/**
 * Fluggesellschaft — Engine (Phase 1)
 *
 * Schwester-Modul zu Busfahrt. Wichtigste Unterschiede:
 *   - Großkreis-Routing (kürzeste Verbindung auf Kugel) statt OSRM
 *   - Flughafen-Marker = Stadtmitte (vereinfacht; reale Flughäfen liegen
 *     oft außerhalb, didaktisch nicht relevant in dieser Stufe)
 *   - Tarif/Kosten in €/km wie Bus, aber andere Werte (Flug ist teurer
 *     pro Sitzplatz, aber schneller)
 *   - Quiz hat 2 Fragen-Typen (Land + Kontinent), Engine wählt
 *     deterministisch pro Auftrag-ID
 *
 * Plattform-Hooks (vom Wrapper):
 *   FLUG_BASE, FLUG_FORCED_LEVEL, STUDENT_EASY,
 *   FLUG_API_BASE, FLUG_SESSION_ID
 */
window.FlugEngine = (function () {
  'use strict';

  let CITIES_INDEX = null;
  let ORDERS_POOL = null;

  /** Bewertungs-Schwellen — Flughafen-Tap (km Abweichung). Großzügiger
   *  als Bus, weil Welt-Karte deutlich größer skaliert ist. */
  const HIT_THRESHOLDS = {
    PERFECT: 200,
    OK:      800,
  };

  /** Wirtschafts-Konstanten. Werte mit {l1,l2,l3} sind pro Level. */
  const ECON = {
    startBudget:       8000,            // höher als Bus (Flugzeug ist teurer)
    targetBudget:      { l1: 14000, l2: 32000, l3: 60000 },
    tariffPerKm:       0.18,            // €/km — Ticketpreis pro Sitzplatz × 50 Pax = effektiv 9 €/km
    costPerKm:         0.13,            // €/km — Treibstoff + Flughafengebühr + Crew
    tapToleranceKm:    { l1: 250, l2: 200, l3: 150 },
    nightFirst:        { l1: 5,  l2: 3,  l3: 1 },
    nightChanceAfter:  { l1: 0.15, l2: 0.30, l3: 0.60 },
    tourLength:        { l1: 10, l2: 14, l3: 18 },
    homeCity:          'frankfurt',
    quizBonusFirstTryEur:   { l1: 100, l2: 150, l3: 200 },
    quizPenaltyPerWrongEur: { l1: 100, l2: 150, l3: 200 },
    // CO2-Daten: pro Flug-km ca. 0.18 kg CO2 pro Passagier (Kurzstrecke).
    // Wird in der Buchhaltung ausgewiesen — Umweltbildung.
    co2KgPerKmPerPax: 0.18,
    paxOnboard: 180,
  };

  function econ(key, levelId) {
    const v = ECON[key];
    if (v && typeof v === 'object' && !Array.isArray(v)) {
      return v[levelId] != null ? v[levelId] : v.l1;
    }
    return v;
  }

  async function loadData() {
    if (CITIES_INDEX && ORDERS_POOL) return;
    const base = (window.FLUG_BASE || './') + 'assets/data/';
    const [cRes, oRes] = await Promise.all([
      fetch(base + 'cities.json'),
      fetch(base + 'orders.json'),
    ]);
    const cJson = await cRes.json();
    const oJson = await oRes.json();
    CITIES_INDEX = { raw: cJson, byId: Object.fromEntries(cJson.map(c => [c.id, c])) };
    ORDERS_POOL = oJson;
  }

  /** Distanz-Filterung: L1 = Nahflug (<1500 km), L2 = Mittelstrecke (<4000 km),
   *  L3 = alles. Distanz wird gegen homeCity gerechnet. Aufträge ohne
   *  auflösbare cityId fallen heraus. Wenn ein Level zu wenig Aufträge hätte
   *  (Sicherheits-Floor 4), wird das Limit für dieses Level ignoriert. */
  function distanceFromHomeKm(order) {
    if (!CITIES_INDEX) return Infinity;
    const home = CITIES_INDEX.byId[ECON.homeCity];
    const dst = CITIES_INDEX.byId[order.cityId];
    if (!home || !dst) return Infinity;
    return haversineKm(home.lat, home.lon, dst.lat, dst.lon);
  }

