feat: add ReportGenerator.java

src/main/java/ReportGenerator.java

@@ -0,0 +1,83 @@
+import java.util.List;
+
+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()
+    {
+        // 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 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
+
+        /* Example Structure
+        ========= SALES REPORT =========
+        Total Quantity Sold: 42
+        Total Final Cost: $1520.75
+        Total Discount Value: $230.50
+        Invalid Rows: 3
+        ================================
+        */
+    }
+}