// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reactive.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Tye.Hosting;
using Microsoft.Tye.Hosting.Model;
using Xunit;
using Microsoft.Tye;
using System.Diagnostics;

namespace Test.Infrastructure
{
    public static class TestHelpers
    {
        private static readonly TimeSpan WaitForServicesTimeout = Debugger.IsAttached ? TimeSpan.FromMinutes(5) : TimeSpan.FromSeconds(20);

        // https://github.com/dotnet/aspnetcore/blob/5a0526dfd991419d5bce0d8ea525b50df2e37b04/src/Testing/src/TestPathUtilities.cs
        // This can get into a bad pattern for having crazy paths in places. Eventually, especially if we use helix,
        // we may want to avoid relying on sln position.
        public static string GetSolutionRootDirectory(string solution)
        {
            var applicationBasePath = AppContext.BaseDirectory;
            var directoryInfo = new DirectoryInfo(applicationBasePath);

            do
            {
                var projectFileInfo = new FileInfo(Path.Combine(directoryInfo.FullName, $"{solution}.sln"));
                if (projectFileInfo.Exists)
                {
                    return projectFileInfo.DirectoryName;
                }

                directoryInfo = directoryInfo.Parent;
            }
            while (directoryInfo.Parent != null);

            throw new Exception($"Solution file {solution}.sln could not be found in {applicationBasePath} or its parent directories.");
        }

        public static DirectoryInfo GetTestAssetsDirectory()
        {
            return new DirectoryInfo(Path.Combine(
                TestHelpers.GetSolutionRootDirectory("tye"),
                "test",
                "E2ETest",
                "testassets"));
        }

        public static DirectoryInfo GetTestProjectDirectory(string projectName)
        {
            var directory = new DirectoryInfo(Path.Combine(
                TestHelpers.GetSolutionRootDirectory("tye"),
                "test",
                "E2ETest",
                "testassets",
                "projects",
                projectName));
            Assert.True(directory.Exists, $"Project {projectName} not found.");
            return directory;
        }

        public static DirectoryInfo GetSampleProjectDirectory(string projectName)
        {
            var directory = new DirectoryInfo(Path.Combine(
                TestHelpers.GetSolutionRootDirectory("tye"),
                "samples",
                projectName));
            Assert.True(directory.Exists, $"Project {projectName} not found.");
            return directory;
        }

        public static TempDirectory CopyTestProjectDirectory(string projectName)
        {
            var temp = TempDirectory.Create(preferUserDirectoryOnMacOS: true);
            DirectoryCopy.Copy(GetTestProjectDirectory(projectName).FullName, temp.DirectoryPath);

            // We need to hijack any P2P references to Tye libraries.
            // Test projects must use $(TyeLibrariesPath) to find their references.
            var libraryPath = Path.Combine(TestHelpers.GetSolutionRootDirectory("tye"), "src");
            if (!libraryPath.EndsWith(Path.DirectorySeparatorChar))
            {
                libraryPath += Path.DirectorySeparatorChar;
            }

            File.WriteAllText(
                Path.Combine(temp.DirectoryPath, "Directory.Build.props"),
                $@"
<Project>
  <PropertyGroup>
    <TyeLibrariesPath>{libraryPath}</TyeLibrariesPath>
  </PropertyGroup>
</Project>");

            return temp;
        }

        public static async Task StartHostAndWaitForReplicasToStart(TyeHost host)
        {
            var startedTask = new TaskCompletionSource<bool>();
            var alreadyStarted = 0;
            var totalReplicas = host.Application.Services.Sum(s => s.Value.Description.Replicas);

            void OnReplicaChange(ReplicaEvent ev)
            {
                if (ev.State == ReplicaState.Started)
                {
                    Interlocked.Increment(ref alreadyStarted);
                }
                else if (ev.State == ReplicaState.Stopped)
                {
                    Interlocked.Decrement(ref alreadyStarted);
                }

                if (alreadyStarted == totalReplicas)
                {
                    startedTask!.TrySetResult(true);
                }
            }

            var servicesStateObserver = host.Application.Services.Select(srv => srv.Value.ReplicaEvents.Subscribe(OnReplicaChange)).ToList();
            await host.StartAsync();

            using var cancellation = new CancellationTokenSource(WaitForServicesTimeout);
            try
            {
                await using (cancellation.Token.Register(() => startedTask.TrySetCanceled()))
                {
                    await startedTask.Task;
                }
            }
            finally
            {
                foreach (var observer in servicesStateObserver)
                {
                    observer.Dispose();
                }
            }
        }

        public static async Task PurgeHostAndWaitForGivenReplicasToStop(TyeHost host, string[] replicas)
        {
            static async Task Purge(TyeHost host)
            {
                var logger = host.DashboardWebApplication!.Logger;
                var replicaRegistry = new ReplicaRegistry(host.Application.ContextDirectory, logger);
                var processRunner = new ProcessRunner(logger, replicaRegistry, new ProcessRunnerOptions());
                var dockerRunner = new DockerRunner(logger, replicaRegistry);

                await processRunner.StartAsync(new Application(new FileInfo(host.Application.Source), new Dictionary<string, Service>()));
                await dockerRunner.StartAsync(new Application(new FileInfo(host.Application.Source), new Dictionary<string, Service>()));
            }

            var stoppedTask = new TaskCompletionSource<bool>();
            var remaining = replicas.Length;

            void OnReplicaChange(ReplicaEvent ev)
            {
                if (replicas.Contains(ev.Replica.Name) && ev.State == ReplicaState.Stopped)
                {
                    Interlocked.Decrement(ref remaining);
                }

                if (remaining == 0)
                {
                    stoppedTask!.TrySetResult(true);
                }
            }

            var servicesStateObserver = host.Application.Services.Select(srv => srv.Value.ReplicaEvents.Subscribe(OnReplicaChange)).ToList();

            // We purge existing replicas by restarting the host which will initiate the purging process
            await Purge(host);

            using var cancellation = new CancellationTokenSource(WaitForServicesTimeout);
            try
            {
                await using (cancellation.Token.Register(() => stoppedTask.TrySetCanceled()))
                {
                    await stoppedTask.Task;
                }
            }
            finally
            {
                foreach (var observer in servicesStateObserver)
                {
                    observer.Dispose();
                }
            }
        }
    }
}