package com.webmanage.service.impl;

import com.webmanage.common.BusinessException;
import com.webmanage.dto.CartItemDTO;
import com.webmanage.entity.Cart;
import com.webmanage.entity.ProductPricing;
import com.webmanage.mapper.CartMapper;
import com.webmanage.mapper.ProductPricingMapper;
import com.webmanage.service.CartService;
import com.webmanage.service.CartPersistenceService;
import com.webmanage.vo.CartItemVO;
import com.webmanage.vo.CartVO;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import com.webmanage.config.CartProperties;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.format.datetime.DateFormatter;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.CollectionUtils;
import org.springframework.util.StringUtils;

import javax.annotation.Resource;
import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

/**
 * 购物车服务实现类
 */
@Slf4j
@Service
public class CartServiceImpl implements CartService {
    
    @Resource
    private RedisTemplate<String, Object> redisTemplate;
    
    @Resource
    private CartMapper cartMapper;
    
    @Resource
    private ProductPricingMapper productPricingMapper;
    
    @Resource
    private CartPersistenceService cartPersistenceService;
    
    @Resource
    private CartProperties cartProperties;
    
    // Redis key前缀
    private static final String CART_KEY_PREFIX = "cart:";
    private static final String CART_ITEM_KEY_PREFIX = "cart_item:";
    private static final int CART_EXPIRE_DAYS = 30; // 购物车过期时间30天

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean addToCart(String userId, String unitId, CartItemDTO cartItemDTO) {
        try {
            // 验证商品定价是否存在
            ProductPricing pricing = productPricingMapper.selectById(cartItemDTO.getPricingId());
            if (pricing == null) {
                throw new BusinessException("商品定价不存在");
            }

            // 构建购物车key
            String cartKey = buildCartKey(userId,unitId, cartItemDTO.getProductId());
            String cartItemKey = buildCartItemKey(userId, unitId, cartItemDTO.getProductId(),cartItemDTO.getPricingId());

            // 检查商品是否已在购物车中
            CartItemVO existingItem = (CartItemVO) redisTemplate.opsForValue().get(cartItemKey);
            if (existingItem != null) {
                // 如果已存在，更新数量
                existingItem.setQuantity(existingItem.getQuantity() + cartItemDTO.getQuantity());
                existingItem.setTotalPrice(existingItem.getUnitPrice().multiply(BigDecimal.valueOf(existingItem.getQuantity())));
                existingItem.setUpdateTime(LocalDateTime.now());
            } else {
                // 如果不存在，创建新的购物车项
                existingItem = new CartItemVO();
                BeanUtils.copyProperties(cartItemDTO, existingItem);
                existingItem.setAddTime(LocalDateTime.now());
                existingItem.setUpdateTime(LocalDateTime.now());
                // 计算小计金额
                if (existingItem.getTotalPrice() == null) {
                    existingItem.setTotalPrice(existingItem.getUnitPrice().multiply(BigDecimal.valueOf(existingItem.getQuantity())));
                }
            }

            // 保存到Redis
            redisTemplate.opsForValue().set(cartItemKey, existingItem, (cartProperties.getExpireDays() != null ? cartProperties.getExpireDays() : CART_EXPIRE_DAYS), TimeUnit.DAYS);

            // 更新购物车商品列表
            updateCartItemList(userId, unitId, cartItemDTO.getProductId(), cartItemDTO.getPricingId(), true);

            // 设置购物车过期时间
            redisTemplate.expire(cartKey, (cartProperties.getExpireDays() != null ? cartProperties.getExpireDays() : CART_EXPIRE_DAYS), TimeUnit.DAYS);

            // 异步持久化到数据库（根据配置）
            if (Boolean.TRUE.equals(cartProperties.getEnablePersistence()) && "realtime".equalsIgnoreCase(cartProperties.getSyncStrategy())) {
                cartPersistenceService.saveOrUpdate(userId, unitId, existingItem);
            }

            log.info("用户{}成功添加商品{}到购物车", userId, cartItemDTO.getProductName());
            return true;
        } catch (Exception e) {
            log.error("添加商品到购物车失败", e);
            throw new BusinessException("添加商品到购物车失败：" + e.getMessage());
        }
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean removeFromCart(String userId, String unitId, String productId, Long pricingId) {
        try {
            String cartItemKey = buildCartItemKey(userId, unitId, productId, pricingId);

