import {
  $, api, esc, sortByName, seatsLabel, showError, renderHeader, formatDate,
} from './common.js';

renderHeader('fahrt');

let members = [];
let points = [];

const DEFAULT_DEPARTURE = '07:00';
const MEET_BEFORE_MIN = 15;

// Zustand der aktuellen Fahrt (nur im Browser, wird nicht gespeichert)
const trip = {
  selected: new Set(),   // IDs der mitfahrenden Mitglieder
  bringsCar: new Map(),  // ID -> bool, ob das Auto diesmal dabei ist
  guests: [],            // { id, name, hasCar, seats, guest: true }
  fixed: new Map(),      // Mitfahrer-ID -> Fahrer-ID, feste Zuteilung für diese Fahrt
};

let guestCounter = 0;

// ---------- Treffpunkt und Uhrzeiten ----------
function renderPoints() {
  $('#trip-points-empty').hidden = points.length > 0;
  $('#trip-point').innerHTML = points.length
    ? points.map((p) => `<option value="${p.id}">${esc(p.name)} – ${esc(p.address)}</option>`).join('')
      + '<option value="">(kein Treffpunkt)</option>'
    : '<option value="">(noch keine Treffpunkte angelegt)</option>';
}

// "07:00" minus 15 Minuten → "06:45" (auch über Mitternacht)
function minusMinutes(time, min) {
  const [h, m] = time.split(':').map(Number);
  const total = (((h * 60 + m - min) % 1440) + 1440) % 1440;
  return `${String(Math.floor(total / 60)).padStart(2, '0')}:${String(total % 60).padStart(2, '0')}`;
}

function setDeparture(time) {
  $('#trip-departure').value = time;
  $('#trip-meet').value = minusMinutes(time, MEET_BEFORE_MIN);
}

// Treffzeit folgt der Abfahrt, kann danach aber noch von Hand angepasst werden
$('#trip-departure').addEventListener('change', (e) => {
  if (e.target.value) setDeparture(e.target.value);
});

// ---------- Mitglieder auswählen ----------
function renderTripMembers() {
  $('#trip-members-empty').hidden = members.length > 0;
  const nameOf = (id) => members.find((m) => m.id === id)?.name;
  $('#trip-members').innerHTML = sortByName(members).map((m) => {
    if (!trip.bringsCar.has(m.id)) trip.bringsCar.set(m.id, m.hasCar);
    const checked = trip.selected.has(m.id);
    return `
    <li>
      <label class="inline name">
        <input type="checkbox" data-select="${m.id}" ${checked ? 'checked' : ''}> ${esc(m.name)}${m.external ? ' <span class="badge">Extern</span>' : ''}
        ${nameOf(m.ridesWith) ? `<span class="meta">(gern bei ${esc(nameOf(m.ridesWith))})</span>` : ''}
      </label>
      <span class="actions">
      ${m.hasCar ? `
        <label class="inline meta">
          <input type="checkbox" data-car="${m.id}" ${trip.bringsCar.get(m.id) ? 'checked' : ''} ${checked ? '' : 'disabled'}>
          Auto dabei (${seatsLabel(m.seats)})
        </label>
        ${m.alwaysDrives ? '<span class="badge" title="Kommt immer mit eigenem Auto">fährt immer</span>' : ''}` : '<span class="meta">kein Auto</span>'}
      </span>
    </li>`;
  }).join('');
  renderFixed();
}

$('#trip-members').addEventListener('change', (e) => {
  const { select, car } = e.target.dataset;
  if (select) {
    e.target.checked ? trip.selected.add(select) : trip.selected.delete(select);
    renderTripMembers();
  }
  if (car) {
    trip.bringsCar.set(car, e.target.checked);
    renderFixed();
  }
});

$('#select-all').addEventListener('click', () => {
  members.forEach((m) => trip.selected.add(m.id));
  renderTripMembers();
});
$('#select-none').addEventListener('click', () => {
  trip.selected.clear();
  renderTripMembers();
});

