import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.List;
import java.util.Scanner;

public class ReportGenerator {

    private final String ordersFilePath;
    private final List<Product> productList;

    private double totalFinalCost;
    private int totalQuantity;
    private double totalDiscountValue;
    private int totalInvalidLines;

    public ReportGenerator(String ordersFilePath, List<Product> productList) {
        this.ordersFilePath = ordersFilePath;
        this.productList = productList;
    }

    public void processFile()
    {
        File file = new File(ordersFilePath);
        if(!file.exists())
        {
            System.err.println("File is not found!");
            return;
        }
        try(Scanner scanner = new Scanner(file))
        {
            while (scanner.hasNextLine())
            {
                String line = scanner.nextLine();
                if(line.isBlank()) continue;
                try
                {
                    String[] parts = line.split(",");
                    int productId = Integer.parseInt(parts[0].trim());
                    int quantity = Integer.parseInt(parts[1].trim());
                    int discountPercent = Integer.parseInt(parts[2].trim());

                    if( quantity<=0 || discountPercent < 0 || discountPercent >99)
                    {
                        throw new Exception("invalid value!");
                    }

                    Product product = null;
                    for (Product p : productList)
                    {
                        if(p.getProductID() == productId)
                        {
                            product = p;
                            break;
                        }
                    }
                    if(product == null)
                    {
                        throw new Exception("Product not found");
                    }

                    double subtotal = quantity * product.getPrice();
                    double discountValue = subtotal * discountPercent / 100;
                    double finalCost = subtotal - discountValue;

                    totalQuantity += quantity;
                    totalFinalCost += finalCost;
                    totalDiscountValue += discountValue;


                }
                catch (Exception e)
                {
                    totalInvalidLines++;
                }
            }
        }
        catch (FileNotFoundException e)
        {
            System.out.println(e.getMessage());
        }
    }

    public void saveReport() throws IOException {
        String report = "========= SALES REPORT =========\n" +
                "Total Quantity: " + totalQuantity + "\n" +
                "Total Final Cost: " + totalFinalCost + "\n" +
                "Total Discount Value: " + totalDiscountValue + "\n" +
                "Invalid Lines: " + totalInvalidLines + "\n" +
                "================================";

        try
        {
            FileWriter writer = new FileWriter("report.txt");
            writer.write(report);
            writer.close();
        }
        catch (IOException e)
        {
            System.err.println("ERROR!");
        }
    }
}