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

import { checkRange, earlyClosing, expandRange, lateOpening, MAX_RANGE_DAYS } from './exceptions';
import type { Slot } from './types';

const FULL: Slot[] = [{ open: '10:00', close: '18:30' }];
const SPLIT: Slot[] = [
  { open: '10:00', close: '13:00' },
  { open: '14:00', close: '18:30' },
];

describe('lateOpening', () => {
  it('trims the only slot', () => {
    expect(lateOpening(FULL, '14:00')).toEqual([{ open: '14:00', close: '18:30' }]);
  });

  it('drops a morning that is entirely before the new opening', () => {
    // A shop opening at 14:00 does not keep its 10:00-13:00 morning.
    expect(lateOpening(SPLIT, '14:00')).toEqual([{ open: '14:00', close: '18:30' }]);
  });

  it('trims the slot the new opening falls inside', () => {
    expect(lateOpening(SPLIT, '11:00')).toEqual([
      { open: '11:00', close: '13:00' },
      { open: '14:00', close: '18:30' },
    ]);
  });

  it('changes nothing when the shop already opens later', () => {
    expect(lateOpening(FULL, '09:00')).toEqual(FULL);
  });

  it('closes the day when the new opening is past every slot', () => {
    expect(lateOpening(FULL, '19:00')).toEqual([]);
    expect(lateOpening(SPLIT, '18:30')).toEqual([]);
  });

  it('leaves a closed day closed', () => {
    expect(lateOpening([], '14:00')).toEqual([]);
  });

  it('does not mutate its input', () => {
    const slots = SPLIT.map((slot) => ({ ...slot }));
    lateOpening(slots, '11:00');
    expect(slots).toEqual(SPLIT);
  });
});

describe('earlyClosing', () => {
  it('trims the only slot', () => {
    expect(earlyClosing(FULL, '15:00')).toEqual([{ open: '10:00', close: '15:00' }]);
  });

  it('drops an afternoon that starts after the new closing', () => {
    expect(earlyClosing(SPLIT, '13:00')).toEqual([{ open: '10:00', close: '13:00' }]);
  });

  it('trims the slot the new closing falls inside', () => {
    expect(earlyClosing(SPLIT, '15:00')).toEqual([
      { open: '10:00', close: '13:00' },
      { open: '14:00', close: '15:00' },
    ]);
  });

  it('changes nothing when the shop already closes earlier', () => {
    expect(earlyClosing(FULL, '19:00')).toEqual(FULL);
  });

  it('closes the day when the new closing is before every slot', () => {
    expect(earlyClosing(FULL, '09:00')).toEqual([]);
    expect(earlyClosing(SPLIT, '10:00')).toEqual([]);
  });

  it('is the mirror of lateOpening on a split day', () => {
    // Opening late then closing early must leave the middle of the day.
    expect(earlyClosing(lateOpening(SPLIT, '11:00'), '15:00')).toEqual([
      { open: '11:00', close: '13:00' },
      { open: '14:00', close: '15:00' },
    ]);
  });
});

describe('expandRange', () => {
  it('includes both ends', () => {
    expect(expandRange('2026-09-20', '2026-09-22')).toEqual([
      '2026-09-20',
      '2026-09-21',
      '2026-09-22',
    ]);
  });

  it('handles a single day', () => {
    expect(expandRange('2026-09-20', '2026-09-20')).toEqual(['2026-09-20']);
  });

  it('crosses a month and a year boundary', () => {
    expect(expandRange('2026-12-30', '2027-01-02')).toEqual([
      '2026-12-30',
      '2026-12-31',
      '2027-01-01',
      '2027-01-02',
    ]);
  });

  it('returns nothing for a reversed range', () => {
    expect(expandRange('2026-09-22', '2026-09-20')).toEqual([]);
  });

  it('refuses a range longer than the ceiling', () => {
    // A typo in a year field should produce an error, not thirty thousand rows.
    expect(expandRange('2026-01-01', '2030-01-01')).toEqual([]);
  });

  it('accepts a range exactly at the ceiling', () => {
    const end = expandRange('2026-01-01', '2026-01-01');
    expect(end).toHaveLength(1);
    expect(expandRange('2026-01-01', '2026-04-01').length).toBeLessThanOrEqual(MAX_RANGE_DAYS + 1);
  });
});

describe('checkRange', () => {
  it('accepts a sound range', () => {
    expect(checkRange('2026-09-20', '2026-09-22')).toBeNull();
  });

  it('names each problem', () => {
    expect(checkRange('', '2026-09-22')).toBe('EMPTY');
    expect(checkRange('2026-09-22', '')).toBe('EMPTY');
    expect(checkRange('2026-09-22', '2026-09-20')).toBe('REVERSED');
    expect(checkRange('2026-01-01', '2030-01-01')).toBe('TOO_LONG');
  });
});