// ---------- Gäste ----------
$('#guest-hascar').addEventListener('change', (e) => {
  $('#guest-seats').hidden = !e.target.checked;
});

$('#guest-form').addEventListener('submit', (e) => {
  e.preventDefault();
  const name = $('#guest-name').value.trim();
  if (!name) return;
  const hasCar = $('#guest-hascar').checked;
  trip.guests.push({
    id: 'guest-' + ++guestCounter,
    name,
    hasCar,
    seats: hasCar ? Math.max(1, parseInt($('#guest-seats').value, 10) || 1) : 0,
    ridesWith: $('#guest-rideswith').value || null,
    guest: true,
  });
  e.target.reset();
  $('#guest-seats').hidden = true;
  renderGuests();
  $('#guest-name').focus();
});

function renderGuests() {
  const people = [...sortByName(members), ...trip.guests];
  const nameOf = (id) => people.find((p) => p.id === id)?.name;
  $('#guest-rideswith').innerHTML = '<option value="">(keine Vorliebe)</option>'
    + people.map((p) => `<option value="${p.id}">gern bei ${esc(p.name)}</option>`).join('');
  $('#guests-list').innerHTML = trip.guests.map((g) => `
    <li>
      <span class="name">${esc(g.name)} <span class="badge">Gast</span>
        ${nameOf(g.ridesWith) ? `<span class="meta">(gern bei ${esc(nameOf(g.ridesWith))})</span>` : ''}</span>
      <span class="meta">${g.hasCar ? `Auto · ${seatsLabel(g.seats)}` : 'kein Auto'}</span>
      <button class="link danger" data-remove="${g.id}">Entfernen</button>
    </li>`).join('');
  renderFixed();
}

$('#guests-list').addEventListener('click', (e) => {
  const id = e.target.dataset.remove;
  if (!id) return;
  trip.guests = trip.guests.filter((g) => g.id !== id);
  for (const g of trip.guests) if (g.ridesWith === id) g.ridesWith = null;
  renderGuests();
});

// ---------- Feste Zuteilung ----------
// Alle, die diesmal mitfahren (Mitglieder mit Auto-Häkchen der Fahrt, plus Gäste)
function currentParticipants() {
  return [
    ...sortByName(members.filter((m) => trip.selected.has(m.id))).map((m) => ({
      ...m,
      hasCar: m.hasCar && trip.bringsCar.get(m.id) !== false,
    })),
    ...trip.guests,
  ];
}

function renderFixed() {
  const people = currentParticipants();
  const byId = new Map(people.map((p) => [p.id, p]));
  const canDrive = (p) => p?.hasCar && p.seats > 0;

  // Einträge entfernen, die nicht mehr passen (abgewählt, Auto nicht dabei, Auto voll)
  const used = new Map();
  for (const [passengerId, driverId] of trip.fixed) {
    const n = (used.get(driverId) || 0) + 1;
    if (!byId.has(passengerId) || !canDrive(byId.get(driverId)) || trip.fixed.has(driverId)
      || n > byId.get(driverId).seats) {
      trip.fixed.delete(passengerId);
    } else {
      used.set(driverId, n);
    }
  }

  const fixedDrivers = new Set(trip.fixed.values());
  const passengers = people.filter((p) => !trip.fixed.has(p.id) && !fixedDrivers.has(p.id));
  const drivers = people.filter((p) => canDrive(p) && !trip.fixed.has(p.id) && (used.get(p.id) || 0) < p.seats);

  $('#fixed-passenger').innerHTML = passengers.length
    ? passengers.map((p) => `<option value="${p.id}">${esc(p.name)}</option>`).join('')
    : '<option value="">(niemand mehr frei)</option>';
  $('#fixed-driver').innerHTML = drivers.length
    ? drivers.map((d) => `<option value="${d.id}">${esc(d.name)} (${d.seats - (used.get(d.id) || 0)} frei)</option>`).join('')
    : '<option value="">(kein Auto dabei)</option>';
  $('#fixed-form button').disabled = !passengers.length || !drivers.length;

