package com.kym.service.impl;

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONObject;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.kym.common.utils.CommUtil;
import com.kym.entity.common.PageBean;
import com.kym.entity.WashDevice;
import com.kym.entity.WashStation;
import com.kym.entity.queryParams.StationQueryParams;
import com.kym.entity.vo.WashStationVo;
import com.kym.mapper.WashStationMapper;
import com.kym.service.RechargeConfigGroupService;
import com.kym.service.WashDeviceService;
import com.kym.service.WashStationService;
import com.kym.service.cache.KymCache;
import com.kym.service.mybatisplus.MyBaseServiceImpl;
import jakarta.annotation.PostConstruct;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;

import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * <p>
 * 洗车站点表 服务实现类
 * </p>
 *
 * @author skyline
 * @since 2024-09-11
 */
@Service
public class WashStationServiceImpl extends MyBaseServiceImpl<WashStationMapper, WashStation> implements WashStationService {
    @PostConstruct
    public void init() {
        var list = list();
        KymCache.INSTANCE.putStationId2Name(list.stream().collect(Collectors.toMap(WashStation::getStationId, WashStation::getStationName)));
        KymCache.INSTANCE.putStationId2ParkingQrCodeUrl(list.stream().collect(Collectors.toMap(WashStation::getStationId, WashStation::getParkingQrCode)));
        KymCache.INSTANCE.putStationId2ParkingCouponMinAmount(list.stream().filter(s -> s.getParkingCouponMinAmount() != null).collect(Collectors.toMap(WashStation::getStationId, WashStation::getParkingCouponMinAmount)));
    }

    private final WashDeviceService washDeviceService;
    private final RechargeConfigGroupService rechargeConfigGroupService;

    public WashStationServiceImpl(WashDeviceService washDeviceService, RechargeConfigGroupService rechargeConfigGroupService) {
        this.washDeviceService = washDeviceService;
        this.rechargeConfigGroupService = rechargeConfigGroupService;
    }


    // ====================================================== 运营平台接口 Start ===========================================================

    @Override
    public void add(WashStation station) {
        Long count = lambdaQuery().eq(WashStation::getStationId, station.getStationId()).count();
        CommUtil.asserts(count == 0, "站点已存在");
        save(station);

        // 新站点不自动创建分组，默认使用平台默认分组。管理员可在充值配置中为该站点分配专属分组。
        // 如需自动创建：rechargeConfigGroupService.createGroup(new RechargeConfigGroup(), List.of(station.getStationId()));
    }

    @Override
    public void modify(WashStation station) {
        CommUtil.assertsNonNulls(List.of(station.getStationName(), station.getStationId(), station.getStationType(), station.getId()), "参数异常");
        List<WashStation> list = lambdaQuery().eq(WashStation::getStationName, station.getStationName()).list();
        CommUtil.asserts(list.size() <= 1, "站点信息异常");
        if (list.size() == 1) {
            CommUtil.asserts(list.get(0).getStationName().equalsIgnoreCase(station.getStationName()), "站点已存在");
        }
        updateById(station);
    }

    @Override
    public PageBean<WashStation> list(StationQueryParams query) {
        PageHelper.startPage(query.getPageNum(), query.getPageSize());
        List<WashStation> list = lambdaQuery()
                .like(CommUtil.isNotEmptyAndNull(query.getStationName()), WashStation::getStationName, query.getStationName())
                .like(CommUtil.isNotEmptyAndNull(query.getAddress()), WashStation::getAddress, query.getAddress())
                .eq(CommUtil.isNotEmptyAndNull(query.getStationType()), WashStation::getStationType, query.getStationType())
                .list();
        return new PageBean<>(list);
    }

    @Override
    public WashStation detail(Long id) {
        return getById(id);
    }

    @Override
    public void remove(Long id) {

    }
    // ====================================================== 运营平台接口 Start ===========================================================


    // ====================================================== 小程序接口 Start ===========================================================

    /**
     * 默认最大距离（公里）
     */
    private static final double DEFAULT_MAX_DISTANCE_KM = 50d;

    @Override
    public PageBean<WashStationVo> listStationForApp(StationQueryParams params) {
        // 传入有效经纬度时启用附近站点模式：内存计算距离、过滤、排序后手动分页
        if (hasUserLocation(params)) {
            return listStationByDistance(params);
        }
        PageHelper.startPage(params.getPageNum(), params.getPageSize());
        var stationList = lambdaQuery()
                .eq(CommUtil.isNotEmptyAndNull(params.getStationId()), WashStation::getStationId, params.getStationId())
                .like(CommUtil.isNotEmptyAndNull(params.getStationName()), WashStation::getStationName, params.getStationName())
                .list();
        if (stationList.isEmpty()) {
            return new PageBean<>(Collections.emptyList());
        }
        var voList = buildStationVoList(stationList, Collections.emptyMap());
        return new PageBean<>(voList);
    }

