#include "packet.h"


/* PUBLIC
----------------------------------------*/
// builds a packet from raw data and returns the error code
uint8_t Packet::read(uint8_t buf[], size_t size){
	// 1. fail on invalid size
	if( size < 1          ) return PKTREAD_EMPTY;
	if( size > PROTO_SIZE ) return PKTREAD_OVERFLOW;

	// 2. extract packet type
	opcode = buf[0];

	// 3. extract depending on type
	return (opcode == 0) ? read_discover(buf, size) : read_message(buf, size);

};

// writes the binary representation of the packet
size_t Packet::write(uint8_t buf[]){
	if( opcode == 0 )
		return write_discover(buf);

	return write_message(buf);
};

/* GETTERS / SETTERS
----------------------------------------*/
uint8_t Packet::getOpcode()           { return opcode; }
void Packet::setOpcode(uint8_t value) { opcode = value; dsc.opcode = value; msg.opcode = value; }

uint8_t Packet::getWave()           { return dsc.wave; }
void Packet::setWave(uint8_t value) { dsc.wave = value; }

uint8_t Packet::getDist()           { return (opcode == 0) ? dsc.dist : msg.dist; }
void Packet::setDist(uint8_t value) { if(opcode == 0) dsc.dist = value; else msg.dist = value; }

uint8_t Packet::getTTL()           { return msg.ttl; }
void Packet::setTTL(uint8_t value) { msg.ttl = value; }

uint8_t Packet::getSize()           { return msg.size; }

uint8_t* Packet::getData()                  { return msg.data; }
void Packet::setData(uint8_t *buffer, uint8_t size) { memcpy(msg.data, buffer, size); msg.size = size; }



/* PRIVATE
----------------------------------------*/
uint8_t Packet::read_discover(uint8_t buf[], size_t size){
	// 1. fail on invalid size
	if( size != DISCOVER_SIZE )
		return PKTREAD_INVALID_DISCOVER_FORMAT;

	dsc.opcode = buf[0];
	dsc.wave   = buf[1];
	dsc.dist   = buf[2];

	return PKTREAD_OK;
};

uint8_t Packet::read_message(uint8_t buf[], size_t size){
	// 1. fail on invalid size
	if( size < MESSAGE_MIN_SIZE || size > MESSAGE_MAX_SIZE )
		return PKTREAD_INVALID_MESSAGE_FORMAT;

	msg.opcode = buf[0];
	msg.dist   = buf[1];
	msg.ttl    = buf[2];
	msg.size   = buf[3];

	// 3. check message size
	if( size - 4 - 1 != msg.size )
		return PKTREAD_INVALID_MESSAGE_FORMAT;

	// 4. extract message
	memcpy(msg.data, buf+4, msg.size);

	return PKTREAD_OK;
};

size_t Packet::write_discover(uint8_t buf[]){
	buf[0] = dsc.opcode;
	buf[1] = dsc.wave;
	buf[2] = dsc.dist;

	return 3;
};

size_t Packet::write_message(uint8_t buf[]){
	buf[0] = msg.opcode;
	buf[1] = msg.dist;
	buf[2] = msg.ttl;
	buf[3] = msg.size;

	memcpy( buf+4, msg.data, msg.size );

	return 4 + msg.size;
};