using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using Microsoft.DotNet.Cli.Build.Framework;
using Microsoft.Extensions.PlatformAbstractions;

using static Microsoft.DotNet.Cli.Build.FS;
using static Microsoft.DotNet.Cli.Build.Framework.BuildHelpers;
using System.Text.RegularExpressions;
using System.Reflection.PortableExecutable;

namespace Microsoft.DotNet.Cli.Build
{
    public class CompileTargets
    {
        public static readonly string CoreCLRVersion = "1.0.2-rc2-23928";
        public static readonly string AppDepSdkVersion = "1.0.6-prerelease-00003";
        public static readonly bool IsWinx86 = CurrentPlatform.IsWindows && CurrentArchitecture.Isx86;

        public static readonly List<string> AssembliesToCrossGen = GetAssembliesToCrossGen();

        public static readonly string[] BinariesForCoreHost = new[]
        {
            "csi",
            "csc",
            "vbc"
        };

        public static readonly string[] ProjectsToPublish = new[]
        {
            "dotnet"
        };

        public static readonly string[] FilesToClean = new[]
        {
            "README.md"
        };

        public static readonly string[] ProjectsToPack = new[]
        {
            "Microsoft.DotNet.Cli.Utils",
            "Microsoft.DotNet.ProjectModel",
            "Microsoft.DotNet.ProjectModel.Loader",
            "Microsoft.DotNet.ProjectModel.Workspaces",
            "Microsoft.Extensions.DependencyModel",
            "Microsoft.Extensions.Testing.Abstractions"
        };

        public const string SharedFrameworkName = "Microsoft.NETCore.App";

        private static string CoreHostBaseName => $"corehost{Constants.ExeSuffix}";
        private static string DotnetHostFxrBaseName => $"{Constants.DynamicLibPrefix}hostfxr{Constants.DynamicLibSuffix}";
        private static string HostPolicyBaseName => $"{Constants.DynamicLibPrefix}hostpolicy{Constants.DynamicLibSuffix}";

        // Updates the stage 2 with recent changes.
        [Target(nameof(PrepareTargets.Init), nameof(CompileStage2))]
        public static BuildTargetResult UpdateBuild(BuildTargetContext c)
        {
            return c.Success();
        }

        [Target(nameof(PrepareTargets.Init), nameof(PackageCoreHost), nameof(CompileStage1), nameof(CompileStage2))]
        public static BuildTargetResult Compile(BuildTargetContext c)
        {
            return c.Success();
        }

        private static string HostVer = "1.0.1";
        private static string HostPolicyVer = "1.0.1";
        private static string HostFxrVer = "1.0.1";

        [Target]
        public static BuildTargetResult CompileCoreHost(BuildTargetContext c)
        {
            var buildVersion = c.BuildContext.Get<BuildVersion>("BuildVersion");
            var versionTag = buildVersion.ReleaseSuffix;
            var buildMajor = buildVersion.CommitCountString;

            var hostPolicyFullVer = $"{HostPolicyVer}-{versionTag}-{buildMajor}";

            // Generate build files
            var cmakeOut = Path.Combine(Dirs.Corehost, "cmake");

            Rmdir(cmakeOut);
            Mkdirp(cmakeOut);

            var configuration = c.BuildContext.Get<string>("Configuration");

            // Run the build
            string rid = GetRuntimeId();
            string corehostSrcDir = Path.Combine(c.BuildContext.BuildDirectory, "src", "corehost");
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                // Why does Windows directly call cmake but Linux/Mac calls "build.sh" in the corehost dir?
                // See the comment in "src/corehost/build.sh" for details. It doesn't work for some reason.
                var visualStudio = IsWinx86 ? "Visual Studio 14 2015" : "Visual Studio 14 2015 Win64";
                var archMacro = IsWinx86 ? "-DCLI_CMAKE_PLATFORM_ARCH_I386=1" : "-DCLI_CMAKE_PLATFORM_ARCH_AMD64=1";
                var ridMacro = $"-DCLI_CMAKE_RUNTIME_ID:STRING={rid}";
                var arch = IsWinx86 ? "x86" : "x64";
                var baseSupportedRid = $"win7-{arch}";
                var cmakeHostPolicyVer = $"-DCLI_CMAKE_HOST_POLICY_VER:STRING={hostPolicyFullVer}";
                var cmakeBaseRid = $"-DCLI_CMAKE_PKG_RID:STRING={baseSupportedRid}";

