/**
 * @file itextstream.h
 */

/*
 Copyright (C) 2001-2006, William Joseph.
 All Rights Reserved.

 This file is part of GtkRadiant.

 GtkRadiant is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 GtkRadiant is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with GtkRadiant; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#if !defined(INCLUDED_ITEXTSTREAM_H)
#define INCLUDED_ITEXTSTREAM_H

/// \file
/// \brief Text-stream interfaces.

#include <cstddef>
#include "generic/static.h"

/// \brief A read-only character-stream.
class TextInputStream
{
	public:
		virtual ~TextInputStream ()
		{
		}

		/// \brief Attempts to read the next \p length characters from the stream to \p buffer.
		/// Returns the number of characters actually stored in \p buffer.
		virtual std::size_t read (char* buffer, std::size_t length) = 0;
};

/// \brief A write-only character-stream.
class TextOutputStream
{
	public:
		virtual ~TextOutputStream ()
		{
		}

		/// \brief Attempts to write \p length characters to the stream from \p buffer.
		/// Returns the number of characters actually read from \p buffer.
		virtual std::size_t write (const char* buffer, std::size_t length) = 0;
};

/// \brief Calls the overloaded function ostream_write() to perform text formatting specific to the type being written.
/*! Note that ostream_write() is not globally defined - it must be defined once for each type supported.\n
 To support writing a custom type MyClass to any kind of text-output-stream with operator<<:
 \code
 template<typename TextOutputStreamType>
 TextOutputStreamType& ostream_write(TextOutputStreamType& ostream, const MyClass& myClass)
 {
 return ostream << myClass.getName() << " " << myClass.getText();
 }
 \endcode
 Expressing this as a template allows it to be used directly with any concrete text-output-stream type, not just the abstract TextOutputStream\n
 \n
 This overload writes a single character to any text-output-stream - ostream_write(TextOutputStreamType& ostream, char c).
 */
template<typename T>
inline TextOutputStream& operator<< (TextOutputStream& ostream, const T& t)
{
	return ostream_write(ostream, t);
}

class NullOutputStream: public TextOutputStream
{
	public:
		std::size_t write (const char*, std::size_t length)
		{
			return length;
		}
};

/**
 * greebo: This is a simple container holding a single output stream.
 * Use the getStream() method to acquire a reference to the stream.
 */
class OutputStreamHolder
{
		NullOutputStream m_nullOutputStream;
		TextOutputStream* m_outputStream;
	public:
		OutputStreamHolder () :
			m_outputStream(&m_nullOutputStream)
		{
		}
		void setOutputStream (TextOutputStream& outputStream)
		{
			m_outputStream = &outputStream;
		}
		TextOutputStream& getOutputStream ()
		{
			return *m_outputStream;
		}
};

typedef Static<OutputStreamHolder> GlobalOutputStream;

/// \brief Returns the global output stream. Used to display messages to the user.
inline TextOutputStream& globalOutputStream ()
{
	return GlobalOutputStream::instance().getOutputStream();
}

class ErrorStreamHolder: public OutputStreamHolder
{
};
typedef Static<ErrorStreamHolder> GlobalErrorStream;

/// \brief Returns the global error stream. Used to display error messages to the user.
inline TextOutputStream& globalErrorStream ()
{
	return GlobalErrorStream::instance().getOutputStream();
}

class WarningStreamHolder: public OutputStreamHolder
{
};
typedef Static<WarningStreamHolder> GlobalWarningStream;

/// \brief Returns the global warning stream. Used to display warning messages to the user.
inline TextOutputStream& globalWarningStream ()
{
	return GlobalWarningStream::instance().getOutputStream();
}

#endif
