// Copyright (c) 2021 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 <node/chainstate.h>

#include <chain.h>
#include <coins.h>
#include <consensus/params.h>
#include <node/blockstorage.h>
#include <node/caches.h>
#include <sync.h>
#include <threadsafety.h>
#include <tinyformat.h>
#include <txdb.h>
#include <uint256.h>
#include <util/time.h>
#include <util/translation.h>
#include <validation.h>

#include <algorithm>
#include <atomic>
#include <cassert>
#include <memory>
#include <vector>

namespace node {
ChainstateLoadResult LoadChainstate(ChainstateManager& chainman, const CacheSizes& cache_sizes,
                                    const ChainstateLoadOptions& options)
{
    auto is_coinsview_empty = [&](Chainstate* chainstate) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
        return options.reindex || options.reindex_chainstate || chainstate->CoinsTip().GetBestBlock().IsNull();
    };

    if (!hashAssumeValid.IsNull()) {
        LogPrintf("Assuming ancestors of block %s have valid signatures.\n", hashAssumeValid.GetHex());
    } else {
        LogPrintf("Validating signatures for all blocks.\n");
    }
    LogPrintf("Setting nMinimumChainWork=%s\n", nMinimumChainWork.GetHex());
    if (nMinimumChainWork < UintToArith256(chainman.GetConsensus().nMinimumChainWork)) {
        LogPrintf("Warning: nMinimumChainWork set below default value of %s\n", chainman.GetConsensus().nMinimumChainWork.GetHex());
    }
    if (nPruneTarget == std::numeric_limits<uint64_t>::max()) {
        LogPrintf("Block pruning enabled.  Use RPC call pruneblockchain(height) to manually prune block and undo files.\n");
    } else if (nPruneTarget) {
        LogPrintf("Prune configured to target %u MiB on disk for block and undo files.\n", nPruneTarget / 1024 / 1024);
    }

    LOCK(cs_main);
    chainman.InitializeChainstate(options.mempool);
    chainman.m_total_coinstip_cache = cache_sizes.coins;
    chainman.m_total_coinsdb_cache = cache_sizes.coins_db;

    auto& pblocktree{chainman.m_blockman.m_block_tree_db};
    // new CBlockTreeDB tries to delete the existing file, which
    // fails if it's still open from the previous loop. Close it first:
    pblocktree.reset();
    pblocktree.reset(new CBlockTreeDB(cache_sizes.block_tree_db, options.block_tree_db_in_memory, options.reindex));

    if (options.reindex) {
        pblocktree->WriteReindexing(true);
        //If we're reindexing in prune mode, wipe away unusable block files and all undo data files
        if (options.prune) {
            CleanupBlockRevFiles();
        }
    }

    if (options.check_interrupt && options.check_interrupt()) return {ChainstateLoadStatus::INTERRUPTED, {}};

    // LoadBlockIndex will load m_have_pruned if we've ever removed a
    // block file from disk.
    // Note that it also sets fReindex global based on the disk flag!
    // From here on, fReindex and options.reindex values may be different!
    if (!chainman.LoadBlockIndex()) {
        if (options.check_interrupt && options.check_interrupt()) return {ChainstateLoadStatus::INTERRUPTED, {}};
        return {ChainstateLoadStatus::FAILURE, _("Error loading block database")};
    }

    if (!chainman.BlockIndex().empty() &&
            !chainman.m_blockman.LookupBlockIndex(chainman.GetConsensus().hashGenesisBlock)) {
        // If the loaded chain has a wrong genesis, bail out immediately
        // (we're likely using a testnet datadir, or the other way around).
        return {ChainstateLoadStatus::FAILURE_INCOMPATIBLE_DB, _("Incorrect or no genesis block found. Wrong datadir for network?")};
    }

    // Check for changed -prune state.  What we are concerned about is a user who has pruned blocks
    // in the past, but is now trying to run unpruned.
    if (chainman.m_blockman.m_have_pruned && !options.prune) {
        return {ChainstateLoadStatus::FAILURE, _("You need to rebuild the database using -reindex to go back to unpruned mode.  This will redownload the entire blockchain")};
    }

