implement ReportGenerator

src/main/java/ReportGenerator.java

@@ -1,83 +1,94 @@
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PrintWriter;
 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;
+    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()
-    {
-        // 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
+    public void processFile() throws IOException {
+
+        File input = new File(ordersFilePath);
+
+        Scanner in = new Scanner(input);
+
+        int productId, quantity, discountPercent;
+
+        while (in.hasNextLine()) {
+
+            Scanner line = new Scanner(in.nextLine());
+            line.useDelimiter(",");
+
+            try {
+                productId = line.nextInt();
+                quantity = line.nextInt();
+                discountPercent = line.nextInt();
+            } catch (Exception e) {
+                line.close();
+                totalInvalidLines++;
+                continue;
             }
 
-    public void saveReport()
-    {
-        // TODO:
-        // 1. Build a formatted report string
-        // 2. Include:
-        //      - total quantity
-        //      - total final cost
-        //      - total discount value
-        //      - total invalid lines
-        // 3. Create/open output report file (name it report.txt)
-        // 4. Write report string into file
-        // 5. Handle file writing exceptions
-        // 6. Close writer resources
+            if(productId<=0 || quantity<=0 || discountPercent<0 || discountPercent>99) {
+                totalInvalidLines++;
+                line.close();
+                continue;
+            }
 
-        /* Example Structure
-        ========= SALES REPORT =========
-        Total Quantity Sold: 42
-        Total Final Cost: $1520.75
-        Total Discount Value: $230.50
-        Invalid Rows: 3
-        ================================
-        */
+            boolean productFound = false;
+            for(Product product : productList) {
+                if(product.getProductID() == productId) {
+
+                    double subtotal = quantity * product.getPrice();
+                    double discountValue = subtotal * discountPercent / 100;
+                    double finalCost = subtotal - discountValue;
+
+                    totalQuantity += quantity;
+                    totalFinalCost += finalCost;
+                    totalDiscountValue += discountValue;
+
+                    productFound = true;
+                    break;
+                }
+            }
+
+            if(!productFound) totalInvalidLines++;
+            line.close();
+        }
+        in.close();
+    }
+
+    public void saveReport() {
+
+        File file = new File("report.txt");
+        String report = String.format("========== SALES REPORT ==========\n" +
+                        "Total Quantity Sold:         %d\n" +
+                        "Total Final Cost:     $%.2f\n" +
+                        "Total Discount Value:  $%.2f\n" +
+                        "Invalid Rows:                   %d",
+                        totalQuantity, totalFinalCost, totalDiscountValue, totalInvalidLines);
+
+        try {
+            PrintWriter out = new PrintWriter(file);
+            out.print(report);
+            out.close();
+        }
+        catch (IOException e) {
+            System.out.println(e.getMessage());
+        }
     }
 }