  $('#fixed-list').innerHTML = [...trip.fixed].map(([passengerId, driverId]) => `
    <li>
      <span class="name">${esc(byId.get(passengerId).name)} <span class="muted">fährt bei</span> ${esc(byId.get(driverId).name)}</span>
      <button class="link danger" data-unfix="${passengerId}">Entfernen</button>
    </li>`).join('');
}

$('#fixed-form').addEventListener('submit', (e) => {
  e.preventDefault();
  const passengerId = $('#fixed-passenger').value;
  const driverId = $('#fixed-driver').value;
  if (!passengerId || !driverId || passengerId === driverId) return;
  trip.fixed.set(passengerId, driverId);
  renderFixed();
});

$('#fixed-list').addEventListener('click', (e) => {
  const id = e.target.dataset.unfix;
  if (!id) return;
  trip.fixed.delete(id);
  renderFixed();
});

// ---------- Zurücksetzen ----------
function resetTrip() {
  trip.selected.clear();
  trip.bringsCar.clear();
  trip.guests = [];
  trip.fixed.clear();
  $('#trip-title').value = '';
  $('#trip-date').value = '';
  $('#trip-point').selectedIndex = 0;
  setDeparture(DEFAULT_DEPARTURE);
  $('#opt-min-cars').checked = true;
  $('#guest-form').reset();
  $('#guest-seats').hidden = true;
  $('#result').innerHTML = '';
  $('#from-event').hidden = true;
  history.replaceState(null, '', location.pathname);
  renderTripMembers();
  renderGuests();
  window.scrollTo({ top: 0, behavior: 'smooth' });
}

$('#reset-btn').addEventListener('click', resetTrip);

// ---------- Einteilung berechnen ----------
/**
 * Verteilt die Teilnehmer auf Autos.
 * - Feste Zuteilung (fixed: Mitfahrer-ID -> Fahrer-ID): der Fahrer fährt sicher, der Mitfahrer sitzt sicher bei ihm.
 * - Wer immer mit eigenem Auto kommt (alwaysDrives) und es dabeihat, fährt auf jeden Fall.
 * - minCars: weitere Autos nur so viele wie nötig (größte zuerst), sonst alle Autos.
 *   Wer lieber bei einem anderen Autobesitzer mitfährt (ridesWith), wird erst zuletzt Fahrer.
 * - Wunsch-Mitfahrer: wer bei einem Fahrer mitfahren möchte, kommt zuerst in dessen Auto;
 *   Mitfahrer mit Vorliebe füreinander kommen nach Möglichkeit ins selbe Auto.
 * - Übrige Mitfahrer: zuerst bekommt jedes Auto jemanden (Immer-Fahrer zuerst), danach gleichmäßig auffüllen.
 */
function planTrip(participants, minCars, fixed = new Map()) {
  const byId = new Map(participants.map((p) => [p.id, p]));
  const hasUsableCar = (p) => !!(p?.hasCar && p.seats > 0);
  const prefersOtherCar = (p) => hasUsableCar(byId.get(p.ridesWith));
  const fixedDrivers = new Set(fixed.values());
  const mustDrive = (p) => p.alwaysDrives || fixedDrivers.has(p.id);

  // Fest zugeteilte Mitfahrer fahren nie selbst
  const carOwners = participants.filter((p) => hasUsableCar(p) && !fixed.has(p.id));
  const forced = carOwners.filter(mustDrive).sort((a, b) => b.seats - a.seats);
  const optional = carOwners.filter((p) => !mustDrive(p))
    .sort((a, b) => prefersOtherCar(a) - prefersOtherCar(b) || b.seats - a.seats);

  let drivers = [...forced, ...optional];
  if (minCars) {
    drivers = [...forced];
    let capacity = forced.reduce((sum, d) => sum + 1 + d.seats, 0);
    for (const owner of optional) {
      if (capacity >= participants.length) break;
      drivers.push(owner);
      capacity += 1 + owner.seats;
    }
  }

  const driverIds = new Set(drivers.map((d) => d.id));
  const cars = drivers.map((d) => ({ driver: d, passengers: [] }));
  const carOf = new Map(cars.map((c) => [c.driver.id, c]));
  const unassigned = [];
  const free = (car) => car.driver.seats - car.passengers.length;
  const place = (p, car) => { car.passengers.push(p); carOf.set(p.id, car); };