                ExecIn(cmakeOut, "cmake",
                    corehostSrcDir,
                    archMacro,
                    ridMacro,
                    cmakeHostPolicyVer,
                    cmakeBaseRid,
                    "-G",
                    visualStudio);

                var pf32 = RuntimeInformation.OSArchitecture == Architecture.X64 ?
                    Environment.GetEnvironmentVariable("ProgramFiles(x86)") :
                    Environment.GetEnvironmentVariable("ProgramFiles");

                if (configuration.Equals("Release"))
                {
                    // Cmake calls it "RelWithDebInfo" in the generated MSBuild
                    configuration = "RelWithDebInfo";
                }

                Exec(Path.Combine(pf32, "MSBuild", "14.0", "Bin", "MSBuild.exe"),
                    Path.Combine(cmakeOut, "ALL_BUILD.vcxproj"),
                    $"/p:Configuration={configuration}");

                // Copy the output out
                File.Copy(Path.Combine(cmakeOut, "cli", configuration, "dotnet.exe"), Path.Combine(Dirs.Corehost, "corehost.exe"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", configuration, "dotnet.pdb"), Path.Combine(Dirs.Corehost, "corehost.pdb"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", configuration, "dotnet.exe"), Path.Combine(Dirs.Corehost, "dotnet.exe"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", configuration, "dotnet.pdb"), Path.Combine(Dirs.Corehost, "dotnet.pdb"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "dll", configuration, "hostpolicy.dll"), Path.Combine(Dirs.Corehost, "hostpolicy.dll"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "dll", configuration, "hostpolicy.pdb"), Path.Combine(Dirs.Corehost, "hostpolicy.pdb"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "fxr", configuration, "hostfxr.dll"), Path.Combine(Dirs.Corehost, "hostfxr.dll"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "fxr", configuration, "hostfxr.pdb"), Path.Combine(Dirs.Corehost, "hostfxr.pdb"), overwrite: true);
            }
            else
            {
                ExecIn(cmakeOut, Path.Combine(c.BuildContext.BuildDirectory, "src", "corehost", "build.sh"),
                        "--arch",
                        "x64",
                        "--policyver",
                        hostPolicyFullVer,
                        "--rid",
                        rid);

                // Copy the output out
                File.Copy(Path.Combine(cmakeOut, "cli", "dotnet"), Path.Combine(Dirs.Corehost, "dotnet"), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "dotnet"), Path.Combine(Dirs.Corehost, CoreHostBaseName), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "dll", HostPolicyBaseName), Path.Combine(Dirs.Corehost, HostPolicyBaseName), overwrite: true);
                File.Copy(Path.Combine(cmakeOut, "cli", "fxr", DotnetHostFxrBaseName), Path.Combine(Dirs.Corehost, DotnetHostFxrBaseName), overwrite: true);
            }
            return c.Success();
        }

        [Target(nameof(CompileCoreHost))]
        public static BuildTargetResult PackageCoreHost(BuildTargetContext c)
        {
            var buildVersion = c.BuildContext.Get<BuildVersion>("BuildVersion");
            var versionTag = buildVersion.ReleaseSuffix;
            var buildMajor = buildVersion.CommitCountString;
            var arch = IsWinx86 ? "x86" : "x64";

