/*
 * Copyright (c) 2016, 2020, Oracle and/or its affiliates.  All rights reserved.
 *
 * This software is dual-licensed to you under the MIT License (MIT) and
 * the Universal Permissive License (UPL).  See the LICENSE file in the root
 * directory for license terms.  You may choose either license, or both.
 */

import oracle.iot.client.DeviceModel;
import oracle.iot.client.device.DirectlyConnectedDevice;
import oracle.iot.client.device.VirtualDevice;

/**
 * An example of sending a "Hello World!" message to the
 * Oracle IoT Cloud Service. This example is meant to illustrate the
 * minimal Java code for sending data to the cloud service and does not
 * fully explore the Client Library API.
 * <p>
 * The example uses the concept of a &quot;virtual device&quot;, which
 * can be thought of as a wrapper around a &quot;device model&quot;. A
 * device model is a set of related attributes, actions, and message formats
 * that can be represented in a real device. For this example, a
 * model for a fictitious device, the "urn:test:helloworld" device model, is
 * used. This device model must be uploaded to the server before running this
 * example.
 * <p>
 * {
 *   "urn": "urn:test:helloworld",
 *   "name": "HelloWorld-DeviceModel",
 *   "description": "Device model for the HelloWorld application",
 *   "attributes": [
 *     {
 *       "name": "greeting",
 *       "description": "This attribute stores the Hello World message.",
 *       "type": "STRING"
 *     }
 *   ]
 * }
 */
public class HelloWorld {

    // This is the URN of model for our fictitious device. This URN is used
    // to load the device model from the server into memory.
    private final static String DEVICE_MODEL_URN = "urn:test:helloworld";

    private static final String GREETING_ATTRIBUTE = "greeting";

    public static void main(String[] args) throws Exception {

        // A directly connected device is used for this example.
        //
        // The configuration is defined by the trusted asset store.
        // The location and passphrase of the asset store are specified
        // using command-line arguments.
        DirectlyConnectedDevice dcd =
            new DirectlyConnectedDevice(args[0], args[1]);

        // Activate the device, if it is not already activated.
        // Always check if the device is activated before calling activate.
        // The device model URN is passed into the activate call to tell
        // the server the device model(s) that are supported by this
        // directly connected device.
        if (!dcd.isActivated()) {
            dcd.activate(DEVICE_MODEL_URN);
        }

        // Before creating the virtual device for the device model,
        // the device model itself is needed.
        DeviceModel deviceModel = dcd.getDeviceModel(DEVICE_MODEL_URN);

        // Create the virtual device and associate it with the endpoint id
        // of the directly connected device.
        String endpointId = dcd.getEndpointId();
        VirtualDevice virtualDevice = dcd.createVirtualDevice(endpointId,
            deviceModel);

        // Once the virtual device is created, any of the attributes in
        // the model can be set. In this example, there is only one
        // attribute, named "message" in the model. Calling set on this
        // attribute will cause a data message, "Hello World!" in this
        // example, to be sent to the server.
        virtualDevice.set(GREETING_ATTRIBUTE, "Hello World!");

        System.out.println("Hello World! message sent.");

        // Calling close on the directly connected device ensures
        // communications channels are closed and resources are
        // cleaned up.
        dcd.close();
    }
}