using System;
using System.Text;
using System.Runtime.InteropServices;
using System.Collections.Generic;

namespace VisualStudioConfiguration
{
    [Flags]
    public enum InstanceState : uint
    {
        None = 0,
        Local = 1,
        Registered = 2,
        NoRebootRequired = 4,
        NoErrors = 8,
        Complete = 4294967295,
    }

    [Guid("6380BCFF-41D3-4B2E-8B2E-BF8A6810C848")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface IEnumSetupInstances
    {

        void Next([MarshalAs(UnmanagedType.U4), In] int celt,
            [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.Interface), Out] ISetupInstance[] rgelt,
            [MarshalAs(UnmanagedType.U4)] out int pceltFetched);

        void Skip([MarshalAs(UnmanagedType.U4), In] int celt);

        void Reset();

        [return: MarshalAs(UnmanagedType.Interface)]
        IEnumSetupInstances Clone();
    }

    [Guid("42843719-DB4C-46C2-8E7C-64F1816EFD5B")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupConfiguration
    {
    }

    [Guid("26AAB78C-4A60-49D6-AF3B-3C35BC93365D")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupConfiguration2 : ISetupConfiguration
    {

        [return: MarshalAs(UnmanagedType.Interface)]
        IEnumSetupInstances EnumInstances();

        [return: MarshalAs(UnmanagedType.Interface)]
        ISetupInstance GetInstanceForCurrentProcess();

        [return: MarshalAs(UnmanagedType.Interface)]
        ISetupInstance GetInstanceForPath([MarshalAs(UnmanagedType.LPWStr), In] string path);

        [return: MarshalAs(UnmanagedType.Interface)]
        IEnumSetupInstances EnumAllInstances();
    }

    [Guid("B41463C3-8866-43B5-BC33-2B0676F7F42E")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupInstance
    {
    }

    [Guid("89143C9A-05AF-49B0-B717-72E218A2185C")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupInstance2 : ISetupInstance
    {
        [return: MarshalAs(UnmanagedType.BStr)]
        string GetInstanceId();

        [return: MarshalAs(UnmanagedType.Struct)]
        System.Runtime.InteropServices.ComTypes.FILETIME GetInstallDate();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetInstallationName();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetInstallationPath();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetInstallationVersion();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetDisplayName([MarshalAs(UnmanagedType.U4), In] int lcid);

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetDescription([MarshalAs(UnmanagedType.U4), In] int lcid);

        [return: MarshalAs(UnmanagedType.BStr)]
        string ResolvePath([MarshalAs(UnmanagedType.LPWStr), In] string pwszRelativePath);

        [return: MarshalAs(UnmanagedType.U4)]
        InstanceState GetState();

        [return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_UNKNOWN)]
        ISetupPackageReference[] GetPackages();

        ISetupPackageReference GetProduct();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetProductPath();

        [return: MarshalAs(UnmanagedType.VariantBool)]
        bool IsLaunchable();

        [return: MarshalAs(UnmanagedType.VariantBool)]
        bool IsComplete();

        [return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_UNKNOWN)]
        ISetupPropertyStore GetProperties();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetEnginePath();
    }

    [Guid("DA8D8A16-B2B6-4487-A2F1-594CCCCD6BF5")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupPackageReference
    {

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetId();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetVersion();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetChip();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetLanguage();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetBranch();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetType();

        [return: MarshalAs(UnmanagedType.BStr)]
        string GetUniqueId();

        [return: MarshalAs(UnmanagedType.VariantBool)]
        bool GetIsExtension();
    }

    [Guid("c601c175-a3be-44bc-91f6-4568d230fc83")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [ComImport]
    public interface ISetupPropertyStore
    {

        [return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_BSTR)]
        string[] GetNames();

        object GetValue([MarshalAs(UnmanagedType.LPWStr), In] string pwszName);
    }

    [Guid("42843719-DB4C-46C2-8E7C-64F1816EFD5B")]
    [CoClass(typeof(SetupConfigurationClass))]
    [ComImport]
    public interface SetupConfiguration : ISetupConfiguration2, ISetupConfiguration
    {
    }

    [Guid("177F0C4A-1CD3-4DE7-A32C-71DBBB9FA36D")]
    [ClassInterface(ClassInterfaceType.None)]
    [ComImport]
    public class SetupConfigurationClass
    {
    }

    public static class Main
    {
        public static void PrintJson()
        {
            ISetupConfiguration query = new SetupConfiguration();
            ISetupConfiguration2 query2 = (ISetupConfiguration2)query;
            IEnumSetupInstances e = query2.EnumAllInstances();

            int pceltFetched;
            ISetupInstance2[] rgelt = new ISetupInstance2[1];
            List<string> instances = new List<string>();
            while (true)
            {
                e.Next(1, rgelt, out pceltFetched);
                if (pceltFetched <= 0)
                {
                    Console.WriteLine(String.Format("[{0}]", string.Join(",", instances.ToArray())));
                    return;
                }

                try
                {
                    instances.Add(InstanceJson(rgelt[0]));
                }
                catch (COMException)
                {
                    // Ignore instances that can't be queried.
                }
            }
        }

        private static string JsonString(string s)
        {
            return "\"" + s.Replace("\\", "\\\\").Replace("\"", "\\\"") + "\"";
        }

        private static string InstanceJson(ISetupInstance2 setupInstance2)
        {
            // Visual Studio component directory:
            // https://docs.microsoft.com/en-us/visualstudio/install/workload-and-component-ids

            StringBuilder json = new StringBuilder();
            json.Append("{");

            string path = JsonString(setupInstance2.GetInstallationPath());
            json.Append(String.Format("\"path\":{0},", path));

            string version = JsonString(setupInstance2.GetInstallationVersion());
            json.Append(String.Format("\"version\":{0},", version));

            List<string> packages = new List<string>();
            foreach (ISetupPackageReference package in setupInstance2.GetPackages())
            {
                string id = JsonString(package.GetId());
                packages.Add(id);
            }
            json.Append(String.Format("\"packages\":[{0}]", string.Join(",", packages.ToArray())));

            json.Append("}");
            return json.ToString();
        }
    }
}