    // At this point blocktree args are consistent with what's on disk.
    // If we're not mid-reindex (based on disk + args), add a genesis block on disk
    // (otherwise we use the one already on disk).
    // This is called again in ThreadImport after the reindex completes.
    if (!fReindex && !chainman.ActiveChainstate().LoadGenesisBlock()) {
        return {ChainstateLoadStatus::FAILURE, _("Error initializing block database")};
    }

    // At this point we're either in reindex or we've loaded a useful
    // block tree into BlockIndex()!

    for (Chainstate* chainstate : chainman.GetAll()) {
        chainstate->InitCoinsDB(
            /*cache_size_bytes=*/cache_sizes.coins_db,
            /*in_memory=*/options.coins_db_in_memory,
            /*should_wipe=*/options.reindex || options.reindex_chainstate);

        if (options.coins_error_cb) {
            chainstate->CoinsErrorCatcher().AddReadErrCallback(options.coins_error_cb);
        }

        // Refuse to load unsupported database format.
        // This is a no-op if we cleared the coinsviewdb with -reindex or -reindex-chainstate
        if (chainstate->CoinsDB().NeedsUpgrade()) {
            return {ChainstateLoadStatus::FAILURE_INCOMPATIBLE_DB, _("Unsupported chainstate database format found. "
                                                                     "Please restart with -reindex-chainstate. This will "
                                                                     "rebuild the chainstate database.")};
        }

        // ReplayBlocks is a no-op if we cleared the coinsviewdb with -reindex or -reindex-chainstate
        if (!chainstate->ReplayBlocks()) {
            return {ChainstateLoadStatus::FAILURE, _("Unable to replay blocks. You will need to rebuild the database using -reindex-chainstate.")};
        }

        // The on-disk coinsdb is now in a good state, create the cache
        chainstate->InitCoinsCache(cache_sizes.coins);
        assert(chainstate->CanFlushToDisk());

        if (!is_coinsview_empty(chainstate)) {
            // LoadChainTip initializes the chain based on CoinsTip()'s best block
            if (!chainstate->LoadChainTip()) {
                return {ChainstateLoadStatus::FAILURE, _("Error initializing block database")};
            }
            assert(chainstate->m_chain.Tip() != nullptr);
        }
    }

    if (!options.reindex) {
        auto chainstates{chainman.GetAll()};
        if (std::any_of(chainstates.begin(), chainstates.end(),
                        [](const Chainstate* cs) EXCLUSIVE_LOCKS_REQUIRED(cs_main) { return cs->NeedsRedownload(); })) {
            return {ChainstateLoadStatus::FAILURE, strprintf(_("Witness data for blocks after height %d requires validation. Please restart with -reindex."),
                                                             chainman.GetConsensus().SegwitHeight)};
        };
    }

    return {ChainstateLoadStatus::SUCCESS, {}};
}

ChainstateLoadResult VerifyLoadedChainstate(ChainstateManager& chainman, const ChainstateLoadOptions& options)
{
    auto is_coinsview_empty = [&](Chainstate* chainstate) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
        return options.reindex || options.reindex_chainstate || chainstate->CoinsTip().GetBestBlock().IsNull();
    };

    LOCK(cs_main);

    for (Chainstate* chainstate : chainman.GetAll()) {
        if (!is_coinsview_empty(chainstate)) {
            const CBlockIndex* tip = chainstate->m_chain.Tip();
            if (tip && tip->nTime > GetTime() + MAX_FUTURE_BLOCK_TIME) {
                return {ChainstateLoadStatus::FAILURE, _("The block database contains a block which appears to be from the future. "
                                                         "This may be due to your computer's date and time being set incorrectly. "
                                                         "Only rebuild the block database if you are sure that your computer's date and time are correct")};
            }

            if (!CVerifyDB().VerifyDB(
                    *chainstate, chainman.GetConsensus(), chainstate->CoinsDB(),
                    options.check_level,
                    options.check_blocks)) {
                return {ChainstateLoadStatus::FAILURE, _("Corrupted block database detected")};
            }
        }
    }

    return {ChainstateLoadStatus::SUCCESS, {}};
}
} // namespace node
