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#include <stdarg.h>
#include <stdio.h>
#include <string.h>

#include "platform/nexus_core.hpp"
#include "platform/nexus_node.hpp"

namespace ot {
namespace Nexus {

void TestMleBlockingDowngrade(void)
{
    // This test validates the MLE router role downgrade logic when a REED is
    // promoted to a router due to a Child ID Request. It verifies that the
    // newly promoted router blocks its own downgrade to ensure the child remains
    // connected, and that this block is correctly lifted when the child detaches
    // or when a new router is introduced to the network (providing an alternative
    // parent for the child).

    static constexpr uint8_t kNumRouters = 10;

    Core  nexus;
    Node &leader    = nexus.CreateNode();
    Node &dut       = nexus.CreateNode();
    Node &child     = nexus.CreateNode();
    Node &newRouter = nexus.CreateNode();
    Node *routers[kNumRouters];

    for (Node *&router : routers)
    {
        router = &nexus.CreateNode();
    }

    nexus.AdvanceTime(0);

    SuccessOrQuit(Instance::SetGlobalLogLevel(kLogLevelNone));

    Log("---------------------------------------------------------------------------------------");
    Log("Form initial topology");

    AllowLinkBetween(leader, dut);
    AllowLinkBetween(leader, newRouter);
    AllowLinkBetween(child, dut);
    AllowLinkBetween(child, newRouter);

    for (Node *router : routers)
    {
        AllowLinkBetween(leader, *router);
        AllowLinkBetween(dut, *router);
        AllowLinkBetween(newRouter, *router);
    }

    leader.Form();
    nexus.AdvanceTime(13 * Time::kOneSecondInMsec);
    VerifyOrQuit(leader.Get<Mle::Mle>().IsLeader());

    for (Node *router : routers)
    {
        router->Join(leader);
    }

    nexus.AdvanceTime(300 * Time::kOneSecondInMsec);

    VerifyOrQuit(leader.Get<Mle::Mle>().IsLeader());

    for (Node *router : routers)
    {
        VerifyOrQuit(router->Get<Mle::Mle>().IsRouter());
    }

    Log("---------------------------------------------------------------------------------------");
    Log("Setup DUT - Validate it stays as a REED");

    dut.Get<Mle::Mle>().SetRouterUpgradeThreshold(3);
    dut.Get<Mle::Mle>().SetRouterDowngradeThreshold(4);

    VerifyOrQuit(!dut.Get<Mle::Mle>().IsDowngradeBlocked());

    dut.Join(leader);

    nexus.AdvanceTime(300 * Time::kOneSecondInMsec);

    VerifyOrQuit(dut.Get<Mle::Mle>().IsChild());
    VerifyOrQuit(!dut.Get<Mle::Mle>().IsDowngradeBlocked());

    Log("---------------------------------------------------------------------------------------");
    Log("Attach `child` only connecting through the DUT");

    child.Join(dut, Node::kAsFed);

    nexus.AdvanceTime(30 * Time::kOneSecondInMsec);

    VerifyOrQuit(child.Get<Mle::Mle>().IsChild());
    VerifyOrQuit(child.Get<Mle::Mle>().GetParent().GetExtAddress() == dut.Get<Mac::Mac>().GetExtAddress());

    Log("---------------------------------------------------------------------------------------");
    Log("Validate that DUT is promoted to router and blocking downgrade");

    VerifyOrQuit(dut.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsDowngradeBlocked());

    nexus.AdvanceTime(10 * Time::kOneMinuteInMsec);

    VerifyOrQuit(dut.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsDowngradeBlocked());

    Log("---------------------------------------------------------------------------------------");
    Log("Disconnect one of the routers - validate that DUT still blocks downgrade");

    routers[0]->Get<Mle::Mle>().Stop();
    routers[0]->Get<ThreadNetif>().Down();

    nexus.AdvanceTime(10);

    VerifyOrQuit(routers[0]->Get<Mle::Mle>().IsDisabled());

    nexus.AdvanceTime(10 * Time::kOneMinuteInMsec);

    VerifyOrQuit(dut.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsDowngradeBlocked());
    VerifyOrQuit(child.Get<Mle::Mle>().IsChild());

    Log("---------------------------------------------------------------------------------------");
    Log("Disconnect the child - validate that DUT can now downgrade");

    child.Get<Mle::Mle>().Stop();
    child.Get<ThreadNetif>().Down();

    nexus.AdvanceTime(10);

    VerifyOrQuit(child.Get<Mle::Mle>().IsDisabled());

    nexus.AdvanceTime(10 * Time::kOneMinuteInMsec);

    VerifyOrQuit(!dut.Get<Mle::Mle>().IsDowngradeBlocked());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsChild());

    Log("---------------------------------------------------------------------------------------");
    Log("Reconnect the child - validate that DUT once again disallow downgrade");

    child.Get<ThreadNetif>().Up();
    SuccessOrQuit(child.Get<Mle::Mle>().Start());

    nexus.AdvanceTime(30 * Time::kOneSecondInMsec);

    VerifyOrQuit(child.Get<Mle::Mle>().IsChild());

    VerifyOrQuit(dut.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsDowngradeBlocked());

    nexus.AdvanceTime(10 * Time::kOneMinuteInMsec);

    VerifyOrQuit(dut.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(dut.Get<Mle::Mle>().IsDowngradeBlocked());

    Log("---------------------------------------------------------------------------------------");
    Log("Introduce `newRouter` as a new router - validate DUT now allows downgrade");

    newRouter.Join(leader);

    nexus.AdvanceTime(15 * Time::kOneMinuteInMsec);

    VerifyOrQuit(newRouter.Get<Mle::Mle>().IsRouter());
    VerifyOrQuit(!dut.Get<Mle::Mle>().IsDowngradeBlocked());

    Log("---------------------------------------------------------------------------------------");
    Log("Validate that DUT is downgraded to REED and child connected to the new router");

    VerifyOrQuit(dut.Get<Mle::Mle>().IsChild());

    VerifyOrQuit(child.Get<Mle::Mle>().IsChild());
    VerifyOrQuit(child.Get<Mle::Mle>().GetParent().GetExtAddress() == newRouter.Get<Mac::Mac>().GetExtAddress());
}

} // namespace Nexus
} // namespace ot

int main(void)
{
    ot::Nexus::TestMleBlockingDowngrade();
    printf("All tests passed\n");
    return 0;
}