// 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/base.h>

#include <chain.h>

#include <common/args.h>

#include <dbwrapper.h>

#include <interfaces/chain.h>

#include <interfaces/types.h>

#include <kernel/types.h>

#include <node/abort.h>

#include <node/blockstorage.h>

#include <node/context.h>

#include <node/database_args.h>

#include <node/interface_ui.h>

#include <primitives/block.h>

#include <sync.h>

#include <tinyformat.h>

#include <uint256.h>

#include <undo.h>

#include <util/check.h>

#include <util/fs.h>

#include <util/log.h>

#include <util/string.h>

#include <util/thread.h>

#include <util/threadinterrupt.h>

#include <util/time.h>

#include <util/translation.h>

#include <validation.h>

#include <validationinterface.h>

#include <compare>

#include <cstdint>

#include <functional>

#include <memory>

#include <optional>

#include <stdexcept>

#include <string>

#include <thread>

#include <utility>

#include <vector>

using kernel::ChainstateRole;

constexpr uint8_t DB_BEST_BLOCK{'B'};

constexpr auto SYNC_LOG_INTERVAL{30s};

constexpr auto SYNC_LOCATOR_WRITE_INTERVAL{30s};

template <typename... Args>

void BaseIndex::FatalErrorf(util::ConstevalFormatString<sizeof...(Args)> fmt, const Args&... args)

{

    auto message = tfm::format(fmt, args...);

    node::AbortNode(m_chain->context()->shutdown_request, m_chain->context()->exit_status, Untranslated(message), m_chain->context()->warnings.get());

}

Unexecuted instantiation: void BaseIndex::FatalErrorf<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>(util::ConstevalFormatString<sizeof...(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>)>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&)

Unexecuted instantiation: void BaseIndex::FatalErrorf<int>(util::ConstevalFormatString<sizeof...(int)>, int const&)

CBlockLocator GetLocator(interfaces::Chain& chain, const uint256& block_hash)

{

    CBlockLocator locator;

    bool found = chain.findBlock(block_hash, interfaces::FoundBlock().locator(locator));

    assert(found);

    assert(!locator.IsNull());

    return locator;

}

BaseIndex::DB::DB(const fs::path& path, size_t n_cache_size, bool f_memory, bool f_wipe, bool f_obfuscate) :

    CDBWrapper{DBParams{

        .path = path,

        .cache_bytes = n_cache_size,

        .memory_only = f_memory,

        .wipe_data = f_wipe,

        .obfuscate = f_obfuscate,

        .options = [] { DBOptions options; node::ReadDatabaseArgs(gArgs, options); return options; }()}}

{}

CBlockLocator BaseIndex::DB::ReadBestBlock() const

{

    CBlockLocator locator;

    bool success = Read(DB_BEST_BLOCK, locator);

    if (!success) {

        locator.SetNull();

    }

    return locator;

}

void BaseIndex::DB::WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator)

{

    batch.Write(DB_BEST_BLOCK, locator);

}

BaseIndex::BaseIndex(std::unique_ptr<interfaces::Chain> chain, std::string name)

    : m_chain{std::move(chain)}, m_name{std::move(name)} {}

BaseIndex::~BaseIndex()

{

    Interrupt();

    Stop();

}

bool BaseIndex::Init()

{

    AssertLockNotHeld(cs_main);

    // May need reset if index is being restarted.

    m_interrupt.reset();

    // m_chainstate member gives indexing code access to node internals. It is

    // removed in followup https://github.com/bitcoin/bitcoin/pull/24230

    m_chainstate = WITH_LOCK(::cs_main,

                             return &m_chain->context()->chainman->ValidatedChainstate());

    // Register to validation interface before setting the 'm_synced' flag, so that

    // callbacks are not missed once m_synced is true.

    m_chain->context()->validation_signals->RegisterValidationInterface(this);

    const auto locator{GetDB().ReadBestBlock()};

    LOCK(cs_main);

    CChain& index_chain = m_chainstate->m_chain;

    if (locator.IsNull()) {

        SetBestBlockIndex(nullptr);

    } else {

        // Setting the best block to the locator's top block. If it is not part of the

        // best chain, we will rewind to the fork point during index sync

        const CBlockIndex* locator_index{m_chainstate->m_blockman.LookupBlockIndex(locator.vHave.at(0))};

        if (!locator_index) {

            return InitError(Untranslated(strprintf("best block of %s not found. Please rebuild the index.", GetName())));

