// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : DetectOS.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Interop services.
//
// --[ Description ] ----------------------------------------------------------
//
//     Detects underlying operating system.
//
// --[ License ] --------------------------------------------------------------
//
//     Permission is hereby granted, free of charge, to any person obtaining a
//     copy of this software and associated documentation files (the
//     "Software"), to deal in the Software without restriction, including
//     without limitation the rights to use, copy, modify, merge, publish,
//     distribute, sublicense, and/or sell copies of the Software, and to
//     permit persons to whom the Software is furnished to do so, subject to
//     the following conditions:
//
//     The above copyright notice and this permission notice shall be included
//     in all copies or substantial portions of the Software.
//
//     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
//     OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
//     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
//     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
//     CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
//     TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
//     SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2018 Natalia Portillo
// ****************************************************************************/

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;

namespace DiscImageChef.Interop
{
    public static class DetectOS
    {
        public static readonly bool IsMono = Type.GetType("Mono.Runtime") != null;

        /// <summary>Checks if the underlying runtime runs in 64-bit mode</summary>
        public static readonly bool Is64Bit = IntPtr.Size == 8;

        /// <summary>Checks if the underlying runtime runs in 32-bit mode</summary>
        public static readonly bool Is32Bit = IntPtr.Size == 4;

        [DllImport("libc", SetLastError = true)]
        static extern int uname(out utsname name);

        [DllImport("libc", SetLastError = true, EntryPoint = "sysctlbyname", CharSet = CharSet.Ansi)]
        static extern int OSX_sysctlbyname(string name, IntPtr oldp, IntPtr oldlenp, IntPtr newp, uint newlen);

        /// <summary>Gets the real platform ID, not the incomplete .NET framework one</summary>
        /// <returns>Platform ID</returns>
        /// <exception cref="Exception">Unhandled exception</exception>
        public static PlatformID GetRealPlatformID()
        {
            if((int)Environment.OSVersion.Platform < 4 ||
               (int)Environment.OSVersion.Platform == 5)
                return (PlatformID)(int)Environment.OSVersion.Platform;

            int error = uname(out utsname unixname);

            if(error != 0)
                throw new Exception($"Unhandled exception calling uname: {Marshal.GetLastWin32Error()}");

            switch(unixname.sysname)
            {
                // TODO: Differentiate Linux, Android, Tizen
                case "Linux":
                {
                #if __ANDROID__
                        return PlatformID.Android;
                #else
                    return PlatformID.Linux;
                #endif
                }
                case "Darwin":
                {
                    int osxError;

                    IntPtr pLen = Marshal.AllocHGlobal(sizeof(int));
                    osxError = OSX_sysctlbyname("hw.machine", IntPtr.Zero, pLen, IntPtr.Zero, 0);

                    if(osxError != 0)
                    {
                        Marshal.FreeHGlobal(pLen);

                        throw new Exception($"Unhandled exception calling uname: {Marshal.GetLastWin32Error()}");
                    }

                    int    length = Marshal.ReadInt32(pLen);
                    IntPtr pStr   = Marshal.AllocHGlobal(length);
                    osxError = OSX_sysctlbyname("hw.machine", pStr, pLen, IntPtr.Zero, 0);

                    if(osxError != 0)
                    {
                        Marshal.FreeHGlobal(pStr);
                        Marshal.FreeHGlobal(pLen);

                        throw new Exception($"Unhandled exception calling uname: {Marshal.GetLastWin32Error()}");
                    }

                    string machine = Marshal.PtrToStringAnsi(pStr);

