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using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using NUnit.Framework;
using Opc.Ua.Server.Hosting;
using Opc.Ua.Server.TestFramework;
using Opc.Ua.Tests;

namespace Opc.Ua.Server.Tests
{
    /// <summary>
    /// OPC 10000-12 Annex G.2: a server in the application setup state
    /// reports ServerState NoConfiguration and still serves requests so it can
    /// be provisioned.
    /// </summary>
    [TestFixture]
    [Category("Server")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [NonParallelizable]
    public class ApplicationSetupServerStateTests
    {
        [Test]
        public async Task ServerInApplicationSetupReportsNoConfigurationAndServesRequestsAsync()
        {
            var fixture = new ServerFixture<ApplicationSetupServer>(
                telemetry => new ApplicationSetupServer(telemetry))
            {
                SecurityNone = true
            };
            await fixture.LoadConfigurationAsync().ConfigureAwait(false);
            await fixture.StartAsync().ConfigureAwait(false);
            try
            {
                StandardServer server = fixture.Server;
                Assert.That(server.CurrentInstance.CurrentState, Is.EqualTo(ServerState.NoConfiguration));
                Assert.That(server.CurrentInstance.IsRunning, Is.True);

                Assert.That(await ReadServerStateAsync(server).ConfigureAwait(false),
                    Is.EqualTo(ServerState.NoConfiguration));
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        [Test]
        public async Task ServerStartsRunningByDefaultAsync()
        {
            var fixture = new ServerFixture<StandardServer>(telemetry => new StandardServer(telemetry))
            {
                SecurityNone = true
            };
            await fixture.LoadConfigurationAsync().ConfigureAwait(false);
            await fixture.StartAsync().ConfigureAwait(false);
            try
            {
                Assert.That(fixture.Server.CurrentInstance.CurrentState, Is.EqualTo(ServerState.Running));
                Assert.That(await ReadServerStateAsync(fixture.Server).ConfigureAwait(false),
                    Is.EqualTo(ServerState.Running));
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        /// <summary>
        /// The hosted server derives its startup state from the registered
        /// <see cref="ServerConfigurationOptions.InApplicationSetup"/>.
        /// </summary>
        [TestCase(true, ServerState.NoConfiguration)]
        [TestCase(false, ServerState.Running)]
        [TestCase(null, ServerState.Running)]
        public async Task DependencyInjectionServerMapsInApplicationSetupToServerStateAsync(
            bool? inApplicationSetup,
            ServerState expected)
        {
            var services = new ServiceCollection();
            if (inApplicationSetup.HasValue)
            {
                services.AddSingleton(new ServerConfigurationOptions { InApplicationSetup = inApplicationSetup });
            }
            using ServiceProvider provider = services.BuildServiceProvider();
            var fixture = new ServerFixture<DependencyInjectionStandardServer>(
                telemetry => new DependencyInjectionStandardServer(provider, telemetry, TimeProvider.System))
            {
                SecurityNone = true
            };
            await fixture.LoadConfigurationAsync().ConfigureAwait(false);
            await fixture.StartAsync().ConfigureAwait(false);
            try
            {
                Assert.That(fixture.Server.CurrentInstance.CurrentState, Is.EqualTo(expected));
                Assert.That(await ReadServerStateAsync(fixture.Server).ConfigureAwait(false), Is.EqualTo(expected));
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        private static async Task<ServerState> ReadServerStateAsync(StandardServer server)
        {
            (RequestHeader requestHeader, SecureChannelContext secureChannelContext) =
                await server.CreateAndActivateSessionAsync(TestContext.CurrentContext.Test.Name)
                    .ConfigureAwait(false);
            try
            {
                ReadResponse response = await server.ReadAsync(
                    secureChannelContext,
                    requestHeader,
                    0,
                    TimestampsToReturn.Neither,
                    [
                        new ReadValueId
                        {
                            NodeId = VariableIds.Server_ServerStatus_State,
                            AttributeId = Attributes.Value
                        }
                    ],
                    RequestLifetime.None).ConfigureAwait(false);
                DataValue value = response.Results[0];
                Assert.That(StatusCode.IsGood(value.StatusCode), Is.True);
                Assert.That(value.WrappedValue.TryGetValue(out ServerState state), Is.True);
                return state;
            }
            finally
            {
                await server.CloseSessionAsync(secureChannelContext, requestHeader, CancellationToken.None)
                    .ConfigureAwait(false);
            }
        }

        /// <summary>
        /// A server that starts in the application setup state.
        /// </summary>
        public sealed class ApplicationSetupServer : StandardServer
        {
            public ApplicationSetupServer(ITelemetryContext telemetry)
                : base(telemetry)
            {
            }

            protected override ServerState StartupServerState => ServerState.NoConfiguration;
        }
    }
}