package com.cyksj.service.relation.impl;

import cn.hutool.core.date.DateUtil;
import com.cyksj.common.exception.BusinessRuntimeException;
import com.cyksj.mapper.TicketDurationRepairMapper;
import com.cyksj.mapper.manage.cms.CmsUserMapper;
import com.cyksj.mapper.manage.statistics.IncrExpiryTimeRecordMapper;
import com.cyksj.model.dto.TicketDurationRepairOrder;
import com.cyksj.model.dto.TicketDurationRepairRow;
import com.cyksj.model.entity.CmsUser;
import com.cyksj.model.entity.GroupsRelation;
import com.cyksj.model.entity.IncrExpiryTimeRecord;
import com.cyksj.model.request.TicketDurationRepairReq;
import com.cyksj.model.response.TicketDurationRepairItemResp;
import com.cyksj.model.response.TicketDurationRepairPreviewResp;
import com.cyksj.service.relation.TicketDurationRepairService;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Transactional;

import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

@Service
@RequiredArgsConstructor
public class TicketDurationRepairServiceImpl implements TicketDurationRepairService {
    private final TicketDurationRepairMapper mapper;
    private final IncrExpiryTimeRecordMapper recordMapper;
    private final CmsUserMapper cmsUserMapper;

    @Override
    @Transactional(readOnly = true, isolation = Isolation.REPEATABLE_READ)
    public TicketDurationRepairPreviewResp preview(Long afterId, Integer limit, Long userId) {
        if (afterId == null || afterId < 0 || limit == null || limit < 1 || limit > 200) {
            throw BusinessRuntimeException.getInstance("afterId必须大于等于0，limit必须在1至200之间");
        }
        if (userId != null && userId <= 0) {
            throw BusinessRuntimeException.getInstance("userId必须大于0");
        }
        List<TicketDurationRepairRow> fetched = mapper.selectPage(afterId, limit + 1, userId);
        boolean hasMore = fetched.size() > limit;
        List<TicketDurationRepairRow> rows = hasMore ? fetched.subList(0, limit) : fetched;
        TicketDurationRepairPreviewResp response = new TicketDurationRepairPreviewResp();
        response.setUserId(userId);
        response.setAfterId(afterId);
        response.setNextAfterId(rows.isEmpty() ? afterId : rows.get(rows.size() - 1).getRelationId());
        response.setHasMore(hasMore);
        response.setItems(classifyAll(rows));
        return response;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public List<TicketDurationRepairItemResp> execute(TicketDurationRepairReq req, Long adminId) {
        validateRequest(req, adminId);
        // Lock in a stable order. The entire batch is validated before the first mutation.
        List<TicketDurationRepairReq.Snapshot> snapshots = new ArrayList<>(req.getItems());
        snapshots.sort(Comparator.comparing(TicketDurationRepairReq.Snapshot::getRelationId));
        List<TicketDurationRepairRow> rows = new ArrayList<>();
        for (TicketDurationRepairReq.Snapshot snapshot : snapshots) {
            TicketDurationRepairRow row = mapper.selectForUpdate(snapshot.getRelationId());
            if (row == null || !matches(row, snapshot)) {
                throw BusinessRuntimeException.getInstance("车票" + snapshot.getRelationId() + "已变化或不属于目标规格，请重新预览");
            }
            rows.add(row);
        }
        List<TicketDurationRepairItemResp> results = classifyAll(rows);
        for (TicketDurationRepairItemResp result : results) {
            if (!"candidate".equals(result.getDecision())) {
                throw BusinessRuntimeException.getInstance("车票" + result.getRelationId() + "不能自动修复：" + result.getReason());
            }
        }
        CmsUser admin = cmsUserMapper.selectById(adminId);
        String operator = admin != null && admin.getNickname() != null
                ? admin.getNickname() : String.valueOf(adminId);
        for (int i = 0; i < rows.size(); i++) {
            TicketDurationRepairRow row = rows.get(i);
            TicketDurationRepairItemResp result = results.get(i);
            Date expiryTime = new Date(result.getNewExpiryTime());
            if (mapper.updateExpiry(row, expiryTime) != 1) {
                throw BusinessRuntimeException.getInstance("车票" + row.getRelationId() + "更新失败，整批修复已回滚");
            }
            IncrExpiryTimeRecord record = new IncrExpiryTimeRecord();
            record.setRelationId(row.getRelationId());
            record.setUserId(row.getUserId());
            record.setExpiryTimeInitial(row.getExpiryTime());
            // Existing audit schema records days; calculate the actual calendar-day difference.
            int days = (int) ChronoUnit.DAYS.between(DateUtil.toLocalDateTime(row.getExpiryTime()).toLocalDate(),
                    DateUtil.toLocalDateTime(expiryTime).toLocalDate());
            record.setIncrExpiryDays(days);
            record.setOperator(operator);
            record.setRemark(req.getRemark() != null && !req.getRemark().isBlank()
                    ? req.getRemark()
                    : "规格772/774半年付时长修复：原到期时间减6个自然月；原到期="
                    + DateUtil.formatDateTime(row.getExpiryTime()) + "；新到期=" + DateUtil.formatDateTime(expiryTime));
            if (recordMapper.insert(record) != 1) {
                throw BusinessRuntimeException.getInstance("车票" + row.getRelationId() + "修复记录保存失败，整批修复已回滚");
            }
            result.setDecision("updated");
            result.setReason("已从原到期时间扣减6个自然月");
        }
        return results;
    }