  // Auto mit den wenigsten Mitfahrern, bei Gleichstand Immer-Fahrer, dann die meisten freien Plätze
  function pickCar(size) {
    let best = null;
    for (const car of cars) {
      if (free(car) < size) continue;
      if (!best
        || car.passengers.length < best.passengers.length
        || (car.passengers.length === best.passengers.length
          && (car.driver.alwaysDrives && !best.driver.alwaysDrives
            || (!!car.driver.alwaysDrives === !!best.driver.alwaysDrives && free(car) > free(best))))) {
        best = car;
      }
    }
    return best;
  }

  // 0. Feste Zuteilung für diese Fahrt
  for (const p of participants) {
    const car = carOf.get(fixed.get(p.id));
    if (car && car.driver.id === fixed.get(p.id) && free(car) > 0) place(p, car);
  }

  // 1. Wer bei einem Fahrer mitfahren möchte, kommt in dessen Auto
  let rest = [];
  for (const p of participants) {
    if (carOf.has(p.id)) continue;
    const car = carOf.get(p.ridesWith);
    if (car && car.driver.id === p.ridesWith && free(car) > 0) place(p, car);
    else rest.push(p);
  }

  // 2. Übrige Mitfahrer in Gruppen zusammenfassen, die über Vorlieben verbunden sind
  const groupOf = new Map(rest.map((p) => [p.id, [p]]));
  for (const p of rest) {
    const a = groupOf.get(p.id);
    const b = groupOf.get(p.ridesWith);
    if (!b || a === b) continue;
    a.push(...b);
    for (const q of b) groupOf.set(q.id, a);
  }
  const groups = [...new Set(groupOf.values())].sort((a, b) => b.length - a.length);

  // 3. Gruppen verteilen – bevorzugt ins Auto, in dem die Wunschperson schon sitzt
  for (const group of groups) {
    const wished = group.map((p) => carOf.get(p.ridesWith)).find((c) => c && free(c) >= group.length);
    const car = wished || pickCar(group.length);
    if (car) {
      group.forEach((p) => place(p, car));
      continue;
    }
    for (const p of group) {
      const own = carOf.get(p.ridesWith);
      const c = own && free(own) > 0 ? own : pickCar(1);
      c ? place(p, c) : unassigned.push(p);
    }
  }

  return { cars, unassigned };
}

// ---------- Ergebnis ----------
const badges = (p) => (p.guest ? ' <span class="badge">Gast</span>' : '')
  + (p.external ? ' <span class="badge">Extern</span>' : '');

const sameMeeting = (a, b) => a.pointId === b.pointId && a.meet === b.meet && a.departure === b.departure;

function meetingLines({ pointId, meet, departure }) {
  const point = points.find((p) => p.id === pointId);
  return [
    point && `Treffpunkt: ${point.name}, ${point.address}`,
    meet && `Treffzeit: ${meet} Uhr`,
    departure && `Abfahrt: ${departure} Uhr`,
  ].filter(Boolean);
}

function meetingHtml({ pointId, meet, departure }) {
  const point = points.find((p) => p.id === pointId);
  let html = '<dl class="meeting">';
  if (point) {
    const maps = `https://www.google.com/maps/search/?api=1&query=${encodeURIComponent(point.address)}`;
    html += `<dt>Treffpunkt</dt><dd>${esc(point.name)}
      <small><a href="${maps}" target="_blank" rel="noopener">${esc(point.address)}</a></small></dd>`;
  }
  if (meet) html += `<dt>Treffzeit</dt><dd>${esc(meet)} Uhr</dd>`;
  if (departure) html += `<dt>Abfahrt</dt><dd>${esc(departure)} Uhr</dd>`;
  return html + '</dl>';
}

