Implement SMS configuration file loading and initialization

components/sms-mgt/io.entgra.sms.mgt.core/src/main/java/io/entgra/sms/mgt/core/config/SMSConfigurationManager.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2021, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.entgra.sms.mgt.core.config;
+
+import io.entgra.sms.mgt.common.SMSMgtConstants;
+import io.entgra.sms.mgt.common.config.SMSConfiguration;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.w3c.dom.Document;
+import org.wso2.carbon.device.mgt.common.exceptions.DeviceManagementException;
+import org.wso2.carbon.device.mgt.core.util.DeviceManagerUtil;
+import org.wso2.carbon.utils.CarbonUtils;
+
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.JAXBException;
+import javax.xml.bind.Unmarshaller;
+import java.io.File;
+
+/**
+ * Responsible for the SMS configuration initialization.
+ */
+public class SMSConfigurationManager {
+
+    private static final Log log = LogFactory.getLog(SMSConfigurationManager.class);
+    private static SMSConfigurationManager smsConfigurationManager;
+    private SMSConfiguration smsConfiguration;
+    private static final String SMS_CONFIG_PATH = CarbonUtils.getCarbonConfigDirPath() + File.separator
+            + SMSMgtConstants.SMS_CONFIG_XML_NAME;
+
+    /**
+     * Retrieve an instance of {@link SMSConfigurationManager}
+     * @return an instance of {@link SMSConfigurationManager}
+     */
+    public static SMSConfigurationManager getInstance() {
+        if (smsConfigurationManager == null) {
+            synchronized (SMSConfigurationManager.class) {
+                if (smsConfigurationManager == null) {
+                    smsConfigurationManager = new SMSConfigurationManager();
+                }
+            }
+        }
+        return smsConfigurationManager;
+    }
+
+    /**
+     * Initialize the SMS Configuration through the provided configuration location
+     * @param configLocation has the path of the SMS configuration file
+     * @throws DeviceManagementException throws when there are any errors during the initialization of
+     * SMS configuration
+     */
+    public synchronized void initConfig(String configLocation) throws DeviceManagementException {
+        try {
+            File smsConfig = new File(configLocation);
+            Document doc = DeviceManagerUtil.convertToDocument(smsConfig);
+
+            /* Un-marshaling SMS configuration */
+            JAXBContext smsContext = JAXBContext.newInstance(SMSConfiguration.class);
+            Unmarshaller unmarshaller = smsContext.createUnmarshaller();
+            this.smsConfiguration = (SMSConfiguration) unmarshaller.unmarshal(doc);
+        } catch (JAXBException e) {
+            String msg = "Error occurred while initializing SMS config '" + configLocation + "'";
+            log.error(msg, e);
+            throw new DeviceManagementException(msg, e);
+        }
+    }
+
+    /**
+     * Initialize the SMS Configuration through the sms-config.xml file in the SMS_CONFIG_PATH
+     * @throws DeviceManagementException throws when there are any errors during the initialization of
+     * SMS configuration
+     */
+    public void initConfig() throws DeviceManagementException {
+        this.initConfig(SMS_CONFIG_PATH);
+    }
+
+    /**
+     * Retrieves the initialized {@link SMSConfiguration}
+     * @return the initialized {@link SMSConfiguration}
+     */
+    public SMSConfiguration getSMSConfig() {
+        return smsConfiguration;
+    }
+}