who sent the last email', NOW)).not.toBeNull();
    expect(detectRecencyIntent('summarize the input of all mails sent in July', NOW)).not.toBeNull();
  });

  it('turns a month name into a bounded range, not a top-N', () => {
    const intent = detectRecencyIntent('summarize all mails sent in July', NOW);
    // Asserted in LOCAL time on purpose. The bounds are local midnight
    // rendered as UTC instants, so west of UTC the ISO string reads as the
    // previous month - and that is correct, not a bug: a mail that arrived
    // 00:30 local on 1 July belongs to the user's July even though its UTC
    // timestamp says 30 June. Asserting the ISO prefix would enshrine the
    // wrong semantics and pass only in UTC.
    const since = new Date(intent!.since!);
    const until = new Date(intent!.until!);
    expect(since.getMonth()).toBe(6);   // local July...
    expect(since.getDate()).toBe(1);    // ...starting on the 1st
    expect(until.getMonth()).toBe(7);   // exclusive upper bound = local 1 Aug
    expect(until.getDate()).toBe(1);
  });

  it('reads a month later in the year as LAST year', () => {
    // Asked in August, "December" cannot mean four months from now.
    const intent = detectRecencyIntent('what came in December?', NOW);
    const since = new Date(intent!.since!);
    expect(since.getFullYear()).toBe(2025);
    expect(since.getMonth()).toBe(11);
  });

  it('handles today and yesterday as distinct bounded days', () => {
    const today = detectRecencyIntent('anything today?', NOW);
    expect(today?.since).toBeDefined();
    expect(today?.until).toBeUndefined();

    const yesterday = detectRecencyIntent('what arrived yesterday', NOW);
    expect(yesterday?.since).toBeDefined();
    expect(yesterday?.until).toBeDefined();
    expect(new Date(yesterday!.until!).getTime()).toBeGreaterThan(new Date(yesterday!.since!).getTime());
  });

  it('understands German recency wording — the app ships a German UI', () => {
    expect(detectRecencyIntent('welche war die letzte Mail?', NOW)).not.toBeNull();
    expect(detectRecencyIntent('was kam heute an', NOW)).not.toBeNull();
    const juli = detectRecencyIntent('Mails aus Juli zusammenfassen', NOW);
    expect(new Date(juli!.since!).getMonth()).toBe(6);
  });

  it('gives an unbounded top-N when recency is implied but no period named', () => {
    const intent = detectRecencyIntent('what is the newest message', NOW);
    expect(intent?.since).toBeUndefined();
    expect(intent?.until).toBeUndefined();
    expect(intent?.limit).toBeGreaterThan(0);
  });

  it('does NOT fire on pure content questions — those are keyword search\'s job', () => {
    expect(detectRecencyIntent('what did Anna say about the invoice?', NOW)).toBeNull();
    expect(detectRecencyIntent('when is check-in for the Villa sul Lago booking?', NOW)).toBeNull();
    expect(detectRecencyIntent('find the contract with Bechtle', NOW)).toBeNull();
  });

  it('does not treat a word merely CONTAINING a keyword as recency', () => {
    // "newsletter" contains "new"; "lastly" contains "last". Word boundaries
    // matter or half a mailbox reads as a time question.
    expect(detectRecencyIntent('unsubscribe from the newsletter', NOW)).toBeNull();
  });
});