src/StructuredLogViewer/FileAssociations.cs

using System;
using System.Diagnostics;
using System.IO;
using Microsoft.Win32;

namespace StructuredLogViewer
{
    public class FileAssociation
    {
        public string Extension { get; set; }
        public string ProgId { get; set; }
        public string FileTypeDescription { get; set; }
        public string ExecutableFilePath { get; set; }
    }

    public class FileAssociations
    {
        // needed so that Explorer windows get refreshed after the registry is updated
        [System.Runtime.InteropServices.DllImport("Shell32.dll")]
        private static extern int SHChangeNotify(int eventId, int flags, IntPtr item1, IntPtr item2);

        private const int SHCNE_ASSOCCHANGED = 0x8000000;
        private const int SHCNF_FLUSH = 0x1000;

        public static void EnsureAssociationsSet(string version = null)
        {
            var filePath = Process.GetCurrentProcess().MainModule.FileName;

            if (version != null)
            {
                var updated = Path.Combine(
                    Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
                    "MSBuildStructuredLogViewer",
                    "app-" + version,
                    Path.GetFileName(filePath));
                if (File.Exists(updated))
                {
                    filePath = updated;
                }
            }

            EnsureAssociationsSet(
                new FileAssociation
                {
                    Extension = ".binlog",
                    ProgId = "MSBuildBinaryLog",
                    FileTypeDescription = "MSBuild Binary Log",
                    ExecutableFilePath = filePath
                },
                new FileAssociation
                {
                    Extension = ".buildlog",
                    ProgId = "MSBuildStructuredLog",
                    FileTypeDescription = "MSBuild Structured Log",
                    ExecutableFilePath = filePath
                });
        }

        public static void EnsureAssociationsSet(params FileAssociation[] associations)
        {
            bool madeChanges = false;
            foreach (var association in associations)
            {
                madeChanges |= SetAssociation(
                    association.Extension,
                    association.ProgId,
                    association.FileTypeDescription,
                    association.ExecutableFilePath);
            }

            if (madeChanges)
            {
                SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_FLUSH, IntPtr.Zero, IntPtr.Zero);
            }
        }

        public static bool SetAssociation(string extension, string progId, string fileTypeDescription, string applicationFilePath)
        {
            bool madeChanges = false;
            madeChanges |= SetKeyDefaultValue(@"Software\Classes\" + extension, progId);
            madeChanges |= SetKeyDefaultValue(@"Software\Classes\" + progId, fileTypeDescription);
            madeChanges |= SetKeyDefaultValue($@"Software\Classes\{progId}\shell\open\command", "\"" + applicationFilePath + "\" \"%1\"");
            return madeChanges;
        }

        private static bool SetKeyDefaultValue(string keyPath, string value)
        {
            using (var key = Registry.CurrentUser.CreateSubKey(keyPath))
            {
                if (key.GetValue(null) as string != value)
                {
                    key.SetValue(null, value);
                    return true;
                }
            }

            return false;
        }
    }
}