//go:build linux

package transport

import (
	"net"
	"testing"
)

func TestKCPPendingTXReservationRollbackRestoresSequence(t *testing.T) {
	conn := &platformKCPPacketConn{
		kcpPacketConnBase: &kcpPacketConnBase{
			closed: make(chan struct{}),
		},
		pendingTX: make(map[uint32]kcpPendingPacketDebug),
	}

	conv := uint32(42)
	txID := conn.reservePendingTX(&net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 9000}, 128, &conv, nil)
	if txID != 0 {
		t.Fatalf("reservePendingTX() txID = %d, want 0", txID)
	}
	if conn.nextTXID != 1 {
		t.Fatalf("nextTXID after reserve = %d, want 1", conn.nextTXID)
	}
	if _, ok := conn.pendingTX[txID]; !ok {
		t.Fatal("pendingTX missing reserved record")
	}

	conn.rollbackPendingTX(txID)

	if conn.nextTXID != 0 {
		t.Fatalf("nextTXID after rollback = %d, want 0", conn.nextTXID)
	}
	if _, ok := conn.pendingTX[txID]; ok {
		t.Fatal("pendingTX still contains rolled back record")
	}
}

func TestKCPPendingTXReservationPreservesLaterSequenceOnOutOfOrderRollback(t *testing.T) {
	conn := &platformKCPPacketConn{
		kcpPacketConnBase: &kcpPacketConnBase{
			closed: make(chan struct{}),
		},
		pendingTX: make(map[uint32]kcpPendingPacketDebug),
	}

	first := conn.reservePendingTX(&net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 9000}, 64, nil, nil)
	second := conn.reservePendingTX(&net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 9001}, 64, nil, nil)
	if first != 0 || second != 1 {
		t.Fatalf("reserved tx IDs = %d,%d, want 0,1", first, second)
	}

	conn.rollbackPendingTX(first)

	if conn.nextTXID != 2 {
		t.Fatalf("nextTXID after out-of-order rollback = %d, want 2", conn.nextTXID)
	}
	if _, ok := conn.pendingTX[second]; !ok {
		t.Fatal("pendingTX lost later reservation after rollback")
	}
}