using System;
using System.IO;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.Text;

namespace DLL
{
    /// <summary>
    /// Allocates and manages a new console for the calling process.
    /// </summary>
    public static class ConsoleCreator
    {
        [DllImport("kernel32.dll", EntryPoint = "AllocConsole", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        private static extern int AllocConsole();

        [DllImport("kernel32.dll", EntryPoint = "FreeConsole", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        private static extern int FreeConsole();

        [DllImport("kernel32.dll")]
        private static extern IntPtr GetConsoleWindow();

        #region hiding windows
        [DllImport("user32.dll")]
        private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

        private const int SW_HIDE = 0;
        private const int SW_SHOW = 5;
        #endregion

        [DllImport("kernel32.dll", EntryPoint = "GetStdHandle", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        private static extern IntPtr GetStdHandle(int nStdHandle);

        private const int STD_OUTPUT_HANDLE = -11;

        /// <summary>
        /// Allocate new console.
        /// </summary>
        /// <exception cref="InvalidOperationException">Console already attached.</exception>

        public static void CreateConsoleWindow()
        {
            var handle = GetConsoleWindow();

            if (GetConsoleWindow() == IntPtr.Zero)
            {
                AllocConsole();
                IntPtr stdHandle = GetStdHandle(STD_OUTPUT_HANDLE);
                SafeFileHandle safeFileHandle = new SafeFileHandle(stdHandle, true);
                FileStream fileStream = new FileStream(safeFileHandle, FileAccess.Write);
                StreamWriter standardOutput = new StreamWriter(fileStream) { AutoFlush = true };
                Console.OutputEncoding = Encoding.UTF8;
                Console.SetOut(standardOutput);
            }
            else
            {
                throw new InvalidOperationException("Console already attached");
            }

        }
        /// <summary>
        /// Remove console.
        /// </summary>
        public static void RemoveConsoleWindow()
        {
            FreeConsole();
            //redirect output to standard output.
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = true };
            Console.SetOut(sw);
        }

        /// <summary>
        /// Show console.
        /// </summary>
        public static void ShowConsoleWindow()
        {
            var handle = GetConsoleWindow();
            ShowWindow(handle, SW_SHOW);
        }

        /// <summary>
        /// Hide console.
        /// </summary>
        public static void HideConsoleWindow()
        {
            var handle = GetConsoleWindow();
            ShowWindow(handle, SW_HIDE);
        }
    }
}