package com.tcm.training.admin.app.member.service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.tcm.training.admin.app.auth.service.AppAuthSessionService;
import com.tcm.training.admin.app.member.dto.AppMemberPurchaseRequest;
import com.tcm.training.admin.app.member.vo.AppMemberPurchaseResultVO;
import com.tcm.training.admin.member.entity.AppUser;
import com.tcm.training.admin.member.entity.MemberPurchaseOrder;
import com.tcm.training.admin.member.mapper.MemberPurchaseOrderMapper;
import com.tcm.training.admin.member.mapper.UserMapper;
import com.tcm.training.admin.member.service.MemberSettingsAppService;
import com.tcm.training.admin.member.vo.MemberPriceSettingsVO;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

/**
 * APP 会员购买服务。
 */
@Service
public class AppMemberPurchaseService {

    private static final int USER_STATUS_ENABLED = 1;
    private static final String STATUS_PAID = "PAID";
    private static final String MEMBER_TYPE_MONTH_CARD = "MONTH_CARD";
    private static final String MEMBER_TYPE_QUARTER_CARD = "QUARTER_CARD";
    private static final String PAYMENT_METHOD_WECHAT = "WECHAT";
    private static final String PAYMENT_METHOD_ALIPAY = "ALIPAY";
    private static final DateTimeFormatter ORDER_NO_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");

    private final AppAuthSessionService appAuthSessionService;
    private final UserMapper userMapper;
    private final MemberSettingsAppService memberSettingsAppService;
    private final MemberPurchaseOrderMapper memberPurchaseOrderMapper;

    /**
     * 注入 APP 会员购买所需依赖。
     */
    public AppMemberPurchaseService(AppAuthSessionService appAuthSessionService,
                                    UserMapper userMapper,
                                    MemberSettingsAppService memberSettingsAppService,
                                    MemberPurchaseOrderMapper memberPurchaseOrderMapper) {
        this.appAuthSessionService = appAuthSessionService;
        this.userMapper = userMapper;
        this.memberSettingsAppService = memberSettingsAppService;
        this.memberPurchaseOrderMapper = memberPurchaseOrderMapper;
    }

    /**
     * 提交 APP 会员购买，当前阶段按模拟直付处理并立即生效。
     */
    @Transactional
    public AppMemberPurchaseResultVO purchase(AppMemberPurchaseRequest request) {
        Long userId = appAuthSessionService.requireLoginUserId();
        AppUser user = requireEnabledUser(userId);
        MemberPriceSettingsVO settings = requirePriceSettings();
        String memberType = normalizeMemberType(request == null ? null : request.getMemberType());
        String paymentMethod = normalizePaymentMethod(request == null ? null : request.getPaymentMethod());

        PackageSnapshot packageSnapshot = resolveEnabledPackage(settings, memberType);
        LocalDateTime now = LocalDateTime.now();
        LocalDateTime memberExpireAt = resolveMemberExpireAt(user.getMemberExpireAt(), packageSnapshot.getMemberDays(), now);

        MemberPurchaseOrder order = buildOrder(user, packageSnapshot, paymentMethod, now);
        memberPurchaseOrderMapper.insert(order);

        // 会员购买成功后立即更新用户到期时间，APP 可直接回写最新会员态。
        user.setMemberExpireAt(memberExpireAt);
        userMapper.updateById(user);
        order.setId(resolveOrderId(order, user.getId(), now));

        return buildPurchaseResult(order, memberExpireAt);
    }

    /**
     * 校验当前登录用户存在且可用。
     */
    private AppUser requireEnabledUser(Long userId) {
        AppUser user = userMapper.selectById(userId);
        if (user == null || user.getDeleted() == null || user.getDeleted().intValue() != 0) {
            throw new IllegalArgumentException("用户不存在");
        }
        if (user.getStatus() == null || user.getStatus().intValue() != USER_STATUS_ENABLED) {
            throw new IllegalArgumentException("用户已禁用");
        }
        return user;
    }

