// Copyright (c) 2017-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 <index/txindex.h>

#include <common/args.h>

#include <dbwrapper.h>

#include <flatfile.h>

#include <index/base.h>

#include <index/disktxpos.h>

#include <interfaces/chain.h>

#include <node/blockstorage.h>

#include <primitives/block.h>

#include <primitives/transaction.h>

#include <serialize.h>

#include <streams.h>

#include <uint256.h>

#include <util/fs.h>

#include <util/log.h>

#include <validation.h>

#include <cassert>

#include <cstdint>

#include <cstdio>

#include <exception>

#include <string>

#include <utility>

#include <vector>

constexpr uint8_t DB_TXINDEX{'t'};

std::unique_ptr<TxIndex> g_txindex;

/** Access to the txindex database (indexes/txindex/) */

class TxIndex::DB : public BaseIndex::DB

{

public:

    explicit DB(size_t n_cache_size, bool f_memory = false, bool f_wipe = false);

    /// Read the disk location of the transaction data with the given hash. Returns false if the

    /// transaction hash is not indexed.

    bool ReadTxPos(const Txid& txid, CDiskTxPos& pos) const;

    /// Write a batch of transaction positions to the DB.

    void WriteTxs(const std::vector<std::pair<Txid, CDiskTxPos>>& v_pos);

};

TxIndex::DB::DB(size_t n_cache_size, bool f_memory, bool f_wipe) :

    BaseIndex::DB(gArgs.GetDataDirNet() / "indexes" / "txindex", n_cache_size, f_memory, f_wipe)

{}

bool TxIndex::DB::ReadTxPos(const Txid& txid, CDiskTxPos& pos) const

{

    return Read(std::make_pair(DB_TXINDEX, txid.ToUint256()), pos);

}

void TxIndex::DB::WriteTxs(const std::vector<std::pair<Txid, CDiskTxPos>>& v_pos)

{

    CDBBatch batch(*this);

    for (const auto& [txid, pos] : v_pos) {

        batch.Write(std::make_pair(DB_TXINDEX, txid.ToUint256()), pos);

    }

    WriteBatch(batch);

}

TxIndex::TxIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory, bool f_wipe)

    : BaseIndex(std::move(chain), "txindex"), m_db(std::make_unique<TxIndex::DB>(n_cache_size, f_memory, f_wipe))

{}

TxIndex::~TxIndex() = default;

bool TxIndex::CustomAppend(const interfaces::BlockInfo& block)

{

    // Exclude genesis block transaction because outputs are not spendable.

    if (block.height == 0) return true;

    assert(block.data);

    CDiskTxPos pos({block.file_number, block.data_pos}, GetSizeOfCompactSize(block.data->vtx.size()));

    std::vector<std::pair<Txid, CDiskTxPos>> vPos;

    vPos.reserve(block.data->vtx.size());

    for (const auto& tx : block.data->vtx) {

        vPos.emplace_back(tx->GetHash(), pos);

        pos.nTxOffset += ::GetSerializeSize(TX_WITH_WITNESS(*tx));

    }

    m_db->WriteTxs(vPos);

    return true;

}

BaseIndex::DB& TxIndex::GetDB() const { return *m_db; }

bool TxIndex::FindTx(const Txid& tx_hash, uint256& block_hash, CTransactionRef& tx) const

{

    CDiskTxPos postx;

    if (!m_db->ReadTxPos(tx_hash, postx)) {

        return false;

    }

    AutoFile file{m_chainstate->m_blockman.OpenBlockFile(postx, true)};

    if (file.IsNull()) {

        LogError("OpenBlockFile failed");

        return false;

    }

    CBlockHeader header;

    try {

        file >> header;

        file.seek(postx.nTxOffset, SEEK_CUR);

        file >> TX_WITH_WITNESS(tx);

    } catch (const std::exception& e) {

        LogError("Deserialize or I/O error - %s", e.what());

        return false;

    }

    if (tx->GetHash() != tx_hash) {

        LogError("txid mismatch");

        return false;

    }

    block_hash = header.GetHash();

    return true;

}