ExampleConfiguration.cs

/*
 * This file supports other examples. See configuration/Configuration.cs for
 * the configuration example.
 */

using System;
using NationalInstruments.SystemLink.Clients.Core;

namespace NationalInstruments.SystemLink.Clients.Examples
{
    /// <summary>
    /// Helper class to support client API examples obtaining a configuration.
    /// </summary>
    static class ExampleConfiguration
    {
        /// <summary>
        /// Helper method to support client API examples obtaining a
        /// configuration. Exits if a suitable configuration is not available.
        /// </summary>
        /// <param name="args">The arguments used to run the example.</param>
        /// <param name="allowCloud">Whether the example supports SystemLink
        /// Cloud or not. When true (default), the --cloud argument may be used
        /// to run the example with SystemLink Cloud. When false, the --cloud
        /// argument will produce an error.</param>
        /// <returns>A configuration to use for the example.</returns>
        public static IHttpConfiguration Obtain(
            string[] args,
            bool allowCloud = true)
        {
            return new Parser(allowCloud).Parse(args);
        }

        private class Parser
        {
            private readonly bool _allowCloud;

            public Parser(bool allowCloud)
            {
                _allowCloud = allowCloud;
            }

            public IHttpConfiguration Parse(string[] args)
            {
                if (args?.Length > 0)
                {
                    switch (args[0])
                    {
                        case "--cloud":
                            return ObtainCloudOrExit(args);
                        case "--server":
                            return ObtainServerOrExit(args);
                        case "--help":
                            return PrintUsageAndExit(string.Empty);
                        default:
                            return PrintUsageAndExit(
                                "Invalid argument " + args[0]);
                    }
                }
                else
                {
                    return ObtainDefaultOrExit();
                }
            }

            private IHttpConfiguration ObtainCloudOrExit(string[] args)
            {
                if (!_allowCloud)
                {
                    return PrintUsageAndExit("This example does not support SystemLink Cloud");
                }

                if (args.Length != 2)
                {
                    return PrintUsageAndExit(
                        "--cloud requires 1 API key argument");
                }

                return new CloudHttpConfiguration(args[1]);
            }

            private IHttpConfiguration ObtainDefaultOrExit()
            {
                try
                {
                    var manager = new HttpConfigurationManager();
                    return manager.GetConfiguration();
                }
                catch (ApiException ex)
                {
                    return PrintUsageAndExit(ex.Message);
                }
            }

            private IHttpConfiguration ObtainServerOrExit(string[] args)
            {
                try
                {
                    switch (args.Length)
                    {
                        case 1:
                            return PrintUsageAndExit("--server requires URL and optional username and password");

                        case 2:
                            return new HttpConfiguration(new Uri(args[1]));

                        case 3:
                            return PrintUsageAndExit("--server requires password when specifying a username");

                        case 4:
                            return new HttpConfiguration(
                                new Uri(args[1]), args[2], args[3]);

                        default:
                            return PrintUsageAndExit("--server does not take more arguments than URL, username, and password");
                    }
                }
                catch (FormatException ex)
                {
                    return PrintUsageAndExit(
                        "Invalid URL for --server: " + ex.Message);
                }
            }

            private IHttpConfiguration PrintUsageAndExit(string error)
            {
                Console.Error.WriteLine("This example requires a configuration.");
                Console.Error.WriteLine(error);
                Console.Error.WriteLine();
                Console.Error.WriteLine("When running on a machine with SystemLink Server installed or on a system");
                Console.Error.WriteLine("managed by a SystemLink Server, do not specify any arguments. Otherwise,");
                Console.Error.WriteLine("specify a configuration using one of the following arguments:");
                Console.Error.WriteLine();
                if (_allowCloud)
                {
                    Console.Error.WriteLine("\t--cloud <api_key>");
                }
                Console.Error.WriteLine("\t--server <url> [<username> <password>]");
                Console.Error.WriteLine();
                if (_allowCloud)
                {
                    Console.Error.WriteLine("Generate an API key on SystemLink Cloud. Go to https://www.systemlinkcloud.com,");
                    Console.Error.WriteLine("log in with your NI User Account, and click Security to create an API key.");
                }
                Console.Error.WriteLine("To run the example against a SystemLink Server, the URL should include the");
                Console.Error.WriteLine("scheme, host, and port if not default. For example:");
                Console.Error.WriteLine("dotnet run -- --server https://myserver:9091 admin my_password");
                Environment.Exit(1);
                return null;
            }
        }
    }
}