    /**
     * 读取当前会员价格配置，不存在时阻止下单。
     */
    private MemberPriceSettingsVO requirePriceSettings() {
        MemberPriceSettingsVO settings = memberSettingsAppService.currentPrice();
        if (settings == null) {
            throw new IllegalArgumentException("会员套餐暂未配置");
        }
        return settings;
    }

    /**
     * 校验并提取当前可购买的会员套餐快照。
     */
    private PackageSnapshot resolveEnabledPackage(MemberPriceSettingsVO settings, String memberType) {
        if (MEMBER_TYPE_MONTH_CARD.equals(memberType)) {
            return buildPackageSnapshot(memberType,
                    settings.getMonthCardEnabled(),
                    settings.getMonthCardDays(),
                    settings.getMonthCardPrice(),
                    "月会员暂未开放购买");
        }
        if (MEMBER_TYPE_QUARTER_CARD.equals(memberType)) {
            return buildPackageSnapshot(memberType,
                    settings.getQuarterCardEnabled(),
                    settings.getQuarterCardDays(),
                    settings.getQuarterCardPrice(),
                    "季度会员暂未开放购买");
        }
        throw new IllegalArgumentException("会员套餐不合法");
    }

    /**
     * 将后台启用配置转换为下单时使用的套餐快照。
     */
    private PackageSnapshot buildPackageSnapshot(String memberType,
                                                Boolean enabled,
                                                Integer memberDays,
                                                BigDecimal orderAmount,
                                                String disabledMessage) {
        if (!Boolean.TRUE.equals(enabled)) {
            throw new IllegalArgumentException(disabledMessage);
        }
        if (memberDays == null || memberDays.intValue() <= 0 || orderAmount == null || orderAmount.compareTo(BigDecimal.ZERO) <= 0) {
            throw new IllegalArgumentException("会员套餐配置不完整");
        }
        return new PackageSnapshot(memberType, memberDays, orderAmount);
    }

    /**
     * 规范化会员套餐类型，仅允许月卡或季卡。
     */
    private String normalizeMemberType(String memberType) {
        String normalized = trimToEmpty(memberType).toUpperCase();
        if (MEMBER_TYPE_MONTH_CARD.equals(normalized) || MEMBER_TYPE_QUARTER_CARD.equals(normalized)) {
            return normalized;
        }
        throw new IllegalArgumentException("会员套餐不合法");
    }

    /**
     * 规范化支付方式入参，仅允许微信或支付宝。
     */
    private String normalizePaymentMethod(String paymentMethod) {
        String normalized = trimToEmpty(paymentMethod).toUpperCase();
        if (PAYMENT_METHOD_WECHAT.equals(normalized) || PAYMENT_METHOD_ALIPAY.equals(normalized)) {
            return normalized;
        }
        throw new IllegalArgumentException("支付方式不合法");
    }

    /**
     * 计算新的会员到期时间；有效会员按原到期时间顺延，过期会员从当前时间起算。
     */
    private LocalDateTime resolveMemberExpireAt(LocalDateTime currentExpireAt, Integer memberDays, LocalDateTime now) {
        LocalDateTime baseTime = currentExpireAt != null && currentExpireAt.isAfter(now) ? currentExpireAt : now;
        return baseTime.plusDays(memberDays == null ? 0L : memberDays.longValue());
    }

    /**
     * 组装会员购买订单，支付方案落地前直接记为已支付。
     */
    private MemberPurchaseOrder buildOrder(AppUser user,
                                           PackageSnapshot packageSnapshot,
                                           String paymentMethod,
                                           LocalDateTime now) {
        MemberPurchaseOrder order = new MemberPurchaseOrder();
        order.setOrderNo(buildOrderNo(user.getId(), now));
        order.setAppUserId(user.getId());
        order.setUserNickname(resolveUserNickname(user));
        order.setUserPhone(trimToEmpty(user.getPhone()));
        order.setMemberType(packageSnapshot.getMemberType());
        order.setMemberDays(packageSnapshot.getMemberDays());
        order.setOrderAmount(packageSnapshot.getOrderAmount());
        order.setPaymentMethod(paymentMethod);
        order.setRefundAmount(null);
        order.setRefundRemark(null);
        order.setStatus(STATUS_PAID);
        order.setPaidAt(now);
        order.setRefundedAt(null);
        order.setCancelledAt(null);
        order.setDeleted(0);
        return order;
    }

