// Copyright (c) 2023 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <consensus/validation.h>

#include <node/context.h>

#include <node/mempool_args.h>

#include <node/miner.h>

#include <node/txdownloadman.h>

#include <node/txdownloadman_impl.h>

#include <test/fuzz/FuzzedDataProvider.h>

#include <test/fuzz/fuzz.h>

#include <test/fuzz/util.h>

#include <test/fuzz/util/mempool.h>

#include <test/util/mining.h>

#include <test/util/script.h>

#include <test/util/setup_common.h>

#include <test/util/txmempool.h>

#include <util/hasher.h>

#include <util/rbf.h>

#include <util/time.h>

#include <txmempool.h>

#include <validation.h>

#include <validationinterface.h>

namespace {

const TestingSetup* g_setup;

constexpr size_t NUM_COINS{50};

COutPoint COINS[NUM_COINS];

static TxValidationResult TESTED_TX_RESULTS[] = {

    // Skip TX_RESULT_UNSET

    TxValidationResult::TX_CONSENSUS,

    TxValidationResult::TX_INPUTS_NOT_STANDARD,

    TxValidationResult::TX_NOT_STANDARD,

    TxValidationResult::TX_MISSING_INPUTS,

    TxValidationResult::TX_PREMATURE_SPEND,

    TxValidationResult::TX_WITNESS_MUTATED,

    TxValidationResult::TX_WITNESS_STRIPPED,

    TxValidationResult::TX_CONFLICT,

    TxValidationResult::TX_MEMPOOL_POLICY,

    // Skip TX_NO_MEMPOOL

    TxValidationResult::TX_RECONSIDERABLE,

    TxValidationResult::TX_UNKNOWN,

};

// Precomputed transactions. Some may conflict with each other.

std::vector<CTransactionRef> TRANSACTIONS;

// Limit the total number of peers because we don't expect coverage to change much with lots more peers.

constexpr int NUM_PEERS = 16;

// Precomputed random durations (positive and negative, each ~exponentially distributed).

std::chrono::microseconds TIME_SKIPS[128];

static CTransactionRef MakeTransactionSpending(const std::vector<COutPoint>& outpoints, size_t num_outputs, bool add_witness)

{

    CMutableTransaction tx;

    // If no outpoints are given, create a random one.

    for (const auto& outpoint : outpoints) {

        tx.vin.emplace_back(outpoint);

    }

    if (add_witness) {

        tx.vin[0].scriptWitness.stack.push_back({1});

    }

    for (size_t o = 0; o < num_outputs; ++o) tx.vout.emplace_back(CENT, P2WSH_OP_TRUE);

    return MakeTransactionRef(tx);

}

static std::vector<COutPoint> PickCoins(FuzzedDataProvider& fuzzed_data_provider)

{

    std::vector<COutPoint> ret;

    ret.push_back(fuzzed_data_provider.PickValueInArray(COINS));

    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10) {

        ret.push_back(fuzzed_data_provider.PickValueInArray(COINS));

    }

    return ret;

}

void initialize()

{

    static const auto testing_setup = MakeNoLogFileContext<const TestingSetup>();

    g_setup = testing_setup.get();

    for (uint32_t i = 0; i < uint32_t{NUM_COINS}; ++i) {

        COINS[i] = COutPoint{Txid::FromUint256((HashWriter() << i).GetHash()), i};

    }

    size_t outpoints_index = 0;

    // 2 transactions same txid different witness

    {

        auto tx1{MakeTransactionSpending({COINS[outpoints_index]}, /*num_outputs=*/5, /*add_witness=*/false)};

        auto tx2{MakeTransactionSpending({COINS[outpoints_index]}, /*num_outputs=*/5, /*add_witness=*/true)};

        Assert(tx1->GetHash() == tx2->GetHash());

        TRANSACTIONS.emplace_back(tx1);

        TRANSACTIONS.emplace_back(tx2);

        outpoints_index += 1;

    }

    // 2 parents 1 child

    {

        auto tx_parent_1{MakeTransactionSpending({COINS[outpoints_index++]}, /*num_outputs=*/1, /*add_witness=*/true)};

        TRANSACTIONS.emplace_back(tx_parent_1);

        auto tx_parent_2{MakeTransactionSpending({COINS[outpoints_index++]}, /*num_outputs=*/1, /*add_witness=*/false)};