// Haben alle Autos denselben Treffpunkt und dieselben Zeiten, steht das einmal oben, sonst bei jedem Auto
function commonMeeting(carMeet, defaults) {
  if (!carMeet.length) return defaults;
  return carMeet.every((m) => sameMeeting(m, carMeet[0])) ? carMeet[0] : null;
}

function buildText(heading, { cars, unassigned }, carMeet, defaults) {
  const lines = [`Fahrgemeinschaften${heading ? ': ' + heading : ''}`, ''];
  const common = commonMeeting(carMeet, defaults);
  if (common) {
    const ml = meetingLines(common);
    if (ml.length) lines.push(...ml, '');
  }
  cars.forEach((car, i) => {
    if (i > 0 && !common) lines.push('');
    lines.push(`Fahrzeug ${i + 1} – Fahrer: ${car.driver.name} (${car.passengers.length}/${car.driver.seats} belegt)`);
    if (!common) meetingLines(carMeet[i]).forEach((l) => lines.push(`   ${l}`));
    car.passengers.forEach((p) => lines.push(`   • ${p.name}`));
    if (!car.passengers.length) lines.push('   • (keine Mitfahrer)');
  });
  if (unassigned.length) {
    lines.push('', `OHNE PLATZ: ${unassigned.map((p) => p.name).join(', ')}`);
  }
  return lines.join('\n');
}

$('#plan-btn').addEventListener('click', () => {
  const participants = currentParticipants();

  const result = $('#result');
  if (!participants.length) {
    result.innerHTML = '<p class="warn">Bitte wähle mindestens eine Person aus.</p>';
    return;
  }

  const plan = planTrip(participants, $('#opt-min-cars').checked, trip.fixed);
  const heading = [$('#trip-title').value.trim(), formatDate($('#trip-date').value)].filter(Boolean).join(' – ');
  const totalSeats = plan.cars.reduce((s, c) => s + 1 + c.driver.seats, 0);

  // Treffpunkt und Zeiten pro Auto: Standard-Treffpunkt des Fahrers, sonst der Treffpunkt der Fahrt
  const defaults = {
    pointId: $('#trip-point').value,
    meet: $('#trip-meet').value,
    departure: $('#trip-departure').value,
  };
  const carMeet = plan.cars.map((car) => ({
    ...defaults,
    pointId: points.some((p) => p.id === car.driver.meetingPoint) ? car.driver.meetingPoint : defaults.pointId,
  }));

  const pointOptions = (selected) => points
    .map((p) => `<option value="${p.id}" ${p.id === selected ? 'selected' : ''}>${esc(p.name)}</option>`).join('')
    + `<option value="" ${selected ? '' : 'selected'}>(kein Treffpunkt)</option>`;

  let html = heading ? `<h3>${esc(heading)}</h3>` : '';
  html += '<div id="meeting-common"></div>';
  html += `<p class="muted">${participants.length} Personen · ${plan.cars.length} ${plan.cars.length === 1 ? 'Auto' : 'Autos'} · ${totalSeats} Sitzplätze</p>`;

  html += '<div class="cars">' + plan.cars.map((car, i) => `
    <div class="car">
      <h3>Auto ${i + 1}: ${esc(car.driver.name)}${badges(car.driver)}</h3>
      <div class="muted">${car.passengers.length} / ${car.driver.seats} Plätze belegt</div>
      <div class="car-meet no-print">
        <label>Treffpunkt <select data-car-point="${i}">${pointOptions(carMeet[i].pointId)}</select></label>
        <div class="grid2">
          <label>Treffzeit <input type="time" data-car-meet="${i}" value="${esc(carMeet[i].meet)}"></label>
          <label>Abfahrt <input type="time" data-car-dep="${i}" value="${esc(carMeet[i].departure)}"></label>
        </div>
      </div>
      <div data-car-info="${i}"></div>
      ${car.passengers.length
        ? `<ol>${car.passengers.map((p) => `<li>${esc(p.name)}${badges(p)}${trip.fixed.get(p.id) === car.driver.id ? ' <span class="badge">fest</span>' : ''}</li>`).join('')}</ol>`
        : '<p class="muted">keine Mitfahrer</p>'}
    </div>`).join('') + '</div>';