            var version = buildVersion.NuGetVersion;
            var content = $@"{c.BuildContext["CommitHash"]}{Environment.NewLine}{version}{Environment.NewLine}";
            File.WriteAllText(Path.Combine(c.BuildContext.BuildDirectory, "src", "corehost", "packaging", "version.txt"), content);
            string corehostSrcDir = Path.Combine(c.BuildContext.BuildDirectory, "src", "corehost");
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                Command.Create(Path.Combine(corehostSrcDir, "packaging", "pack.cmd"))
                    // Workaround to arg escaping adding backslashes for arguments to .cmd scripts.
                    .Environment("__WorkaroundCliCoreHostBuildArch", arch)
                    .Environment("__WorkaroundCliCoreHostBinDir", Dirs.Corehost)
                    .Environment("__WorkaroundCliCoreHostPolicyVer", HostPolicyVer)
                    .Environment("__WorkaroundCliCoreHostFxrVer", HostFxrVer)
                    .Environment("__WorkaroundCliCoreHostVer", HostVer)
                    .Environment("__WorkaroundCliCoreHostBuildMajor", buildMajor)
                    .Environment("__WorkaroundCliCoreHostVersionTag", versionTag)
                    .ForwardStdOut()
                    .ForwardStdErr()
                    .Execute()
                    .EnsureSuccessful();
            }
            else
            {
                Exec(Path.Combine(corehostSrcDir, "packaging", "pack.sh"),
                    "--arch",
                    "x64",
                    "--hostbindir",
                    Dirs.Corehost,
                    "--policyver",
                    HostPolicyVer,
                    "--fxrver",
                    HostFxrVer,
                    "--hostver",
                    HostVer,
                    "--build",
                    buildMajor,
                    "--vertag",
                    versionTag);
            }
            int runtimeCount = 0;
            foreach (var file in Directory.GetFiles(Path.Combine(corehostSrcDir, "packaging", "bin", "packages"), "*.nupkg"))
            {
                var fileName = Path.GetFileName(file);
                File.Copy(file, Path.Combine(Dirs.Corehost, fileName));
                runtimeCount += (fileName.StartsWith("runtime.") ? 1 : 0);
            }
            if (runtimeCount < 3)
            {
                throw new BuildFailureException("Not all corehost nupkgs were successfully created");
            }
            return c.Success();
        }

        private static string GetRuntimeId()
        {
            string info = DotNetCli.Stage0.Exec("", "--info").CaptureStdOut().Execute().StdOut;
            string rid = Array.Find<string>(info.Split(Environment.NewLine.ToCharArray()), (e) => e.Contains("RID:"))?.Replace("RID:", "").Trim();

            // TODO: when Stage0 is updated with the new --info, remove this legacy check for --version
            if (string.IsNullOrEmpty(rid))
            {
                string version = DotNetCli.Stage0.Exec("", "--version").CaptureStdOut().Execute().StdOut;
                rid = Array.Find<string>(version.Split(Environment.NewLine.ToCharArray()), (e) => e.Contains("Runtime Id:")).Replace("Runtime Id:", "").Trim();
            }

            if (string.IsNullOrEmpty(rid))
            {
                throw new BuildFailureException("Could not find the Runtime ID from Stage0 --info or --version");
            }

            return rid;
        }

        [Target]
        public static BuildTargetResult CompileStage1(BuildTargetContext c)
        {
            CleanBinObj(c, Path.Combine(c.BuildContext.BuildDirectory, "src"));
            CleanBinObj(c, Path.Combine(c.BuildContext.BuildDirectory, "test"));

            if (Directory.Exists(Dirs.Stage1))
            {
                Utils.DeleteDirectory(Dirs.Stage1);
            }
            Directory.CreateDirectory(Dirs.Stage1);

            CopySharedHost(Dirs.Stage1);
            PublishSharedFramework(c, Dirs.Stage1, DotNetCli.Stage0);
            return CompileCliSdk(c,
                dotnet: DotNetCli.Stage0,
                outputDir: Dirs.Stage1);
        }

        [Target]
        public static BuildTargetResult CompileStage2(BuildTargetContext c)
        {
            var configuration = c.BuildContext.Get<string>("Configuration");

            CleanBinObj(c, Path.Combine(c.BuildContext.BuildDirectory, "src"));
            CleanBinObj(c, Path.Combine(c.BuildContext.BuildDirectory, "test"));

            if (Directory.Exists(Dirs.Stage2))
            {
                Utils.DeleteDirectory(Dirs.Stage2);
            }
            Directory.CreateDirectory(Dirs.Stage2);

            PublishSharedFramework(c, Dirs.Stage2, DotNetCli.Stage1);
            CopySharedHost(Dirs.Stage2);
            var result = CompileCliSdk(c,
                dotnet: DotNetCli.Stage1,
                outputDir: Dirs.Stage2);

            if (!result.Success)
            {
                return result;
            }

            // Build projects that are packed in NuGet packages, but only on Windows
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                var packagingOutputDir = Path.Combine(Dirs.Stage2Compilation, "forPackaging");
                Mkdirp(packagingOutputDir);
                foreach (var project in ProjectsToPack)
                {
                    // Just build them, we'll pack later
                    DotNetCli.Stage1.Build(
                        "--build-base-path",
                        packagingOutputDir,
                        "--configuration",
                        configuration,
                        Path.Combine(c.BuildContext.BuildDirectory, "src", project))
                        .Execute()
                        .EnsureSuccessful();
                }
            }

