public class AggregateUtil {
//static methods that do the calculations..


    static double getTheAveragePriceForEachCategory(List<Double> product){
        double average = getTotalSalesValueForEachCategory(product)/(double)getNumberOfProductsInEachCategory(product);
        return Math.round(average * 100D) / 100D;
    }

    static double getTotalSalesValueForEachCategory(List<Double> product){
        double sum = 0.0;
        for(Double value : product){
            sum+=value;
        }
        return Math.round(sum * 100D) / 100D;
    }

    static int getNumberOfProductsInEachCategory(List<Double> product){
        return (product.size());
    }

    static double getTheMostExpensiveProductInEachCategory(List<Double> product){
        double highest = Double.MIN_VALUE;
        for(Double value : product){
            if(value>highest) highest = value;
        }
        return highest;
    }
}

public class DisplayUtil {
//prints the values under each product category..
    public static void DisplayProducts( Map<String, List<Double>> db){
        StringBuilder builder = new StringBuilder();
        for (Map.Entry<String,List<Double>> entry : db.entrySet()) {
              builder = new StringBuilder();
              System.out.println(entry.getKey());
              System.out.println("----------------------------------");
              builder.append("average_price = ");
              double avrg_price = AggregateUtil.getTheAveragePriceForEachCategory(entry.getValue());
              builder.append(avrg_price);
              builder.append("n");
              builder.append("total_sales_value = ");
              double total_sales = AggregateUtil.getTotalSalesValueForEachCategory(entry.getValue());
              builder.append(total_sales);
              builder.append("n");
              builder.append("number_of_products = ");
              double numberOfProducts = AggregateUtil.getNumberOfProductsInEachCategory(entry.getValue());
              builder.append(numberOfProducts);
              builder.append("n");
              builder.append("most_expensive = ");
              double mostExpensive = AggregateUtil.getTheMostExpensiveProductInEachCategory(entry.getValue());
              builder.append(mostExpensive);
              builder.append("n");
              System.out.println(builder + "n");

            }
    }
}

public static void ReadFile(String path, Map<String, List<Double>> db){
    try(BufferedReader br = new BufferedReader(new FileReader(path))){
        String line;
        if((line = br.readLine()) != null){
            //this is the first heading..and needed to be skipped
        }
        while ((line = br.readLine()) != null) {
            String[] keys = line.split(",");
            keys[1] = keys[1].replace(""", "");
            if(db.containsKey(keys[1])){
                List<Double> list = db.get(keys[1]);
                list.add(Double.valueOf(keys[2]));
                db.put(keys[1], list);

            }
            else{
                List<Double> list = new ArrayList<>();
                list.add(Double.valueOf(keys[2]));
                db.put(keys[1],list);
            }
        }

    }catch(IOException e){}
}


}

public class ControllerClass {

    public static void main(String []args){
        Map<String, List<Double>> db = new HashMap<>();
        FileUtils.ReadFile("./Files/products.csv", db);
        DisplayUtil.DisplayProducts(db);

    }

}