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 = 0;
    private int totalQuantity = 0;
    private double totalDiscountValue = 0;
    private int totalInvalidLines = 0;

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

    public void processFile()
    {

        File file = new File(ordersFilePath);

        try (Scanner scanner = new Scanner(file)){

            while (scanner.hasNextLine()) {

                String line = scanner.nextLine();

                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 (productId <= 0 || quantity <= 0 || discountPercent < 0 || discountPercent > 99) {
                        totalInvalidLines++;
                        continue;
                    }

                    Product foundProduct = null;

                    for (Product currentProduct : productList) {
                        if (currentProduct.getProductID() == productId) {
                            foundProduct = currentProduct;
                            break;
                        }
                    }

                    if (foundProduct == null) {
                        totalInvalidLines++;
                        continue;
                    }

                    double subtotal = quantity * foundProduct.getPrice();
                    double discountValue = subtotal * discountPercent / 100.0;
                    double finalCost = subtotal - discountValue;

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

                } catch (NumberFormatException | ArrayIndexOutOfBoundsException e) {
                    totalInvalidLines++;
                }
            }

        } catch (FileNotFoundException e) {
            System.out.println("File not found: " + ordersFilePath);
        }

    }

    public void saveReport()
    {
        String report =
                "========= SALES REPORT =========\n" +
                        "Total Quantity Sold: " + totalQuantity + "\n" +
                        "Total Final Cost: $" + String.format("%.2f", totalFinalCost) + "\n" +
                        "Total Discount Value: $" + String.format("%.2f", totalDiscountValue) + "\n" +
                        "Invalid Rows: " + totalInvalidLines + "\n" +
                        "================================";

        try
        {
            FileWriter fileWriter = new FileWriter("report.txt");

            fileWriter.write(report);

            fileWriter.close();
        }
        catch (IOException e)
        {
            System.out.println("Error writing report: " + e.getMessage());
        }
    }

}