import { test } from 'node:test';
import assert from 'node:assert/strict';
import { workingDays, generateSchedule, isAbsent, addDays, isValidDate, countAssignments } from '../server/scheduler.js';

function seeded(seed = 42) {
  let s = seed;
  return () => { s = (s * 1664525 + 1013904223) % 4294967296; return s / 4294967296; };
}
const persons = (n, extra = {}) => Array.from({ length: n }, (_, i) => ({ id: `p${i}`, canMain: true, canCo: true, active: true, ...extra }));

test('workingDays liefert nur Mo–Fr ohne blockierte Tage', () => {
  // 2026-09-14 ist ein Montag
  const days = workingDays('2026-09-12', '2026-09-20', new Set(['2026-09-16']));
  assert.deepEqual(days, ['2026-09-14', '2026-09-15', '2026-09-17', '2026-09-18']);
});

test('isValidDate lehnt Unsinn ab', () => {
  assert.ok(isValidDate('2026-02-28'));
  assert.ok(!isValidDate('2026-02-30'));
  assert.ok(!isValidDate('2026-2-3'));
  assert.ok(!isValidDate('heute'));
});

test('jeder Werktag bekommt zwei verschiedene Personen', () => {
  const dates = workingDays('2026-10-01', '2026-10-31');
  const result = generateSchedule({ dates, persons: persons(6), rng: seeded(1) });
  for (const d of dates) {
    assert.ok(result[d].main, `main fehlt am ${d}`);
    assert.ok(result[d].co, `co fehlt am ${d}`);
    assert.notEqual(result[d].main, result[d].co);
  }
});

test('Einsätze sind fair verteilt (Differenz höchstens 1)', () => {
  const dates = workingDays('2026-10-01', '2026-12-31');
  const result = generateSchedule({ dates, persons: persons(7), rng: seeded(7) });
  const counts = countAssignments(result, '2026-10-01', '2026-12-31');
  const totals = Object.values(counts).map((c) => c.total);
  assert.equal(totals.length, 7);
  assert.ok(Math.max(...totals) - Math.min(...totals) <= 1, `Verteilung: ${totals}`);
  // Rollen ebenfalls ausgewogen
  for (const c of Object.values(counts)) assert.ok(Math.abs(c.main - c.co) <= 2, JSON.stringify(c));
});

test('Abwesende werden nicht eingeplant', () => {
  const dates = workingDays('2026-10-05', '2026-10-09');
  const absences = [{ personId: 'p0', from: '2026-10-06', to: '2026-10-08' }];
  const result = generateSchedule({ dates, persons: persons(3), absences, rng: seeded(3) });
  for (const d of ['2026-10-06', '2026-10-07', '2026-10-08']) {
    assert.notEqual(result[d].main, 'p0');
    assert.notEqual(result[d].co, 'p0');
  }
  assert.ok(isAbsent('p0', '2026-10-07', absences));
  assert.ok(!isAbsent('p0', '2026-10-09', absences));
});

test('Nicht-Moderatoren und Inaktive werden nie ausgelost, Nur-Neben nie Haupt', () => {
  const ps = [
    ...persons(3),
    { id: 'none', canMain: false, canCo: false, active: true },
    { id: 'gone', canMain: true, canCo: true, active: false },
    { id: 'coonly', canMain: false, canCo: true, active: true },
  ];
  const dates = workingDays('2026-10-01', '2026-11-30');
  const result = generateSchedule({ dates, persons: ps, rng: seeded(9) });
  const used = new Set();
  for (const a of Object.values(result)) { used.add(a.main); used.add(a.co); assert.notEqual(a.main, 'coonly'); }
  assert.ok(!used.has('none'));
  assert.ok(!used.has('gone'));
  assert.ok(used.has('coonly'));
});

test('niemand an zwei Werktagen hintereinander, wenn genug Leute da sind', () => {
  const dates = workingDays('2026-10-01', '2026-10-31');
  const result = generateSchedule({ dates, persons: persons(6), rng: seeded(11) });
  for (let i = 1; i < dates.length; i += 1) {
    const prev = [result[dates[i - 1]].main, result[dates[i - 1]].co];
    const cur = [result[dates[i]].main, result[dates[i]].co];
    for (const id of cur) assert.ok(!prev.includes(id), `${id} am ${dates[i - 1]} und ${dates[i]}`);
  }
});

test('fixierte und freie Tage bleiben erhalten, keep-Tage ebenfalls', () => {
  const dates = workingDays('2026-10-05', '2026-10-09');
  const existing = {
    '2026-10-05': { main: 'p2', co: 'p1', locked: true },
    '2026-10-06': { off: true, main: null, co: null, locked: false },
    '2026-10-07': { main: 'p0', co: 'p2', locked: false, keep: true },
  };
  const result = generateSchedule({ dates, persons: persons(4), existing, rng: seeded(5) });
  assert.deepEqual(result['2026-10-05'], { main: 'p2', co: 'p1', locked: true });
  assert.equal(result['2026-10-06'].off, true);
  assert.deepEqual(result['2026-10-07'], { main: 'p0', co: 'p2', locked: false });
  assert.ok(result['2026-10-08'].main);
});