            return c.Success();
        }

        private static void CopySharedHost(string outputDir)
        {
            // corehost will be renamed to dotnet at some point and then this can be removed.
            File.Copy(
                Path.Combine(Dirs.Corehost, CoreHostBaseName),
                Path.Combine(outputDir, $"dotnet{Constants.ExeSuffix}"), true);
            File.Copy(
                Path.Combine(Dirs.Corehost, DotnetHostFxrBaseName),
                Path.Combine(outputDir, DotnetHostFxrBaseName), true);
        }

        public static void PublishSharedFramework(BuildTargetContext c, string outputDir, DotNetCli dotnetCli)
        {
            string SharedFrameworkSourceRoot = Path.Combine(Dirs.RepoRoot, "src", "sharedframework", "framework");
            string SharedFrameworkNugetVersion = c.BuildContext.Get<string>("SharedFrameworkNugetVersion");

            // We publish to a sub folder of the PublishRoot so tools like heat and zip can generate folder structures easier.
            string SharedFrameworkNameAndVersionRoot = Path.Combine(outputDir, "shared", SharedFrameworkName, SharedFrameworkNugetVersion);
            c.BuildContext["SharedFrameworkPath"] = SharedFrameworkNameAndVersionRoot;

            if (Directory.Exists(SharedFrameworkNameAndVersionRoot))
            {
                Utils.DeleteDirectory(SharedFrameworkNameAndVersionRoot);
            }

            string publishFramework = "dnxcore50"; // Temporary, use "netcoreapp" when we update nuget.
            string publishRuntime;
            if (PlatformServices.Default.Runtime.OperatingSystemPlatform == Platform.Windows)
            {
                publishRuntime = $"win7-{PlatformServices.Default.Runtime.RuntimeArchitecture}";
            }
            else
            {
                publishRuntime = PlatformServices.Default.Runtime.GetRuntimeIdentifier();
            }

            dotnetCli.Publish(
                "--output", SharedFrameworkNameAndVersionRoot,
                "-r", publishRuntime,
                "-f", publishFramework,
                SharedFrameworkSourceRoot).Execute().EnsureSuccessful();

            // Clean up artifacts that dotnet-publish generates which we don't need
            DeleteMainPublishOutput(SharedFrameworkNameAndVersionRoot, "framework");
            File.Delete(Path.Combine(SharedFrameworkNameAndVersionRoot, "framework.runtimeconfig.json"));

            // Rename the .deps file
            var destinationDeps = Path.Combine(SharedFrameworkNameAndVersionRoot, $"{SharedFrameworkName}.deps.json");
            File.Move(Path.Combine(SharedFrameworkNameAndVersionRoot, "framework.deps"), Path.Combine(SharedFrameworkNameAndVersionRoot, $"{SharedFrameworkName}.deps"));
            File.Move(Path.Combine(SharedFrameworkNameAndVersionRoot, "framework.deps.json"), destinationDeps);

            // Generate RID fallback graph
            string runtimeGraphGeneratorRuntime = null;
            switch (PlatformServices.Default.Runtime.OperatingSystemPlatform)
            {
                case Platform.Windows:
                    runtimeGraphGeneratorRuntime = "win";
                    break;
                case Platform.Linux:
                    runtimeGraphGeneratorRuntime = "linux";
                    break;
                case Platform.Darwin:
                    runtimeGraphGeneratorRuntime = "osx";
                    break;
            }
            if (!string.IsNullOrEmpty(runtimeGraphGeneratorRuntime))
            {
                var runtimeGraphGeneratorName = "RuntimeGraphGenerator";
                var runtimeGraphGeneratorProject = Path.Combine(Dirs.RepoRoot, "tools", runtimeGraphGeneratorName);
                var runtimeGraphGeneratorOutput = Path.Combine(Dirs.Output, "tools", runtimeGraphGeneratorName);

                dotnetCli.Publish(
                    "--output", runtimeGraphGeneratorOutput,
                    runtimeGraphGeneratorProject).Execute().EnsureSuccessful();
                var runtimeGraphGeneratorExe = Path.Combine(runtimeGraphGeneratorOutput, $"{runtimeGraphGeneratorName}{Constants.ExeSuffix}");