  function filterPoolByLevel(levelId) {
    if (!ORDERS_POOL) return [];
    const inLevel = ORDERS_POOL.filter(o => {
      if (levelId === 'l1') return o.level === 'l1';
      if (levelId === 'l2') return o.level === 'l1' || o.level === 'l2';
      return true;
    });
    // Distanz-Cap pro Level
    const caps = { l1: 1500, l2: 4000, l3: Infinity };
    const cap = caps[levelId] != null ? caps[levelId] : Infinity;
    if (!isFinite(cap)) return inLevel;
    const capped = inLevel.filter(o => distanceFromHomeKm(o) <= cap);
    // Sicherheits-Floor: wenn unter 4 Aufträge übrig, Cap ignorieren
    return capped.length >= 4 ? capped : inLevel;
  }

  function init(levelId, seed) {
    const lvl = levelId || 'l1';
    const seedNum = (seed || Date.now()) >>> 0;
    const rng = mulberry32(seedNum);
    const pool = filterPoolByLevel(lvl);
    const tourLen = econ('tourLength', lvl) || 8;
    const nightFirst = econ('nightFirst', lvl);
    const nightChanceAfter = econ('nightChanceAfter', lvl);
    const shuffled = shuffleSeeded(pool, rng);

    // Tour-Auswahl analog Busfahrt: dreistufiger Filter, damit jede Stadt
    // nur einmal pro Tour auftaucht (auch wenn mehrere Auftragstypen
    // dieselbe cityId teilen).
    const usedCities = new Set([ECON.homeCity]);
    const candidates = shuffled.slice();
    const tour = [];
    let prevCity = ECON.homeCity;
    for (let i = 0; i < tourLen && candidates.length; i++) {
      let pickIdx = candidates.findIndex(c => !usedCities.has(c.cityId));
      if (pickIdx === -1) pickIdx = candidates.findIndex(c => c.cityId !== prevCity);
      if (pickIdx === -1) pickIdx = 0;
      const pick = candidates.splice(pickIdx, 1)[0];
      let isNight = false;
      if (i === nightFirst) isNight = true;
      else if (i > nightFirst && rng() < nightChanceAfter) isNight = true;
      tour.push({ ...pick, isNight });
      prevCity = pick.cityId;
      usedCities.add(pick.cityId);
    }

    return {
      levelId: lvl,
      seed: seedNum,
      tourOrders: tour,
      orderIndex: 0,
      currentOrder: null,
      currentQuestion: null,
      attempts: [],
      score: 0,
      budget: ECON.startBudget,
      earnings: 0,
      co2Kg: 0,
      lastCity: ECON.homeCity,
      reports: [],
    };
  }

  /** Nächster Auftrag. Setzt auch game.currentQuestion mit Quiz-Daten.
   *  Wechselt deterministisch zwischen Land-Frage und Kontinent-Frage
   *  (basierend auf Auftrag-ID) — damit das Quiz nicht monoton wird. */
  function nextOrder(game) {
    if (game.orderIndex >= game.tourOrders.length) return null;
    const order = game.tourOrders[game.orderIndex];
    game.currentOrder = order;
    game.attempts = [];

    let q = null;
    if (order.type === 'B' && Array.isArray(order.choices) && order.choices.length) {
      const correctIdx = order.choices.indexOf(order.cityId);
      q = {
        kind: 'capital',
        prompt: order.prompt,
        choices: order.choices,
        choiceLabels: order.choices.map(cid => {
          const c = CITIES_INDEX && CITIES_INDEX.byId[cid];
          return c ? c.title : cid;
        }),
        correctIndex: correctIdx >= 0 ? correctIdx : 0,
        attempts: [], resolved: false, wasFirstTryCorrect: false,
        bonusEur: 0, penaltyEur: 0,
      };
    } else {
      const city = CITIES_INDEX && CITIES_INDEX.byId[order.cityId];
      // Wechsel Land/Kontinent: gerade Hash → Land, ungerade → Kontinent
      const h = simpleHash(order.id);
      const cq = (h % 2 === 0) ? city && city.question : city && city.questionContinent;
      const kind = (h % 2 === 0) ? 'country' : 'continent';
      if (cq && Array.isArray(cq.choices)) {
        q = {
          kind,
          prompt: cq.prompt,
          choices: cq.choices.slice(),
          choiceLabels: cq.choices.slice(),
          correctIndex: cq.correctIndex,
          attempts: [], resolved: false, wasFirstTryCorrect: false,
          bonusEur: 0, penaltyEur: 0,
        };
      }
    }
    game.currentQuestion = q;
    return order;
  }