        TRANSACTIONS.emplace_back(tx_parent_2);

        TRANSACTIONS.emplace_back(MakeTransactionSpending({COutPoint{tx_parent_1->GetHash(), 0}, COutPoint{tx_parent_2->GetHash(), 0}},

                                                            /*num_outputs=*/1, /*add_witness=*/true));

    }

    // 1 parent 2 children

    {

        auto tx_parent{MakeTransactionSpending({COINS[outpoints_index++]}, /*num_outputs=*/2, /*add_witness=*/true)};

        TRANSACTIONS.emplace_back(tx_parent);

        TRANSACTIONS.emplace_back(MakeTransactionSpending({COutPoint{tx_parent->GetHash(), 0}},

                                                            /*num_outputs=*/1, /*add_witness=*/true));

        TRANSACTIONS.emplace_back(MakeTransactionSpending({COutPoint{tx_parent->GetHash(), 1}},

                                                            /*num_outputs=*/1, /*add_witness=*/true));

    }

    // chain of 5 segwit

    {

        COutPoint& last_outpoint = COINS[outpoints_index++];

        for (auto i{0}; i < 5; ++i) {

            auto tx{MakeTransactionSpending({last_outpoint}, /*num_outputs=*/1, /*add_witness=*/true)};

            TRANSACTIONS.emplace_back(tx);

            last_outpoint = COutPoint{tx->GetHash(), 0};

        }

    }

    // chain of 5 non-segwit

    {

        COutPoint& last_outpoint = COINS[outpoints_index++];

        for (auto i{0}; i < 5; ++i) {

            auto tx{MakeTransactionSpending({last_outpoint}, /*num_outputs=*/1, /*add_witness=*/false)};

            TRANSACTIONS.emplace_back(tx);

            last_outpoint = COutPoint{tx->GetHash(), 0};

        }

    }

    // Also create a loose tx for each outpoint. Some of these transactions conflict with the above

    // or have the same txid.

    for (const auto& outpoint : COINS) {

        TRANSACTIONS.emplace_back(MakeTransactionSpending({outpoint}, /*num_outputs=*/1, /*add_witness=*/true));

    }

    // Create random-looking time jumps

    int i = 0;

    // TIME_SKIPS[N] for N=0..15 is just N microseconds.

    for (; i < 16; ++i) {

        TIME_SKIPS[i] = std::chrono::microseconds{i};

    }

    // TIME_SKIPS[N] for N=16..127 has randomly-looking but roughly exponentially increasing values up to

    // 198.416453 seconds.

    for (; i < 128; ++i) {

        int diff_bits = ((i - 10) * 2) / 9;

        uint64_t diff = 1 + (CSipHasher(0, 0).Write(i).Finalize() >> (64 - diff_bits));

        TIME_SKIPS[i] = TIME_SKIPS[i - 1] + std::chrono::microseconds{diff};

    }

}

void CheckPackageToValidate(const node::PackageToValidate& package_to_validate, NodeId peer)

{

    Assert(package_to_validate.m_senders.size() == 2);

    Assert(package_to_validate.m_senders.front() == peer);

    Assert(package_to_validate.m_senders.back() < NUM_PEERS);

    // Package is a 1p1c

    const auto& package = package_to_validate.m_txns;

    Assert(IsChildWithParents(package));

    Assert(package.size() == 2);

}

FUZZ_TARGET(txdownloadman, .init = initialize)

{

    SeedRandomStateForTest(SeedRand::ZEROS);

    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());

    SetMockTime(ConsumeTime(fuzzed_data_provider));

    // Initialize txdownloadman

    bilingual_str error;

    CTxMemPool pool{MemPoolOptionsForTest(g_setup->m_node), error};

    FastRandomContext det_rand{true};

    node::TxDownloadManager txdownloadman{node::TxDownloadOptions{pool, det_rand, true}};

    std::chrono::microseconds time{244466666};

    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 500)

    {

        NodeId rand_peer = fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(0, NUM_PEERS - 1);

        // Transaction can be one of the premade ones or a randomly generated one

        auto rand_tx = fuzzed_data_provider.ConsumeBool() ?

