implement proccesFile method

src/main/java/ReportGenerator.java

@@ -1,4 +1,6 @@
+import java.io.*;
 import java.util.List;
+import java.util.Scanner;
 
 public class ReportGenerator {
 
@@ -17,44 +19,49 @@ public class ReportGenerator {
 
     public void processFile()
     {
-        // TODO:
-        // 1. Open the order details CSV file
-        // 2. Read the file line by line
-        // 3. Split each line using comma delimiter
-        //      (each line is guaranteed to contain exactly two commas)
-        // 4. Each line contains exactly 3 values in the format:
-        //      [productId],[quantity],[discountPercent]
-        // 5. Attempt to convert values:
-        //      - productId -> int
-        //      - quantity -> int
-        //      - discountPercent -> int
-        //    NOTE:
-        //      - quantity and discountPercent may contain invalid characters
-        //        (e.g., letters instead of numbers).
-        //      - If parsing any value fails (NumberFormatException),
-        //        the entire line must be considered invalid.
-        //      - Use try-catch blocks and exception handling to safely
-        //        handle parsing and validation errors without stopping
-        //        the processing of the remaining lines.
-        // 6. Validate parsed values:
-        //      - productId must be greater than 0
-        //      - quantity must be greater than 0
-        //      - discountPercent must be between 0 and 99 inclusive
-        // 7. Look for a Product in productList that matches productId
-        // 8. If no Product with that ID exists in the catalog,
-        //      the entire line is considered invalid
-        // 9. If all values are valid and the product exists, calculate:
-        //      subtotal = quantity * product price
-        //      discountValue = subtotal * discountPercent / 100
-        //      finalCost = subtotal - discountValue
-        // 10. Update report totals:
-        //      - totalQuantity += quantity
-        //      - totalFinalCost += finalCost
-        //      - totalDiscountValue += discountValue
-        // 11. If any parsing error, validation failure, or missing product occurs:
-        //      - increment totalInvalidLines
-        //      - skip the line and continue processing the next line
-        // 12. Close all file resources
+        // use try-catch to check is file available
+        try {
+            File file = new File(ordersFilePath);
+            Scanner input = new Scanner(file);
+            // counter for better reporting invalid lines
+            int lineNumber = 0;
+            while (input.hasNextLine()) {
+                lineNumber++;
+                // use try-catch to validate the lines
+                try {
+                    String line = input.nextLine();
+                    String[] fields = line.split(",");
+                    int productID = Integer.parseInt(fields[0]);
+                    int quantity = Integer.parseInt(fields[1]);
+                    int discountPercent = Integer.parseInt(fields[2]);
+                    // check if any field has wrong amounts
+                    if ((discountPercent < 0 || discountPercent > 100) || (quantity <= 0) || (!productList.contains(productID)))
+                    { throw  new IllegalArgumentException(); }
+
+                    double subtotal = quantity * discountPercent / 100;
+                    double discountValue = subtotal * discountPercent / 100;
+                    double finalCost = subtotal + discountValue;
+
+                    //updating report attributes
+                    totalQuantity += quantity;
+                    totalFinalCost += finalCost;
+                    totalDiscountValue += discountValue;
+                }
+                catch (Exception e) {
+                    totalInvalidLines++;
+                    System.out.println("Inavalid line: " + lineNumber);
+                    continue;
+                }
+                finally {
+                    input.close();
+                }
+            }
+
+        }
+        catch (IOException e) {
+            System.out.println("Orders file not found");
+        }
+
     }
 
     public void saveReport()
@@ -79,5 +86,6 @@ public class ReportGenerator {
         Invalid Rows: 3
         ================================
         */
+
     }
 }