namespace TPSBR
{
	using System;
	using System.IO;
	using System.Text;

	public sealed class StatsRecorder
	{
		// CONSTANTS

		public static readonly Encoding DefaultEncoding  = Encoding.UTF8;
		public static readonly string   DefaultSeparator = ",";
		public static readonly string   DefaultComment   = "#";
		public static readonly string   DefaultNewLine   = "\n";

		// PUBLIC MEMBERS

		public bool IsInitialized => _fileStream != null;

		// PRIVATE MEMBERS

		private int        _size;
		private int        _count;
		private string[]   _values;
		private FileStream _fileStream;

		private readonly Encoding _encoding;
		private readonly byte[]   _separator;
		private readonly byte[]   _comment;
		private readonly byte[]   _newLine;
		private readonly byte[]   _buffer = new byte[8192];

		// CONSTRUCTORS

		public StatsRecorder()
		{
			_encoding  = DefaultEncoding;
			_separator = _encoding.GetBytes(DefaultSeparator);
			_comment   = _encoding.GetBytes(DefaultComment);
			_newLine   = _encoding.GetBytes(DefaultNewLine);
		}

		public StatsRecorder(Encoding encoding, string separator, string comment, string newLine)
		{
			_encoding  = encoding;
			_separator = _encoding.GetBytes(separator);
			_comment   = _encoding.GetBytes(comment);
			_newLine   = _encoding.GetBytes(newLine);
		}

		// PUBLIC METHODS

		public void Initialize(string name, int size)
		{
			if (size <= 0)
				throw new ArgumentException(nameof(size));
			if (_fileStream != null)
				return;

			_size       = size;
			_values     = new string[_size];
			_fileStream = File.OpenWrite(name);
		}

		public void Initialize(string name, string caption, params string[] headers)
		{
			if (_fileStream != null)
				return;
			if (headers == null || headers.Length == 0)
				throw new ArgumentNullException(nameof(headers));

			for (int i = 0; i < headers.Length; ++i)
			{
				if (string.IsNullOrEmpty(headers[i]) == true)
					throw new ArgumentNullException($"{nameof(headers)}[{i}]");
			}

			_size       = headers.Length;
			_values     = new string[_size];
			_fileStream = File.OpenWrite(name);

			if (string.IsNullOrEmpty(caption) == false)
			{
				_fileStream.Write(_comment, 0, _comment.Length);

				int captionCount = _encoding.GetBytes(caption, 0, caption.Length, _buffer, 0);
				_fileStream.Write(_buffer, 0, captionCount);

				_fileStream.Write(_newLine, 0, _newLine.Length);
			}

			string header      = headers[0];
			int    headerCount = _encoding.GetBytes(header, 0, header.Length, _buffer, 0);
			_fileStream.Write(_buffer, 0, headerCount);

			for (int i = 1; i < headers.Length; ++i)
			{
				_fileStream.Write(_separator, 0, _separator.Length);

				header      = headers[i];
				headerCount = _encoding.GetBytes(header, 0, header.Length, _buffer, 0);
				_fileStream.Write(_buffer, 0, headerCount);
			}

			_fileStream.Write(_newLine, 0, _newLine.Length);
		}

		public void Deinitialize()
		{
			if (_fileStream == null)
				return;

			_size   = 0;
			_values = null;

			_fileStream.Flush(true);
			_fileStream.Close();
			_fileStream = null;
		}

		public void Add(string value)
		{
			if (_count < _size)
			{
				_values[_count] = value;
				++_count;
			}
		}

		public void Write()
		{
			if (_count <= 0)
				return;
			if (_count != _size)
				throw new ArgumentException($"Expected {_size} values!");

			string value      = _values[0];
			int    valueCount = _encoding.GetBytes(value, 0, value.Length, _buffer, 0);

			_fileStream.Write(_buffer, 0, valueCount);

			for (int i = 1; i < _count; ++i)
			{
				_fileStream.Write(_separator, 0, _separator.Length);

				value      = _values[i];
				valueCount = _encoding.GetBytes(value, 0, value.Length, _buffer, 0);

				_fileStream.Write(_buffer, 0, valueCount);
			}

			_fileStream.Write(_newLine, 0, _newLine.Length);

			_count = 0;
		}

		public void Write(params string[] values)
		{
			if (_fileStream == null)
				return;
			if (values.Length != _size)
				throw new ArgumentException($"Expected {_size} values!");

			string value      = values[0];
			int    valueCount = _encoding.GetBytes(value, 0, value.Length, _buffer, 0);

			_fileStream.Write(_buffer, 0, valueCount);

			for (int i = 1; i < values.Length; ++i)
			{
				_fileStream.Write(_separator, 0, _separator.Length);

				value      = values[i];
				valueCount = _encoding.GetBytes(value, 0, value.Length, _buffer, 0);

				_fileStream.Write(_buffer, 0, valueCount);
			}

			_fileStream.Write(_newLine, 0, _newLine.Length);
		}

		public void WriteComment(string comment)
		{
			if (_fileStream == null)
				return;
			if (string.IsNullOrEmpty(comment) == true)
				return;

			_fileStream.Write(_comment, 0, _comment.Length);

			int commentCount = _encoding.GetBytes(comment, 0, comment.Length, _buffer, 0);
			_fileStream.Write(_buffer, 0, commentCount);

			_fileStream.Write(_newLine, 0, _newLine.Length);
		}

		public void Flush()
		{
			if (_fileStream == null)
				return;

			_fileStream.Flush(true);
		}
	}
}