    private List<TicketDurationRepairItemResp> classifyAll(List<TicketDurationRepairRow> rows) {
        if (rows.isEmpty()) {
            return Collections.emptyList();
        }
        List<Long> ids = rows.stream().map(TicketDurationRepairRow::getRelationId).collect(Collectors.toList());
        Map<Long, Map<Long, TicketDurationRepairOrder>> orders = new HashMap<>();
        for (TicketDurationRepairOrder order : mapper.selectOrders(ids)) {
            Map<Long, TicketDurationRepairOrder> byId = orders.computeIfAbsent(order.getRelationId(), key -> new HashMap<>());
            TicketDurationRepairOrder previous = byId.putIfAbsent(order.getOrderId(), order);
            if (previous != null && Boolean.TRUE.equals(order.getSlot())) {
                previous.setSlot(true);
            }
        }
        Set<Long> adjusted = new HashSet<>(mapper.selectAdjustedRelationIds(ids));
        List<TicketDurationRepairItemResp> results = new ArrayList<>();
        for (TicketDurationRepairRow row : rows) {
            results.add(classify(row, new ArrayList<>(orders.getOrDefault(row.getRelationId(), Collections.emptyMap()).values()),
                    adjusted.contains(row.getRelationId())));
        }
        return results;
    }

    private TicketDurationRepairItemResp classify(TicketDurationRepairRow row,
                                                 List<TicketDurationRepairOrder> orders, boolean adjusted) {
        TicketDurationRepairItemResp result = new TicketDurationRepairItemResp();
        result.setRelationId(row.getRelationId());
        result.setGroupsId(row.getGroupsId());
        result.setSkuId(row.getSkuId());
        result.setUserId(row.getUserId());
        result.setStartTime(millis(row.getStartTime()));
        result.setExpiryTime(millis(row.getExpiryTime()));
        result.setUpdateTime(millis(row.getUpdateTime()));
        result.setOrderCount(orders.size());
        if (!isTarget(row.getSkuId())) {
            return decision(result, "skipped", "不是规格772或774");
        }
        if (row.getStartTime() == null || row.getExpiryTime() == null) {
            return decision(result, "skipped", "未设置完整起止时间");
        }
        Date expected = DateUtil.offsetMonth(row.getStartTime(), 12);
        long difference = row.getExpiryTime().getTime() - expected.getTime();
        result.setYearDifferenceMillis(difference);
        if (difference != 0) {
            if (Math.abs(difference) <= 60_000 || DateUtil.isSameDay(expected, row.getExpiryTime())) {
                return decision(result, "review", "接近一年但存在时间偏差，需核对");
            }
            return decision(result, "skipped", "已设置的时长不是12个自然月");
        }
        List<String> reasons = new ArrayList<>();
        if (row.getUserId() == null || row.getUserId() <= 0
                || (row.getStatus() != GroupsRelation.Status.validity && row.getStatus() != GroupsRelation.Status.outside)) {
            reasons.add("车票无当前用户或状态无效");
        }
        if (Boolean.TRUE.equals(row.getIsFrozen()) || Boolean.TRUE.equals(row.getIsRecover()) || nonzero(row.getReservedDays())) {
            reasons.add("有冻结/恢复/保留天数");
        }
        if (nonzero(row.getCompensationDays()) || adjusted) {
            reasons.add("有补偿或手工时长调整");
        }
        if (Boolean.TRUE.equals(row.getIsVip()) || !Objects.equals(row.getAqType(), 1)) {
