import React, { useState } from 'react';
import { format, differenceInMinutes, parseISO } from 'date-fns';
import { CheckCircle2, Circle, Clock, MapPin, AlertCircle, Zap, Navigation, Edit2, Trash2, Plus, List } from 'lucide-react';
import { useTourStore } from './useTourStore.js';
import { ConfirmModal } from './ConfirmModal.js';

const TimeVariance = ({ planned, actual }: { planned: string, actual: string | null }) => {
  if (!actual) return null;
  
  const diff = differenceInMinutes(parseISO(actual), parseISO(planned));
  const isLate = diff > 0;
  
  return (
    <div className={`flex items-center text-xs font-medium mt-1 ${isLate ? 'text-red-500' : 'text-green-600'}`}>
      {isLate ? <AlertCircle className="w-3 h-3 mr-1" /> : <CheckCircle2 className="w-3 h-3 mr-1" />}
      <span>
        {isLate ? `Trễ ${diff} phút` : diff === 0 ? 'Đúng giờ' : `Sớm ${Math.abs(diff)} phút`}
      </span>
    </div>
  );
};

const calculateDistance = (lat1: number, lon1: number, lat2: number, lon2: number) => {
  const p = 0.017453292519943295; // Math.PI / 180
  const c = Math.cos;
  const a = 0.5 - c((lat2 - lat1) * p) / 2 + 
            c(lat1 * p) * c(lat2 * p) * 
            (1 - c((lon2 - lon1) * p)) / 2;
  return 12742 * Math.asin(Math.sqrt(a)); // 2 * R; R = 6371 km
};

const formatTravelTime = (minutes: number) => {
  if (minutes < 60) return `${minutes} phút`;
  const hours = Math.floor(minutes / 60);
  const mins = minutes % 60;
  return mins > 0 ? `${hours} giờ ${mins} phút` : `${hours} giờ`;
};

export const ItineraryTimeline = ({ 
  onAddLocation, 
  onEditLocation 
}: { onAddLocation?: (legId: string) => void, onEditLocation?: (location: any) => void }) => {
  const { currentTour, legs, optimizeRouting, userRole, addLeg, updateLeg, deleteLeg, initializeLegs, deleteLocation } = useTourStore();
  const [confirmState, setConfirmState] = useState<{ open: boolean; title?: string; message?: string; onConfirm?: () => void }>({ open: false });

  const toggleComplete = async (locationId: string) => {
    // Gọi API PATCH /api/v1/locations/:id để cập nhật trạng thái
    console.log("Toggle status for location:", locationId);
  };

  const handleAddLeg = async () => {
    const note = window.prompt("Nhập ghi chú cho chặng mới:", `Chặng ${legs.length + 1}`);
    if (note && currentTour) {
      await addLeg(currentTour.id, { note });
    }
  };

  const handleDeclareLegs = async () => {
    const countStr = window.prompt("Chuyến đi này bạn muốn chia làm bao nhiêu chặng?", "3");
    const count = parseInt(countStr || "0");
    if (count > 0 && currentTour) {
      await initializeLegs(currentTour.id, count);
    }
  };

  const handleEditLeg = async (leg: any) => {
    const note = window.prompt("Sửa ghi chú chặng:", leg.note || "");
    if (note !== null) {
      await updateLeg(leg.id, { note });
    }
  };

  const handleDeleteLeg = async (legId: string) => {
    setConfirmState({
      open: true,
      title: 'Xóa chặng',
      message: 'Bạn có chắc chắn muốn xóa chặng này?',
      onConfirm: async () => {
        try {
          await deleteLeg(legId);
        } catch (err: any) {
          alert(err.message);
        } finally {
          setConfirmState({ open: false });
        }
      },
    });
  };

  const handleDeleteLocation = async (id: string) => {
    setConfirmState({
      open: true,
      title: 'Xóa địa điểm',
      message: 'Bạn có chắc chắn muốn xóa địa điểm này?',
      onConfirm: async () => {
        try {
          await deleteLocation(id);
        } catch (err: any) { alert(err.message); } finally {
          setConfirmState({ open: false });
        }
      },
    });
  };

  return (
    <div className="max-w-2xl mx-auto p-0 bg-gray-50 min-h-screen">
      <div className="px-2 pt-4">
        {legs.length === 0 ? (
          <div className="text-center py-20 bg-white rounded-3xl border-2 border-dashed border-gray-200">
             <List className="w-12 h-12 text-gray-300 mx-auto mb-4" />
             <p className="text-gray-500 font-medium">Chưa có chặng nào trong lộ trình.</p>
          </div>
        ) : (
          legs.map((leg, legIdx) => {
              const totalDwellMinutes = leg.locations.reduce((acc: number, loc: any) => {
                if (loc.plannedStart && loc.plannedEnd) {
                  return acc + differenceInMinutes(parseISO(loc.plannedEnd), parseISO(loc.plannedStart));
                }
                return acc;
              }, 0);

