Reorder summary columns and calculate amount from volume * avg_price

Summary now shows: Produkt | Volym (L) | Snittpris/L | Belopp
Amount is calculated as volume * average_price instead of summing transactions.

src/main.rs

@@ -77,8 +77,8 @@ fn clean_csv_file(
 struct ProductSummary {
     name: String,
     volume: String,
-    amount: String,
     avg_price: String,
+    amount: String,
 }
 
 #[derive(Clone)]
@@ -149,11 +149,6 @@ impl PreparedCustomer {
             })
             .collect();
 
-        let grand_total: f64 = cards
-            .iter()
-            .map(|c| c.total_amount.parse::<f64>().unwrap())
-            .sum();
-
         let mut product_totals: HashMap<String, (f64, f64)> = HashMap::new();
         for card in &cards {
             for tx in &card.transactions {
@@ -171,11 +166,12 @@ impl PreparedCustomer {
             .into_iter()
             .map(|(name, (volume, amount))| {
                 let avg_price = if volume > 0.0 { amount / volume } else { 0.0 };
+                let calculated_amount = volume * avg_price;
                 ProductSummary {
                     name,
                     volume: fmt(volume),
-                    amount: fmt(amount),
                     avg_price: fmt(avg_price),
+                    amount: fmt(calculated_amount),
                 }
             })
             .collect();
@@ -186,6 +182,11 @@ impl PreparedCustomer {
             .map(|p| p.volume.parse::<f64>().unwrap())
             .sum();
 
+        let grand_total: f64 = products
+            .iter()
+            .map(|p| p.amount.parse::<f64>().unwrap())
+            .sum();
+
         let summary = Summary {
             total_volume: fmt(total_volume),
             grand_total: fmt(grand_total),