            // 从Redis中删除商品项
            Boolean removed = redisTemplate.delete(cartItemKey);
            if (Boolean.TRUE.equals(removed)) {
                // 更新购物车商品列表
                updateCartItemList(userId, unitId, productId, pricingId, false);

                // 异步从数据库中删除（根据配置）
                if (Boolean.TRUE.equals(cartProperties.getEnablePersistence()) && "realtime".equalsIgnoreCase(cartProperties.getSyncStrategy())) {
                    cartPersistenceService.remove(userId, unitId, productId,pricingId);
                }

                log.info("用户{}成功从购物车移除商品{}", userId, pricingId);
                return true;
            }
            return false;
        } catch (Exception e) {
            log.error("从购物车移除商品失败", e);
            throw new BusinessException("从购物车移除商品失败：" + e.getMessage());
        }
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean updateCartItemQuantity(String userId, String unitId, String productId, Long pricingId, Integer quantity) {
        try {
            if (quantity <= 0) {
                return removeFromCart(userId, unitId, productId, pricingId);
            }

            String cartItemKey = buildCartItemKey(userId, unitId, productId, pricingId);
            CartItemVO cartItem = (CartItemVO) redisTemplate.opsForValue().get(cartItemKey);
            if (cartItem == null) {
                throw new BusinessException("购物车商品不存在");
            }

            cartItem.setQuantity(quantity);
            cartItem.setTotalPrice(cartItem.getUnitPrice().multiply(BigDecimal.valueOf(quantity)));
            cartItem.setUpdateTime(LocalDateTime.now());

            // 更新到Redis
            redisTemplate.opsForValue().set(cartItemKey, cartItem, (cartProperties.getExpireDays() != null ? cartProperties.getExpireDays() : CART_EXPIRE_DAYS), TimeUnit.DAYS);

            // 异步持久化到数据库（根据配置）
            if (Boolean.TRUE.equals(cartProperties.getEnablePersistence()) && "realtime".equalsIgnoreCase(cartProperties.getSyncStrategy())) {
                cartPersistenceService.saveOrUpdate(userId, unitId, cartItem);
            }

            log.info("用户{}成功更新购物车商品{}数量为{}", userId, pricingId, quantity);
            return true;
        } catch (Exception e) {
            log.error("更新购物车商品数量失败", e);
            throw new BusinessException("更新购物车商品数量失败：" + e.getMessage());
        }
    }


    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean updateCartItemDuration(String userId, String unitId, String productId, Long pricingId, Integer duration) {
        try {

            String cartItemKey = buildCartItemKey(userId, unitId, productId, pricingId);
            CartItemVO cartItem = (CartItemVO) redisTemplate.opsForValue().get(cartItemKey);
            if (cartItem == null) {
                throw new BusinessException("购物车商品不存在");
            }

            cartItem.setDuration(duration);
            cartItem.setUpdateTime(LocalDateTime.now());

            // 更新到Redis
            redisTemplate.opsForValue().set(cartItemKey, cartItem, (cartProperties.getExpireDays() != null ? cartProperties.getExpireDays() : CART_EXPIRE_DAYS), TimeUnit.DAYS);

            // 异步持久化到数据库（根据配置）
            if (Boolean.TRUE.equals(cartProperties.getEnablePersistence()) && "realtime".equalsIgnoreCase(cartProperties.getSyncStrategy())) {
                cartPersistenceService.saveOrUpdate(userId, unitId, cartItem);
            }

            log.info("用户{}成功更新购物车商品{}年限为{}", userId, pricingId, duration);
            return true;
        } catch (Exception e) {
            log.error("更新购物车商品数量失败", e);
            throw new BusinessException("更新购物车商品数量失败：" + e.getMessage());
        }
    }