    /**
     * 生成会员订单号。
     */
    private String buildOrderNo(Long userId, LocalDateTime now) {
        String seed = String.valueOf(Math.abs((userId == null ? 0L : userId.longValue()) % 10000L));
        int nanoTail = Math.abs(now.getNano() / 1000) % 1000000;
        return "MPO" + ORDER_NO_TIME_FORMATTER.format(now)
                + String.format("%06d", nanoTail)
                + String.format("%04d", Integer.parseInt(seed));
    }

    /**
     * 订单插入后优先使用主键；极端情况下回查同一订单号，避免响应缺少订单编号。
     */
    private Long resolveOrderId(MemberPurchaseOrder order, Long userId, LocalDateTime now) {
        if (order.getId() != null) {
            return order.getId();
        }
        MemberPurchaseOrder latestOrder = memberPurchaseOrderMapper.selectOne(new LambdaQueryWrapper<MemberPurchaseOrder>()
                .eq(MemberPurchaseOrder::getAppUserId, userId)
                .eq(MemberPurchaseOrder::getOrderNo, order.getOrderNo())
                .eq(MemberPurchaseOrder::getDeleted, 0)
                .orderByDesc(MemberPurchaseOrder::getPaidAt)
                .orderByDesc(MemberPurchaseOrder::getId)
                .last("LIMIT 1"));
        if (latestOrder != null && latestOrder.getId() != null) {
            return latestOrder.getId();
        }
        return null;
    }

    /**
     * 将购买结果转换为 APP 可直接消费的响应体。
     */
    private AppMemberPurchaseResultVO buildPurchaseResult(MemberPurchaseOrder order, LocalDateTime memberExpireAt) {
        AppMemberPurchaseResultVO resultVO = new AppMemberPurchaseResultVO();
        resultVO.setOrderId(order.getId());
        resultVO.setOrderNo(order.getOrderNo());
        resultVO.setMemberType(order.getMemberType());
        resultVO.setMemberDays(order.getMemberDays());
        resultVO.setOrderAmount(order.getOrderAmount());
        resultVO.setPaymentMethod(order.getPaymentMethod());
        resultVO.setStatus(order.getStatus());
        resultVO.setPaidAt(order.getPaidAt());
        resultVO.setMemberExpireAt(memberExpireAt);
        return resultVO;
    }

    /**
     * 优先使用昵称快照，没有昵称时降级到微信昵称或用户编号。
     */
    private String resolveUserNickname(AppUser user) {
        String nickname = trimToEmpty(user.getNickname());
        if (!nickname.isEmpty()) {
            return nickname;
        }
        String wechatNickname = trimToEmpty(user.getWechatNickname());
        if (!wechatNickname.isEmpty()) {
            return wechatNickname;
        }
        return "用户" + user.getId();
    }

    /**
     * 将可空文本转换为去空格字符串。
     */
    private String trimToEmpty(String value) {
        if (value == null) {
            return "";
        }
        return value.trim();
    }

    /**
     * 会员套餐快照，避免业务逻辑反复透传零散字段。
     */
    private static final class PackageSnapshot {

        private final String memberType;
        private final Integer memberDays;
        private final BigDecimal orderAmount;

        /**
         * 创建会员套餐快照。
         */
        private PackageSnapshot(String memberType, Integer memberDays, BigDecimal orderAmount) {
            this.memberType = memberType;
            this.memberDays = memberDays;
            this.orderAmount = orderAmount;
        }

        /**
         * 获取会员套餐类型。
         */
        private String getMemberType() {
            return memberType;
        }

        /**
         * 获取会员有效天数。
         */
        private Integer getMemberDays() {
            return memberDays;
        }

        /**
         * 获取订单金额。
         */
        private BigDecimal getOrderAmount() {
            return orderAmount;
        }
    }
}