        }

        SetBestBlockIndex(locator_index);

    }

    // Child init

    const CBlockIndex* start_block = m_best_block_index.load();

    if (!CustomInit(start_block ? std::make_optional(interfaces::BlockRef{start_block->GetBlockHash(), start_block->nHeight}) : std::nullopt)) {

        return false;

    }

    // Note: this will latch to true immediately if the user starts up with an empty

    // datadir and an index enabled. If this is the case, indexation will happen solely

    // via `BlockConnected` signals until, possibly, the next restart.

    m_synced = start_block == index_chain.Tip();

    m_init = true;

    return true;

}

static const CBlockIndex* NextSyncBlock(const CBlockIndex* const pindex_prev, CChain& chain) EXCLUSIVE_LOCKS_REQUIRED(cs_main)

{

    AssertLockHeld(cs_main);

    if (!pindex_prev) {

        return chain.Genesis();

    }

    if (const auto* pindex{chain.Next(*pindex_prev)}) {

        return pindex;

    }

    // If there is no next block, we might be synced

    if (pindex_prev == chain.Tip()) {

        return nullptr;

    }

    // Since block is not in the chain, return the next block in the chain AFTER the last common ancestor.

    // Caller will be responsible for rewinding back to the common ancestor.

    const auto* fork{chain.FindFork(*pindex_prev)};

    // Common ancestor must exist (genesis).

    return chain.Next(*Assert(fork));

}

bool BaseIndex::ProcessBlock(const CBlockIndex* pindex, const CBlock* block_data)

{

    interfaces::BlockInfo block_info = kernel::MakeBlockInfo(pindex, block_data);

    CBlock block;

    if (!block_data) { // disk lookup if block data wasn't provided

        if (!m_chainstate->m_blockman.ReadBlock(block, *pindex)) {

            FatalErrorf("Failed to read block %s from disk",

                        pindex->GetBlockHash().ToString());

            return false;

        }

        block_info.data = █

    }

    CBlockUndo block_undo;

    if (CustomOptions().connect_undo_data) {

        if (pindex->nHeight > 0 && !m_chainstate->m_blockman.ReadBlockUndo(block_undo, *pindex)) {

            FatalErrorf("Failed to read undo block data %s from disk",

                        pindex->GetBlockHash().ToString());

            return false;

        }

        block_info.undo_data = &block_undo;

    }

    if (!CustomAppend(block_info)) {

        FatalErrorf("Failed to write block %s to index database",

                    pindex->GetBlockHash().ToString());

        return false;

    }

    return true;

}

void BaseIndex::Sync()

{

    const CBlockIndex* pindex = m_best_block_index.load();

    if (!m_synced) {

        auto last_log_time{NodeClock::now()};

        auto last_locator_write_time{last_log_time};

        while (true) {

            if (m_interrupt) {

                LogInfo("%s: m_interrupt set; exiting ThreadSync", GetName());

                SetBestBlockIndex(pindex);

                // No need to handle errors in Commit. If it fails, the error will be already be

                // logged. The best way to recover is to continue, as index cannot be corrupted by

                // a missed commit to disk for an advanced index state.

                Commit();

                return;

            }

            const CBlockIndex* pindex_next = WITH_LOCK(cs_main, return NextSyncBlock(pindex, m_chainstate->m_chain));

            // If pindex_next is null, it means pindex is the chain tip, so

            // commit data indexed so far.

            if (!pindex_next) {

                SetBestBlockIndex(pindex);

                // No need to handle errors in Commit. See rationale above.

                Commit();

                // If pindex is still the chain tip after committing, exit the

                // sync loop. It is important for cs_main to be locked while

                // setting m_synced = true, otherwise a new block could be

                // attached while m_synced is still false, and it would not be

                // indexed.

                LOCK(::cs_main);

                pindex_next = NextSyncBlock(pindex, m_chainstate->m_chain);

                if (!pindex_next) {

                    m_synced = true;

                    break;

                }

            }

            if (pindex_next->pprev != pindex && !Rewind(pindex, pindex_next->pprev)) {

                FatalErrorf("Failed to rewind %s to a previous chain tip", GetName());

                return;

            }

            pindex = pindex_next;

            if (!ProcessBlock(pindex)) return; // error logged internally

            auto current_time{NodeClock::now()};

            if (current_time - last_log_time >= SYNC_LOG_INTERVAL) {

                LogInfo("Syncing %s with block chain from height %d", GetName(), pindex->nHeight);

                last_log_time = current_time;

            }

            if (current_time - last_locator_write_time >= SYNC_LOCATOR_WRITE_INTERVAL) {

                SetBestBlockIndex(pindex);

                last_locator_write_time = current_time;

                // No need to handle errors in Commit. See rationale above.

