// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.IO;
using System.Security;
using System.Text;

namespace Microsoft.Build.CommandLine
{
    /// <summary>
    /// Ported from https://github.com/dotnet/sdk/blob/bcea1face15458814b8e53e8785b52ba464f6538/src/Cli/dotnet/AutomaticEncodingRestorer.cs.
    /// A program can change the encoding of the console which would affect other programs.
    /// We would prefer to have a pattern where the program does not affect encoding of other programs.
    /// Create this class in a function akin to Main and let it manage the console encoding resources to return it to the state before execution upon destruction.
    /// </summary>
    public class AutomaticEncodingRestorer : IDisposable
    {
        private Encoding? _originalOutputEncoding = null;
        private Encoding? _originalInputEncoding = null;

        public AutomaticEncodingRestorer()
        {
            try
            {
#if NET
                if (OperatingSystem.IsIOS() || OperatingSystem.IsAndroid() || OperatingSystem.IsTvOS()) // Output + Input Encoding are unavailable on these platforms per docs, and they're only available past net 5.
                {
                    return;
                }
#endif
                _originalOutputEncoding = Console.OutputEncoding;

#if NET
                if (OperatingSystem.IsBrowser()) // Input Encoding is also unavailable in this platform. (No concern for net472 as browser is unavailable.)
                {
                    return;
                }
#endif
                _originalInputEncoding = Console.InputEncoding;
            }
            catch (Exception ex) when (ex is IOException || ex is SecurityException)
            {
                // The encoding is unavailable. Do nothing.
            }
        }

        public void Dispose()
        {
            try
            {
                if (_originalOutputEncoding != null)
                {
                    Console.OutputEncoding = _originalOutputEncoding;
                }
                if (_originalInputEncoding != null)
                {
                    Console.InputEncoding = _originalInputEncoding;
                }
            }
            catch (Exception ex) when (ex is IOException || ex is SecurityException)
            {
                // The encoding is unavailable. Do nothing.
            }
        }
    }
}