import { TariffDefinition, TariffWindow } from './entities/tariff.entity';

export interface QuoteInput {
  distanceKm: number;
  durationMin: number;
  waitingMin?: number;
  at?: Date; // لحظة الحساب (لاختيار النافذة الزمنية)
}

export interface QuoteBreakdown {
  window: string;
  flag: number;
  distance: number;
  time: number;
  waiting: number;
  bookingFee: number;
  subtotal: number;
  surgeMultiplier: number;
  total: number;
  currency: string;
}

/**
 * محرك التعرفة النقي (قابل للاختبار بوحدات) — نفس المدخل = نفس المخرج.
 * يدعم أوضاع docs/04: time_and_distance و time_or_distance (عتبة سرعة).
 */
export class TariffEngine {
  static quote(def: TariffDefinition, input: QuoteInput): QuoteBreakdown {
    const at = input.at ?? new Date();
    const win = TariffEngine.pickWindow(def.windows, at);
    const distanceKm = Math.max(0, input.distanceKm);
    const durationMin = Math.max(0, input.durationMin);
    const waitingMin = Math.max(0, input.waitingMin ?? 0);

    let distanceCharge = 0;
    let timeCharge = 0;

    if (def.mode === 'time_or_distance') {
      // العداد المنظَّم: تحت العتبة يُحسب بالدقيقة (زحمة)، فوقها بالكيلومتر.
      const avgSpeed = durationMin > 0 ? (distanceKm / durationMin) * 60 : 999;
      const threshold = def.speed_threshold_kmh ?? 18;
      if (avgSpeed < threshold) {
        timeCharge = durationMin * win.per_min;
      } else {
        distanceCharge = distanceKm * win.per_km;
      }
    } else {
      // time_and_distance (و fixed_quote يُحسب مرة ويثبّت)
      distanceCharge = distanceKm * win.per_km;
      timeCharge = durationMin * win.per_min;
    }

    const waitingCharge = waitingMin * (win.per_min_waiting ?? 0);
    const bookingFee = def.booking_fee ?? 0;

    let subtotal =
      win.flag + distanceCharge + timeCharge + waitingCharge + bookingFee;

    const surgeMultiplier =
      def.surge?.enabled && def.surge.multiplier ? def.surge.multiplier : 1;
    let total = subtotal * surgeMultiplier;

    if (def.min_fare && total < def.min_fare) total = def.min_fare;
    total = TariffEngine.round(total, def.rounding);

    return {
      window: win.name,
      flag: win.flag,
      distance: TariffEngine.n(distanceCharge),
      time: TariffEngine.n(timeCharge),
      waiting: TariffEngine.n(waitingCharge),
      bookingFee,
      subtotal: TariffEngine.n(subtotal),
      surgeMultiplier,
      total: TariffEngine.n(total),
      currency: def.currency,
    };
  }

  /**
   * رسم الانتظار بعد وصول السائق (docs/17 — B2). الدقائق المجانية (5 قانوناً)
   * تُخصم أولاً، والباقي يُحسب بسعر انتظار النافذة الفعّالة.
   */
  static waitingCharge(
    def: TariffDefinition,
    waitedMin: number,
    at: Date = new Date(),
  ): { freeMin: number; billableMin: number; charge: number } {
    const win = TariffEngine.pickWindow(def.windows, at);
    const freeMin = def.free_waiting_min ?? 5;
    const billableMin = Math.max(0, (waitedMin ?? 0) - freeMin);
    return {
      freeMin,
      billableMin: TariffEngine.n(billableMin),
      charge: TariffEngine.n(billableMin * (win.per_min_waiting ?? 0)),
    };
  }

  /**
   * رسم مشوار وصول السائق للراكب (docs/17 — B3).
   * يرجع صفراً ما لم يُفعِّله المالك صراحةً في التعرفة.
   */
  static pickupCharge(
    def: TariffDefinition,
    distanceKm: number,
    durationMin: number,
    at: Date = new Date(),
  ): number {
    if (!def.pickup_leg?.charge) return 0;
    const win = TariffEngine.pickWindow(def.windows, at);
    const charge =
      Math.max(0, distanceKm ?? 0) * win.per_km + Math.max(0, durationMin ?? 0) * win.per_min;
    return TariffEngine.n(charge);
  }

  /**
   * فصل السعر (docs/17 — B6): يقسم ما يدفعه الراكب إلى عمولة المنصة وحصة
   * السائق. العمولة لا تتجاوز الأجرة مهما كانت الإعدادات — وإلا صار دخل
   * السائق سالباً.
   */
  static split(
    def: TariffDefinition,
    passengerTotal: number,
  ): { forPassenger: number; forDriver: number; commission: number; rate: number } {
    const total = Math.max(0, passengerTotal ?? 0);
    const c = def.commission;
    if (!c) {
      return { forPassenger: TariffEngine.n(total), forDriver: TariffEngine.n(total), commission: 0, rate: 0 };
    }
    const percent = c.percent ?? 0;
    let commission = total * (percent / 100) + (c.flat ?? 0);
    if (c.min != null && commission < c.min) commission = c.min;
    if (commission > total) commission = total;
    commission = TariffEngine.n(commission);
    return {
      forPassenger: TariffEngine.n(total),
      forDriver: TariffEngine.n(total - commission),
      commission,
      rate: percent,
    };
  }

  private static pickWindow(windows: TariffWindow[], at: Date): TariffWindow {
    const mins = at.getUTCHours() * 60 + at.getUTCMinutes();
    for (const w of windows) {
      const [fromH, fromM] = w.from.split(':').map(Number);
      const [toH, toM] = w.to.split(':').map(Number);
      const from = fromH * 60 + fromM;
      const to = toH * 60 + toM;
      // نافذة تعبر منتصف الليل (مثل 22:00 → 06:00)
      if (from <= to ? mins >= from && mins < to : mins >= from || mins < to) {
        return w;
      }
    }
    return windows[0];
  }

  private static round(
    value: number,
    rounding?: { increment: number; mode?: 'nearest' | 'up' | 'down' },
  ): number {
    if (!rounding || !rounding.increment) return TariffEngine.n(value);
    const q = value / rounding.increment;
    const r =
      rounding.mode === 'up'
        ? Math.ceil(q)
        : rounding.mode === 'down'
          ? Math.floor(q)
          : Math.round(q);
    return TariffEngine.n(r * rounding.increment);
  }

  private static n(v: number): number {
    return Number(v.toFixed(3));
  }
}