                Cmd(runtimeGraphGeneratorExe, "--project", SharedFrameworkSourceRoot, "--deps", destinationDeps, runtimeGraphGeneratorRuntime)
                    .Execute()
                    .EnsureSuccessful();
            }
            else
            {
                c.Error($"Could not determine rid graph generation runtime for platform {PlatformServices.Default.Runtime.OperatingSystemPlatform}");
            }

            // corehost will be renamed to dotnet at some point and then we will not need to rename it here.
            File.Copy(
                Path.Combine(Dirs.Corehost, CoreHostBaseName),
                Path.Combine(SharedFrameworkNameAndVersionRoot, $"dotnet{Constants.ExeSuffix}"), true);
            File.Copy(
                Path.Combine(Dirs.Corehost, CoreHostBaseName),
                Path.Combine(SharedFrameworkNameAndVersionRoot, CoreHostBaseName), true);
            File.Copy(
                Path.Combine(Dirs.Corehost, HostPolicyBaseName),
                Path.Combine(SharedFrameworkNameAndVersionRoot, HostPolicyBaseName), true);

            if (File.Exists(Path.Combine(SharedFrameworkNameAndVersionRoot, "mscorlib.ni.dll")))
            {
                // Publish already places the crossgen'd version of mscorlib into the output, so we can
                // remove the IL version
                File.Delete(Path.Combine(SharedFrameworkNameAndVersionRoot, "mscorlib.dll"));
            }

            CrossgenSharedFx(c, SharedFrameworkNameAndVersionRoot);

            // Generate .version file for sharedfx
            var version = SharedFrameworkNugetVersion;
            var content = $@"{c.BuildContext["CommitHash"]}{Environment.NewLine}{version}{Environment.NewLine}";
            File.WriteAllText(Path.Combine(SharedFrameworkNameAndVersionRoot, ".version"), content);
        }

        private static BuildTargetResult CompileCliSdk(BuildTargetContext c, DotNetCli dotnet, string outputDir)
        {
            var configuration = c.BuildContext.Get<string>("Configuration");
            var buildVersion = c.BuildContext.Get<BuildVersion>("BuildVersion");
            outputDir = Path.Combine(outputDir, "sdk", buildVersion.NuGetVersion);

            Rmdir(outputDir);
            Mkdirp(outputDir);

            foreach (var project in ProjectsToPublish)
            {
                // TODO: Use the flag once we get a full build round tripped
                // --version-suffix buildVesion.VersionSuffix
                dotnet.Publish(
                    "--native-subdirectory",
                    "--output",
                    outputDir,
                    "--configuration",
                    configuration,
                    Path.Combine(c.BuildContext.BuildDirectory, "src", project))
                    .Environment("DOTNET_BUILD_VERSION", buildVersion.VersionSuffix)
                    .Execute()
                    .EnsureSuccessful();
            }

            FixModeFlags(outputDir);

            string compilersProject = Path.Combine(Dirs.RepoRoot, "src", "compilers");
            dotnet.Publish(compilersProject,
                    "--output",
                    outputDir,
                    "--framework",
                    "netstandard1.5") 
                    .Execute()
                    .EnsureSuccessful();

            var compilersDeps = Path.Combine(outputDir, "compilers.deps.json");
            var compilersRuntimeConfig = Path.Combine(outputDir, "compilers.runtimeconfig.json");

            // Copy corehost
            File.Copy(Path.Combine(Dirs.Corehost, $"corehost{Constants.ExeSuffix}"), Path.Combine(outputDir, $"corehost{Constants.ExeSuffix}"), overwrite: true);
            File.Copy(Path.Combine(Dirs.Corehost, $"{Constants.DynamicLibPrefix}hostpolicy{Constants.DynamicLibSuffix}"), Path.Combine(outputDir, $"{Constants.DynamicLibPrefix}hostpolicy{Constants.DynamicLibSuffix}"), overwrite: true);
            File.Copy(Path.Combine(Dirs.Corehost, $"{Constants.DynamicLibPrefix}hostfxr{Constants.DynamicLibSuffix}"), Path.Combine(outputDir, $"{Constants.DynamicLibPrefix}hostfxr{Constants.DynamicLibSuffix}"), overwrite: true);