    /**
     * 附近站点：站点表数据量小且坐标存于 JSON 字符串无法走索引，
     * 故全量查出后在内存中按 Haversine 公式计算距离，过滤超远站点并按距离升序，再分页。
     */
    private PageBean<WashStationVo> listStationByDistance(StationQueryParams params) {
        double userLat = params.getLatitude();
        double userLng = params.getLongitude();
        double maxDistance = params.getMaxDistance() != null && params.getMaxDistance() > 0
                ? params.getMaxDistance() : DEFAULT_MAX_DISTANCE_KM;

        // 距离模式下需要先过滤排序再分页，因此不能用 PageHelper 分页查询
        Map<String, Double> distanceMap = new HashMap<>();
        var matchedList = lambdaQuery()
                .eq(CommUtil.isNotEmptyAndNull(params.getStationId()), WashStation::getStationId, params.getStationId())
                .like(CommUtil.isNotEmptyAndNull(params.getStationName()), WashStation::getStationName, params.getStationName())
                .list().stream()
                .filter(station -> {
                    Double distance = calcDistanceKm(userLat, userLng, station.getLocation());
                    if (distance == null || distance > maxDistance) {
                        return false;
                    }
                    distanceMap.put(station.getStationId(), distance);
                    return true;
                })
                .sorted(Comparator.comparing(distanceMap::get))
                .toList();

        int total = matchedList.size();
        int pageNum = Math.max(params.getPageNum(), 1);
        int pageSize = Math.max(params.getPageSize(), 1);
        int fromIndex = (pageNum - 1) * pageSize;
        List<WashStation> pageList = fromIndex >= total
                ? Collections.emptyList()
                : matchedList.subList(fromIndex, Math.min(fromIndex + pageSize, total));
        if (pageList.isEmpty()) {
            Page<WashStationVo> emptyPage = new Page<>(pageNum, pageSize);
            emptyPage.setTotal(total);
            return new PageBean<>(emptyPage);
        }
        var voList = buildStationVoList(pageList, distanceMap);
        Page<WashStationVo> page = new Page<>(pageNum, pageSize);
        page.setTotal(total);
        page.addAll(voList);
        return new PageBean<>(page);
    }

    private static boolean hasUserLocation(StationQueryParams params) {
        return params.getLatitude() != null && params.getLongitude() != null
                && (params.getLatitude() != 0 || params.getLongitude() != 0);
    }

    /**
     * 解析站点 location JSON 并计算与用户的球面距离（公里），坐标缺失或格式异常返回 null
     */
    private static Double calcDistanceKm(double userLat, double userLng, String location) {
        if (CommUtil.isEmptyOrNull(location)) {
            return null;
        }
        double stationLat;
        double stationLng;
        try {
            JSONObject json = JSON.parseObject(location);
            stationLat = json.getDoubleValue("stationLat");
            stationLng = json.getDoubleValue("stationLng");
        } catch (Exception e) {
            return null;
        }
        if (stationLat == 0 && stationLng == 0) {
            return null;
        }
        double radLat1 = Math.toRadians(userLat);
        double radLat2 = Math.toRadians(stationLat);
        double a = radLat1 - radLat2;
        double b = Math.toRadians(userLng) - Math.toRadians(stationLng);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
                + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));
        s = s * 6378.137;
        return Math.round(s * 100) / 100.0;
    }

    /**
     * 组装站点 VO（含空闲设备数），distanceMap 非空时回填距离
     */
    private List<WashStationVo> buildStationVoList(List<WashStation> stationList, Map<String, Double> distanceMap) {
        // 查询站点下的所有设备，按照站点统计可用设备数量
        var res = washDeviceService.lambdaQuery().in(WashDevice::getStationId, stationList.stream().map(WashStation::getStationId).toList())
                .eq(WashDevice::getState, WashDevice.STATE_空闲)
                .list().stream().collect(Collectors.groupingBy(WashDevice::getStationId, Collectors.counting()));
        return stationList.stream().map(station -> {
            var vo = new WashStationVo();
            BeanUtils.copyProperties(station, vo);
            vo.setIdleParkingNum(Math.toIntExact(res.getOrDefault(station.getStationId(), 0L)));
            vo.setDistance(distanceMap.get(station.getStationId()));
            return vo;
        }).toList();
    }

    // ====================================================== 小程序接口 End ===========================================================

}