// Copyright (c) 2022-present 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/amount.h>

#include <consensus/validation.h>

#include <net_processing.h>

#include <node/eviction.h>

#include <policy/policy.h>

#include <primitives/transaction.h>

#include <script/script.h>

#include <sync.h>

#include <test/fuzz/FuzzedDataProvider.h>

#include <test/fuzz/fuzz.h>

#include <test/fuzz/util.h>

#include <test/util/setup_common.h>

#include <txorphanage.h>

#include <uint256.h>

#include <util/check.h>

#include <util/time.h>

#include <cstdint>

#include <memory>

#include <set>

#include <utility>

#include <vector>

void initialize_orphanage()

{

    static const auto testing_setup = MakeNoLogFileContext();

}

FUZZ_TARGET(txorphan, .init = initialize_orphanage)

{

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

    FastRandomContext orphanage_rng{/*fDeterministic=*/true};

    SetMockTime(ConsumeTime(fuzzed_data_provider));

    TxOrphanage orphanage;

    std::vector<COutPoint> outpoints; // Duplicates are tolerated

    outpoints.reserve(200'000);

    // initial outpoints used to construct transactions later

    for (uint8_t i = 0; i < 4; i++) {

        outpoints.emplace_back(Txid::FromUint256(uint256{i}), 0);

    }

    CTransactionRef ptx_potential_parent = nullptr;

    std::vector<CTransactionRef> tx_history;

    LIMITED_WHILE(outpoints.size() < 200'000 && fuzzed_data_provider.ConsumeBool(), 10 * DEFAULT_MAX_ORPHAN_TRANSACTIONS)

    {

        // construct transaction

        const CTransactionRef tx = [&] {

            CMutableTransaction tx_mut;

            const auto num_in = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(1, outpoints.size());

            const auto num_out = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(1, 256);

            // pick outpoints from outpoints as input. We allow input duplicates on purpose, given we are not

            // running any transaction validation logic before adding transactions to the orphanage

            tx_mut.vin.reserve(num_in);

            for (uint32_t i = 0; i < num_in; i++) {

                auto& prevout = PickValue(fuzzed_data_provider, outpoints);

                // try making transactions unique by setting a random nSequence, but allow duplicate transactions if they happen

                tx_mut.vin.emplace_back(prevout, CScript{}, fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(0, CTxIn::SEQUENCE_FINAL));

            }

            // output amount will not affect txorphanage

            tx_mut.vout.reserve(num_out);

            for (uint32_t i = 0; i < num_out; i++) {

                tx_mut.vout.emplace_back(CAmount{0}, CScript{});

            }

            auto new_tx = MakeTransactionRef(tx_mut);

            // add newly constructed outpoints to the coin pool

            for (uint32_t i = 0; i < num_out; i++) {

                outpoints.emplace_back(new_tx->GetHash(), i);

            }

            return new_tx;

        }();

        tx_history.push_back(tx);

        const auto wtxid{tx->GetWitnessHash()};

        // Trigger orphanage functions that are called using parents. ptx_potential_parent is a tx we constructed in a

        // previous loop and potentially the parent of this tx.

        if (ptx_potential_parent) {

            // Set up future GetTxToReconsider call.

            orphanage.AddChildrenToWorkSet(*ptx_potential_parent, orphanage_rng);

            // Check that all txns returned from GetChildrenFrom* are indeed a direct child of this tx.

            NodeId peer_id = fuzzed_data_provider.ConsumeIntegral<NodeId>();

            for (const auto& child : orphanage.GetChildrenFromSamePeer(ptx_potential_parent, peer_id)) {

                assert(std::any_of(child->vin.cbegin(), child->vin.cend(), [&](const auto& input) {

                    return input.prevout.hash == ptx_potential_parent->GetHash();

                }));

            }

        }

        // trigger orphanage functions

        LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10 * DEFAULT_MAX_ORPHAN_TRANSACTIONS)

        {

            NodeId peer_id = fuzzed_data_provider.ConsumeIntegral<NodeId>();

            const auto total_bytes_start{orphanage.TotalOrphanUsage()};

            const auto total_peer_bytes_start{orphanage.UsageByPeer(peer_id)};

            const auto tx_weight{GetTransactionWeight(*tx)};

            CallOneOf(

                fuzzed_data_provider,

                [&] {

                    {

                        CTransactionRef ref = orphanage.GetTxToReconsider(peer_id);

                        if (ref) {

                            Assert(orphanage.HaveTx(ref->GetWitnessHash()));

                        }

                    }

                },

                [&] {

                    bool have_tx = orphanage.HaveTx(tx->GetWitnessHash());

                    // AddTx should return false if tx is too big or already have it

                    // tx weight is unknown, we only check when tx is already in orphanage

                    {

                        bool add_tx = orphanage.AddTx(tx, peer_id);

                        // have_tx == true -> add_tx == false

                        Assert(!have_tx || !add_tx);

                        if (add_tx) {

                            Assert(orphanage.UsageByPeer(peer_id) == tx_weight + total_peer_bytes_start);

                            Assert(orphanage.TotalOrphanUsage() == tx_weight + total_bytes_start);

                            Assert(tx_weight <= MAX_STANDARD_TX_WEIGHT);

                        } else {

                            // Peer may have been added as an announcer.