              // Xác định địa điểm cuối cùng của chặng trước đó để hiển thị tính liên tục
              const prevLegLastLoc = legIdx > 0 ? legs[legIdx - 1]?.locations.slice(-1)[0] : null;

              return (
                <div key={leg.id} className="relative mb-12 animate-in fade-in slide-in-from-bottom-4 duration-300">
                  {/* Leg Header */}
                  <div className="sticky top-[136px] z-20 bg-gray-50/90 backdrop-blur-sm flex items-center mb-6 py-2 px-2">
                    <div className="font-black text-blue-600 text-xl truncate flex-1 flex flex-col gap-1">
                      <div className="flex items-center gap-2">
                      <span className="bg-blue-600 text-white w-8 h-8 rounded-lg flex items-center justify-center text-sm">
                        {leg.sequence}
                      </span>
                      {leg.note || `Chi tiết Chặng ${leg.sequence}`}
                      </div>
                      {prevLegLastLoc && (
                        <div className="flex items-center gap-1 text-[10px] text-gray-400 uppercase tracking-widest ml-10">
                          <Navigation className="w-2.5 h-2.5 rotate-90" /> Tiếp nối từ {prevLegLastLoc.name}
                        </div>
                      )}
                    </div>
                    <div className="flex items-center gap-2 ml-4">
                      {['OWNER', 'MANAGER'].includes(userRole || '') && (
                        <>
                          <button 
                            onClick={() => onAddLocation?.(leg.id)}
                            className="p-2 text-gray-400 hover:text-blue-600 hover:bg-blue-50 rounded-xl transition-all"
                            title="Thêm địa điểm vào chặng này"
                          >
                            <Plus className="w-4 h-4" />
                          </button>
                          <button 
                            onClick={() => handleEditLeg(leg)}
                            className="p-2 text-gray-400 hover:text-blue-600 hover:bg-blue-50 rounded-xl transition-all"
                          >
                            <Edit2 className="w-4 h-4" />
                          </button>
                          <button 
                            onClick={() => handleDeleteLeg(leg.id)}
                            className="p-2 text-gray-400 hover:text-red-600 hover:bg-red-50 rounded-xl transition-all"
                          >
                            <Trash2 className="w-4 h-4" />
                          </button>
                        </>
                      )}
                      {leg.totalDistance !== undefined && (
                        <div className="hidden sm:flex items-center gap-2">
                        <div className="text-xs font-bold text-blue-600 bg-blue-50 px-2 py-1 rounded-lg border border-blue-100">
                          {leg.totalDistance} km
                        </div>
                        <div className="text-xs font-bold text-gray-500 bg-gray-50 px-2 py-1 rounded-lg border border-gray-100 flex items-center gap-1">
                          <Clock className="w-3 h-3" />
                          ~ {formatTravelTime(Math.round((leg.totalDistance / 35) * 60))}
                        </div>
                      </div>
                    )}
                      {totalDwellMinutes > 0 && (
                        <div className="hidden md:flex text-xs font-bold text-amber-600 bg-amber-50 px-2 py-1 rounded-lg border border-amber-100 items-center gap-1">
                          <Clock className="w-3 h-3" />
                          Dừng: {formatTravelTime(totalDwellMinutes)}
                        </div>
                      )}
                    </div>
                    {['OWNER', 'MANAGER'].includes(userRole || '') && legs.length > 0 && (
                      <button 
                        onClick={() => optimizeRouting(leg.id)}
                        className="ml-auto flex items-center gap-1.5 text-xs font-bold text-indigo-600 hover:text-indigo-700 bg-indigo-50 hover:bg-indigo-100 px-3 py-1.5 rounded-xl transition-all"
                      >
                        <Zap className="w-3 h-3" />
                        Tối ưu
                      </button>
                    )}
                  </div>