    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean clearCart(String userId, String unitId, String productId) {
        try {
            String cartKey = buildCartKey(userId, unitId, productId);
            List<Long> pricingIds = getCartItemPricingIds(userId, unitId, productId);

            // 删除所有商品项
            for (Long pricingId : pricingIds) {
                String cartItemKey = buildCartItemKey(userId, unitId, productId,pricingId);
                redisTemplate.delete(cartItemKey);
            }

            // 删除购物车列表
            redisTemplate.delete(cartKey);

            // 异步清空数据库中的购物车数据（根据配置）
            if (Boolean.TRUE.equals(cartProperties.getEnablePersistence()) && "realtime".equalsIgnoreCase(cartProperties.getSyncStrategy())) {
                cartPersistenceService.clear(userId, unitId, productId);
            }

            log.info("用户{}成功清空购物车", userId);
            return true;
        } catch (Exception e) {
            log.error("清空购物车失败", e);
            throw new BusinessException("清空购物车失败：" + e.getMessage());
        }
    }

    @Override
    public CartVO getCart(String userId, String unitId, String productId) {
        try {
            CartVO cartVO = new CartVO();
            cartVO.setUserId(userId);
            if (StringUtils.hasText(unitId)){
                cartVO.setUnitId(unitId);
            }
            List<CartItemVO> items = getCartItems(userId, unitId, productId);
            cartVO.setItems(items);

            // 计算总数量和总金额
            int totalQuantity = items.stream().mapToInt(item -> item.getQuantity()).sum();
            BigDecimal totalAmount = items.stream()
                    .map(item -> item.getTotalPrice())
                    .reduce(BigDecimal.ZERO, BigDecimal::add);

            cartVO.setTotalQuantity(totalQuantity);
            cartVO.setTotalAmount(totalAmount);
            cartVO.setLastUpdateTime(LocalDateTime.now());

            return cartVO;
        } catch (Exception e) {
            log.error("获取购物车信息失败", e);
            throw new BusinessException("获取购物车信息失败：" + e.getMessage());
        }
    }

    @Override
    public List<CartItemVO> getCartItems(String userId, String unitId,String productId) {
        try {
            // 优先从Redis获取
            List<CartItemVO> items = getCartItemsFromRedis(userId, unitId,productId);
            if (items != null && !items.isEmpty()) {
                return items;
            }

            // Redis中没有数据，从数据库加载
            log.info("Redis中无购物车数据，从数据库加载用户{}的购物车", userId);
            return loadCartFromDatabase(userId, unitId, productId) ? getCartItemsFromRedis(userId, unitId, productId) : new ArrayList<>();
        } catch (Exception e) {
            log.error("获取购物车商品列表失败", e);
            // 降级到数据库查询
            return getCartItemsFromDatabase(userId, unitId, productId);
        }
    }

    @Override
    public boolean checkCartItemStock(String userId, String unitId, Long pricingId) {
        // TODO: 实现库存检查逻辑
        return true;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean batchRemoveFromCart(String userId, String unitId, String productId,List<Long> pricingIds) {
        try {
            if (CollectionUtils.isEmpty(pricingIds)) {
                return true;
            }

            for (Long pricingId : pricingIds) {
                removeFromCart(userId, unitId, productId,pricingId);
            }

            return true;
        } catch (Exception e) {
            log.error("批量删除购物车商品失败", e);
            throw new BusinessException("批量删除购物车商品失败：" + e.getMessage());
        }
    }

    @Override
    public Integer getCartItemCount(String userId, String unitId, String productId) {
        try {
            // 优先从Redis获取
            String cartKey = buildCartKey(userId, unitId, productId);
            List<Long> pricingIds = (List<Long>) redisTemplate.opsForValue().get(cartKey);
            if (pricingIds != null) {
                return pricingIds.size();
            }

            // 从数据库获取
            return cartMapper.countByUserIdAndUnitId(userId, unitId, productId);
        } catch (Exception e) {
            log.error("获取购物车商品数量失败", e);
            return 0;
        }
    }

