//
// VMime library (http://www.vmime.org)
// Copyright (C) 2002 Vincent Richard <vincent@vmime.org>
//
// This program 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 3 of
// the License, or (at your option) any later version.
//
// This program 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 this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// Linking this library statically or dynamically with other modules is making
// a combined work based on this library.  Thus, the terms and conditions of
// the GNU General Public License cover the whole combination.
//

#include "vmime/utility/filteredStream.hpp"

#include <algorithm>


namespace vmime {
namespace utility {


// filteredInputStream

size_t filteredInputStream::getBlockSize() {

	return std::min(inputStream::getBlockSize(), getPreviousInputStream().getBlockSize());
}


// filteredOutputStream

size_t filteredOutputStream::getBlockSize() {

	return std::min(outputStream::getBlockSize(), getNextOutputStream().getBlockSize());
}


// dotFilteredInputStream

dotFilteredInputStream::dotFilteredInputStream(inputStream& is)
	: m_stream(is),
	  m_previousChar2('\0'),
	  m_previousChar1('\0') {

}


inputStream& dotFilteredInputStream::getPreviousInputStream() {

	return m_stream;
}


bool dotFilteredInputStream::eof() const {

	return m_stream.eof();
}


void dotFilteredInputStream::reset() {

	m_previousChar2 = '\0';
	m_previousChar1 = '\0';

	m_stream.reset();
}


size_t dotFilteredInputStream::read(byte_t* const data, const size_t count) {

	const size_t read = m_stream.read(data, count);

	const byte_t* readPtr = data;
	byte_t* writePtr = data;

	const byte_t* end = data + read;

	size_t written = 0;

	byte_t prevChar2 = m_previousChar2;
	byte_t prevChar1 = m_previousChar1;

	// Replace "\n.." with "\n."
	while (readPtr < end) {

		if (*readPtr == '.' && prevChar2 == '\n' && prevChar1 == '.') {

			// Ignore last dot
			prevChar2 = '\0';
			prevChar1 = '.';

		} else {

			*writePtr = *readPtr;

			++writePtr;
			++written;

			prevChar2 = prevChar1;
			prevChar1 = *readPtr;
		}

		++readPtr;
	}

	m_previousChar2 = prevChar2;
	m_previousChar1 = prevChar1;

	return written;
}


size_t dotFilteredInputStream::skip(const size_t /* count */) {

	// Skipping bytes is not supported
	return 0;
}


// dotFilteredOutputStream

dotFilteredOutputStream::dotFilteredOutputStream(outputStream& os)
	: m_stream(os),
	  m_previousChar('\0'),
	  m_start(true) {

}


outputStream& dotFilteredOutputStream::getNextOutputStream() {

	return m_stream;
}


void dotFilteredOutputStream::writeImpl(const byte_t* const data, const size_t count) {

	if (count == 0) {
		return;
	}

	const byte_t* pos = data;
	const byte_t* end = data + count;
	const byte_t* start = data;

	if (m_previousChar == '.') {

		if (data[0] == '\n' || data[0] == '\r') {

			m_stream.write(".", 1);  // extra <DOT>
			m_stream.write(data, 1);

			pos = data + 1;
		}
	}

	// Replace "\n." with "\n.."
	while ((pos = std::find(pos, end, '.')) != end) {

		const byte_t previousChar = (pos == data ? m_previousChar : *(pos - 1));

		if (previousChar == '\n') {

			m_stream.write(start, pos - start);
			m_stream.write("..", 2);

			start = pos + 1;

