feat : java-sdk main implementation

sdk/java-sdk/src/main/java/org/lightswitch/sdk/client/LightSwitchClient.java

@@ -0,0 +1,16 @@
+package org.lightswitch.sdk.client;
+
+import org.lightswitch.sdk.user.LightSwitchUser;
+
+public interface LightSwitchClient {
+
+    boolean getBooleanFlag(String key, boolean defaultValue, LightSwitchUser user);
+
+    int getIntFlag(String key, int defaultValue, LightSwitchUser user);
+
+    String getStringFlag(String key, String defaultValue, LightSwitchUser user);
+
+    void destroy();
+
+    boolean isEnabled(String key, LightSwitchUser user);
+}

sdk/java-sdk/src/main/java/org/lightswitch/sdk/client/LightSwitchClientImpl.java

@@ -0,0 +1,92 @@
+package org.lightswitch.sdk.client;
+
+import org.lightswitch.sdk.exception.LightSwitchCastException;
+import org.lightswitch.sdk.model.FeatureFlag;
+import org.lightswitch.sdk.user.LightSwitchUser;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class LightSwitchClientImpl implements LightSwitchClient {
+
+    // TODO develop FeatureFlagRepository, httpClient, SSEClient
+    private final Map<String, FeatureFlag> featureFlags; // Mock
+
+    public LightSwitchClientImpl() {
+        // Mock data
+        this.featureFlags = new HashMap<>();
+
+        featureFlags.put("new-dashboard", new FeatureFlag(
+                "new-dashboard",
+                false, // default
+                Map.of(
+                        Map.of("region", "US"), true // active "US" user
+                )
+        ));
+
+        featureFlags.put("beta-feature", new FeatureFlag(
+                "beta-feature",
+                false,
+                Map.of(
+                        Map.of("plan", "premium"), true // active "premium" user
+                )
+        ));
+
+        featureFlags.put("discount", new FeatureFlag(
+                "discount",
+                0, // default sale rates : 0%
+                Map.of(
+                        Map.of("region", "US"), 100,  // US user 100% sale
+                        Map.of("region", "EU"), 50   // EU user 50% sale
+                )
+        ));
+    }
+
+    private FeatureFlag getMockFlag(String key) {
+        return featureFlags.get(key);
+    }
+
+    private <T> T castValue(String key, Object value, Class<T> expectedType) {
+        if (!expectedType.isInstance(value)) {
+            throw new LightSwitchCastException(key, value, expectedType);
+        }
+        return expectedType.cast(value);
+    }
+
+    @Override
+    public boolean getBooleanFlag(String key, boolean defaultValue, LightSwitchUser user) {
+        FeatureFlag flag = getMockFlag(key);
+        if (flag == null) return defaultValue;
+
+        Object value = flag.evaluate(user);
+        return castValue(key, value, Boolean.class);
+    }
+
+    @Override
+    public int getIntFlag(String key, int defaultValue, LightSwitchUser user) {
+        FeatureFlag flag = getMockFlag(key);
+        if (flag == null) return defaultValue;
+
+        Object value = flag.evaluate(user);
+        return castValue(key, value, Integer.class);
+    }
+
+    @Override
+    public String getStringFlag(String key, String defaultValue, LightSwitchUser user) {
+        FeatureFlag flag = getMockFlag(key);
+        if (flag == null) return defaultValue;
+
+        Object value = flag.evaluate(user);
+        return castValue(key, value, String.class);
+    }
+
+    @Override
+    public void destroy() {
+        featureFlags.clear();
+    }
+
+    @Override
+    public boolean isEnabled(String key, LightSwitchUser user) {
+        return getBooleanFlag(key, false, user);
+    }
+}