  if (plan.unassigned.length) {
    const missing = plan.unassigned.length;
    html += `<div class="warn"><strong>Nicht genug Plätze!</strong> Es fehlen ${seatsLabel(missing)}.<br>
      Ohne Platz: ${plan.unassigned.map((p) => esc(p.name)).join(', ')}</div>`;
  }

  html += `
    <div class="row wrap no-print">
      <button id="copy-btn">Als Text kopieren</button>
      <button id="print-btn">Drucken</button>
      <button id="reset-after-btn">Neue Fahrt</button>
    </div>`;

  result.innerHTML = html;

  function renderMeetings() {
    const common = commonMeeting(carMeet, defaults);
    $('#meeting-common').innerHTML = common ? meetingHtml(common) : '';
    carMeet.forEach((m, i) => {
      $(`[data-car-info="${i}"]`).innerHTML = common ? '' : meetingHtml(m);
    });
  }
  renderMeetings();

  result.querySelector('.cars').addEventListener('change', (e) => {
    const { carPoint, carMeet: meetIdx, carDep } = e.target.dataset;
    if (carPoint !== undefined) carMeet[carPoint].pointId = e.target.value;
    if (meetIdx !== undefined) carMeet[meetIdx].meet = e.target.value;
    if (carDep !== undefined) {
      // Treffzeit folgt der Abfahrt wie oben bei der Fahrt
      const m = carMeet[carDep];
      m.departure = e.target.value;
      if (m.departure) {
        m.meet = minusMinutes(m.departure, MEET_BEFORE_MIN);
        $(`[data-car-meet="${carDep}"]`).value = m.meet;
      }
    }
    $('#copy-btn').textContent = 'Als Text kopieren';
    renderMeetings();
  });

  $('#copy-btn').addEventListener('click', async (e) => {
    const text = buildText(heading, plan, carMeet, defaults);
    try {
      await navigator.clipboard.writeText(text);
      e.target.textContent = 'Kopiert';
    } catch {
      prompt('Text zum Kopieren:', text);
    }
  });
  $('#print-btn').addEventListener('click', () => window.print());
  $('#reset-after-btn').addEventListener('click', resetTrip);
});

// ---------- Übernahme aus Kalender-Termin ----------
async function applyEventFromUrl() {
  const eventId = new URLSearchParams(location.search).get('termin');
  if (!eventId) return;
  let ev;
  try {
    ev = await api('GET', `/events/${encodeURIComponent(eventId)}`);
  } catch {
    showError(new Error('Der Termin wurde nicht gefunden.'));
    return;
  }
  const known = ev.attendees.filter((id) => members.some((m) => m.id === id));
  known.forEach((id) => trip.selected.add(id));
  $('#trip-title').value = ev.title;
  $('#trip-date').value = ev.date;
  const notice = $('#from-event');
  notice.innerHTML = `Übernommen aus dem Kalender: <strong>${esc(ev.title)}</strong> am ${formatDate(ev.date, true)} –
    ${known.length} ${known.length === 1 ? 'Zusage ist' : 'Zusagen sind'} schon als „kommt mit“ ausgewählt.`;
  notice.hidden = false;
}

// ---------- Start ----------
async function init() {
  [members, points] = await Promise.all([api('GET', '/members'), api('GET', '/meeting-points')]);
  renderPoints();
  await applyEventFromUrl();
  renderTripMembers();
  renderGuests();
}

init().catch(showError);