  function evaluateQuestion(game, pickedIndex) {
    const q = game.currentQuestion;
    if (!q || q.resolved) return null;
    if (typeof pickedIndex !== 'number' || pickedIndex < 0 || pickedIndex >= q.choices.length) return null;
    q.attempts.push(pickedIndex);
    const correct = pickedIndex === q.correctIndex;
    const bonus = econ('quizBonusFirstTryEur', game.levelId);
    const penalty = econ('quizPenaltyPerWrongEur', game.levelId);
    let delta = 0;
    if (correct) {
      if (q.attempts.length === 1) {
        q.wasFirstTryCorrect = true;
        q.bonusEur = bonus;
        delta = bonus;
      }
      q.resolved = true;
    } else {
      q.penaltyEur += penalty;
      delta = -penalty;
    }
    game.budget += delta;
    return {
      correct, resolved: q.resolved, deltaEur: delta,
      bonusEur: q.bonusEur, penaltyEur: q.penaltyEur,
      attempts: q.attempts.slice(),
    };
  }

  function checkTap(game, tap) {
    if (!game.currentOrder || !CITIES_INDEX) return null;
    const target = CITIES_INDEX.byId[game.currentOrder.cityId];
    if (!target) return null;
    const distanceKm = haversineKm(tap.lat, tap.lon, target.lat, target.lon);
    let score = 0;
    if (distanceKm < HIT_THRESHOLDS.PERFECT) score = 3;
    else if (distanceKm < HIT_THRESHOLDS.OK) score = 1;
    const hint = directionHint(tap, target, distanceKm);
    const attempt = { tap, distanceKm, score, hint };
    game.attempts.push(attempt);
    const resolved = score > 0 || game.attempts.length >= 3;
    return { ...attempt, resolved };
  }

  /** Auftrag abrechnen — Großkreis-Distanz vom Start-Flughafen zum Ziel-Flughafen.
   *  Tap-Abweichung: wenn weit daneben, fliegt der Pilot einen „Umweg" über die
   *  Tap-Position (didaktisch). Sonst Direkt-Großkreis. */
  function settleOrder(game) {
    if (!game.currentOrder || !CITIES_INDEX) return null;
    if (!game.attempts.length) return null;
    const lastAttempt = game.attempts[game.attempts.length - 1];
    const tap = lastAttempt.tap;
    const order = game.currentOrder;
    const fromCity = CITIES_INDEX.byId[game.lastCity];
    const toCity = CITIES_INDEX.byId[order.cityId];
    if (!fromCity || !toCity) return null;

    const realDistanceKm = haversineKm(fromCity.lat, fromCity.lon, toCity.lat, toCity.lon);
    const startToTap = haversineKm(fromCity.lat, fromCity.lon, tap.lat, tap.lon);
    const tapToTarget = haversineKm(tap.lat, tap.lon, toCity.lat, toCity.lon);
    const viaTap = startToTap + tapToTarget;

    const withinTolerance = lastAttempt.distanceKm < econ('tapToleranceKm', game.levelId);
    const actualDistanceKm = withinTolerance ? realDistanceKm : viaTap;
    const detourKm = Math.max(0, actualDistanceKm - realDistanceKm);

    const tariff = order.tariffPerKm || ECON.tariffPerKm;
    const playerPrice = realDistanceKm * tariff * ECON.paxOnboard;
    const busCost = actualDistanceKm * ECON.costPerKm * ECON.paxOnboard;
    const baseMargin = playerPrice - busCost;
    const margin = Math.round(baseMargin);
    const co2Kg = Math.round(actualDistanceKm * ECON.co2KgPerKmPerPax * ECON.paxOnboard);
    const finalScore = lastAttempt.score;

    game.score += finalScore;
    game.budget += margin;
    game.earnings += margin;
    game.co2Kg += co2Kg;

    const q = game.currentQuestion;
    const quizBonus = q ? (q.bonusEur || 0) : 0;
    const quizPenalty = q ? (q.penaltyEur || 0) : 0;

