package com.tourguide.modules.dashboard.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.tourguide.modules.dashboard.dto.DashboardOrderTypeRow;
import com.tourguide.modules.dashboard.dto.DashboardResponse;
import com.tourguide.modules.dashboard.dto.DashboardScenicRow;
import com.tourguide.modules.dashboard.mapper.DashboardMapper;
import com.tourguide.modules.order.entity.TourOrder;
import com.tourguide.modules.order.mapper.TourOrderMapper;
import com.tourguide.modules.review.entity.OrderReview;
import com.tourguide.modules.review.mapper.OrderReviewMapper;
import com.tourguide.modules.user.entity.MiniUser;
import com.tourguide.modules.user.mapper.MiniUserMapper;
import org.springframework.stereotype.Service;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

@Service
public class DashboardService {
    private final MiniUserMapper miniUserMapper;
    private final TourOrderMapper orderMapper;
    private final OrderReviewMapper reviewMapper;
    private final DashboardMapper dashboardMapper;

    public DashboardService(MiniUserMapper miniUserMapper, TourOrderMapper orderMapper,
                            OrderReviewMapper reviewMapper, DashboardMapper dashboardMapper) {
        this.miniUserMapper = miniUserMapper;
        this.orderMapper = orderMapper;
        this.reviewMapper = reviewMapper;
        this.dashboardMapper = dashboardMapper;
    }

    public DashboardResponse overview() {
        long userCount = miniUserMapper.selectCount(new LambdaQueryWrapper<MiniUser>());
        long orderCount = orderMapper.selectCount(new LambdaQueryWrapper<TourOrder>());
        long reviewCount = reviewMapper.selectCount(new LambdaQueryWrapper<OrderReview>());
        BigDecimal dailyGrowth = calculateDailyOrderGrowth();
        List<DashboardResponse.TrendPoint> trend = dashboardMapper.selectRevenueTrend().stream()
                .map(row -> new DashboardResponse.TrendPoint(row.getDateLabel(), defaultDecimal(row.getRevenue())))
                .collect(Collectors.toList());
        List<DashboardResponse.ScenicRank> scenicRanking = buildScenicRanking(dashboardMapper.selectScenicRanking());
        List<DashboardResponse.OrderTypeStat> typeStats = buildOrderTypeStats(dashboardMapper.selectOrderTypeStats());
        return new DashboardResponse(userCount, orderCount, reviewCount, dailyGrowth,
                defaultDecimal(dashboardMapper.selectTotalRevenue()), trend, scenicRanking, typeStats);
    }

    private BigDecimal calculateDailyOrderGrowth() {
        LocalDate today = LocalDate.now();
        long todayCount = countOrders(today.atStartOfDay(), today.plusDays(1).atStartOfDay());
        long yesterdayCount = countOrders(today.minusDays(1).atStartOfDay(), today.atStartOfDay());
        if (yesterdayCount == 0) return todayCount == 0 ? BigDecimal.ZERO : new BigDecimal("100.0");
        return BigDecimal.valueOf(todayCount - yesterdayCount)
                .multiply(new BigDecimal("100"))
                .divide(BigDecimal.valueOf(yesterdayCount), 1, RoundingMode.HALF_UP);
    }

    private long countOrders(LocalDateTime start, LocalDateTime end) {
        return orderMapper.selectCount(new LambdaQueryWrapper<TourOrder>()
                .ge(TourOrder::getCreatedAt, start)
                .lt(TourOrder::getCreatedAt, end));
    }

    private List<DashboardResponse.ScenicRank> buildScenicRanking(List<DashboardScenicRow> rows) {
        List<DashboardResponse.ScenicRank> result = new ArrayList<DashboardResponse.ScenicRank>();
        for (int index = 0; index < rows.size(); index++) {
            DashboardScenicRow row = rows.get(index);
            long today = row.getTodayCount() == null ? 0 : row.getTodayCount();
            long yesterday = row.getYesterdayCount() == null ? 0 : row.getYesterdayCount();
            BigDecimal growth = yesterday == 0
                    ? (today == 0 ? BigDecimal.ZERO : new BigDecimal("100.0"))
                    : BigDecimal.valueOf(today - yesterday).multiply(new BigDecimal("100"))
                    .divide(BigDecimal.valueOf(yesterday), 1, RoundingMode.HALF_UP);
            result.add(new DashboardResponse.ScenicRank(index + 1, row.getScenicName(), row.getOrderCount(), growth));
        }
        return result;
    }

    private List<DashboardResponse.OrderTypeStat> buildOrderTypeStats(List<DashboardOrderTypeRow> rows) {
        long total = rows.stream().mapToLong(row -> row.getOrderCount() == null ? 0 : row.getOrderCount()).sum();
        return rows.stream().map(row -> {
            long count = row.getOrderCount() == null ? 0 : row.getOrderCount();
            BigDecimal percentage = total == 0 ? BigDecimal.ZERO
                    : BigDecimal.valueOf(count).multiply(new BigDecimal("100"))
                    .divide(BigDecimal.valueOf(total), 1, RoundingMode.HALF_UP);
            return new DashboardResponse.OrderTypeStat(row.getOrderType(), count, percentage);
        }).collect(Collectors.toList());
    }

    private BigDecimal defaultDecimal(BigDecimal value) { return value == null ? BigDecimal.ZERO : value; }
}