		} else if (pos == data && m_start) {  // <DOT><CR><LF> at the beginning of content

			m_stream.write(start, pos - start);

			if (pos + 1 < end && (*(pos + 1) == '\n' || *(pos + 1) == '\r')) {
				m_stream.write("..", 2);
			} else {
				m_stream.write(".", 1);
			}

			start = pos + 1;
		}

		++pos;
	}

	m_stream.write(start, end - start);
	m_previousChar = data[count - 1];
	m_start = false;
}


void dotFilteredOutputStream::flush() {

	// Do nothing
	m_stream.flush();
}


size_t dotFilteredOutputStream::getBlockSize() {

	return m_stream.getBlockSize();
}


// CRLFToLFFilteredOutputStream

CRLFToLFFilteredOutputStream::CRLFToLFFilteredOutputStream(outputStream& os)
	: m_stream(os),
	  m_previousChar('\0') {

}


outputStream& CRLFToLFFilteredOutputStream::getNextOutputStream() {

	return m_stream;
}


void CRLFToLFFilteredOutputStream::writeImpl(const byte_t* const data, const size_t count) {

	if (count == 0) {
		return;
	}

	const byte_t* pos = data;
	const byte_t* end = data + count;
	const byte_t* start = data;

	// Warning: if the whole buffer finishes with '\r', this
	// last character will not be written back if flush() is
	// not called
	if (m_previousChar == '\r') {

		if (*pos != '\n') {
			m_stream.write("\r", 1); // write back \r
			m_previousChar = *pos;
		}
	}

	// Replace "\r\n" (CRLF) with "\n" (LF)
	while ((pos = std::find(pos, end, '\n')) != end) {

		const byte_t previousChar = (pos == data ? m_previousChar : *(pos - 1));

		if (previousChar == '\r') {

			if (pos != start) {
				m_stream.write(start, pos - 1 - start);  // do not write \r
			}

			m_stream.write("\n", 1);

			start = pos + 1;
		}

		++pos;
	}

	if (data[count - 1] == '\r') {

		m_stream.write(start, end - start - 1);
		m_previousChar = '\r';

	} else {

		m_stream.write(start, end - start);
		m_previousChar = data[count - 1];
	}
}


void CRLFToLFFilteredOutputStream::flush() {

	m_stream.flush();

	// TODO
}


size_t CRLFToLFFilteredOutputStream::getBlockSize() {

	return m_stream.getBlockSize();
}


// LFToCRLFFilteredOutputStream

LFToCRLFFilteredOutputStream::LFToCRLFFilteredOutputStream(outputStream& os)
	: m_stream(os),
	m_previousChar('\0') {

}


outputStream& LFToCRLFFilteredOutputStream::getNextOutputStream() {

	return m_stream;
}


void LFToCRLFFilteredOutputStream::writeImpl(const byte_t* const data, const size_t count)
{
	if (count == 0) {
		return;
	}

	string buffer;
	buffer.reserve(count);

	const byte_t* pos = data;
	const byte_t* end = data + count;

	byte_t previousChar = m_previousChar;

	while (pos < end) {

		switch (*pos) {

			case '\r':

				buffer.append(1, '\r');
				buffer.append(1, '\n');

				break;

			case '\n':

				if (previousChar != '\r') {
					buffer.append(1, '\r');
					buffer.append(1, '\n');
				}

				break;

			default:

				buffer.append(1, *pos);
				break;
		}

		previousChar = *pos;
		++pos;
	}

	m_stream.write(&buffer[0], buffer.length());

	m_previousChar = previousChar;
}


void LFToCRLFFilteredOutputStream::flush() {

	m_stream.flush();
}


size_t LFToCRLFFilteredOutputStream::getBlockSize() {

	return m_stream.getBlockSize();
}


// stopSequenceFilteredInputStream <1>

template <>
size_t stopSequenceFilteredInputStream <1>::read(byte_t* const data, const size_t count) {

	if (eof() || m_stream.eof()) {
		m_eof = true;
		return 0;
	}

	const size_t read = m_stream.read(data, count);
	byte_t* end = data + read;

	byte_t* pos = std::find(data, end, m_sequence[0]);

	if (pos == end) {

		return read;

	} else {

		m_found = 1;
		return pos - data;
	}
}


} // utility
} // vmime