                Commit();

            }

        }

    }

    if (pindex) {

        LogInfo("%s is enabled at height %d", GetName(), pindex->nHeight);

    } else {

        LogInfo("%s is enabled", GetName());

    }

}

bool BaseIndex::Commit()

{

    // Don't commit anything if we haven't indexed any block yet

    // (this could happen if init is interrupted).

    bool ok = m_best_block_index != nullptr;

    if (ok) {

        CDBBatch batch(GetDB());

        ok = CustomCommit(batch);

        if (ok) {

            GetDB().WriteBestBlock(batch, GetLocator(*m_chain, m_best_block_index.load()->GetBlockHash()));

            GetDB().WriteBatch(batch);

        }

    }

    if (!ok) {

        LogError("Failed to commit latest %s state", GetName());

        return false;

    }

    return true;

}

bool BaseIndex::Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip)

{

    assert(current_tip->GetAncestor(new_tip->nHeight) == new_tip);

    CBlock block;

    CBlockUndo block_undo;

    for (const CBlockIndex* iter_tip = current_tip; iter_tip != new_tip; iter_tip = iter_tip->pprev) {

        interfaces::BlockInfo block_info = kernel::MakeBlockInfo(iter_tip);

        if (CustomOptions().disconnect_data) {

            if (!m_chainstate->m_blockman.ReadBlock(block, *iter_tip)) {

                LogError("Failed to read block %s from disk",

                         iter_tip->GetBlockHash().ToString());

                return false;

            }

            block_info.data = █

        }

        if (CustomOptions().disconnect_undo_data && iter_tip->nHeight > 0) {

            if (!m_chainstate->m_blockman.ReadBlockUndo(block_undo, *iter_tip)) {

                return false;

            }

            block_info.undo_data = &block_undo;

        }

        if (!CustomRemove(block_info)) {

            return false;

        }

    }

    // Don't commit here - the committed index state must never be ahead of the

    // flushed chainstate, otherwise unclean restarts would lead to index corruption.

    // Pruning has a minimum of 288 blocks-to-keep and getting the index

    // out of sync may be possible but a users fault.

    // In case we reorg beyond the pruned depth, ReadBlock would

    // throw and lead to a graceful shutdown

    SetBestBlockIndex(new_tip);

    return true;

}

void BaseIndex::BlockConnected(const ChainstateRole& role, const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex)

{

    // Ignore events from not fully validated chains to avoid out-of-order indexing.

    //

    // TODO at some point we could parameterize whether a particular index can be

    // built out of order, but for now just do the conservative simple thing.

    if (!role.validated) {

        return;

    }

    // Ignore BlockConnected signals until we have fully indexed the chain.

    if (!m_synced) {

        return;

    }

    const CBlockIndex* best_block_index = m_best_block_index.load();

    if (!best_block_index) {

        if (pindex->nHeight != 0) {

            FatalErrorf("First block connected is not the genesis block (height=%d)",

                       pindex->nHeight);

            return;

        }

    } else {

        // Ensure block connects to an ancestor of the current best block. This should be the case

        // most of the time, but may not be immediately after the sync thread catches up and sets

        // m_synced. Consider the case where there is a reorg and the blocks on the stale branch are

        // in the ValidationInterface queue backlog even after the sync thread has caught up to the

        // new chain tip. In this unlikely event, log a warning and let the queue clear.

        if (best_block_index->GetAncestor(pindex->nHeight - 1) != pindex->pprev) {

            LogWarning("Block %s does not connect to an ancestor of "

                      "known best chain (tip=%s); not updating index",

                      pindex->GetBlockHash().ToString(),

                      best_block_index->GetBlockHash().ToString());

            return;

        }

        if (best_block_index != pindex->pprev && !Rewind(best_block_index, pindex->pprev)) {

            FatalErrorf("Failed to rewind %s to a previous chain tip",

                       GetName());

            return;

        }

    }

    // Dispatch block to child class; errors are logged internally and abort the node.

    if (ProcessBlock(pindex, block.get())) {

        // Setting the best block index is intentionally the last step of this

        // function, so BlockUntilSyncedToCurrentChain callers waiting for the

        // best block index to be updated can rely on the block being fully

        // processed, and the index object being safe to delete.