                            if (orphanage.UsageByPeer(peer_id) == tx_weight + total_peer_bytes_start) {

                                Assert(orphanage.HaveTxFromPeer(wtxid, peer_id));

                            } else {

                                // Otherwise, there must not be any change to the peer byte count.

                                Assert(orphanage.UsageByPeer(peer_id) == total_peer_bytes_start);

                            }

                            // Regardless, total bytes should not have changed.

                            Assert(orphanage.TotalOrphanUsage() == total_bytes_start);

                        }

                    }

                    have_tx = orphanage.HaveTx(tx->GetWitnessHash());

                    {

                        bool add_tx = orphanage.AddTx(tx, peer_id);

                        // if have_tx is still false, it must be too big

                        Assert(!have_tx == (tx_weight > MAX_STANDARD_TX_WEIGHT));

                        Assert(!have_tx || !add_tx);

                    }

                },

                [&] {

                    bool have_tx = orphanage.HaveTx(tx->GetWitnessHash());

                    bool have_tx_and_peer = orphanage.HaveTxFromPeer(tx->GetWitnessHash(), peer_id);

                    // AddAnnouncer should return false if tx doesn't exist or we already HaveTxFromPeer.

                    {

                        bool added_announcer = orphanage.AddAnnouncer(tx->GetWitnessHash(), peer_id);

                        // have_tx == false -> added_announcer == false

                        Assert(have_tx || !added_announcer);

                        // have_tx_and_peer == true -> added_announcer == false

                        Assert(!have_tx_and_peer || !added_announcer);

                        // Total bytes should not have changed. If peer was added as announcer, byte

                        // accounting must have been updated.

                        Assert(orphanage.TotalOrphanUsage() == total_bytes_start);

                        if (added_announcer) {

                            Assert(orphanage.UsageByPeer(peer_id) == tx_weight + total_peer_bytes_start);

                        } else {

                            Assert(orphanage.UsageByPeer(peer_id) == total_peer_bytes_start);

                        }

                    }

                },

                [&] {

                    bool have_tx = orphanage.HaveTx(tx->GetWitnessHash());

                    bool have_tx_and_peer{orphanage.HaveTxFromPeer(wtxid, peer_id)};

                    // EraseTx should return 0 if m_orphans doesn't have the tx

                    {

                        auto bytes_from_peer_before{orphanage.UsageByPeer(peer_id)};

                        Assert(have_tx == orphanage.EraseTx(tx->GetWitnessHash()));

                        if (have_tx) {

                            Assert(orphanage.TotalOrphanUsage() == total_bytes_start - tx_weight);

                            if (have_tx_and_peer) {

                                Assert(orphanage.UsageByPeer(peer_id) == bytes_from_peer_before - tx_weight);

                            } else {

                                Assert(orphanage.UsageByPeer(peer_id) == bytes_from_peer_before);

                            }

                        } else {

                            Assert(orphanage.TotalOrphanUsage() == total_bytes_start);

                        }

                    }

                    have_tx = orphanage.HaveTx(tx->GetWitnessHash());

                    have_tx_and_peer = orphanage.HaveTxFromPeer(wtxid, peer_id);

                    // have_tx should be false and EraseTx should fail

                    {

                        Assert(!have_tx && !have_tx_and_peer && !orphanage.EraseTx(wtxid));

                    }

                },

                [&] {

                    orphanage.EraseForPeer(peer_id);

                    Assert(!orphanage.HaveTxFromPeer(tx->GetWitnessHash(), peer_id));

                    Assert(orphanage.UsageByPeer(peer_id) == 0);

                },

                [&] {

                    // Make a block out of txs and then EraseForBlock

                    CBlock block;

                    int num_txs = fuzzed_data_provider.ConsumeIntegralInRange<unsigned int>(0, 1000);

                    for (int i{0}; i < num_txs; ++i) {

                        auto& tx_to_remove = PickValue(fuzzed_data_provider, tx_history);

                        block.vtx.push_back(tx_to_remove);

                    }

                    orphanage.EraseForBlock(block);

                    for (const auto& tx_removed : block.vtx) {

                        Assert(!orphanage.HaveTx(tx_removed->GetWitnessHash()));

                        Assert(!orphanage.HaveTxFromPeer(tx_removed->GetWitnessHash(), peer_id));

                    }

                },

                [&] {

                    // test mocktime and expiry

                    SetMockTime(ConsumeTime(fuzzed_data_provider));

                    auto limit = fuzzed_data_provider.ConsumeIntegral<unsigned int>();

                    orphanage.LimitOrphans(limit, orphanage_rng);

                    Assert(orphanage.Size() <= limit);

                });

        }

        // Set tx as potential parent to be used for future GetChildren() calls.

        if (!ptx_potential_parent || fuzzed_data_provider.ConsumeBool()) {

            ptx_potential_parent = tx;

        }

        const bool have_tx{orphanage.HaveTx(tx->GetWitnessHash())};

        const bool get_tx_nonnull{orphanage.GetTx(tx->GetWitnessHash()) != nullptr};

        Assert(have_tx == get_tx_nonnull);

    }

    orphanage.SanityCheck();

}