    @Override
    public boolean loadCartFromDatabase(String userId, String unitId, String productId) {
        try {
            List<Cart> cartItems = cartMapper.selectByUserIdAndUnitId(userId, unitId, productId);
            if (CollectionUtils.isEmpty(cartItems)) {
                return false;
            }

            String cartKey = buildCartKey(userId, unitId, productId);
            List<Long> pricingIds = new ArrayList<>();

            for (Cart cartItem : cartItems) {
                CartItemVO itemVO = convertCartToCartItemVO(cartItem);
                String cartItemKey = buildCartItemKey(userId, unitId,cartItem.getProductId(), cartItem.getPricingId());

                // 保存到Redis
                redisTemplate.opsForValue().set(cartItemKey, itemVO, CART_EXPIRE_DAYS, TimeUnit.DAYS);
                pricingIds.add(cartItem.getPricingId());
            }

            // 保存购物车列表到Redis
            redisTemplate.opsForValue().set(cartKey, pricingIds, CART_EXPIRE_DAYS, TimeUnit.DAYS);

            log.info("成功从数据库加载用户{}的购物车数据到Redis", userId);
            return true;
        } catch (Exception e) {
            log.error("从数据库加载购物车数据失败", e);
            return false;
        }
    }

    @Override
    public boolean syncCartToDatabase(String userId, String unitId, String productId) {
        try {
            List<CartItemVO> redisItems = getCartItemsFromRedis(userId, unitId, productId);
            if (CollectionUtils.isEmpty(redisItems)) {
                return true;
            }

            // 清空数据库中的购物车数据
            clearCartFromDatabase(userId, unitId, productId);

            // 同步Redis数据到数据库
            for (CartItemVO item : redisItems) {
                syncCartItemToDatabase(userId, unitId,productId, item);
            }

            log.info("成功同步Redis购物车数据到数据库，用户{}", userId);
            return true;
        } catch (Exception e) {
            log.error("同步购物车数据到数据库失败", e);
            return false;
        }
    }

    @Override
    public boolean checkCartConsistency(String userId, String unitId, String productId) {
        try {
            List<CartItemVO> redisItems = getCartItemsFromRedis(userId, unitId, productId);
            List<Cart> dbItems = cartMapper.selectByUserIdAndUnitId(userId, unitId, productId);

            if (redisItems.size() != dbItems.size()) {
                log.warn("购物车数据不一致：Redis数量{}，数据库数量{}", redisItems.size(), dbItems.size());
                return false;
            }

            // 检查每个商品项是否一致
            for (CartItemVO redisItem : redisItems) {
                boolean found = false;
                for (Cart dbItem : dbItems) {
                    if (redisItem.getPricingId().equals(dbItem.getPricingId()) &&
                        redisItem.getQuantity().equals(dbItem.getQuantity())) {
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    log.warn("购物车商品项不一致：pricingId={}", redisItem.getPricingId());
                    return false;
                }
            }

            return true;
        } catch (Exception e) {
            log.error("检查购物车数据一致性失败", e);
            return false;
        }
    }

    // ==================== 私有方法 ====================

    private String buildCartKey(String userId, String unitId,String productId) {
        if(StringUtils.hasText(unitId)){
            return CART_KEY_PREFIX + userId + ":" + unitId + ":" + productId;
        }
        return CART_KEY_PREFIX + userId + ":" + productId;
    }

    private String buildCartItemKey(String userId, String unitId,String productId, Long pricingId) {
        if(StringUtils.hasText(unitId)){
            return CART_ITEM_KEY_PREFIX + userId + ":" + unitId + ":" + productId + ":" + pricingId;
        }
        return CART_ITEM_KEY_PREFIX + userId + ":" + productId + ":" + pricingId;
    }

    private void updateCartItemList(String userId, String unitId,String productId ,Long pricingId, boolean add) {
        String cartKey = buildCartKey(userId, unitId, productId);
        List<Long> pricingIds = (List<Long>) redisTemplate.opsForValue().get(cartKey);

