// 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 <node/utxo_snapshot.h>

#include <logging.h>

#include <streams.h>

#include <sync.h>

#include <tinyformat.h>

#include <txdb.h>

#include <uint256.h>

#include <util/fs.h>

#include <validation.h>

#include <cassert>

#include <cstdio>

#include <optional>

#include <string>

namespace node {

bool WriteSnapshotBaseBlockhash(Chainstate& snapshot_chainstate)

{

    AssertLockHeld(::cs_main);

    assert(snapshot_chainstate.m_from_snapshot_blockhash);

    const std::optional<fs::path> chaindir = snapshot_chainstate.CoinsDB().StoragePath();

    assert(chaindir); // Sanity check that chainstate isn't in-memory.

    const fs::path write_to = *chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;

    FILE* file{fsbridge::fopen(write_to, "wb")};

    AutoFile afile{file};

    if (afile.IsNull()) {

        LogPrintf("[snapshot] failed to open base blockhash file for writing: %s\n",

                  fs::PathToString(write_to));

        return false;

    }

    afile << *snapshot_chainstate.m_from_snapshot_blockhash;

    if (afile.fclose() != 0) {

        LogPrintf("[snapshot] failed to close base blockhash file %s after writing\n",

                  fs::PathToString(write_to));

        return false;

    }

    return true;

}

std::optional<uint256> ReadSnapshotBaseBlockhash(fs::path chaindir)

{

    if (!fs::exists(chaindir)) {

        LogPrintf("[snapshot] cannot read base blockhash: no chainstate dir "

            "exists at path %s\n", fs::PathToString(chaindir));

        return std::nullopt;

    }

    const fs::path read_from = chaindir / node::SNAPSHOT_BLOCKHASH_FILENAME;

    const std::string read_from_str = fs::PathToString(read_from);

    if (!fs::exists(read_from)) {

        LogPrintf("[snapshot] snapshot chainstate dir is malformed! no base blockhash file "

            "exists at path %s. Try deleting %s and calling loadtxoutset again?\n",

            fs::PathToString(chaindir), read_from_str);

        return std::nullopt;

    }

    uint256 base_blockhash;

    FILE* file{fsbridge::fopen(read_from, "rb")};

    AutoFile afile{file};

    if (afile.IsNull()) {

        LogPrintf("[snapshot] failed to open base blockhash file for reading: %s\n",

            read_from_str);

        return std::nullopt;

    }

    afile >> base_blockhash;

    int64_t position = afile.tell();

    afile.seek(0, SEEK_END);

    if (position != afile.tell()) {

        LogPrintf("[snapshot] warning: unexpected trailing data in %s\n", read_from_str);

    }

    return base_blockhash;

}

std::optional<fs::path> FindSnapshotChainstateDir(const fs::path& data_dir)

{

    fs::path possible_dir =

        data_dir / fs::u8path(strprintf("chainstate%s", SNAPSHOT_CHAINSTATE_SUFFIX));

    if (fs::exists(possible_dir)) {

        return possible_dir;

    }

    return std::nullopt;

}

} // namespace node