/*
	Aseba - an event-based framework for distributed robot control
	Created by Stéphane Magnenat <stephane at magnenat dot net> (http://stephane.magnenat.net)
	with contributions from the community.
	Copyright (C) 2007--2018 the authors, see authors.txt for details.

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published
	by the Free Software Foundation, version 3 of the License.

	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 Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <sstream>
#include <dashel/dashel.h>
#include "zeroconf.h"

using namespace std;

namespace Aseba
{
	//! TXT data for an Aseba target, with node ids and product ids
	Zeroconf::TxtRecord::TxtRecord(const unsigned int protovers, const std::string& type, bool busy, const std::vector<unsigned int>& ids, const std::vector<unsigned int>& pids)
	{
		assign("txtvers", 1);
		assign("protovers", int(protovers));
		assign("type", type);
		assign("busy", busy);
		assign("ids", ids);
		assign("pids", pids);
	}

	//! TXT data for an Aseba target, deserialized from a TXT record string
	Zeroconf::TxtRecord::TxtRecord(const std::string & txtRecord)
	{
		istringstream txt{txtRecord};
		do
		{
			char length;
			txt >> length;
			string data;
			txt >> setw(int(length)) >> data;
			auto key_pos = data.find('=');
			fields[data.substr(0, key_pos)] = (key_pos==std::string::npos) ? "" : data.substr(key_pos+1);
		} while (txt.peek() != std::char_traits<char>::eof());
	}

	//! TXT data for an Aseba target, deserialized from a TXT record buffer
	Zeroconf::TxtRecord::TxtRecord(const unsigned char * txtRecord, uint16_t txtLen)
	{
		size_t pos = 0;
		while (pos < txtLen)
		{
			size_t length{size_t(txtRecord[pos++])};
			string data{reinterpret_cast<const char*>(txtRecord)+pos, min(length,txtLen-pos)};
			auto key_pos = data.find('=');
			fields[data.substr(0, key_pos)] = (key_pos==std::string::npos) ? "" : data.substr(key_pos+1);
			pos += length;
		}
	}

	//! A string value in the TXT record is a sequence of bytes
	void Zeroconf::TxtRecord::assign(const std::string& key, const std::string& value)
	{
		fields[key] = value.substr(0,20); // silently truncate name to 20 characters
	}

	//! A simple integer value in the TXT record is the string of its decimal value
	void Zeroconf::TxtRecord::assign(const std::string& key, const int value)
	{
		ostringstream field;
		field << value;
		assign(key, field.str());
	}

	//! A vector of integers in the TXT record is a sequence of big-endian 16-bit values
	//! note that the size of the vector is implicit in the record length: (record.length()-record.find("=")-1)/2.
	void Zeroconf::TxtRecord::assign(const std::string& key, const std::vector<unsigned int>& values)
	{
		ostringstream field;
		for (const auto &value : values)
			field.put(value<<8), field.put(value % 0xff);
		assign(key, field.str());
	}

	//! A boolean value in the TXT record is either the key (true) or nothing (false)
	void Zeroconf::TxtRecord::assign(const std::string& key, const bool value)
	{
		if (value)
			fields[key] = ""; // length will be 0, so no "=" in the record
	}

	//! Retrieve the encoded TXT record.
	//! A serialized TXT record is composed of length-prefixed strings of the form KEY[=VALUE]
	string Zeroconf::TxtRecord::record() const
	{
		ostringstream txt;
		serializeField(txt, "txtvers");
		serializeField(txt, "protovers");
		serializeField(txt, "type");
		serializeField(txt, "busy");
		serializeField(txt, "ids");
		serializeField(txt, "pids");
		return txt.str();
	}

	//!< serialize a field into the encoded TXT record
	void Zeroconf::TxtRecord::serializeField(ostringstream& txt, const std::string& key) const
	{
		if (fields.find(key) != fields.end()) // key will be absent if it was boolean and false
		{
			string record{key};
			if (fields.at(key).length() > 0)
				record += "=" + fields.at(key);
			txt.put(record.length());
			txt << record;
		}
	}

} // namespace Aseba