        if (pricingIds == null) {
            pricingIds = new ArrayList<>();
        }

        if (add && !pricingIds.contains(pricingId)) {
            pricingIds.add(pricingId);
        } else if (!add) {
            pricingIds.remove(pricingId);
        }

        redisTemplate.opsForValue().set(cartKey, pricingIds, CART_EXPIRE_DAYS, TimeUnit.DAYS);
    }

    private List<Long> getCartItemPricingIds(String userId, String unitId, String productId) {
        String cartKey = buildCartKey(userId, unitId, productId);
        List<Long> pricingIds = (List<Long>) redisTemplate.opsForValue().get(cartKey);
        return pricingIds != null ? pricingIds : new ArrayList<>();
    }

    private List<CartItemVO> getCartItemsFromRedis(String userId, String unitId, String productId) {
        try {
            String cartKey = buildCartKey(userId, unitId, productId);
            List<Long> pricingIds = (List<Long>) redisTemplate.opsForValue().get(cartKey);

            if (CollectionUtils.isEmpty(pricingIds)) {
                return new ArrayList<>();
            }

            List<CartItemVO> items = new ArrayList<>();
            for (Long pricingId : pricingIds) {
                String cartItemKey = buildCartItemKey(userId, unitId, productId,pricingId);
                CartItemVO item = (CartItemVO) redisTemplate.opsForValue().get(cartItemKey);
                if (item != null) {
                    items.add(item);
                }
            }

            return items;
        } catch (Exception e) {
            log.error("从Redis获取购物车商品列表失败", e);
            return new ArrayList<>();
        }
    }
    
    private List<CartItemVO> getCartItemsFromDatabase(String userId, String unitId, String productId) {
        try {
            List<Cart> cartItems = cartMapper.selectByUserIdAndUnitId(userId, unitId, productId);
            List<CartItemVO> items = new ArrayList<>();
            
            for (Cart cartItem : cartItems) {
                items.add(convertCartToCartItemVO(cartItem));
            }
            
            return items;
        } catch (Exception e) {
            log.error("从数据库获取购物车商品列表失败", e);
            return new ArrayList<>();
        }
    }
    
    private CartItemVO convertCartToCartItemVO(Cart cart) {
        CartItemVO itemVO = new CartItemVO();
        BeanUtils.copyProperties(cart, itemVO);
        return itemVO;
    }
    
    private void syncCartItemToDatabase(String userId, String unitId, String productId,CartItemVO item) {
        try {
            Cart cart = new Cart();
            BeanUtils.copyProperties(item, cart);
            cart.setUserId(userId);
            cart.setUnitId(unitId);
            cart.setUpdateTime(LocalDateTime.now());
            
            // 检查是否已存在
            Cart existingCart = cartMapper.selectByUserIdUnitIdAndPricingId(userId, unitId, productId,item.getPricingId());
            if (existingCart != null) {
                // 更新
                cart.setId(existingCart.getId());
                cartMapper.updateById(cart);
            } else {
                // 新增
                cart.setAddTime(LocalDateTime.now());
                cartMapper.insert(cart);
            }
        } catch (Exception e) {
            log.error("同步购物车商品到数据库失败", e);
        }
    }
    
    private void removeCartItemFromDatabase(String userId, String unitId, String productId, Long pricingId) {
        try {
            Cart existingCart = cartMapper.selectByUserIdUnitIdAndPricingId(userId, unitId, productId,pricingId);
            if (existingCart != null) {
                cartMapper.deleteByCustomerCondition(existingCart.getId());
            }
        } catch (Exception e) {
            log.error("从数据库删除购物车商品失败", e);
        }
    }
    
    private void clearCartFromDatabase(String userId, String unitId, String productId) {
        try {
            // 使用逻辑删除
            List<Cart> cartItems = cartMapper.selectByUserIdAndUnitId(userId, unitId, productId);
            for (Cart item : cartItems) {
                cartMapper.deleteById(item.getId());
            }
        } catch (Exception e) {
            log.error("清空数据库购物车失败", e);
        }
    }
}