Add the draft of the transaction structure

plugin/src/main/java/de/epiceric/shopchest/shop/Product.java

@@ -0,0 +1,17 @@
+package de.epiceric.shopchest.shop;
+
+import org.bukkit.inventory.ItemStack;
+
+public class Product {
+
+    private final ItemStack itemStack;
+    private final ProductValue productValue;
+
+    public Product(ItemStack itemStack, ProductValue productValue) {
+        this.itemStack = itemStack;
+        this.productValue = productValue;
+    }
+
+
+
+}

plugin/src/main/java/de/epiceric/shopchest/shop/ProductValue.java

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+package de.epiceric.shopchest.shop;
+
+public class ProductValue {
+
+    private final int amount;
+    private final double price;
+
+}

plugin/src/main/java/de/epiceric/shopchest/shop/Shop_.java

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+package de.epiceric.shopchest.shop;
+
+import org.bukkit.inventory.ItemStack;
+
+public class Shop_ {
+
+    private final ItemStack itemStack;
+    private final ProductValue buyValue, sellValue;
+
+    public Product getBuyProduct() {
+        return new Product(itemStack, buyValue);
+    }
+
+    public Product getSellProduct() {
+        return new Product(itemStack, sellValue);
+    }
+
+}

plugin/src/main/java/de/epiceric/shopchest/transaction/Actor.java

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+package de.epiceric.shopchest.transaction;
+
+public interface Actor {
+}

plugin/src/main/java/de/epiceric/shopchest/transaction/Transaction.java

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+package de.epiceric.shopchest.transaction;
+
+import org.bukkit.inventory.ItemStack;
+
+public class Transaction {
+
+    private final Actor buyer, seller;
+    private final ItemStack itemStack;
+    private int amount;
+    private final double buyPrice, sellPrice;
+
+    public void apply() {
+        if(!check()) {
+            return;
+        }
+
+        transferItems();
+
+        transferMoney();
+
+        inform();
+
+        // log
+    }
+
+    private boolean check() {
+        // Check buyer money
+
+        // Check seller item quantity
+
+        // Check buyer inventory space
+    }
+
+    private void transferItems() {
+        // Remove items from seller inventory
+
+        // Add items in buyer inventory
+    }
+
+    private void transferMoney() {
+        // Remove buyer money
+
+        // Add seller money
+    }
+
+    private void inform() {
+        // Inform buyer
+
+        // Inform seller
+    }
+
+}

plugin/src/main/java/de/epiceric/shopchest/transaction/TransactionRequest.java

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+package de.epiceric.shopchest.transaction;
+
+import de.epiceric.shopchest.shop.Product;
+
+public class TransactionRequest {
+
+    private final Actor buyer, seller;
+    private final Product product;
+    private final int amount;
+
+    public Transaction prepare() {
+        // Calculate price
+
+        // Apply taxes
+
+    }
+
+}