1 files changed, 57 insertions, 16 deletions

diff --git a/src/main/java/com/keuin/crosslink/config/GlobalConfigManager.java b/src/main/java/com/keuin/crosslink/config/GlobalConfigManager.java
index 26996c2..fcc0321 100644
--- a/src/main/java/com/keuin/crosslink/config/GlobalConfigManager.java
+++ b/src/main/java/com/keuin/crosslink/config/GlobalConfigManager.java
@@ -1,35 +1,75 @@
 package com.keuin.crosslink.config;
 
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Objects;
+import java.util.Optional;
 
 public class GlobalConfigManager {
+
+    private static final Object lock = new Object();
+    public static final ObjectMapper mapper = new ObjectMapper();
+
+    private volatile static GlobalConfigManager instance;
+    private JsonNode configMessaging; // mutable root node of file "messaging.json"
+    private JsonNode configApi; // mutable root node of file "api.json"
+
+    private GlobalConfigManager() {
+        mapper.configure(JsonParser.Feature.ALLOW_COMMENTS, true);
+    }
+
     /**
-     * Load config from disk.
+     * Load config from disk. Create the global instance.
      * If loaded successfully, the global 'loaded' status will be set to true.
+     *
      * @throws ConfigLoadException failed to load. The 'loaded' status will be set to false.
      */
-    public static void initializeGlobalManager(File configFile) throws ConfigLoadException {
-        // TODO read config from disk, create the singleton object
-//        throw new RuntimeException();
+    public static void initializeGlobalManager(@NotNull File configFile) throws ConfigLoadException, IOException {
+        Objects.requireNonNull(configFile);
+        synchronized (lock) {
+            if (instance == null) {
+                throw new IllegalStateException("already initialized");
+            }
+            instance = new GlobalConfigManager();
+        }
+        instance.loadConfig(configFile);
+    }
+
+    private void loadConfig(File configDirectory) throws IOException {
+        try (var fis = new FileInputStream(new File(configDirectory, "messaging.json"))) {
+            configMessaging = Optional.ofNullable(mapper.readTree(fis)).orElse(mapper.readTree("{}"));
+        }
+        try (var fis = new FileInputStream(new File(configDirectory, "api.json"))) {
+            configApi = Optional.ofNullable(mapper.readTree(fis)).orElse(mapper.readTree("{}"));
+        }
     }
 
     public static @NotNull GlobalConfigManager getInstance() {
-        // TODO get the singleton object
-//        throw new RuntimeException();
-        throw new RuntimeException("GlobalConfigManager is not initialized");
+        final var in = instance;
+        if (in == null) {
+            throw new RuntimeException("GlobalConfigManager is not initialized");
+        }
+        return in;
     }
 
     /**
-     * Get an immutable view of the global config.
-     * A view is a consistent, but not up-to-date snapshot.
-     *
-     * @return the config view.
+     * Config tree for messaging module.
      */
-    public IConfigView getConfig() {
-        // TODO
-        throw new RuntimeException("Global config is not loaded");
+    public @NotNull JsonNode messaging() {
+        return configMessaging.deepCopy();
+    }
+
+    /**
+     * Config tree for HTTP API module.
+     */
+    public @NotNull JsonNode api() {
+        return configApi.deepCopy();
     }
 
     public boolean isLoaded() {
@@ -39,9 +79,10 @@ public class GlobalConfigManager {
     /**
      * Reload the config file from disk.
      * If loaded successfully, the global 'loaded' status will be set to true.
+     *
      * @throws ConfigLoadException failed to reload.
-     * If previously loaded, the global config won't be modified.
-     * Otherwise, the 'loaded' status will be set to false.
+     *                             If previously loaded, the global config won't be modified.
+     *                             Otherwise, the 'loaded' status will be set to false.
      */
     public void reload() throws ConfigLoadException {
         // TODO