Various error handling improvements and user feedback

src/main/java/io/kamax/mxisd/exception/FeatureNotAvailable.java

@@ -0,0 +1,43 @@
+/*
+ * mxisd - Matrix Identity Server Daemon
+ * Copyright (C) 2017 Maxime Dor
+ *
+ * https://max.kamax.io/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package io.kamax.mxisd.exception;
+
+import org.apache.http.HttpStatus;
+
+public class FeatureNotAvailable extends MatrixException {
+
+    private String internalReason;
+
+    public FeatureNotAvailable(String internalReason) {
+        super(
+                HttpStatus.SC_INTERNAL_SERVER_ERROR,
+                "M_NOT_AVAILABLE",
+                "This action is currently not available. Contact your administrator to enable it."
+        );
+
+        this.internalReason = internalReason;
+    }
+
+    public String getInternalReason() {
+        return internalReason;
+    }
+
+}