    // Zeitzonen-Differenz beim Ankunft-Land (für Sachinfo in InfoCard)
    const utcFrom = fromCity.utcOffset || 0;
    const utcTo = toCity.utcOffset || 0;
    const tzDiffHours = utcTo - utcFrom;

    const report = {
      orderId: order.id, cityId: order.cityId, fromCityId: game.lastCity,
      realDistanceKm, actualDistanceKm, detourKm,
      tapDistanceKm: lastAttempt.distanceKm, withinTolerance,
      tariff,
      playerPrice: Math.round(playerPrice),
      busCost: Math.round(busCost),
      baseMargin: Math.round(baseMargin),
      co2Kg,
      tzDiffHours,
      quizBonus, quizPenalty,
      quizFirstTry: !!(q && q.wasFirstTryCorrect),
      quizAttemptsCount: q ? q.attempts.length : 0,
      quizKind: q ? q.kind : null,
      won: margin >= 0,
      margin,
      finalScore,
      isNight: !!order.isNight,
      attempts: game.attempts.slice(),
      tap,
    };
    game.reports.push(report);

    game.lastCity = order.cityId;
    game.orderIndex += 1;
    game.currentOrder = null;
    game.currentQuestion = null;
    game.attempts = [];
    return report;
  }

  function haversineKm(lat1, lon1, lat2, lon2) {
    const R = 6371;
    const toRad = d => d * Math.PI / 180;
    const dLat = toRad(lat2 - lat1);
    const dLon = toRad(lon2 - lon1);
    const a = Math.sin(dLat/2)**2 + Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLon/2)**2;
    return 2 * R * Math.asin(Math.sqrt(a));
  }

  /** Großkreis-Linie als Polyline-Punkte (für Karten-Darstellung). 64 Segmente. */
  function greatCirclePoints(lat1, lon1, lat2, lon2, segments) {
    segments = segments || 64;
    const toRad = d => d * Math.PI / 180;
    const toDeg = r => r * 180 / Math.PI;
    const φ1 = toRad(lat1), λ1 = toRad(lon1);
    const φ2 = toRad(lat2), λ2 = toRad(lon2);
    const d = 2 * Math.asin(Math.sqrt(
      Math.sin((φ2-φ1)/2)**2 + Math.cos(φ1)*Math.cos(φ2) * Math.sin((λ2-λ1)/2)**2
    ));
    if (d === 0) return [[lat1, lon1]];
    const pts = [];
    for (let i = 0; i <= segments; i++) {
      const f = i / segments;
      const A = Math.sin((1-f)*d) / Math.sin(d);
      const B = Math.sin(f*d) / Math.sin(d);
      const x = A*Math.cos(φ1)*Math.cos(λ1) + B*Math.cos(φ2)*Math.cos(λ2);
      const y = A*Math.cos(φ1)*Math.sin(λ1) + B*Math.cos(φ2)*Math.sin(λ2);
      const z = A*Math.sin(φ1) + B*Math.sin(φ2);
      const φ = Math.atan2(z, Math.sqrt(x*x + y*y));
      const λ = Math.atan2(y, x);
      pts.push([toDeg(φ), toDeg(λ)]);
    }
    return pts;
  }

  function directionHint(tap, target, distanceKm) {
    const dLat = target.lat - tap.lat;
    const dLon = target.lon - tap.lon;
    const ns = dLat > 0 ? 'nördlich' : 'südlich';
    const ew = dLon > 0 ? 'östlich' : 'westlich';
    return `Du musst ${Math.round(distanceKm)} km Richtung ${ns}/${ew}.`;
  }

  function mulberry32(seed) {
    let t = seed >>> 0;
    return function() {
      t = (t + 0x6D2B79F5) >>> 0;
      let r = Math.imul(t ^ (t >>> 15), 1 | t);
      r = (r + Math.imul(r ^ (r >>> 7), 61 | r)) ^ r;
      return ((r ^ (r >>> 14)) >>> 0) / 4294967296;
    };
  }

  function shuffleSeeded(arr, rng) {
    const a = arr.slice();
    for (let i = a.length - 1; i > 0; i--) {
      const j = Math.floor(rng() * (i + 1));
      [a[i], a[j]] = [a[j], a[i]];
    }
    return a;
  }

  function simpleHash(s) {
    let h = 2166136261;
    for (let i = 0; i < s.length; i++) {
      h ^= s.charCodeAt(i);
      h = (h * 16777619) >>> 0;
    }
    return h;
  }

  function getCity(id) { return CITIES_INDEX ? CITIES_INDEX.byId[id] : null; }
  function getCapitals() { return CITIES_INDEX ? CITIES_INDEX.raw.filter(c => c.isCapital) : []; }

  return {
    loadData, init, nextOrder, evaluateQuestion, checkTap, settleOrder,
    greatCirclePoints, getCity, getCapitals,
    HIT_THRESHOLDS, ECON,
  };
})();