            var binaryToCorehostifyOutDir = Path.Combine(outputDir, "runtimes", "any", "native");
            // Corehostify binaries
            foreach (var binaryToCorehostify in BinariesForCoreHost)
            {
                try
                {
                    // Yes, it is .exe even on Linux. This is the managed exe we're working with
                    File.Copy(Path.Combine(binaryToCorehostifyOutDir, $"{binaryToCorehostify}.exe"), Path.Combine(outputDir, $"{binaryToCorehostify}.dll"));
                    File.Delete(Path.Combine(binaryToCorehostifyOutDir, $"{binaryToCorehostify}.exe"));
                    File.Copy(compilersDeps, Path.Combine(outputDir, binaryToCorehostify + ".deps.json"));
                    File.Copy(compilersRuntimeConfig, Path.Combine(outputDir, binaryToCorehostify + ".runtimeconfig.json"));
                }
                catch (Exception ex)
                {
                    return c.Failed($"Failed to corehostify '{binaryToCorehostify}': {ex.ToString()}");
                }
            }

            // cleanup compilers project output we don't need
            DeleteMainPublishOutput(outputDir, "compilers");
            File.Delete(compilersDeps);
            File.Delete(compilersRuntimeConfig);

            // Crossgen Roslyn
            var result = CrossgenCliSdk(c, outputDir);
            if (!result.Success)
            {
                return result;
            }

            // Copy AppDeps
            result = CopyAppDeps(c, outputDir);
            if (!result.Success)
            {
                return result;
            }

            // Generate .version file
            var version = buildVersion.NuGetVersion;
            var content = $@"{c.BuildContext["CommitHash"]}{Environment.NewLine}{version}{Environment.NewLine}";
            File.WriteAllText(Path.Combine(outputDir, ".version"), content);

            return c.Success();
        }

        private static BuildTargetResult CopyAppDeps(BuildTargetContext c, string outputDir)
        {
            var appDepOutputDir = Path.Combine(outputDir, "appdepsdk");
            Rmdir(appDepOutputDir);
            Mkdirp(appDepOutputDir);

            // Find toolchain package
            string packageId;

            if (CurrentPlatform.IsWindows)
            {
                if (CurrentArchitecture.Isx86)
                {
                    // https://github.com/dotnet/cli/issues/1550
                    c.Warn("Native compilation is not yet working on Windows x86");
                    return c.Success();
                }

                packageId = "toolchain.win7-x64.Microsoft.DotNet.AppDep";
            }
            else if (CurrentPlatform.IsUbuntu)
            {
                packageId = "toolchain.ubuntu.14.04-x64.Microsoft.DotNet.AppDep";
            }
            else if (CurrentPlatform.IsCentOS || CurrentPlatform.IsRHEL || CurrentPlatform.IsDebian)
            {
                c.Warn($"Native compilation is not yet working on {CurrentPlatform.Current}");
                return c.Success();
            }
            else if (CurrentPlatform.IsOSX)
            {
                packageId = "toolchain.osx.10.10-x64.Microsoft.DotNet.AppDep";
            }
            else
            {
                return c.Failed("Unsupported OS Platform");
            }

            var appDepPath = Path.Combine(
                Dirs.NuGetPackages,
                packageId,
                AppDepSdkVersion);
            CopyRecursive(appDepPath, appDepOutputDir, overwrite: true);

            return c.Success();
        }

        private static BuildTargetResult CrossgenCliSdk(BuildTargetContext c, string outputDir)
        {
            // Check if we need to skip crossgen
            if (string.Equals(Environment.GetEnvironmentVariable("DOTNET_BUILD_SKIP_CROSSGEN"), "1"))
            {
                c.Warn("Skipping crossgen for Cli Sdk because DOTNET_BUILD_SKIP_CROSSGEN is set");
                return c.Success();
            }

            // Find crossgen
            var crossGenExePath = Microsoft.DotNet.Cli.Build.Crossgen.GetCrossgenPathForVersion(CoreCLRVersion);

            if (string.IsNullOrEmpty(crossGenExePath))
            {
                return c.Failed("Unsupported OS Platform");
            }

            // We have to copy crossgen next to mscorlib
            var crossgen = Path.Combine(outputDir, $"crossgen{Constants.ExeSuffix}");
            File.Copy(crossGenExePath, crossgen, overwrite: true);
            Chmod(crossgen, "a+x");

