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 InvalidLines;

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

    public void processFile()
    {
        //opening and doing the math
        try {
            File source = new File(ordersFilePath);
            Scanner scanner = new Scanner(source);
            //
            while (scanner.hasNextLine()) {
                int productId;
                int count;
                int discountPercentage;
                String line = scanner.nextLine();
                String[] parts  = line.split(",");
                try {
                    productId = Integer.parseInt(parts[0].trim());
                    if (productId < 1 || productId > productList.size()) {
                        InvalidLines++;
                        continue;
                    }

                } catch (NumberFormatException e) {
                    InvalidLines++;
                    continue;
                }
                try {
                    count = Integer.parseInt(parts[1].trim());
                    if(count < 1) {
                        InvalidLines++;
                        continue;
                    }
                } catch (NumberFormatException e) {
                    InvalidLines++;
                    continue;
                }
                try {
                    discountPercentage = Integer.parseInt(parts[2].trim());
                    if (discountPercentage < 0 || discountPercentage > 99) {
                        InvalidLines++;
                        continue;
                    }
                } catch (NumberFormatException e) {
                    InvalidLines++;
                    continue;
                }

                //computing the results
                double cost = count * productList.get(productId - 1).getPrice();
                double discount = count * productList.get(productId - 1).getPrice() * discountPercentage / 100;
                totalFinalCost += cost - discount;
                totalDiscountValue += discount;
                totalQuantity += count;

            }
            scanner.close();
        } catch (FileNotFoundException e) {
            System.out.println("File not found.");
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
    }

    public void saveReport()
    {
        String report =
                        "===== SALES REPORT =====\n" +
                        "Total Quantity: " + totalQuantity + "\n" +
                        "Total Final Cost: $" + String.format("%.2f", totalFinalCost) + "\n" +
                        "Total Discount: $" + String.format("%.2f", totalDiscountValue) + "\n" +
                        "Invalid Lines: " + InvalidLines + "\n" +
                        "=========================\n";
        try
        {
            FileWriter fileWriter = new FileWriter("output.txt");
            fileWriter.write(report);
            fileWriter.close();
        }
        catch (IOException e)
        {
            System.out.println("Error in outputting report: " + e.getMessage());
        }
    }
}