                    Marshal.FreeHGlobal(pStr);
                    Marshal.FreeHGlobal(pLen);

                    if(machine != null &&
                       (machine.StartsWith("iPad", StringComparison.Ordinal) ||
                        machine.StartsWith("iPod", StringComparison.Ordinal) ||
                        machine.StartsWith("iPhone", StringComparison.Ordinal)))
                        return PlatformID.iOS;

                    return PlatformID.MacOSX;
                }
                case "GNU": return PlatformID.Hurd;
                case "FreeBSD":
                case "GNU/kFreeBSD": return PlatformID.FreeBSD;
                case "DragonFly": return PlatformID.DragonFly;
                case "Haiku":     return PlatformID.Haiku;
                case "HP-UX":     return PlatformID.HPUX;
                case "AIX":       return PlatformID.AIX;
                case "OS400":     return PlatformID.OS400;
                case "IRIX":
                case "IRIX64": return PlatformID.IRIX;
                case "Minix":          return PlatformID.Minix;
                case "NetBSD":         return PlatformID.NetBSD;
                case "NONSTOP_KERNEL": return PlatformID.NonStop;
                case "OpenBSD":        return PlatformID.OpenBSD;
                case "QNX":            return PlatformID.QNX;
                case "SINIX-Y":        return PlatformID.SINIX;
                case "SunOS":          return PlatformID.Solaris;
                case "OSF1":           return PlatformID.Tru64;
                case "ULTRIX":         return PlatformID.Ultrix;
                case "SCO_SV":         return PlatformID.OpenServer;
                case "UnixWare":       return PlatformID.UnixWare;
                case "Interix":
                case "UWIN-W7": return PlatformID.Win32NT;
                default:
                {
                    if(unixname.sysname.StartsWith("CYGWIN_NT", StringComparison.Ordinal)  ||
                       unixname.sysname.StartsWith("MINGW32_NT", StringComparison.Ordinal) ||
                       unixname.sysname.StartsWith("MSYS_NT", StringComparison.Ordinal)    ||
                       unixname.sysname.StartsWith("UWIN", StringComparison.Ordinal))
                        return PlatformID.Win32NT;

                    return PlatformID.Unknown;
                }
            }
        }

        /// <summary>Gets a string for the current operating system REAL version (handles Darwin 1.4 and Windows 10 falsifying)</summary>
        /// <returns>Current operating system version</returns>
        public static string GetVersion()
        {
            string environ = Environment.OSVersion.Version.ToString();

            switch(GetRealPlatformID())
            {
                case PlatformID.MacOSX:
                    if(Environment.OSVersion.Version.Major != 1)
                        return $"10.{Environment.OSVersion.Version.Major - 4}.{Environment.OSVersion.Version.Minor}";

                    switch(Environment.OSVersion.Version.Minor)
                    {
                        case 3: return "10.0";
                        case 4: return "10.1";
                    }

                    goto default;
                case PlatformID.Win32NT:
                    // From Windows 8.1 the reported version is simply falsified...
                    if((Environment.OSVersion.Version.Major == 6 && Environment.OSVersion.Version.Major >= 2) ||
                       Environment.OSVersion.Version.Major > 6)
                        return FileVersionInfo.
                               GetVersionInfo(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.System),
                                                           "KERNEL32.DLL")).ProductVersion;

                    return environ;
                default: return environ;
            }
        }

        /// <summary>From a platform ID and version returns a human-readable version</summary>
        /// <param name="id">Platform ID</param>
        /// <param name="version">Version number</param>
        /// <returns>Operating system name</returns>
        public static string GetPlatformName(PlatformID id, string version = null)
        {
            switch(id)
            {
                case PlatformID.AIX:       return "AIX";
                case PlatformID.Android:   return "Android";
                case PlatformID.DragonFly: return "DragonFly BSD";
                case PlatformID.FreeBSD:   return "FreeBSD";
                case PlatformID.Haiku:     return "Haiku";
                case PlatformID.HPUX:      return "HP/UX";
                case PlatformID.Hurd:      return "Hurd";
                case PlatformID.iOS:       return "iOS";
                case PlatformID.IRIX:      return "IRIX";
                case PlatformID.Linux:     return "Linux";
                case PlatformID.MacOSX:
                    if(string.IsNullOrEmpty(version))
                        return "macOS";

                    string[] pieces = version.Split('.');

