Implement a contacts store and contacts sync

src/main/java/org/asamk/signal/JsonContactsStore.java

@@ -0,0 +1,57 @@
+package org.asamk.signal;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class JsonContactsStore {
+    @JsonProperty("contacts")
+    @JsonSerialize(using = JsonContactsStore.MapToListSerializer.class)
+    @JsonDeserialize(using = ContactsDeserializer.class)
+    private Map<String, ContactInfo> contacts = new HashMap<>();
+
+    private static final ObjectMapper jsonProcessot = new ObjectMapper();
+
+    void updateContact(ContactInfo contact) {
+        contacts.put(contact.number, contact);
+    }
+
+    ContactInfo getContact(String number) {
+        ContactInfo c = contacts.get(number);
+        return c;
+    }
+
+    List<ContactInfo> getContacts() {
+        return new ArrayList<>(contacts.values());
+    }
+
+    public static class MapToListSerializer extends JsonSerializer<Map<?, ?>> {
+        @Override
+        public void serialize(final Map<?, ?> value, final JsonGenerator jgen, final SerializerProvider provider) throws IOException {
+            jgen.writeObject(value.values());
+        }
+    }
+
+    public static class ContactsDeserializer extends JsonDeserializer<Map<String, ContactInfo>> {
+        @Override
+        public Map<String, ContactInfo> deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
+            Map<String, ContactInfo> contacts = new HashMap<>();
+            JsonNode node = jsonParser.getCodec().readTree(jsonParser);
+            for (JsonNode n : node) {
+                ContactInfo c = jsonProcessot.treeToValue(n, ContactInfo.class);
+                contacts.put(c.number, c);
+            }
+
+            return contacts;
+        }
+    }
+}