        SetBestBlockIndex(pindex);

    }

}

void BaseIndex::ChainStateFlushed(const ChainstateRole& role, const CBlockLocator& locator)

{

    // Ignore events from not fully validated chains to avoid out-of-order indexing.

    if (!role.validated) {

        return;

    }

    if (!m_synced) {

        return;

    }

    const uint256& locator_tip_hash = locator.vHave.front();

    const CBlockIndex* locator_tip_index;

    {

        LOCK(cs_main);

        locator_tip_index = m_chainstate->m_blockman.LookupBlockIndex(locator_tip_hash);

    }

    if (!locator_tip_index) {

        FatalErrorf("First block (hash=%s) in locator was not found",

                   locator_tip_hash.ToString());

        return;

    }

    // This checks that ChainStateFlushed callbacks are received after BlockConnected. The check may fail

    // immediately after the sync thread catches up and sets m_synced. Consider the case where

    // there is a reorg and the blocks on the stale branch are in the ValidationInterface queue

    // backlog even after the sync thread has caught up to the new chain tip. In this unlikely

    // event, log a warning and let the queue clear.

    const CBlockIndex* best_block_index = m_best_block_index.load();

    if (best_block_index->GetAncestor(locator_tip_index->nHeight) != locator_tip_index) {

        LogWarning("Locator contains block (hash=%s) not on known best "

                  "chain (tip=%s); not writing index locator",

                  locator_tip_hash.ToString(),

                  best_block_index->GetBlockHash().ToString());

        return;

    }

    // No need to handle errors in Commit. If it fails, the error will be already be logged. The

    // best way to recover is to continue, as index cannot be corrupted by a missed commit to disk

    // for an advanced index state.

    Commit();

}

bool BaseIndex::BlockUntilSyncedToCurrentChain() const

{

    AssertLockNotHeld(cs_main);

    if (!m_synced) {

        return false;

    }

    {

        // Skip the queue-draining stuff if we know we're caught up with

        // m_chain.Tip().

        LOCK(cs_main);

        const CBlockIndex* chain_tip = m_chainstate->m_chain.Tip();

        const CBlockIndex* best_block_index = m_best_block_index.load();

        if (best_block_index->GetAncestor(chain_tip->nHeight) == chain_tip) {

            return true;

        }

    }

    LogInfo("%s is catching up on block notifications", GetName());

    m_chain->context()->validation_signals->SyncWithValidationInterfaceQueue();

    return true;

}

void BaseIndex::Interrupt()

{

    m_interrupt();

}

bool BaseIndex::StartBackgroundSync()

{

    if (!m_init) throw std::logic_error("Error: Cannot start a non-initialized index");

    m_thread_sync = std::thread(&util::TraceThread, GetName(), [this] { Sync(); });

    return true;

}

void BaseIndex::Stop()

{

    if (m_chain->context()->validation_signals) {

        m_chain->context()->validation_signals->UnregisterValidationInterface(this);

    }

    if (m_thread_sync.joinable()) {

        m_thread_sync.join();

    }

}

IndexSummary BaseIndex::GetSummary() const

{

    IndexSummary summary{};

    summary.name = GetName();

    summary.synced = m_synced;

    if (const auto& pindex = m_best_block_index.load()) {

        summary.best_block_height = pindex->nHeight;

        summary.best_block_hash = pindex->GetBlockHash();

    } else {

        summary.best_block_height = 0;

        summary.best_block_hash = m_chain->getBlockHash(0);

    }

    return summary;

}

void BaseIndex::SetBestBlockIndex(const CBlockIndex* block)

{

    assert(!m_chainstate->m_blockman.IsPruneMode() || AllowPrune());

    if (AllowPrune() && block) {

        node::PruneLockInfo prune_lock;

        prune_lock.height_first = block->nHeight;

        WITH_LOCK(::cs_main, m_chainstate->m_blockman.UpdatePruneLock(GetName(), prune_lock));

    }

    // Intentionally set m_best_block_index as the last step in this function,

    // after updating prune locks above, and after making any other references

    // to *this, so the BlockUntilSyncedToCurrentChain function (which checks

    // m_best_block_index as an optimization) can be used to wait for the last

    // BlockConnected notification and safely assume that prune locks are

    // updated and that the index object is safe to delete.

    m_best_block_index = block;

}