1 files changed, 100 insertions, 0 deletions
diff --git a/src/main/java/design/persistence/JSONLeagueDatabase.java b/src/main/java/design/persistence/JSONLeagueDatabase.java
new file mode 100644
index 0000000..8b201e6
--- /dev/null
+++ b/src/main/java/design/persistence/JSONLeagueDatabase.java
@@ -0,0 +1,100 @@
+package design.persistence;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
+import design.model.Course;
+import design.model.Golfer;
+import design.model.League;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
+public class JSONLeagueDatabase implements LeagueDatabase {
+
+    private static JSONLeagueDatabase INSTANCE;
+
+    public static JSONLeagueDatabase instance() {
+        if (INSTANCE == null) {
+            INSTANCE = new JSONLeagueDatabase("data/leaguedb.json");
+        }
+        return INSTANCE;
+    }
+
+    private final Map<Integer, League> cache;
+    private final ObjectMapper mapper;
+    private final File file;
+    private int nextLeagueID;
+
+    public JSONLeagueDatabase(String filename) {
+        this.file = new File(filename);
+        this.cache = new HashMap<>();
+        this.mapper = new ObjectMapper();
+
+        SimpleModule module = new SimpleModule();
+        module.addDeserializer(Course.class, new Serializers.CourseIdDeserializer());
+        module.addSerializer(Course.class, new Serializers.CourseIdSerializer());
+        module.addDeserializer(Golfer.class, new Serializers.GolferUsernameDeserializer());
+        module.addSerializer(Golfer.class, new Serializers.GolferUsernameSerializer());
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        mapper.registerModule(module);
+        mapper.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY);
+        mapper.registerModule(new ParameterNamesModule(JsonCreator.Mode.PROPERTIES));
+        mapper.registerModule(new JavaTimeModule());
+
+        try {
+            load();
+        } catch (IOException ex) {
+            throw new RuntimeException(ex);
+        }
+
+        this.nextLeagueID = cache.values().stream().mapToInt(League::getId).max().orElse(0) + 1;
+    }
+
+    private void load() throws IOException {
+        League[] data = mapper.readValue(file, League[].class);
+        cache.clear();
+        Arrays.stream(data).forEach(i -> cache.put(i.getId(), i));
+    }
+
+    private void save() throws IOException {
+        League[] data = cache.values().toArray(League[]::new);
+        mapper.writer(new Serializers.CustomPrettyPrinter()).writeValue(file, data);
+    }
+
+    @Override
+    public League getLeague(int id) {
+        return cache.get(id);
+    }
+
+    @Override
+    public League[] getLeagues() {
+        return cache.values().toArray(League[]::new);
+    }
+
+    @Override
+    public void addLeague(League league) throws IOException {
+        league.setId(nextLeagueID++);
+        cache.putIfAbsent(league.getId(), league);
+        save();
+    }
+
+    @Override
+    public void removeLeague(League league) throws IOException {
+        cache.remove(league.getId());
+        save();
+    }
+
+    @Override
+    public void updateLeague(League league) throws IOException {
+        cache.put(league.getId(), league);
+        save();
+    }
+}