            MakeTransactionSpending(PickCoins(fuzzed_data_provider),

                                    /*num_outputs=*/fuzzed_data_provider.ConsumeIntegralInRange(1, 500),

                                    /*add_witness=*/fuzzed_data_provider.ConsumeBool()) :

            TRANSACTIONS.at(fuzzed_data_provider.ConsumeIntegralInRange<unsigned>(0, TRANSACTIONS.size() - 1));

        CallOneOf(

            fuzzed_data_provider,

            [&] {

                node::TxDownloadConnectionInfo info{

                    .m_preferred = fuzzed_data_provider.ConsumeBool(),

                    .m_relay_permissions = fuzzed_data_provider.ConsumeBool(),

                    .m_wtxid_relay = fuzzed_data_provider.ConsumeBool()

                };

                txdownloadman.ConnectedPeer(rand_peer, info);

            },

            [&] {

                txdownloadman.DisconnectedPeer(rand_peer);

                txdownloadman.CheckIsEmpty(rand_peer);

            },

            [&] {

                txdownloadman.ActiveTipChange();

            },

            [&] {

                CBlock block;

                block.vtx.push_back(rand_tx);

                txdownloadman.BlockConnected(std::make_shared<CBlock>(block));

            },

            [&] {

                txdownloadman.BlockDisconnected();

            },

            [&] {

                txdownloadman.MempoolAcceptedTx(rand_tx);

            },

            [&] {

                TxValidationState state;

                state.Invalid(fuzzed_data_provider.PickValueInArray(TESTED_TX_RESULTS), "");

                bool first_time_failure{fuzzed_data_provider.ConsumeBool()};

                node::RejectedTxTodo todo = txdownloadman.MempoolRejectedTx(rand_tx, state, rand_peer, first_time_failure);

                Assert(first_time_failure || !todo.m_should_add_extra_compact_tx);

            },

            [&] {

                auto gtxid = fuzzed_data_provider.ConsumeBool() ?

                             GenTxid{rand_tx->GetHash()} :

                             GenTxid{rand_tx->GetWitnessHash()};

                txdownloadman.AddTxAnnouncement(rand_peer, gtxid, time);

            },

            [&] {

                txdownloadman.GetRequestsToSend(rand_peer, time);

            },

            [&] {

                txdownloadman.ReceivedTx(rand_peer, rand_tx);

                const auto& [should_validate, maybe_package] = txdownloadman.ReceivedTx(rand_peer, rand_tx);

                // The only possible results should be:

                // - Don't validate the tx, no package.

                // - Don't validate the tx, package.

                // - Validate the tx, no package.

                // The only combination that doesn't make sense is validate both tx and package.

                Assert(!(should_validate && maybe_package.has_value()));

                if (maybe_package.has_value()) CheckPackageToValidate(*maybe_package, rand_peer);

            },

            [&] {

                txdownloadman.ReceivedNotFound(rand_peer, {rand_tx->GetWitnessHash()});

            },

            [&] {

                const bool expect_work{txdownloadman.HaveMoreWork(rand_peer)};

                const auto ptx = txdownloadman.GetTxToReconsider(rand_peer);

                // expect_work=true doesn't necessarily mean the next item from the workset isn't a

                // nullptr, as the transaction could have been removed from orphanage without being

                // removed from the peer's workset.

                if (ptx) {

                    // However, if there was a non-null tx in the workset, HaveMoreWork should have

                    // returned true.

                    Assert(expect_work);

                }

            });

        // Jump forwards or backwards

        auto time_skip = fuzzed_data_provider.PickValueInArray(TIME_SKIPS);

        if (fuzzed_data_provider.ConsumeBool()) time_skip *= -1;

        time += time_skip;

    }

    // Disconnect everybody, check that all data structures are empty.

    for (NodeId nodeid = 0; nodeid < NUM_PEERS; ++nodeid) {

        txdownloadman.DisconnectedPeer(nodeid);

        txdownloadman.CheckIsEmpty(nodeid);

    }

    txdownloadman.CheckIsEmpty();

}

// Give node 0 relay permissions, and nobody else. This helps us remember who is a RelayPermissions

// peer without tracking anything (this is only for the txdownload_impl target).

static bool HasRelayPermissions(NodeId peer) { return peer == 0; }

static void CheckInvariants(const node::TxDownloadManagerImpl& txdownload_impl)

{

    txdownload_impl.m_orphanage->SanityCheck();

    // We should never have more than the maximum in-flight requests out for a peer.

