/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.tinkerpop.gremlin.driver;

import org.apache.tinkerpop.gremlin.util.Gremlin;

public class UserAgent {

    /**
     * Request header name for user agent
     */
    public static final String USER_AGENT_HEADER_NAME = "User-Agent";
    /**
     * User Agent body to be sent in web socket handshake
     * Has the form of:
     * [Application Name] [GLV Name]/[Version] [Language Runtime Version] [OS]/[Version] [CPU Architecture]
     */
    public static final String USER_AGENT;

    static {
        final String applicationName = getAttributeOrDefault(()->{ return (String)(new javax.naming.InitialContext().lookup("java:app/AppName")); });

        String glvVersion = getAttributeOrDefault(()->{ return Gremlin.version(); });
        if(glvVersion.equals("VersionNotFound")) {
            glvVersion = "NotAvailable";
        }

        final String javaVersion = getAttributeOrDefault(()->{ return System.getProperty("java.version", "NotAvailable"); });

        final String osName = getAttributeOrDefault(()->{ return System.getProperty("os.name", "NotAvailable"); });

        final String osVersion = getAttributeOrDefault(()->{ return System.getProperty("os.version", "NotAvailable"); });

        final String cpuArch = getAttributeOrDefault(()->{ return System.getProperty("os.arch", "NotAvailable"); });

        USER_AGENT =  String.format("%s Gremlin-Java.%s %s %s.%s %s",
                                            applicationName, glvVersion, javaVersion,
                                            osName, osVersion, cpuArch);
    }

    private static String getAttributeOrDefault(ThrowingSupplier<String> supplier){
        String ret = "NotAvailable";
        try {
            ret = supplier.get().replace(' ', '_');
        }
        catch (Exception e) {
            // No action taken, default value of "NotAvailable" will be used if supplier fails
        }
        return ret;
    }

    @FunctionalInterface
    private interface ThrowingSupplier<T> {
        T get() throws Exception;
    }
}
