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

import {
  countDays,
  findOverlap,
  MAX_PERIOD_DAYS,
  periodsOverlap,
  upcomingPeriods,
  validatePeriod,
  type NamedPeriod,
} from './vacations';

const period = (startDate: string, endDate: string): { startDate: string; endDate: string } => ({
  startDate,
  endDate,
});

const named = (id: string, startDate: string, endDate: string): NamedPeriod => ({
  id,
  labelFr: id,
  startDate,
  endDate,
});

describe('countDays', () => {
  it('counts both ends', () => {
    // The shop reads "closed from the 20th to the 22nd" as three days.
    expect(countDays(period('2026-09-20', '2026-09-22'))).toBe(3);
  });

  it('counts a single day as one', () => {
    expect(countDays(period('2026-09-20', '2026-09-20'))).toBe(1);
  });

  it('crosses a year boundary', () => {
    expect(countDays(period('2026-12-30', '2027-01-02'))).toBe(4);
  });
});

describe('periodsOverlap', () => {
  it('detects a full overlap', () => {
    expect(periodsOverlap(period('2026-09-20', '2026-09-30'), period('2026-09-22', '2026-09-24'))).toBe(
      true,
    );
  });

  it('detects a partial overlap from either side', () => {
    expect(periodsOverlap(period('2026-09-20', '2026-09-25'), period('2026-09-24', '2026-09-28'))).toBe(
      true,
    );
    expect(periodsOverlap(period('2026-09-24', '2026-09-28'), period('2026-09-20', '2026-09-25'))).toBe(
      true,
    );
  });

  it('counts a single shared day as an overlap', () => {
    expect(periodsOverlap(period('2026-09-20', '2026-09-22'), period('2026-09-22', '2026-09-24'))).toBe(
      true,
    );
  });

  it('leaves adjacent periods alone', () => {
    // Ending on the 22nd and starting on the 23rd share nothing.
    expect(periodsOverlap(period('2026-09-20', '2026-09-22'), period('2026-09-23', '2026-09-25'))).toBe(
      false,
    );
  });

  it('leaves distant periods alone', () => {
    expect(periodsOverlap(period('2026-01-01', '2026-01-10'), period('2026-08-01', '2026-08-10'))).toBe(
      false,
    );
  });
});

describe('findOverlap', () => {
  const existing = [named('été', '2026-07-20', '2026-08-10'), named('noël', '2026-12-24', '2027-01-02')];

  it('names the period that collides', () => {
    expect(findOverlap(period('2026-08-05', '2026-08-15'), existing)?.id).toBe('été');
  });

  it('returns nothing when the candidate is free', () => {
    expect(findOverlap(period('2026-09-01', '2026-09-10'), existing)).toBeNull();
  });

  it('returns nothing against an empty list', () => {
    expect(findOverlap(period('2026-09-01', '2026-09-10'), [])).toBeNull();
  });
});

describe('validatePeriod', () => {
  it('accepts a sound period', () => {
    expect(validatePeriod({ startDate: '2026-07-20', endDate: '2026-08-10', labelFr: 'Congés' })).toEqual(
      [],
    );
  });

  it('refuses missing dates', () => {
    expect(validatePeriod({ startDate: '', endDate: '2026-08-10', labelFr: 'Congés' })).toHaveLength(1);
  });

  it('refuses a reversed range', () => {
    expect(
      validatePeriod({ startDate: '2026-08-10', endDate: '2026-07-20', labelFr: 'Congés' }).join(' '),
    ).toMatch(/précède/);
  });

  it('refuses a period longer than a year', () => {
    expect(
      validatePeriod({ startDate: '2026-01-01', endDate: '2027-06-01', labelFr: 'Congés' }).join(' '),
    ).toMatch(String(MAX_PERIOD_DAYS));
  });

  it('requires a label, because it is shown on the screen', () => {
    expect(
      validatePeriod({ startDate: '2026-07-20', endDate: '2026-08-10', labelFr: '   ' }).join(' '),
    ).toMatch(/libellé/);
  });

  it('reports several problems at once', () => {
    expect(
      validatePeriod({ startDate: '2026-08-10', endDate: '2026-07-20', labelFr: '' }),
    ).toHaveLength(2);
  });
});

describe('upcomingPeriods', () => {
  const periods = [
    named('noël', '2026-12-24', '2027-01-02'),
    named('passé', '2026-02-01', '2026-02-10'),
    named('été', '2026-07-20', '2026-08-10'),
  ];

  it('drops periods that have finished', () => {
    expect(upcomingPeriods(periods, '2026-09-20').map((p) => p.id)).toEqual(['noël']);
  });

  it('keeps a period currently in progress', () => {
    expect(upcomingPeriods(periods, '2026-08-01').map((p) => p.id)).toEqual(['été', 'noël']);
  });

  it('keeps a period ending today', () => {
    expect(upcomingPeriods(periods, '2026-08-10').map((p) => p.id)).toContain('été');
  });

  it('sorts by start date', () => {
    expect(upcomingPeriods(periods, '2026-01-01').map((p) => p.id)).toEqual(['passé', 'été', 'noël']);
  });
});