test('Historie zählt für die Fairness – wer viel dran war, kommt seltener', () => {
  const history = {};
  // p0 und p1 waren in den letzten zwei Wochen jeden Tag dran
  for (const d of workingDays('2026-09-14', '2026-09-25')) history[d] = { main: 'p0', co: 'p1' };
  const dates = workingDays('2026-09-28', '2026-10-09');
  const result = generateSchedule({ dates, persons: persons(6), history, rng: seeded(2) });
  const counts = countAssignments(result, '2026-09-28', '2026-10-09');
  const heavy = (counts.p0?.total || 0) + (counts.p1?.total || 0);
  const light = ['p2', 'p3', 'p4', 'p5'].reduce((n, id) => n + (counts[id]?.total || 0), 0);
  assert.equal(heavy, 0, `p0/p1 sollten aussetzen: ${JSON.stringify(counts)}`);
  assert.equal(light, dates.length * 2);
});

test('ohne Kandidaten bleibt der Platz leer statt zu scheitern', () => {
  const result = generateSchedule({ dates: ['2026-10-05'], persons: [{ id: 'a', canMain: true, canCo: false, active: true }], rng: seeded(1) });
  assert.equal(result['2026-10-05'].main, 'a');
  assert.equal(result['2026-10-05'].co, null);
  const empty = generateSchedule({ dates: ['2026-10-05'], persons: [] });
  assert.equal(empty['2026-10-05'].main, null);
});

test('addDays über Monatsgrenzen', () => {
  assert.equal(addDays('2026-01-31', 1), '2026-02-01');
  assert.equal(addDays('2026-03-01', -1), '2026-02-28');
});

test('feste freie Wochentage (Teilzeit) werden respektiert', async () => {
  const { isAvailable, isoWeekday } = await import('../server/scheduler.js');
  assert.equal(isoWeekday('2026-10-05'), 1);
  assert.equal(isoWeekday('2026-10-11'), 7);
  const ps = [...persons(4), { id: 'teilzeit', canMain: true, canCo: true, active: true, freeDays: [1, 5] }];
  const dates = workingDays('2026-10-01', '2026-11-30');
  const result = generateSchedule({ dates, persons: ps, rng: seeded(4) });
  for (const d of dates) {
    const wd = isoWeekday(d);
    if (wd === 1 || wd === 5) assert.ok(result[d].main !== 'teilzeit' && result[d].co !== 'teilzeit', `Teilzeit am ${d}`);
  }
  assert.ok(Object.values(result).some((a) => a.main === 'teilzeit' || a.co === 'teilzeit'));
  assert.ok(!isAvailable({ id: 'x', freeDays: [3] }, '2026-10-07', []));
  assert.ok(isAvailable({ id: 'x', freeDays: [3] }, '2026-10-08', []));
});

test('„nicht zwei Werktage in Folge" gilt auch über einen Feiertag hinweg', () => {
  // Mi 2026-10-07 blockiert → Di und Do gelten als aufeinanderfolgend
  const blocked = new Set(['2026-10-07']);
  const dates = workingDays('2026-10-06', '2026-10-08', blocked);
  assert.deepEqual(dates, ['2026-10-06', '2026-10-08']);
  for (let seed = 1; seed <= 20; seed += 1) {
    const result = generateSchedule({ dates, persons: persons(6), blocked, rng: seeded(seed) });
    const tue = [result['2026-10-06'].main, result['2026-10-06'].co];
    for (const id of [result['2026-10-08'].main, result['2026-10-08'].co]) assert.ok(!tue.includes(id), `seed ${seed}: ${id} Di und Do`);
  }
});

test('fill: halb besetzte Tage werden nur aufgefüllt, der vorhandene Slot bleibt', () => {
  const existing = { '2026-10-05': { main: 'p2', co: null, locked: false, fill: true }, '2026-10-06': { main: null, co: 'p1', locked: false, fill: true } };
  const result = generateSchedule({ dates: ['2026-10-05', '2026-10-06'], persons: persons(4), existing, rng: seeded(3) });
  assert.equal(result['2026-10-05'].main, 'p2');
  assert.ok(result['2026-10-05'].co && result['2026-10-05'].co !== 'p2');
  assert.equal(result['2026-10-06'].co, 'p1');
  assert.ok(result['2026-10-06'].main && result['2026-10-06'].main !== 'p1');
  assert.equal('fill' in result['2026-10-05'], false);
});