                  {/* Vertical Line for the whole leg */}
                  {/* Mở rộng đường kẻ xuống dưới (bottom-[-3rem]) để nối liền với chặng tiếp theo */}
                  <div className={`absolute left-6 top-16 ${legIdx === legs.length - 1 ? 'bottom-0' : 'bottom-[-3.5rem]'} w-0.5 bg-blue-100 -z-0`} />

                  <div className="ml-2">
                    {leg.locations.map((location, idx) => {
                      // Logic quan trọng: Gán điểm cuối chặng này nối với điểm đầu chặng sau
                      const nextLocation = leg.locations[idx + 1] || legs[legIdx + 1]?.locations[0];
                      const distanceToNext = nextLocation 
                        ? calculateDistance(location.latitude, location.longitude, nextLocation.latitude, nextLocation.longitude)
                        : null;

                      const averageSpeed = 35; // km/h
                      const travelTimeMinutes = distanceToNext ? Math.round((distanceToNext / averageSpeed) * 60) : null;

                      const dwellMinutes = (location.plannedStart && location.plannedEnd)
                        ? differenceInMinutes(parseISO(location.plannedEnd), parseISO(location.plannedStart))
                        : null;
                        
                      const locationExpense = leg.expenses?.find((e: any) => e.locationId === location.id);

                      const isStartPoint = legs[0]?.id === leg.id && idx === 0;
                      const isEndPoint = legs[legs.length - 1]?.id === leg.id && idx === leg.locations.length - 1;

                      return (
                        <div key={location.id}>
                          <div className="relative flex group mb-6">
                            {/* Timeline Node */}
                            <div className="z-10 mt-1.5 mr-4">
                              <button 
                                onClick={() => toggleComplete(location.id)}
                                className={`transition-colors duration-200 ${location.status === 'COMPLETED' ? 'text-green-500' : 'text-gray-300 hover:text-blue-500'}`}
                              >
                                {location.status === 'COMPLETED' ? (
                                  <CheckCircle2 className="w-8 h-8 bg-white rounded-full" />
                                ) : (
                                  <Circle className="w-8 h-8 bg-white rounded-full fill-white" />
                                )}
                              </button>
                            </div>

                            {/* Card Content */}
                            <div className={`flex-1 bg-white p-4 rounded-xl border transition-all duration-200 ${
                              location.status === 'COMPLETED' ? 'border-green-100 bg-green-50/30' : 'border-gray-100 shadow-sm hover:shadow-md'
                            }`}>
                              <div className="flex justify-between items-start">
                                <div>
                                  {isStartPoint && (
                                    <span className="inline-block px-2 py-0.5 bg-green-100 text-green-700 text-[10px] font-bold rounded-md mb-1 uppercase tracking-wider">Điểm bắt đầu</span>
                                  )}
                                  {isEndPoint && (
                                    <span className="inline-block px-2 py-0.5 bg-red-100 text-red-700 text-[10px] font-bold rounded-md mb-1 uppercase tracking-wider">Điểm kết thúc</span>
                                  )}
                                  <h3 className={`font-semibold text-lg ${location.status === 'COMPLETED' ? 'text-gray-500 line-through' : 'text-gray-800'}`}>
                                    {location.name}
                                  </h3>
                                  <div className="flex items-center text-sm text-gray-500 mt-1">
                                    <MapPin className="w-3 h-3 mr-1" />
                                    <span className="truncate max-w-[200px] sm:max-w-md">{location.address}</span>
                                  </div>
                                  {location.note && (
                                    <div className="mt-2 text-xs text-gray-600 bg-gray-50 p-2 rounded-lg border border-gray-100 italic">
                                      {location.note}
                                    </div>
                                  )}
                                  {dwellMinutes !== null && (
                                    <div className="flex items-center text-xs text-amber-600 font-medium mt-1">
                                      <Clock className="w-3 h-3 mr-1" />
                                      <span>Thời gian dừng: {formatTravelTime(dwellMinutes)}</span>
                                    </div>
                                  )}
                                   {locationExpense && (
                                     <div className="mt-2 text-xs text-indigo-600 bg-indigo-50/80 p-2 rounded-lg border border-indigo-100 space-y-1">
                                       <div className="flex items-center gap-1 font-bold">
                                         <Zap className="w-3 h-3" />
                                         <span>Chi phí: {Number(locationExpense.amount).toLocaleString()}đ ({locationExpense.category})</span>
                                       </div>
                                       {locationExpense.description && (
                                         <div className="text-[10px] text-gray-600">Dịch vụ: {locationExpense.description}</div>
                                       )}
                                       {locationExpense.note && (
                                         <div className="text-[10px] text-gray-500 italic">{locationExpense.note}</div>
                                       )}
                                       {locationExpense.paidBy && (
                                         <div className="text-[10px] font-semibold text-indigo-700">Đã thanh toán: {locationExpense.paidBy.name}</div>
                                       )}
                                     </div>
                                   )}
                                </div>
                                
