using System;
using System.IO;
using System.Text;
using System.Threading;
using AspClassic.Scripting.Utils;

namespace AspClassic.Scripting.Runtime;

public sealed class SharedIO
{
	private sealed class StreamProxy : Stream
	{
		private readonly ConsoleStreamType _type;

		private readonly SharedIO _io;

		public override bool CanRead => _type == ConsoleStreamType.Input;

		public override bool CanSeek => false;

		public override bool CanWrite => !CanRead;

		public override long Length
		{
			get
			{
				throw new NotSupportedException();
			}
		}

		public override long Position
		{
			get
			{
				throw new NotSupportedException();
			}
			set
			{
				throw new NotSupportedException();
			}
		}

		public StreamProxy(SharedIO io, ConsoleStreamType type)
		{
			_io = io;
			_type = type;
		}

		public override void Flush()
		{
			_io.GetStream(_type).Flush();
		}

		public override int Read(byte[] buffer, int offset, int count)
		{
			return _io.GetStream(_type).Read(buffer, offset, count);
		}

		public override void Write(byte[] buffer, int offset, int count)
		{
			_io.GetStream(_type).Write(buffer, offset, count);
		}

		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException();
		}

		public override void SetLength(long value)
		{
			throw new NotSupportedException();
		}
	}

	private readonly object _mutex = new object();

	private Stream _inputStream;

	private Stream _outputStream;

	private Stream _errorStream;

	private TextReader _inputReader;

	private TextWriter _outputWriter;

	private TextWriter _errorWriter;

	private Encoding _inputEncoding;

	public Stream InputStream
	{
		get
		{
			InitializeInput();
			return _inputStream;
		}
	}

	public Stream OutputStream
	{
		get
		{
			InitializeOutput();
			return _outputStream;
		}
	}

	public Stream ErrorStream
	{
		get
		{
			InitializeErrorOutput();
			return _errorStream;
		}
	}

	public TextReader InputReader
	{
		get
		{
			InitializeInput();
			return _inputReader;
		}
	}

	public TextWriter OutputWriter
	{
		get
		{
			InitializeOutput();
			return _outputWriter;
		}
	}

	public TextWriter ErrorWriter
	{
		get
		{
			InitializeErrorOutput();
			return _errorWriter;
		}
	}

	public Encoding InputEncoding
	{
		get
		{
			InitializeInput();
			return _inputEncoding;
		}
	}

	public Encoding OutputEncoding
	{
		get
		{
			InitializeOutput();
			return _outputWriter.Encoding;
		}
	}

	public Encoding ErrorEncoding
	{
		get
		{
			InitializeErrorOutput();
			return _errorWriter.Encoding;
		}
	}

	internal SharedIO()
	{
	}

	private void InitializeInput()
	{
		if (_inputStream != null)
		{
			return;
		}
		lock (_mutex)
		{
			if (_inputStream == null)
			{
				_inputStream = ConsoleInputStream.Instance;
				_inputEncoding = Console.InputEncoding;
				_inputReader = Console.In;
			}
		}
	}

	private void InitializeOutput()
	{
		if (_outputStream != null)
		{
			return;
		}
		lock (_mutex)
		{
			if (_outputStream == null)
			{
				_outputStream = Console.OpenStandardOutput();
				_outputWriter = Console.Out;
			}
		}
	}

	private void InitializeErrorOutput()
	{
		if (_errorStream == null)
		{
			Stream value = Console.OpenStandardError();
			Interlocked.CompareExchange(ref _errorStream, value, null);
			Interlocked.CompareExchange(ref _errorWriter, Console.Error, null);
		}
	}

	public void SetOutput(Stream stream, TextWriter writer)
	{
		lock (_mutex)
		{
			_outputStream = stream;
			_outputWriter = writer;
		}
	}

	public void SetErrorOutput(Stream stream, TextWriter writer)
	{
		lock (_mutex)
		{
			_errorStream = stream;
			_errorWriter = writer;
		}
	}

	public void SetInput(Stream stream, TextReader reader, Encoding encoding)
	{
		lock (_mutex)
		{
			_inputStream = stream;
			_inputReader = reader;
			_inputEncoding = encoding;
		}
	}

	public void RedirectToConsole()
	{
		lock (_mutex)
		{
			_inputEncoding = null;
			_inputStream = null;
			_outputStream = null;
			_errorStream = null;
			_inputReader = null;
			_outputWriter = null;
			_errorWriter = null;
		}
	}

	public Stream GetStream(ConsoleStreamType type)
	{
		return type switch
		{
			ConsoleStreamType.Input => InputStream, 
			ConsoleStreamType.Output => OutputStream, 
			ConsoleStreamType.ErrorOutput => ErrorStream, 
			_ => throw Error.InvalidStreamType(type), 
		};
	}

	public TextWriter GetWriter(ConsoleStreamType type)
	{
		return type switch
		{
			ConsoleStreamType.Output => OutputWriter, 
			ConsoleStreamType.ErrorOutput => ErrorWriter, 
			_ => throw Error.InvalidStreamType(type), 
		};
	}

	public Encoding GetEncoding(ConsoleStreamType type)
	{
		return type switch
		{
			ConsoleStreamType.Input => InputEncoding, 
			ConsoleStreamType.Output => OutputEncoding, 
			ConsoleStreamType.ErrorOutput => ErrorEncoding, 
			_ => throw Error.InvalidStreamType(type), 
		};
	}

	public TextReader GetReader(out Encoding encoding)
	{
		lock (_mutex)
		{
			TextReader inputReader = InputReader;
			encoding = InputEncoding;
			return inputReader;
		}
	}

	public Stream GetStreamProxy(ConsoleStreamType type)
	{
		return new StreamProxy(this, type);
	}
}