            // And if we have mscorlib.ni.dll, we need to rename it to mscorlib.dll
            if (File.Exists(Path.Combine(outputDir, "mscorlib.ni.dll")))
            {
                File.Copy(Path.Combine(outputDir, "mscorlib.ni.dll"), Path.Combine(outputDir, "mscorlib.dll"), overwrite: true);
            }

            foreach (var assemblyToCrossgen in AssembliesToCrossGen)
            {
                c.Info($"Crossgenning {assemblyToCrossgen}");
                ExecInSilent(outputDir, 
                    crossgen, 
                    "-readytorun",
                    "-nologo",
                    "-platform_assemblies_paths",
                    $"{outputDir}{Path.PathSeparator}{c.BuildContext["SharedFrameworkPath"]}",
                    assemblyToCrossgen);
            }

            c.Info("Crossgen complete");

            // Check if csc/vbc.ni.exe exists, and overwrite the dll with it just in case
            if (File.Exists(Path.Combine(outputDir, "csc.ni.exe")) && !File.Exists(Path.Combine(outputDir, "csc.ni.dll")))
            {
                File.Move(Path.Combine(outputDir, "csc.ni.exe"), Path.Combine(outputDir, "csc.ni.dll"));
            }

            if (File.Exists(Path.Combine(outputDir, "vbc.ni.exe")) && !File.Exists(Path.Combine(outputDir, "vbc.ni.dll")))
            {
                File.Move(Path.Combine(outputDir, "vbc.ni.exe"), Path.Combine(outputDir, "vbc.ni.dll"));
            }

            return c.Success();
        }

        public static BuildTargetResult CrossgenSharedFx(BuildTargetContext c, string pathToAssemblies)
        {
            // Check if we need to skip crossgen
            if (string.Equals(Environment.GetEnvironmentVariable("DONT_CROSSGEN_SHAREDFRAMEWORK"), "1"))
            {
                c.Warn("Skipping crossgen for SharedFx because DONT_CROSSGEN_SHAREDFRAMEWORK is set to 1");
                return c.Success();
            }

            foreach (var file in Directory.GetFiles(pathToAssemblies))
            {
                string fileName = Path.GetFileName(file);

                if (fileName == "mscorlib.dll" || fileName == "mscorlib.ni.dll" || !HasMetadata(file))
                {
                    continue;
                }

                string tempPathName = Path.ChangeExtension(file, "readytorun");

                // This is not always correct. The version of crossgen we need to pick up is whatever one was restored as part
                // of the Microsoft.NETCore.Runtime.CoreCLR package that is part of the shared library. For now, the version hardcoded
                // in CompileTargets and the one in the shared library project.json match and are updated in lock step, but long term
                // we need to be able to look at the project.lock.json file and figure out what version of Microsoft.NETCore.Runtime.CoreCLR
                // was used, and then select that version.
                ExecSilent(Crossgen.GetCrossgenPathForVersion(CompileTargets.CoreCLRVersion),
                    "-readytorun", "-in", file, "-out", tempPathName, "-platform_assemblies_paths", pathToAssemblies);

                File.Delete(file);
                File.Move(tempPathName, file);
            }

            return c.Success();
        }

        private static void DeleteMainPublishOutput(string path, string name)
        {
            File.Delete(Path.Combine(path, $"{name}{Constants.ExeSuffix}"));
            File.Delete(Path.Combine(path, $"{name}.dll"));
            File.Delete(Path.Combine(path, $"{name}.pdb"));
        }

        private static bool HasMetadata(string pathToFile)
        {
            try
            {
                using (var inStream = File.OpenRead(pathToFile))
                {
                    using (var peReader = new PEReader(inStream))
                    {
                        return peReader.HasMetadata;
                    }
                }
            }
            catch (BadImageFormatException) { }

            return false;
        }

        private static List<string> GetAssembliesToCrossGen()
        {
            return new List<string>
            {
                "System.Collections.Immutable.dll",
                "System.Reflection.Metadata.dll",
                "Microsoft.CodeAnalysis.dll",
                "Microsoft.CodeAnalysis.CSharp.dll",
                "Microsoft.CodeAnalysis.VisualBasic.dll",
                "csc.dll",
                "vbc.dll"
            };
        }
    }
}