//
// ============LICENSE_START=======================================================
//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
// ================================================================================
// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
// 
// SPDX-License-Identifier: CC-BY-4.0
// ============LICENSE_END=========================================================
//
// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
//

== CLI Example

Using the APEX CLI utilities can be done as follows.
First, add the dependency of the utility project to your POM file.

[source,xml,subs="attributes+"]
----
<dependency>
  <groupId>org.onap.policy.apex-pdp.tools</groupId>
  <artifactId>tools-common</artifactId>
  <version>{release-version}</version>
</dependency>
----

Now, create a new application project, for instance `MyApp`.
In this project, create a new main application class as `Application.java`.
In this class, create a new main method as `public static void main(String[] args)`.

No use the provided `CliOptions` and `CliParser`.
Manually importing means to add the following lines to the start of your application (in Eclipse this import will be done automatically):

[source,java, linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=import,indent=0]
----

Now, inside your `main()` method, start setting some general application properties.
Important are the application name and some description of your application.
For instance:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=setApp,indent=0]
----

Next, create a new CLI Parser and add a few CLI options from the standard `CliOptions`.
The following example adds options for help, version, and a model file:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=setCli,indent=0]
----

Next, parse the given CLI arguments:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=parseCli,indent=0]
----

Once the command line is parsed, we can look into the individual options, check if they are set, and then act accordingly.
We start with the option for __help__.
If the option is present, we print a help screen and return:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=processCliHelp,indent=0]
----

Next, we process the option for __version__.
Here, we want to print a version for our application and return.
The CLI Parser already provides a method to obtain the correct version for an APEX build, so we use that:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=processCliVersion,indent=0]
----

Once help and version arguments are processed, we can proceed to look at all other options.
We have added an option for a model file, so check this option and test if we can actually load a model file with the given argument.
If we can load a model, everything is ok.
If we cannot load a model, we print an error and return.

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=processCliModel,indent=0]
----

With a model file being loadable, we finish parsing command line arguments.
We also print some status messages to note that the application now is ready to start:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=someStartPrint,indent=0]
----

The last action now is to run the actual application.
The example below is taken from a version of the `Model2Cli` application, which creates a new object and runs it in a `try` block, since exceptions might be thrown by the object:

[source,java,linenums,subs="attributes+"]
----
include::{adsite-tools-common-dir}/test/java/org/onap/policy/apex/tools/common/docs/ExampleCliParser.java[tags=yourApp,indent=0]
----

If this new application is now called with the command line `-h` or `--help` it will print the following help screen:

[source,sh,subs="attributes+"]
----
test-app v{release-version} - a test app for documenting how to use the CLI utilities
usage: test-app
 -h,--help                 prints this help and usage screen
 -m,--model <MODEL-FILE>   set the input policy model file
 -v,--version              prints the application version
----

If this new application is called with the option `-v` or `--version` it will print its version information as:

[source,sh,subs="attributes+"]
----
test-app {release-version}
----

