/*
 * Copyright (C) 2001-2017 Jacek Sieka, arnetheduck on gmail point com
 *
 * 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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef DCPLUSPLUS_DCPP_STREAMS_H
#define DCPLUSPLUS_DCPP_STREAMS_H

#include <algorithm>

#include "typedefs.h"
#include "format.h"

#include "SettingsManager.h"
#include "Exception.h"

namespace dcpp {

using std::min;

STANDARD_EXCEPTION(FileException);

/**
 * A simple output stream. Intended to be used for nesting streams one inside the other.
 */
class OutputStream {
public:
	OutputStream() { }
	virtual ~OutputStream() { }

	/**
	 * @return The actual number of bytes written. len bytes will always be
	 *         consumed, but fewer or more bytes may actually be written,
	 *         for example if the stream is being compressed.
	 */
	virtual size_t write(const void* buf, size_t len) = 0;
	/**
	 * This must be called before destroying the object to make sure all data
	 * is properly written (we don't want destructors that throw exceptions
	 * and the last flush might actually throw). Note that some implementations
	 * might not need it...
	 */
	virtual size_t flush() = 0;

	/**
	 * @return True if stream is at expected end
	 */
	virtual bool eof() { return false; }

	size_t write(const string& str) { return write(str.c_str(), str.size()); }
};

class InputStream {
public:
	InputStream() { }
	virtual ~InputStream() { }
	/**
	 * Call this function until it returns 0 to get all bytes.
	 * @return The number of bytes read. len reflects the number of bytes
	 *		   actually read from the stream source in this call.
	 */
	virtual size_t read(void* buf, size_t& len) = 0;
};

class MemoryInputStream : public InputStream {
public:
	MemoryInputStream(const uint8_t* src, size_t len) : pos(0), size(len), buf(new uint8_t[len]) {
		memcpy(buf, src, len);
	}
	MemoryInputStream(const string& src) : pos(0), size(src.size()), buf(new uint8_t[src.size()]) {
		memcpy(buf, src.data(), src.size());
	}

	virtual ~MemoryInputStream() {
		delete [] buf;
	}

	virtual size_t read(void* tgt, size_t& len) {
		len = min(len, size - pos);
		memcpy(tgt, buf+pos, len);
		pos += len;
		return len;
	}

	size_t getSize() { return size; }

private:
	size_t pos;
	size_t size;
	uint8_t* buf;
};

class IOStream : public InputStream, public OutputStream {
};

/** Count how many bytes have been read. */
template<bool managed>
class CountedInputStream : public InputStream {
public:
	CountedInputStream(InputStream* is) : s(is), readBytes(0) { }
	virtual ~CountedInputStream() { if(managed) delete s; }

	size_t read(void* buf, size_t& len) {
		auto ret = s->read(buf, len);
		readBytes += len;
		return ret;
	}

	uint64_t getReadBytes() const { return readBytes; }

private:
	InputStream* s;
	uint64_t readBytes;
};

template<bool managed>
class LimitedInputStream : public InputStream {
public:
	LimitedInputStream(InputStream* is, uint64_t aMaxBytes) : s(is), maxBytes(aMaxBytes) { 	}
	/*virtual*/ ~LimitedInputStream() { if(managed) delete s; }

	size_t read(void* buf, size_t& len) {
		len = (size_t)min(maxBytes, (uint64_t)len);
		if(len == 0)
			return 0;
		size_t x = s->read(buf, len);
		maxBytes -= x;
		return x;
	}

private:
	InputStream* s;
	uint64_t maxBytes;
};

/** Limits the number of bytes that are requested to be written (not the number actually written!) */
template<bool managed>
class LimitedOutputStream : public OutputStream {
public:
	LimitedOutputStream(OutputStream* os, uint64_t aMaxBytes) : s(os), maxBytes(aMaxBytes) {	}
	virtual ~LimitedOutputStream() { if(managed) delete s; }

	virtual size_t write(const void* buf, size_t len) {
		if(maxBytes < len) {
			throw FileException("More bytes written than requested");
		}
		maxBytes -= len;
		return s->write(buf, len);
	}

	virtual size_t flush() {
		return s->flush();
	}

	virtual bool eof() { return maxBytes == 0; }
private:
	OutputStream* s;
	uint64_t maxBytes;
};

template<bool managed>
class BufferedOutputStream : public OutputStream {
public:
	using OutputStream::write;

	BufferedOutputStream(OutputStream* aStream, size_t aBufSize = SETTING(BUFFER_SIZE) * 1024) : s(aStream), pos(0), buf(aBufSize) { }
	virtual ~BufferedOutputStream() {
		try {
			// We must do this in order not to lose bytes when a download
			// is disconnected prematurely
			flush();
		} catch(const Exception&) {
		}
		if(managed) delete s;
	}

	virtual size_t flush() {
		if(pos > 0)
			s->write(&buf[0], pos);
		pos = 0;
		s->flush();
		return 0;
	}

	virtual size_t write(const void* wbuf, size_t len) {
		uint8_t* b = (uint8_t*)wbuf;
		size_t l2 = len;
		size_t bufSize = buf.size();
		while(len > 0) {
			if(pos == 0 && len >= bufSize) {
				s->write(b, len);
				break;
			} else {
				size_t n = min(bufSize - pos, len);
				memcpy(&buf[pos], b, n);
				b += n;
				pos += n;
				len -= n;
				if(pos == bufSize) {
					s->write(&buf[0], bufSize);
					pos = 0;
				}
			}
		}
		return l2;
	}
private:
	OutputStream* s;
	size_t pos;
	ByteVector buf;
};

class StringOutputStream : public OutputStream {
public:
	StringOutputStream() { }
	virtual ~StringOutputStream() { }
	using OutputStream::write;

	virtual size_t flush() { return 0; }
	virtual size_t write(const void* buf, size_t len) {
		str.append(reinterpret_cast<const char*>(buf), len);
		return len;
	}

	string getString() { return move(str); }
	string& stringRef() { return str; }

private:
	string str;
};

class StringRefOutputStream : public OutputStream {
public:
	StringRefOutputStream(string& out) : str(out) { }
	virtual ~StringRefOutputStream() { }
	using OutputStream::write;

	virtual size_t flush() { return 0; }
	virtual size_t write(const void* buf, size_t len) {
		str.append(reinterpret_cast<const char*>(buf), len);
		return len;
	}

private:
	string& str;
};

} // namespace dcpp

#endif // !defined(STREAMS_H)
