module.exports = (req, res, next) => {
    if (req.url.startsWith('/report') && req.method === 'GET') {
      const { startDate, endDate } = req.query;

      try {
        delete require.cache[require.resolve('./data.json')];
        const data = require('./data.json');

        const filteredPurchase = data.users_tanks.filter(purchase => {
          const purchaseDate = new Date(purchase.date);
          return purchaseDate >= new Date(startDate) && purchaseDate <= new Date(endDate);
        });

        //ПОИСК САМОГО ПОПУЛЯРНОГО ТАНКА ЗА ПЕРИОД
        //список танков с кол-во их покупок
        let tankList = [];

        filteredPurchase.forEach(purchase => {
            const tankId = purchase.tankId;

            const tankInList = tankList.some(item => item.tankId === tankId);

            if (tankInList) {
                tankList[tankList.findIndex(index => index.tankId === tankId)].count++;
            } else {
                tankList.push(
                    {
                        tankId: tankId,
                        count: 1
                    }
                )
            }
        });

        tankList.sort((a, b) => b.count - a.count);

        //нашли самый популярный танк
        const supportTank = data.tanks.find(tank => tank.id === tankList[0].tankId);
        const supportLevel = data.levels.find(level => level.id === supportTank.levelId).level;
        const supportNation = data.nations.find(nation => nation.id === supportTank.nationId).nationName;

        const popularTank = {
            id: supportTank.id,
            name: supportTank.name,
            price: supportTank.price,
            miniature: supportTank.miniature,
            level: supportLevel,
            nation: supportNation
        };

        //ПОИСК САМЫХ ПОПУЛЯРНЫХ УРОВНЯ И НАЦИИ ЗА ПЕРИОД
        //список уроней и кол-во их покупок
        let levelList = [];

        //список уроней и кол-во их покупок
        let nationList = [];

        tankList.forEach(element => {
            const tank = data.tanks.find(tank => tank.id === element.tankId);

            //смотрим, сколько раз танк был куплен, чтобы сразу прибавить к соответствующему уровню текущее кол-во
            const countCurrentTank = element.count;

            const levelId = tank.levelId;
            const nationId = tank.nationId;

            const levelInList = levelList.some(item => item.levelId === levelId);
            const nationInList = nationList.some(item => item.nationId === nationId);

            if (levelInList) {
                levelList[levelList.findIndex(index => index.levelId === levelId)].count += countCurrentTank;
            } else {
                levelList.push(
                    {
                        levelId: levelId,
                        count: countCurrentTank
                    }
                )
            }

            if (nationInList) {
                nationList[nationList.findIndex(index => index.nationId === nationId)].count += countCurrentTank;
            } else {
                nationList.push(
                    {
                        nationId: nationId,
                        count: countCurrentTank
                    }
                )
            }
        });

        levelList.sort((a, b) => b.count - a.count);
        nationList.sort((a, b) => b.count - a.count);

        //нашли самые популярные уровень и нацию
        const popularLevel = data.levels.find(level => level.id === levelList[0].levelId)
        const popularNation = data.nations.find(nation => nation.id === nationList[0].nationId)

        finalDataReport = {
            id: popularTank.id,
            tankName: popularTank.name,
            price: popularTank.price,
            miniature: popularTank.miniature,
            tankLevel: popularTank.level,
            tankNation: popularTank.nation,
            countTankPurchase: tankList[0].count,

            level: popularLevel.level,
            countLevelPurchase: levelList[0].count,

            nationName: popularNation.nationName,
            countNationPurchase: nationList[0].count
        };

        console.log(finalDataReport)

        res.json(finalDataReport);
      } catch (error) {
        console.error('Error loading data:', error);
        res.status(500).json({ message: 'Internal Server Error' });
      }
    } else {
      next();
    }
  };