//
// EndianBinaryWriter.cs
//
// Copyright (c) 2007 Lukas Lipka.
//

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

namespace IcqSharp.Util
{
	/// <summary>
	/// Equivalent of System.IO.BinaryWriter, but with either endianness, depending on
	/// the EndianBitConverter it is constructed with.
	/// </summary>
	public class EndianBinaryWriter : IDisposable
	{
		#region Fields not directly related to properties
		/// <summary>
		/// Whether or not this writer has been disposed yet.
		/// </summary>
		bool disposed=false;
		/// <summary>
		/// Buffer used for temporary storage during conversion from primitives
		/// </summary>
		byte[] buffer = new byte[16];
		/// <summary>
		/// Buffer used for Write(char)
		/// </summary>
		char[] charBuffer = new char[1];
		#endregion

		#region Constructors
		/// <summary>
		/// Constructs a new binary writer with the given bit converter, writing
		/// to the given stream, using UTF-8 encoding.
		/// </summary>
		/// <param name="bitConverter">Converter to use when writing data</param>
		/// <param name="stream">Stream to write data to</param>
		public EndianBinaryWriter (EndianBitConverter bitConverter,
			Stream stream) : this (bitConverter, stream, Encoding.UTF8)
		{
		}

		/// <summary>
		/// Constructs a new binary writer with the given bit converter, writing
		/// to the given stream, using the given encoding.
		/// </summary>
		/// <param name="bitConverter">Converter to use when writing data</param>
		/// <param name="stream">Stream to write data to</param>
		/// <param name="encoding">Encoding to use when writing character data</param>
		public EndianBinaryWriter (EndianBitConverter bitConverter,	Stream stream, Encoding encoding)
		{
			if (bitConverter==null)
			{
				throw new ArgumentNullException("bitConverter");
			}
			if (stream==null)
			{
				throw new ArgumentNullException("stream");
			}
			if (encoding==null)
			{
				throw new ArgumentNullException("encoding");
			}
			if (!stream.CanWrite)
			{
				throw new ArgumentException("Stream isn't writable", "stream");
			}
			this.stream = stream;
			this.bitConverter = bitConverter;
			this.encoding = encoding;
		}
		#endregion

		#region Properties
		EndianBitConverter bitConverter;
		/// <summary>
		/// The bit converter used to write values to the stream
		/// </summary>
		public EndianBitConverter BitConverter
		{
			get { return bitConverter; }
		}

		Encoding encoding;
		/// <summary>
		/// The encoding used to write strings
		/// </summary>
		public Encoding Encoding
		{
			get { return encoding; }
		}

		Stream stream;
		/// <summary>
		/// Gets the underlying stream of the EndianBinaryWriter.
		/// </summary>
		public Stream BaseStream
		{
			get { return stream; }
		}
		#endregion
	
		#region Public methods
		/// <summary>
		/// Closes the writer, including the underlying stream.
		/// </summary>
		public void Close()
		{
			Dispose();
		}

		/// <summary>
		/// Flushes the underlying stream.
		/// </summary>
		public void Flush()
		{
			CheckDisposed();
			stream.Flush();
		}

		/// <summary>
		/// Seeks within the stream.
		/// </summary>
		/// <param name="offset">Offset to seek to.</param>
		/// <param name="origin">Origin of seek operation.</param>
		public void Seek (int offset, SeekOrigin origin)
		{
			CheckDisposed();
			stream.Seek (offset, origin);
		}

		/// <summary>
		/// Writes a boolean value to the stream. 1 byte is written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (bool value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 1);
		}

		/// <summary>
		/// Writes a 16-bit signed integer to the stream, using the bit converter
		/// for this writer. 2 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (short value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 2);
		}

		/// <summary>
		/// Writes a 32-bit signed integer to the stream, using the bit converter
		/// for this writer. 4 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (int value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 4);
		}

		/// <summary>
		/// Writes a 64-bit signed integer to the stream, using the bit converter
		/// for this writer. 8 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (long value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 8);
		}

		/// <summary>
		/// Writes a 16-bit unsigned integer to the stream, using the bit converter
		/// for this writer. 2 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (ushort value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 2);
		}

		/// <summary>
		/// Writes a 32-bit unsigned integer to the stream, using the bit converter
		/// for this writer. 4 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (uint value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 4);
		}

		/// <summary>
		/// Writes a 64-bit unsigned integer to the stream, using the bit converter
		/// for this writer. 8 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (ulong value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 8);
		}