                                <div className="text-right flex flex-col items-end">
                                  <div className="flex items-center text-sm font-medium text-blue-600">
                                    <Clock className="w-3 h-3 mr-1" />
                                    {location.plannedStart ? format(parseISO(location.plannedStart), 'HH:mm') : '--:--'}
                                  </div>
                                  {location.status === 'COMPLETED' && location.actualStart && (
                                    <div className="text-[10px] text-gray-400 mt-1 italic">
                                      Thực tế: {format(parseISO(location.actualStart), 'HH:mm')}
                                    </div>
                                  )}
                                  {['OWNER', 'MANAGER'].includes(userRole || '') && !isStartPoint && !isEndPoint && (
                                    <div className="flex gap-1 mt-2">
                                      <button onClick={() => onEditLocation?.(location)} className="p-1 text-gray-400 hover:text-blue-600 transition-colors">
                                        <Edit2 className="w-3.5 h-3.5" />
                                      </button>
                                      <button onClick={() => handleDeleteLocation(location.id)} className="p-1 text-gray-400 hover:text-red-600 transition-colors">
                                        <Trash2 className="w-3.5 h-3.5" />
                                      </button>
                                    </div>
                                  )}
                                </div>
                              </div>

                              {/* Logic tính toán độ lệch thời gian */}
                              <TimeVariance planned={location.plannedStart || ''} actual={location.actualStart || null} />
                            </div>
                          </div>

                          {distanceToNext !== null && travelTimeMinutes !== null && (
                            <div className="ml-4 -mt-4 mb-2 flex items-center gap-3">
                              <div className="w-8 flex justify-center">
                                <Navigation className="w-3 h-3 text-blue-400 rotate-180" />
                              </div>
                              <div className="flex items-center gap-2">
                                <span className="text-[10px] font-bold text-blue-500 bg-blue-50 px-2 py-0.5 rounded-full border border-blue-100">
                                  {distanceToNext.toFixed(2)} km
                                </span>
                                <span className="text-[10px] font-bold text-gray-500 bg-gray-50 px-2 py-0.5 rounded-full border border-gray-100 flex items-center gap-1">
                                  <Clock className="w-2.5 h-2.5" />
                                  ~ {formatTravelTime(travelTimeMinutes)}
                                </span>
                              </div>
                            </div>
                          )}
                        </div>
                      );
                    })}
                  </div>
                </div>
              );
          })
        )}

        {/* Actions at the bottom of the list */}
        {['OWNER', 'MANAGER'].includes(userRole || '') && (
          <div className="flex flex-col gap-3 pb-20 mt-8">
            <button
              onClick={handleDeclareLegs}
              className="w-full py-4 rounded-2xl bg-white text-blue-600 border-2 border-dashed border-blue-200 hover:bg-blue-50 transition-all flex items-center justify-center gap-2 text-sm font-bold"
            >
              <List className="w-5 h-5" /> 
              {legs.length > 0 ? "Khai báo lại số lượng chặng" : "Bắt đầu bằng việc khai báo số chặng"}
            </button>
            <button
              onClick={handleAddLeg}
              className="w-full py-4 rounded-2xl bg-blue-600 text-white shadow-lg shadow-blue-100 hover:bg-blue-700 transition-all flex items-center justify-center gap-2 text-sm font-bold"
            >
              <Plus className="w-5 h-5" /> Thêm chặng lẻ vào cuối
            </button>
          </div>
        )}
      </div>
      <ConfirmModal
        isOpen={confirmState.open}
        title={confirmState.title}
        message={confirmState.message}
        onConfirm={() => confirmState.onConfirm?.()}
        onCancel={() => setConfirmState({ open: false })}
      />
    </div>
  );
};