// 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.

#ifndef BITCOIN_NODE_CHAINSTATE_H
#define BITCOIN_NODE_CHAINSTATE_H

#include <validation.h>

#include <cstdint>
#include <functional>
#include <optional>

class ChainstateManager;
class CTxMemPool;

namespace node {

struct CacheSizes;

struct ChainstateLoadOptions {
    CTxMemPool* mempool{nullptr};
    bool block_tree_db_in_memory{false};
    bool coins_db_in_memory{false};
    bool reindex{false};
    bool reindex_chainstate{false};
    bool prune{false};
    int64_t check_blocks{DEFAULT_CHECKBLOCKS};
    int64_t check_level{DEFAULT_CHECKLEVEL};
    std::function<bool()> check_interrupt;
    std::function<void()> coins_error_cb;
};

enum class ChainstateLoadingError {
    ERROR_LOADING_BLOCK_DB,
    ERROR_BAD_GENESIS_BLOCK,
    ERROR_PRUNED_NEEDS_REINDEX,
    ERROR_LOAD_GENESIS_BLOCK_FAILED,
    ERROR_CHAINSTATE_UPGRADE_FAILED,
    ERROR_REPLAYBLOCKS_FAILED,
    ERROR_LOADCHAINTIP_FAILED,
    ERROR_GENERIC_BLOCKDB_OPEN_FAILED,
    ERROR_BLOCKS_WITNESS_INSUFFICIENTLY_VALIDATED,
    SHUTDOWN_PROBED,
};

/** This sequence can have 4 types of outcomes:
 *
 *  1. Success
 *  2. Shutdown requested
 *    - nothing failed but a shutdown was triggered in the middle of the
 *      sequence
 *  3. Soft failure
 *    - a failure that might be recovered from with a reindex
 *  4. Hard failure
 *    - a failure that definitively cannot be recovered from with a reindex
 *
 *  Currently, LoadChainstate returns a std::optional<ChainstateLoadingError>
 *  which:
 *
 *  - if has_value()
 *      - Either "Soft failure", "Hard failure", or "Shutdown requested",
 *        differentiable by the specific enumerator.
 *
 *        Note that a return value of SHUTDOWN_PROBED means ONLY that "during
 *        this sequence, when we explicitly checked shutdown_requested() at
 *        arbitrary points, one of those calls returned true". Therefore, a
 *        return value other than SHUTDOWN_PROBED does not guarantee that
 *        shutdown hasn't been called indirectly.
 *  - else
 *      - Success!
 */
std::optional<ChainstateLoadingError> LoadChainstate(ChainstateManager& chainman, const CacheSizes& cache_sizes,
                                                     const ChainstateLoadOptions& options);

enum class ChainstateLoadVerifyError {
    ERROR_BLOCK_FROM_FUTURE,
    ERROR_CORRUPTED_BLOCK_DB,
    ERROR_GENERIC_FAILURE,
};

std::optional<ChainstateLoadVerifyError> VerifyLoadedChainstate(ChainstateManager& chainman,
                                                                const ChainstateLoadOptions& options);
} // namespace node

#endif // BITCOIN_NODE_CHAINSTATE_H