#include <cstring></cstring>

#include "tunnel.h"

#include "connection.h"

#include "udpsendqueue.h"

UdpSendQueue::UdpSendQueue(Connection &connection):

	connection(connection),

	nextSendTime(connection.tunnel.time + connection.tunnel.udpSendDuration),

	nextPartialSendTime(connection.tunnel.time + connection.tunnel.udpPartialSendDuration),

	finalEntryAdded(),

	nextIndex(),

	freeFirst(entries),

	busyFirst(),

	busyLast(),

	entries()

{

	Entry *e = entries;

	Entry *end = e + sizeof(entries)/sizeof(*entries) - 1;

	while(e < end) { e->next = e + 1; ++e; }

}

UdpSendQueue::~UdpSendQueue()

	{ }

UdpSendQueue::Entry* UdpSendQueue::allocEntry() {

	Entry *e = freeFirst;

	if (!e) return nullptr;

	freeFirst = e->next;

	e->prev = nullptr;

	e->next = busyFirst;

	(e->next ? e->next->prev : busyLast) = e;

	busyLast = e;

	return e;

}

void UdpSendQueue::moveToEnd(Entry *e) {

	if (!e->next) return;

	(e->prev ? e->prev->next : busyFirst) = e->next;

	(e->next ? e->next->prev : busyLast ) = e->prev;

	e->next = nullptr;

	e->prev = busyLast;

	(e->prev ? e->prev->next : busyFirst) = e;

}

void UdpSendQueue::freeEntry(Entry *e) {

	(e->prev ? e->prev->next : busyFirst) = e->next;

	(e->next ? e->next->prev : busyLast ) = e->prev;

	memset(e, 0, sizeof(*e));

	e->next = freeFirst;

	freeFirst = e;

}

void UdpSendQueue::confirm(unsigned int index, const unsigned char *bits, unsigned int bitsCount) {

	while(busyFirst && cycleLess(busyFirst->index, index))

		freeEntry(busyFirst);

	Entry *e = busyFirst;

	while(e) {

		unsigned int bit = e->index - index;

		if (bit > bitsCount)

			break;

		unsigned int byte = bit / 8;

		bit %= 8;

		if (bits[byte] & (1 << bit)) {

			Entry *ee = e;

			e = e->next;

			freeEntry(ee);

		} else {

			e = e->next;

		}

	}

}

bool UdpSendQueue::sendUdpSingle() {

	Time time = connection.tunnel.time;

	if (timeLess(time, nextSendTime))

		return false;

	Entry *e = busyFirst;

	if (!timeLequal(e->resendTime, time))

		e = nullptr;

	if (!e && !freeFirst)

		return false;

	if (!e) {

		int size = connection.tcpRecvQueue.busySize();

		if (size > PACKET_SIZE) size = PACKET_SIZE;

		if (size < 0) size = 0;

		if (size == 0) {

			if (connection.tcpSockId >= 0 || finalEntryAdded) {

				nextPartialSendTime = time + connection.tunnel.udpPartialSendDuration;

				return false;

			}

		} else {

			if (size < PACKET_SIZE && timeLess(time, nextPartialSendTime))

				return false;

		}

		if (( e = allocEntry() ))

			return false;

		e->index = nextIndex++;

		e->size = size;

		if (e->size) connection.tcpRecvQueue.pop(e->data, e->size); else finalEntryAdded = true;

	}

	Packet packet;

	packet.init(connection.id.id, e->index, CMD_DATA, e->size);

	if (e->size) memcpy(packet.payload, e->data, e->size);

	connection.tunnel.sendUdpPacket(connection.id.address, packet);

	e->resendTime = time + connection.tunnel.udpResendDuration;

	nextSendTime += connection.tunnel.udpPartialSendDuration;

	nextPartialSendTime = time + connection.tunnel.udpPartialSendDuration;

	moveToEnd(e);

	return true;

}

int UdpSendQueue::sendUdp() {

	int sent = 0;

	while(sendUdpSingle()) {

		++sent;

		if (sent == 100) {

			if (timeLess(nextSendTime, connection.tunnel.time))

				nextSendTime = connection.tunnel.time;

			break;

		}

	}

	return sent;

}

bool UdpSendQueue::canSentToUdp() const

	{ return connection.udpActive && (busyFirst || connection.tcpRecvQueue.busySize()); }

void UdpSendQueue::whenWriteToUdp(Time &t) const {

	int size = connection.tcpRecvQueue.busySize();

	if (size >= PACKET_SIZE) {

		if (timeLess(nextSendTime, t)) t = nextSendTime;

		return;

	}

	Time tt = t;

	if (size > 0 && timeLess(nextPartialSendTime, tt)) tt = nextPartialSendTime;

	if (timeLess(busyFirst->resendTime, tt)) tt = busyFirst->resendTime;

	if (timeLess(tt, nextSendTime)) tt = nextSendTime;

	if (timeLess(t, tt)) t = tt;

}