    for (NodeId peer = 0; peer < NUM_PEERS; ++peer) {

        if (!HasRelayPermissions(peer)) {

            Assert(txdownload_impl.m_txrequest.Count(peer) <= node::MAX_PEER_TX_ANNOUNCEMENTS);

        }

    }

    txdownload_impl.m_txrequest.SanityCheck();

}

FUZZ_TARGET(txdownloadman_impl, .init = initialize)

{

    SeedRandomStateForTest(SeedRand::ZEROS);

    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());

    SetMockTime(ConsumeTime(fuzzed_data_provider));

    // Initialize a TxDownloadManagerImpl

    bilingual_str error;

    CTxMemPool pool{MemPoolOptionsForTest(g_setup->m_node), error};

    FastRandomContext det_rand{true};

    node::TxDownloadManagerImpl txdownload_impl{node::TxDownloadOptions{pool, det_rand, true}};

    std::chrono::microseconds time{244466666};

    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 500)

    {

        NodeId rand_peer = fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(0, NUM_PEERS - 1);

        // Transaction can be one of the premade ones or a randomly generated one

        auto rand_tx = fuzzed_data_provider.ConsumeBool() ?

            MakeTransactionSpending(PickCoins(fuzzed_data_provider),

                                    /*num_outputs=*/fuzzed_data_provider.ConsumeIntegralInRange(1, 500),

                                    /*add_witness=*/fuzzed_data_provider.ConsumeBool()) :

            TRANSACTIONS.at(fuzzed_data_provider.ConsumeIntegralInRange<unsigned>(0, TRANSACTIONS.size() - 1));

        CallOneOf(

            fuzzed_data_provider,

            [&] {

                node::TxDownloadConnectionInfo info{

                    .m_preferred = fuzzed_data_provider.ConsumeBool(),

                    .m_relay_permissions = HasRelayPermissions(rand_peer),

                    .m_wtxid_relay = fuzzed_data_provider.ConsumeBool()

                };

                txdownload_impl.ConnectedPeer(rand_peer, info);

            },

            [&] {

                txdownload_impl.DisconnectedPeer(rand_peer);

                txdownload_impl.CheckIsEmpty(rand_peer);

            },

            [&] {

                txdownload_impl.ActiveTipChange();

                // After a block update, nothing should be in the rejection caches

                for (const auto& tx : TRANSACTIONS) {

                    Assert(!txdownload_impl.RecentRejectsFilter().contains(tx->GetWitnessHash().ToUint256()));

                    Assert(!txdownload_impl.RecentRejectsFilter().contains(tx->GetHash().ToUint256()));

                    Assert(!txdownload_impl.RecentRejectsReconsiderableFilter().contains(tx->GetWitnessHash().ToUint256()));

                    Assert(!txdownload_impl.RecentRejectsReconsiderableFilter().contains(tx->GetHash().ToUint256()));

                }

            },

            [&] {

                CBlock block;

                block.vtx.push_back(rand_tx);

                txdownload_impl.BlockConnected(std::make_shared<CBlock>(block));

                // Block transactions must be removed from orphanage

                Assert(!txdownload_impl.m_orphanage->HaveTx(rand_tx->GetWitnessHash()));

            },

            [&] {

                txdownload_impl.BlockDisconnected();

                Assert(!txdownload_impl.RecentConfirmedTransactionsFilter().contains(rand_tx->GetWitnessHash().ToUint256()));

                Assert(!txdownload_impl.RecentConfirmedTransactionsFilter().contains(rand_tx->GetHash().ToUint256()));

            },

            [&] {

                txdownload_impl.MempoolAcceptedTx(rand_tx);

            },

            [&] {

                TxValidationState state;

                state.Invalid(fuzzed_data_provider.PickValueInArray(TESTED_TX_RESULTS), "");

                bool first_time_failure{fuzzed_data_provider.ConsumeBool()};

                bool reject_contains_wtxid{txdownload_impl.RecentRejectsFilter().contains(rand_tx->GetWitnessHash().ToUint256())};

                node::RejectedTxTodo todo = txdownload_impl.MempoolRejectedTx(rand_tx, state, rand_peer, first_time_failure);

                Assert(first_time_failure || !todo.m_should_add_extra_compact_tx);

                if (!reject_contains_wtxid) Assert(todo.m_unique_parents.size() <= rand_tx->vin.size());

            },

            [&] {

                auto gtxid = fuzzed_data_provider.ConsumeBool() ?