                    if(pieces.Length < 2 ||
                       !int.TryParse(pieces[1], out int minor))
                        return "macOS";

                    if(minor >= 12)
                        return "macOS";

                    if(minor >= 8)
                        return "OS X";

                    return "Mac OS X";

                case PlatformID.Minix:        return "MINIX";
                case PlatformID.NetBSD:       return "NetBSD";
                case PlatformID.NonStop:      return "NonStop OS";
                case PlatformID.OpenBSD:      return "OpenBSD";
                case PlatformID.OpenServer:   return "SCO OpenServer";
                case PlatformID.OS400:        return "OS/400";
                case PlatformID.PlayStation3: return "Sony CellOS";
                case PlatformID.PlayStation4: return "Sony Orbis OS";
                case PlatformID.QNX:          return "QNX";
                case PlatformID.SINIX:        return "SINIX";
                case PlatformID.Solaris:      return "Sun Solaris";
                case PlatformID.Tizen:        return "Samsung Tizen";
                case PlatformID.Tru64:        return "Tru64 UNIX";
                case PlatformID.Ultrix:       return "Ultrix";
                case PlatformID.Unix:         return "UNIX";
                case PlatformID.UnixWare:     return "SCO UnixWare";
                case PlatformID.Wii:          return "Nintendo Wii";
                case PlatformID.WiiU:         return "Nintendo Wii U";
                case PlatformID.Win32NT:
                    if(string.IsNullOrEmpty(version))
                        return "Windows NT/2000/XP/Vista/7/10";

                    if(version.StartsWith("3.", StringComparison.Ordinal) ||
                       version.StartsWith("4.", StringComparison.Ordinal))
                        return "Windows NT";

                    if(version.StartsWith("5.0", StringComparison.Ordinal))
                        return "Windows 2000";

                    if(version.StartsWith("5.1", StringComparison.Ordinal))
                        return "Windows XP";

                    if(version.StartsWith("5.2", StringComparison.Ordinal))
                        return "Windows 2003";

                    if(version.StartsWith("6.0", StringComparison.Ordinal))
                        return "Windows Vista";

                    if(version.StartsWith("6.1", StringComparison.Ordinal))
                        return "Windows 7";

                    if(version.StartsWith("6.2", StringComparison.Ordinal))
                        return "Windows 8";

                    if(version.StartsWith("6.3", StringComparison.Ordinal))
                        return "Windows 8.1";

                    if(version.StartsWith("10.0", StringComparison.Ordinal))
                        return "Windows 10";

                    return "Windows NT/2000/XP/Vista/7/10";
                case PlatformID.Win32S: return "Windows 3.x with win32s";
                case PlatformID.Win32Windows:
                    if(string.IsNullOrEmpty(version))
                        return "Windows 9x/Me";

                    if(version.StartsWith("4.0", StringComparison.Ordinal))
                        return "Windows 95";

                    if(version.StartsWith("4.10.2222", StringComparison.Ordinal))
                        return "Windows 98 SE";

                    if(version.StartsWith("4.1", StringComparison.Ordinal))
                        return "Windows 98";

                    if(version.StartsWith("4.9", StringComparison.Ordinal))
                        return "Windows Me";

                    return "Windows 9x/Me";
                case PlatformID.WinCE:        return "Windows CE/Mobile";
                case PlatformID.WindowsPhone: return "Windows Phone";
                case PlatformID.Xbox:         return "Xbox OS";
                case PlatformID.zOS:          return "z/OS";
                default:                      return id.ToString();
            }
        }

        /// <summary>POSIX uname structure, size from OSX, big enough to handle extra fields</summary>
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        struct utsname
        {
            /// <summary>System name</summary>
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public readonly string sysname;
            /// <summary>Node name</summary>
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public readonly string nodename;
            /// <summary>Release level</summary>
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public readonly string release;
            /// <summary>Version level</summary>
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public readonly string version;
            /// <summary>Hardware level</summary>
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public readonly string machine;
        }
    }
}