// Copyright (c) 2022 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>

//! Default maximum number of maximum size orphan transactions that can be kept in memory
static const uint32_t DEFAULT_MAX_ORPHAN_TRANSACTIONS{(DEFAULT_MAX_ORPHAN_TRANSACTIONS_SIZE * 1000000) / MAX_STANDARD_TX_SIZE};

void initialize_orphanage()
{
    static const auto testing_setup = MakeNoLogFileContext();
}

FUZZ_TARGET(txorphan, .init = initialize_orphanage)
{
    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
    SetMockTime(ConsumeTime(fuzzed_data_provider));

    TxOrphanage orphanage;
    std::vector<COutPoint> outpoints;
    // initial outpoints used to construct transactions later
    for (uint8_t i = 0; i < 4; i++) {
        outpoints.emplace_back(uint256{i}, 0);
    }
    // if true, allow duplicate input when constructing tx
    const bool duplicate_input = fuzzed_data_provider.ConsumeBool();

    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, outpoints.size());
            // pick unique outpoints from outpoints as input
            for (uint32_t i = 0; i < num_in; i++) {
                auto& prevout = PickValue(fuzzed_data_provider, outpoints);
                tx_mut.vin.emplace_back(prevout);
                // pop the picked outpoint if duplicate input is not allowed
                if (!duplicate_input) {
                    std::swap(prevout, outpoints.back());
                    outpoints.pop_back();
                }
            }
            // 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{});
            }
            // restore previously popped outpoints
            for (auto& in : tx_mut.vin) {
                outpoints.push_back(in.prevout);
            }
            auto new_tx = MakeTransactionRef(tx_mut);
            // add newly constructed transaction to outpoints
            for (uint32_t i = 0; i < num_out; i++) {
                outpoints.emplace_back(new_tx->GetHash(), i);
            }
            return new_tx;
        }();

        // trigger orphanage functions
        LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10 * DEFAULT_MAX_ORPHAN_TRANSACTIONS)
        {
            NodeId peer_id = fuzzed_data_provider.ConsumeIntegral<NodeId>();

            CallOneOf(
                fuzzed_data_provider,
                [&] {
                    orphanage.AddChildrenToWorkSet(*tx, peer_id);
                },
                [&] {
                    {
                        NodeId originator;
                        bool more = true;
                        CTransactionRef ref = orphanage.GetTxToReconsider(peer_id, originator, more);
                        if (!ref) {
                            Assert(!more);
                        } else {
                            bool have_tx = orphanage.HaveTx(ref->GetHash());
                            Assert(have_tx);
                        }
                    }
                },
                [&] {
                    bool have_tx = orphanage.HaveTx(tx->GetHash());
                    // AddTx should return false if tx is too big or already have it
                    // tx size 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);
                    }
                    have_tx = orphanage.HaveTx(tx->GetHash());
                    {
                        bool add_tx = orphanage.AddTx(tx, peer_id);
                        // if have_tx is still false, it must be too big
                        Assert(!have_tx == (::GetSerializeSize(*tx, PROTOCOL_VERSION) > MAX_STANDARD_TX_SIZE));
                        Assert(!have_tx || !add_tx);
                    }
                },
                [&] {
                    bool have_tx = orphanage.HaveTx(tx->GetHash());
                    // EraseTx should return 0 if m_orphans doesn't have the tx
                    {
                        Assert(have_tx == orphanage.EraseTx(tx->GetHash()));
                    }
                    have_tx = orphanage.HaveTx(tx->GetHash());
                    // have_tx should be false and EraseTx should fail
                    {
                        Assert(!have_tx && !orphanage.EraseTx(tx->GetHash()));
                    }
                },
                [&] {
                    orphanage.EraseForPeer(peer_id);
                },
                [&] {
                    // test mocktime and expiry
                    SetMockTime(ConsumeTime(fuzzed_data_provider));
                    auto limit = fuzzed_data_provider.ConsumeIntegral<unsigned int>();
                    orphanage.LimitOrphans(limit);
                    Assert(orphanage.Size() <= limit);
                });
        }
    }
}
