using System;
using System.Collections.Generic;
using System.Linq;
using System.Management;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace Tango.PPC.Common.OS
{
    using System.Collections.ObjectModel;
    using System.Diagnostics;
    using Tango.Core;
    using Tango.Core.Components;
    using SLID = Guid; //SLID id declaration as typedef GUID SLID; in slpublic.h 

    /// <summary>
    /// Represents the default windows activation manager.
    /// </summary>
    /// <seealso cref="Tango.PPC.Common.OS.IOperationSystemManager" />
    public class DefaultOperationSystemManager : ExtendedObject, IOperationSystemManager
    {
        #region Win32

        private enum SL_GENUINE_STATE
        {
            SL_GEN_STATE_IS_GENUINE = 0,
            SL_GEN_STATE_INVALID_LICENSE = 1,
            SL_GEN_STATE_TAMPERED = 2,
            SL_GEN_STATE_OFFLINE = 3,
            SL_GEN_STATE_LAST = 4
        }

        [DllImportAttribute("Slwga.dll", EntryPoint = "SLIsGenuineLocal", CharSet = CharSet.None, ExactSpelling = false, SetLastError = false, PreserveSig = true, CallingConvention = CallingConvention.Winapi, BestFitMapping = false, ThrowOnUnmappableChar = false)]
        [PreserveSigAttribute()]
        private static extern uint SLIsGenuineLocal(ref SLID slid, [In, Out] ref SL_GENUINE_STATE genuineState, IntPtr val3);

        #endregion

        /// <summary>
        /// Determines whether the OS is activated.
        /// </summary>
        /// <returns></returns>
        public Task<bool> IsActivated()
        {
            return Task.Factory.StartNew<bool>(() =>
            {
                LogManager.Log("Validating windows activation...");

                Guid ApplicationID = new Guid("55c92734-d682-4d71-983e-d6ec3f16059f"); //Application ID GUID http://technet.microsoft.com/en-us/library/dd772270.aspx
                SLID windowsSlid = (Guid)ApplicationID;
                try
                {
                    SL_GENUINE_STATE genuineState = SL_GENUINE_STATE.SL_GEN_STATE_LAST;
                    uint ResultInt = SLIsGenuineLocal(ref windowsSlid, ref genuineState, IntPtr.Zero);
                    if (ResultInt == 0)
                    {
                        LogManager.Log("OS activation status: " + genuineState.ToString());
                        return (genuineState == SL_GENUINE_STATE.SL_GEN_STATE_IS_GENUINE);
                    }
                    else
                    {
                        throw LogManager.Log(new InvalidOperationException("An error occurred while trying to get the OS activation status."));
                    }

                }
                catch (Exception ex)
                {
                    throw ex;
                }
            });
        }

        /// <summary>
        /// Activates the OS using the specified activation key.
        /// </summary>
        /// <param name="activationKey">The activation key.</param>
        /// <returns></returns>
        public async Task Activate(string activationKey)
        {
            if (!(await IsActivated()))
            {
                CmdCommand command = new CmdCommand("cscript", $"C:\\Windows\\System32\\slmgr.vbs -ipk {activationKey}");
                await command.Run();

                bool activated = false;

                for (int i = 0; i < 10; i++)
                {
                    await Task.Delay(2000);
                    activated = await IsActivated();
                    if (activated) break;
                }

                if (!activated)
                {
                    throw new ApplicationException("The activation was completed but activation status returned a false response.");
                }
            }
            else
            {
                LogManager.Log("Windows is already activated. Skipping activation...");
            }
        }

        /// <summary>
        /// Deactivates the OS license.
        /// </summary>
        /// <returns></returns>
        /// <exception cref="System.NotImplementedException"></exception>
        public Task Deactivate()
        {
            throw new NotImplementedException("Deactivating windows license is not supported.");
        }

        /// <summary>
        /// Gets the available time zones.
        /// </summary>
        /// <returns></returns>
        public ReadOnlyCollection<TimeZoneInfo> GetAvailableTimeZones()
        {
            return TimeZoneInfo.GetSystemTimeZones();
        }

        /// <summary>
        /// Changes the operation system time zone.
        /// </summary>
        /// <param name="timeZone">The time zone.</param>
        /// <returns></returns>
        public async Task ChangeTimeZone(TimeZoneInfo timeZone)
        {
            CmdCommand cmd = new CmdCommand("tzutil", $"/s \"{timeZone.Id}\"");
            await cmd.Run();
        }

        /// <summary>
        /// Restarts the system.
        /// </summary>
        /// <returns></returns>
        public void Restart()
        {
            Process.Start("shutdown.exe", "-r -t 0");
        }
    }
}