                             GenTxid{rand_tx->GetHash()} :

                             GenTxid{rand_tx->GetWitnessHash()};

                txdownload_impl.AddTxAnnouncement(rand_peer, gtxid, time);

            },

            [&] {

                const auto getdata_requests = txdownload_impl.GetRequestsToSend(rand_peer, time);

                // TxDownloadManager should not be telling us to request things we already have.

                // Exclude m_lazy_recent_rejects_reconsiderable because it may request low-feerate parent of orphan.

                for (const auto& gtxid : getdata_requests) {

                    Assert(!txdownload_impl.AlreadyHaveTx(gtxid, /*include_reconsiderable=*/false));

                }

            },

            [&] {

                const auto& [should_validate, maybe_package] = txdownload_impl.ReceivedTx(rand_peer, rand_tx);

                // The only possible results should be:

                // - Don't validate the tx, no package.

                // - Don't validate the tx, package.

                // - Validate the tx, no package.

                // The only combination that doesn't make sense is validate both tx and package.

                Assert(!(should_validate && maybe_package.has_value()));

                if (should_validate) {

                    Assert(!txdownload_impl.AlreadyHaveTx(rand_tx->GetWitnessHash(), /*include_reconsiderable=*/true));

                }

                if (maybe_package.has_value()) {

                    CheckPackageToValidate(*maybe_package, rand_peer);

                    const auto& package = maybe_package->m_txns;

                    // Parent is in m_lazy_recent_rejects_reconsiderable and child is in m_orphanage

                    Assert(txdownload_impl.RecentRejectsReconsiderableFilter().contains(rand_tx->GetWitnessHash().ToUint256()));

                    Assert(txdownload_impl.m_orphanage->HaveTx(maybe_package->m_txns.back()->GetWitnessHash()));

                    // Package has not been rejected

                    Assert(!txdownload_impl.RecentRejectsReconsiderableFilter().contains(GetPackageHash(package)));

                    // Neither is in m_lazy_recent_rejects

                    Assert(!txdownload_impl.RecentRejectsFilter().contains(package.front()->GetWitnessHash().ToUint256()));

                    Assert(!txdownload_impl.RecentRejectsFilter().contains(package.back()->GetWitnessHash().ToUint256()));

                }

            },

            [&] {

                txdownload_impl.ReceivedNotFound(rand_peer, {rand_tx->GetWitnessHash()});

            },

            [&] {

                const bool expect_work{txdownload_impl.HaveMoreWork(rand_peer)};

                const auto ptx{txdownload_impl.GetTxToReconsider(rand_peer)};

                // expect_work=true doesn't necessarily mean the next item from the workset isn't a

                // nullptr, as the transaction could have been removed from orphanage without being

                // removed from the peer's workset.

                if (ptx) {

                    // However, if there was a non-null tx in the workset, HaveMoreWork should have

                    // returned true.

                    Assert(expect_work);

                    Assert(txdownload_impl.AlreadyHaveTx(ptx->GetWitnessHash(), /*include_reconsiderable=*/false));

                    // Presumably we have validated this tx. Use "missing inputs" to keep it in the

                    // orphanage longer. Later iterations might call MempoolAcceptedTx or

                    // MempoolRejectedTx with a different error.

                    TxValidationState state_missing_inputs;

                    state_missing_inputs.Invalid(TxValidationResult::TX_MISSING_INPUTS, "");

                    txdownload_impl.MempoolRejectedTx(ptx, state_missing_inputs, rand_peer, fuzzed_data_provider.ConsumeBool());

                }

            });

        auto time_skip = fuzzed_data_provider.PickValueInArray(TIME_SKIPS);

        if (fuzzed_data_provider.ConsumeBool()) time_skip *= -1;

        time += time_skip;

    }

    CheckInvariants(txdownload_impl);

    // Disconnect everybody, check that all data structures are empty.

    for (NodeId nodeid = 0; nodeid < NUM_PEERS; ++nodeid) {

        txdownload_impl.DisconnectedPeer(nodeid);

        txdownload_impl.CheckIsEmpty(nodeid);

    }

    txdownload_impl.CheckIsEmpty();

}

} // namespace