#75 Added transaction logic

src/main/java/de/rwu/easydrop/service/processing/TransactionHandler.java

@@ -0,0 +1,47 @@
+package de.rwu.easydrop.service.processing;
+
+import de.rwu.easydrop.api.dto.TransactionDTO;
+import de.rwu.easydrop.data.connector.TransactionPersistenceInterface;
+import de.rwu.easydrop.model.Offer;
+import de.rwu.easydrop.model.Transaction;
+import de.rwu.easydrop.service.mapping.TransactionMapper;
+import de.rwu.easydrop.util.Timestamp;
+
+/**
+ * Handles transactions.
+ *
+ * @since 0.3.0
+ */
+public class TransactionHandler {
+    /**
+     * Transaction persistence.
+     */
+    private TransactionPersistenceInterface txPersistence;
+
+    /**
+     * Creates new transaction handler.
+     *
+     * @param txdb transaction persistence
+     */
+    public TransactionHandler(final TransactionPersistenceInterface txdb) {
+        this.txPersistence = txdb;
+    }
+
+    /**
+     * Creates transaction from offer.
+     *
+     * @param offer Offer
+     */
+    public void turnOfferToTransaction(final Offer offer) {
+        Transaction tx = new Transaction();
+        tx.setOfferId(offer.getOfferId());
+        tx.setVolume(offer.getTargetProduct().getCurrentPrice());
+        tx.setEarnings(offer.getTargetProduct().getCurrentPrice()
+                - offer.getSourceProduct().getCurrentPrice());
+        tx.setTransactionTime(Timestamp.now());
+
+        // Write transaction to persistence
+        TransactionDTO txDTO = TransactionMapper.mapTXToDTO(tx);
+        txPersistence.writeTX(txDTO);
+    }
+}

src/main/java/de/rwu/easydrop/service/validation/TransactionValidator.java

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+package de.rwu.easydrop.service.validation;
+
+import de.rwu.easydrop.exception.InvalidTransactionException;
+import de.rwu.easydrop.model.Transaction;
+
+/**
+ * Validates transactions.
+ *
+ * @since 0.3.0
+ */
+public final class TransactionValidator {
+    /**
+     * Private constructor to prevent unwanted instantiation.
+     *
+     * @throws UnsupportedOperationException always
+     */
+    private TransactionValidator() throws UnsupportedOperationException {
+        throw new UnsupportedOperationException("This is a validator class, don't instantiate it.");
+    }
+
+    /**
+     * Makes sure a transaction does not contain invalid information.
+     *
+     * @param tx the Transaction
+     */
+    public static void validate(final Transaction tx) {
+        try {
+            if (tx.getOfferId().equals("")) {
+                throw new InvalidTransactionException("Offer ID cannot be empty");
+            }
+            if (tx.getEarnings() == 0) {
+                throw new InvalidTransactionException("Earnings can't be zero");
+            }
+            if (tx.getVolume() == 0) {
+                throw new InvalidTransactionException("Volume can't be zero");
+            }
+        } catch (NullPointerException e) {
+            throw new InvalidTransactionException(
+                    "Required information is missing in the transaction", e);
+        }
+    }
+}

src/main/java/de/rwu/easydrop/service/writer/TransactionWriter.java

@@ -0,0 +1,33 @@
+package de.rwu.easydrop.service.writer;
+
+import de.rwu.easydrop.api.dto.TransactionDTO;
+import de.rwu.easydrop.data.connector.TransactionPersistenceInterface;
+import de.rwu.easydrop.model.Transaction;
+import de.rwu.easydrop.service.mapping.TransactionMapper;
+import de.rwu.easydrop.service.validation.TransactionValidator;
+
+public class TransactionWriter {
+    /**
+     * Persistence.
+     */
+    private TransactionPersistenceInterface persistence;
+
+    /**
+     * @param newPersistence the persistence to set
+     */
+    public TransactionWriter(final TransactionPersistenceInterface newPersistence) {
+        this.persistence = newPersistence;
+    }
+
+    /**
+     * Validates and saves a transaction to persistence.
+     *
+     * @param tx Transaction
+     */
+    public void writeTXToPersistence(final Transaction tx) {
+        TransactionDTO dto = TransactionMapper.mapTXToDTO(tx);
+        TransactionValidator.validate(tx);
+
+        persistence.writeTX(dto);
+    }
+}