            reasons.add("VIP或非普通购买车票");
        }
        if (orders.size() != 1) {
            reasons.add("有效关联订单不是一笔");
        } else {
            TicketDurationRepairOrder order = orders.get(0);
            if (!Objects.equals(order.getOrderType(), 1)) {
                reasons.add("续费或未知订单类型");
            }
            if (!Objects.equals(order.getSkuId(), row.getSkuId())) {
                reasons.add("订单规格与当前车票不一致");
            }
            if (order.getNum() == null || order.getNum() < 1
                    || (order.getNum() > 1 && !Boolean.TRUE.equals(order.getSlot()))) {
                reasons.add("购买数量可能叠加时长");
            }
        }
        if (!reasons.isEmpty()) {
            return decision(result, "review", String.join("；", reasons));
        }
        Date newExpiry = DateUtil.offsetMonth(row.getExpiryTime(), -6);
        result.setNewExpiryTime(newExpiry.getTime());
        result.setExpiredAfterRepair(!newExpiry.after(new Date()));
        return decision(result, "candidate", "可修复：原到期时间减6个自然月");
    }

    private TicketDurationRepairItemResp decision(TicketDurationRepairItemResp result, String decision, String reason) {
        result.setDecision(decision);
        result.setReason(reason);
        return result;
    }

    private boolean matches(TicketDurationRepairRow row, TicketDurationRepairReq.Snapshot snapshot) {
        return Objects.equals(row.getRelationId(), snapshot.getRelationId())
                && Objects.equals(row.getGroupsId(), snapshot.getGroupsId())
                && Objects.equals(row.getSkuId(), snapshot.getSkuId()) && isTarget(row.getSkuId())
                && Objects.equals(row.getUserId(), snapshot.getUserId())
                && Objects.equals(millis(row.getStartTime()), snapshot.getStartTime())
                && Objects.equals(millis(row.getExpiryTime()), snapshot.getExpiryTime())
                && Objects.equals(millis(row.getUpdateTime()), snapshot.getUpdateTime());
    }

    private void validateRequest(TicketDurationRepairReq req, Long adminId) {
        if (adminId == null || adminId <= 0 || req == null || req.getItems() == null
                || req.getItems().isEmpty() || req.getItems().size() > 200) {
            throw BusinessRuntimeException.getInstance("请以后台账号提交1至200张预览中的车票");
        }
        Set<Long> ids = new HashSet<>();
        for (TicketDurationRepairReq.Snapshot item : req.getItems()) {
            if (item == null || item.getRelationId() == null || item.getRelationId() <= 0
                    || item.getGroupsId() == null || item.getGroupsId() <= 0
                    || item.getUserId() == null || item.getUserId() <= 0 || !isTarget(item.getSkuId())
                    || item.getStartTime() == null || item.getExpiryTime() == null) {
                throw BusinessRuntimeException.getInstance("车票快照不完整或规格不属于772/774");
            }
            if (!ids.add(item.getRelationId())) {
                throw BusinessRuntimeException.getInstance("不能重复提交同一张车票");
            }
        }
    }

    private static Long millis(Date date) {
        return date == null ? null : date.getTime();
    }

    private static boolean nonzero(Integer value) {
        return value != null && value != 0;
    }

    private static boolean isTarget(Long skuId) {
        return Objects.equals(skuId, 772L) || Objects.equals(skuId, 774L);
    }
}