		/// <summary>
		/// Writes a single-precision floating-point value to the stream, using the bit converter
		/// for this writer. 4 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (float value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 4);
		}

		/// <summary>
		/// Writes a decimal value to the stream, using the bit converter for this writer.
		/// 16 bytes are written.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (decimal value)
		{
			bitConverter.CopyBytes(value, buffer, 0);
			WriteInternal(buffer, 16);
		}

		/// <summary>
		/// Writes a signed byte to the stream.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (byte value)
		{
			buffer[0] = value;
			WriteInternal(buffer, 1);
		}

		/// <summary>
		/// Writes an unsigned byte to the stream.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write (sbyte value)
		{
			buffer[0] = unchecked((byte)value);
			WriteInternal(buffer, 1);
		}

		/// <summary>
		/// Writes an array of bytes to the stream.
		/// </summary>
		/// <param name="value">The values to write</param>
		public void Write (byte[] value)
		{
			if (value == null)
			{
				throw (new System.ArgumentNullException("value"));
			}
			WriteInternal(value, value.Length);
		}

		/// <summary>
		/// Writes a portion of an array of bytes to the stream.
		/// </summary>
		/// <param name="value">An array containing the bytes to write</param>
		/// <param name="offset">The index of the first byte to write within the array</param>
		/// <param name="count">The number of bytes to write</param>
		public void Write (byte[] value, int offset, int count)
		{
			CheckDisposed();
			stream.Write(value, offset, count);
		}

		/// <summary>
		/// Writes a single character to the stream, using the encoding for this writer.
		/// </summary>
		/// <param name="value">The value to write</param>
		public void Write(char value)
		{
			charBuffer[0] = value;
			Write(charBuffer);
		}

		/// <summary>
		/// Writes an array of characters to the stream, using the encoding for this writer.
		/// </summary>
		/// <param name="value">An array containing the characters to write</param>
		public void Write(char[] value)
		{
			if (value==null)
			{
				throw new ArgumentNullException("value");
			}
			CheckDisposed();
			byte[] data = Encoding.GetBytes(value, 0, value.Length);
			WriteInternal(data, data.Length);
		}

		/// <summary>
		/// Writes a string to the stream, using the encoding for this writer.
		/// </summary>
		/// <param name="value">The value to write. Must not be null.</param>
		/// <exception cref="ArgumentNullException">value is null</exception>
		public void Write(string value)
		{
			if (value==null)
			{
				throw new ArgumentNullException("value");
			}
			CheckDisposed();
			byte[] data = Encoding.GetBytes(value);
			Write7BitEncodedInt(data.Length);
			WriteInternal(data, data.Length);
		}

		/// <summary>
		/// Writes a 7-bit encoded integer from the stream. This is stored with the least significant
		/// information first, with 7 bits of information per byte of value, and the top
		/// bit as a continuation flag.
		/// </summary>
		/// <param name="value">The 7-bit encoded integer to write to the stream</param>
		public void Write7BitEncodedInt(int value)
		{
			CheckDisposed();
			if (value < 0)
			{
				throw new ArgumentOutOfRangeException("value", "Value must be greater than or equal to 0.");
			}
			int index=0;
			while (value >= 128)
			{
				buffer[index++]= (byte)((value&0x7f) | 0x80);
				value = value >> 7;
				index++;
			}
			buffer[index++]=(byte)value;
			stream.Write(buffer, 0, index);
		}

		#endregion

		#region Private methods
		/// <summary>
		/// Checks whether or not the writer has been disposed, throwing an exception if so.
		/// </summary>
		void CheckDisposed()
		{
			if (disposed)
			{
				throw new ObjectDisposedException("EndianBinaryWriter");
			}
		}

		/// <summary>
		/// Writes the specified number of bytes from the start of the given byte array,
		/// after checking whether or not the writer has been disposed.
		/// </summary>
		/// <param name="bytes">The array of bytes to write from</param>
		/// <param name="length">The number of bytes to write</param>
		void WriteInternal (byte[] bytes, int length)
		{
			CheckDisposed();
			stream.Write(bytes, 0, length);
		}
		#endregion

		#region IDisposable Members
		/// <summary>
		/// Disposes of the underlying stream.
		/// </summary>
		public void Dispose()
		{
			if (!disposed)
			{
				Flush();
				disposed = true;
				((IDisposable)stream).Dispose();
			}
		}
		#endregion
	}
}
