From 04c00af3baa8fefd75b68c26217efc2b61144527 Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Sat, 12 Jun 2021 11:57:56 +0200
Subject: [PATCH] WIP

---
 .../transfer/controller/TransferDTO.java      | 54 +++++++++++++
 .../InMemoryTransferRepository.java           | 81 +++++++++++++++++++
 2 files changed, 135 insertions(+)
 create mode 100644 transfer/src/main/java/de/juplo/kafka/payment/transfer/controller/TransferDTO.java
 create mode 100644 transfer/src/main/java/de/juplo/kafka/payment/transfer/persistence/InMemoryTransferRepository.java

diff --git a/transfer/src/main/java/de/juplo/kafka/payment/transfer/controller/TransferDTO.java b/transfer/src/main/java/de/juplo/kafka/payment/transfer/controller/TransferDTO.java
new file mode 100644
index 0000000..6f1310e
--- /dev/null
+++ b/transfer/src/main/java/de/juplo/kafka/payment/transfer/controller/TransferDTO.java
@@ -0,0 +1,54 @@
+package de.juplo.kafka.payment.transfer.controller;
+
+import de.juplo.kafka.payment.transfer.domain.Transfer;
+import lombok.Builder;
+import lombok.Data;
+
+import javax.validation.constraints.NotNull;
+
+
+/**
+ * Simple DTO used by the REST interface
+ */
+@Data
+@Builder
+public class TransferDTO
+{
+  @NotNull(message = "Cannot be null")
+  private long id;
+  @NotNull(message = "Cannot be null")
+  private long payer;
+  @NotNull(message = "Cannot be null")
+  private long payee;
+  @NotNull(message = "Cannot be null")
+  private int amount;
+
+  private Transfer.State state;
+
+
+  public Transfer toTransfer()
+  {
+    return
+        Transfer
+            .builder()
+            .id(id)
+            .payer(payer)
+            .payee(payee)
+            .amount(amount)
+            .build();
+  }
+
+
+  public static TransferDTO of(Transfer transfer)
+  {
+    return
+        TransferDTO
+            .builder()
+            .id(transfer.getId())
+            .payer(transfer.getPayer())
+            .payee(transfer.getPayee())
+            .amount(transfer.getAmount())
+            .state(transfer.getState())
+            .build();
+  }
+}
diff --git a/transfer/src/main/java/de/juplo/kafka/payment/transfer/persistence/InMemoryTransferRepository.java b/transfer/src/main/java/de/juplo/kafka/payment/transfer/persistence/InMemoryTransferRepository.java
new file mode 100644
index 0000000..5ef2094
--- /dev/null
+++ b/transfer/src/main/java/de/juplo/kafka/payment/transfer/persistence/InMemoryTransferRepository.java
@@ -0,0 +1,81 @@
+package de.juplo.kafka.payment.transfer.persistence;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import de.juplo.kafka.payment.transfer.domain.Transfer;
+import de.juplo.kafka.payment.transfer.domain.TransferRepository;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+
+@Component
+@RequiredArgsConstructor
+@Slf4j
+public class InMemoryTransferRepository implements TransferRepository
+{
+  private final Map<Long, String> map = new HashMap<>();
+  private final ObjectMapper mapper;
+
+
+  @Override
+  public synchronized void store(Transfer transfer)
+  {
+    Optional
+        .ofNullable(map.get(transfer.getId()))
+        .ifPresent(
+            json ->
+            {
+              throw new IllegalArgumentException("Could not overwrite " + json + " with " + transfer);
+            });
+
+    try
+    {
+      map.put(transfer.getId(), mapper.writeValueAsString(transfer));
+    }
+    catch (JsonProcessingException e)
+    {
+      log.error("Could not convert Transfer.class: {}", transfer, e);
+    }
+  }
+
+  @Override
+  public synchronized Optional<Transfer> get(Long id)
+  {
+    return
+        Optional
+            .ofNullable(map.get(id))
+            .map(json -> {
+              try
+              {
+                return mapper.readValue(json, Transfer.class);
+              }
+              catch (JsonProcessingException e)
+              {
+                throw new RuntimeException("Could not convert JSON: " + json, e);
+              }
+            });
+  }
+
+  @Override
+  public synchronized void update(Long id, Transfer.State oldState, Transfer.State newState)
+  {
+    Transfer transfer = get(id).orElseThrow(() -> new IllegalArgumentException("Could not find transfer " + id));
+
+    if (transfer.getState() != oldState)
+      throw new IllegalArgumentException(("Unexpectd state for " + transfer + ", expected: " + oldState));
+
+    transfer.setState(newState);
+    store(transfer);
+  }
+
+  @Override
+  public void remove(Long id)
+  {
+    map.remove(id);
+  }
+}
-- 
2.20.1