const Price = require('../models/Price');
const { validateAndCleanPricesData } = require('../utils/validator');

/**
 * 价格服务
 * 处理价格相关的业务逻辑
 */
class PriceService {
  /**
   * 按地区查询价格
   */
  static async getByRegion(region, date, page = 1, pageSize = 20) {
    try {
      const prices = await Price.getByRegion(region, date);

      // 手动分页
      const total = prices.length;
      const startIndex = (page - 1) * pageSize;
      const endIndex = startIndex + parseInt(pageSize, 10);
      const paginatedData = prices.slice(startIndex, endIndex);

      return {
        success: true,
        data: paginatedData,
        pagination: {
          page: parseInt(page, 10),
          pageSize: parseInt(pageSize, 10),
          total,
          totalPages: Math.ceil(total / pageSize)
        }
      };
    } catch (error) {
      throw error;
    }
  }

  /**
   * 搜索价格数据
   */
  static async search(filters) {
    try {
      // 解析分页参数
      const page = parseInt(filters.page) || 1;
      const pageSize = parseInt(filters.pageSize) || 20;

      const searchFilters = {
        material: filters.material,
        specification: filters.specification,
        startDate: filters.startDate,
        endDate: filters.endDate,
        region: filters.region,
        page,
        pageSize
      };

      // 获取数据
      const data = await Price.search(searchFilters);

      // 获取总数
      const total = await Price.count({
        material: filters.material,
        specification: filters.specification,
        startDate: filters.startDate,
        endDate: filters.endDate,
        region: filters.region
      });

      return {
        success: true,
        data,
        pagination: {
          page,
          pageSize,
          total,
          totalPages: Math.ceil(total / pageSize)
        }
      };
    } catch (error) {
      throw error;
    }
  }

  /**
   * 获取价格统计
   */
  static async getStats(filters) {
    try {
      const stats = await Price.getStats(filters);

      // 计算趋势（如果提供了天数）
      let trend = null;
      let changeRate = null;

      if (filters.days && stats.avgPrice) {
        const previousStats = await Price.getStats({
          region: filters.region,
          material: filters.material,
          days: parseInt(filters.days) * 2 // 获取双倍天数的范围
        });

        if (previousStats.avgPrice) {
          const currentAvg = parseFloat(stats.avgPrice);
          const previousAvg = parseFloat(previousStats.avgPrice);
          const change = currentAvg - previousAvg;
          changeRate = (change / previousAvg * 100).toFixed(2);
          trend = change > 0 ? 'up' : change < 0 ? 'down' : 'stable';
        }
      }

      return {
        success: true,
        data: {
          count: stats.count,
          avgPrice: stats.avgPrice ? parseFloat(parseFloat(stats.avgPrice).toFixed(2)) : null,
          minPrice: stats.minPrice,
          maxPrice: stats.maxPrice,
          stdDev: stats.stdDev ? parseFloat(parseFloat(stats.stdDev).toFixed(2)) : null,
          trend,
          changeRate: changeRate ? `${changeRate > 0 ? '+' : ''}${changeRate}%` : null
        }
      };
    } catch (error) {
      throw error;
    }
  }

  /**
   * 获取价格趋势
   */
  static async getTrend(filters) {
    try {
      const trend = await Price.getTrend(filters);

      return {
        success: true,
        data: trend.map(item => ({
          date: item.date,
          avgPrice: item.avgPrice ? parseFloat(parseFloat(item.avgPrice).toFixed(2)) : null,
          minPrice: item.minPrice,
          maxPrice: item.maxPrice
        })),
        meta: {
          total: trend.length,
          filters: {
            region: filters.region || null,
            material: filters.material || null,
            days: filters.days || null
          }
        }
      };
    } catch (error) {
      throw error;
    }
  }

  /**
   * 导入数据
   */
  static async importData(prices) {
    try {
      if (!Array.isArray(prices) || prices.length === 0) {
        throw new Error('无效的数据格式');
      }

      // 验证并清洗数据
      const validation = validateAndCleanPricesData(prices);

      if (validation.validCount === 0) {
        return {
          success: false,
          message: '没有有效的数据可以导入',
          data: {
            total: validation.total,
            imported: 0,
            errors: validation.errors
          }
        };
      }

      // 批量插入有效数据
      const result = await Price.batchInsert(validation.validData);

      return {
        success: true,
        message: `成功导入 ${result} 条数据${validation.errorCount > 0 ? `，${validation.errorCount} 条数据因格式错误被跳过` : ''}`,
        data: {
          imported: result,
          total: validation.total,
          validCount: validation.validCount,
          errorCount: validation.errorCount,
          errors: validation.errorCount > 0 ? validation.errors.slice(0, 10) : undefined // 只返回前 10 个错误
        }
      };
    } catch (error) {
      throw error;
    }
  }
}

module.exports = PriceService;