// Copyright (c) 2011-2021 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_BLOCKSTORAGE_H
#define BITCOIN_NODE_BLOCKSTORAGE_H

#include <fs.h>
#include <protocol.h> // For CMessageHeader::MessageStartChars
#include <sync.h>
#include <txdb.h>

#include <atomic>
#include <cstdint>
#include <vector>

extern RecursiveMutex cs_main;

class ArgsManager;
class BlockValidationState;
class CBlock;
class CBlockFileInfo;
class CBlockIndex;
class CBlockUndo;
class CChain;
class CChainParams;
class CChainState;
class ChainstateManager;
struct CCheckpointData;
struct FlatFilePos;
namespace Consensus {
struct Params;
}

namespace node {
static constexpr bool DEFAULT_STOPAFTERBLOCKIMPORT{false};

/** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
/** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
/** The maximum size of a blk?????.dat file (since 0.8) */
static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB

extern std::atomic_bool fImporting;
extern std::atomic_bool fReindex;
/** Pruning-related variables and constants */
/** True if any block files have ever been pruned. */
extern bool fHavePruned;
/** True if we're running in -prune mode. */
extern bool fPruneMode;
/** Number of MiB of block files that we're trying to stay below. */
extern uint64_t nPruneTarget;
/** True if we're running in -trim_headers mode. */
extern bool fTrimHeaders;
/** Minimum number of full untrimmed headers to keep, for blocks we have. */
extern uint64_t nMustKeepFullHeaders;
/** Target number of headers to download beyond the blocks we have. */
// NOTE: this currently only operates when in header trim mode, but it's really independent of that.
extern int64_t nHeaderDownloadBuffer;

typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;

struct CBlockIndexWorkComparator {
    bool operator()(const CBlockIndex* pa, const CBlockIndex* pb) const;
};

/**
 * Maintains a tree of blocks (stored in `m_block_index`) which is consulted
 * to determine where the most-work tip is.
 *
 * This data is used mostly in `CChainState` - information about, e.g.,
 * candidate tips is not maintained here.
 */
class BlockManager
{
    friend CChainState;
    friend ChainstateManager;
    friend CBlockIndex;

private:
    void FlushBlockFile(bool fFinalize = false, bool finalize_undo = false);
    void FlushUndoFile(int block_file, bool finalize = false);
    bool FindBlockPos(FlatFilePos& pos, unsigned int nAddSize, unsigned int nHeight, CChain& active_chain, uint64_t nTime, bool fKnown);
    bool FindUndoPos(BlockValidationState& state, int nFile, FlatFilePos& pos, unsigned int nAddSize);

    /* Calculate the block/rev files to delete based on height specified by user with RPC command pruneblockchain */
    void FindFilesToPruneManual(std::set<int>& setFilesToPrune, int nManualPruneHeight, int chain_tip_height);

    /**
     * Prune block and undo files (blk???.dat and rev???.dat) so that the disk space used is less than a user-defined target.
     * The user sets the target (in MB) on the command line or in config file.  This will be run on startup and whenever new
     * space is allocated in a block or undo file, staying below the target. Changing back to unpruned requires a reindex
     * (which in this case means the blockchain must be re-downloaded.)
     *
     * Pruning functions are called from FlushStateToDisk when the m_check_for_pruning flag has been set.
     * Block and undo files are deleted in lock-step (when blk00003.dat is deleted, so is rev00003.dat.)
     * Pruning cannot take place until the longest chain is at least a certain length (CChainParams::nPruneAfterHeight).
     * Pruning will never delete a block within a defined distance (currently 288) from the active chain's tip.
     * The block index is updated by unsetting HAVE_DATA and HAVE_UNDO for any blocks that were stored in the deleted files.
     * A db flag records the fact that at least some block files have been pruned.
     *
     * @param[out]   setFilesToPrune   The set of file indices that can be unlinked will be returned
     */
    void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight, int chain_tip_height, int prune_height, bool is_ibd);

    RecursiveMutex cs_LastBlockFile;
    std::vector<CBlockFileInfo> m_blockfile_info;
    int m_last_blockfile = 0;
    /** Global flag to indicate we should check to see if there are
     *  block/undo files that should be deleted.  Set on startup
     *  or if we allocate more file space when we're in prune mode
     */
    bool m_check_for_pruning = false;

    /** Dirty block index entries. */
    std::set<CBlockIndex*> m_dirty_blockindex;

    /** Dirty block file entries. */
    std::set<int> m_dirty_fileinfo;

public:
    BlockMap m_block_index GUARDED_BY(cs_main);

    /**
     * All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
     * Pruned nodes may have entries where B is missing data.
     */
    std::multimap<CBlockIndex*, CBlockIndex*> m_blocks_unlinked;

    std::unique_ptr<CBlockTreeDB> m_block_tree_db GUARDED_BY(::cs_main);

    bool WriteBlockIndexDB() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
    bool LoadBlockIndexDB(ChainstateManager& chainman) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    /**
     * Load the blocktree off disk and into memory. Populate certain metadata
     * per index entry (nStatus, nChainWork, nTimeMax, etc.) as well as peripheral
     * collections like m_dirty_blockindex.
     */
    bool LoadBlockIndex(
        const Consensus::Params& consensus_params,
        ChainstateManager& chainman) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Clear all data members. */
    void Unload() EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    CBlockIndex* AddToBlockIndex(const CBlockHeader& block) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    /** Create a new block index entry for a given block hash */
    CBlockIndex* InsertBlockIndex(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Mark one block file as pruned (modify associated database entries)
    void PruneOneBlockFile(const int fileNumber) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    CBlockIndex* LookupBlockIndex(const uint256& hash) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Get block file info entry for one block file */
    CBlockFileInfo* GetBlockFileInfo(size_t n);

    bool WriteUndoDataForBlock(const CBlockUndo& blockundo, BlockValidationState& state, CBlockIndex* pindex, const CChainParams& chainparams)
        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    FlatFilePos SaveBlockToDisk(const CBlock& block, int nHeight, CChain& active_chain, const CChainParams& chainparams, const FlatFilePos* dbp);

    /** Calculate the amount of disk space the block & undo files currently use */
    uint64_t CalculateCurrentUsage();

    //! Returns last CBlockIndex* that is a checkpoint
    CBlockIndex* GetLastCheckpoint(const CCheckpointData& data) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    ~BlockManager()
    {
        Unload();
    }
};

//! Check whether the block associated with this index entry is pruned or not.
bool IsBlockPruned(const CBlockIndex* pblockindex) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

void CleanupBlockRevFiles();

/** Open a block file (blk?????.dat) */
FILE* OpenBlockFile(const FlatFilePos& pos, bool fReadOnly = false);
/** Translation to a filesystem path */
fs::path GetBlockPosFilename(const FlatFilePos& pos);

/**
 *  Actually unlink the specified files
 */
void UnlinkPrunedFiles(const std::set<int>& setFilesToPrune);

/** Functions for disk access for blocks */
bool ReadBlockFromDisk(CBlock& block, const FlatFilePos& pos, const Consensus::Params& consensusParams);
bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex, const Consensus::Params& consensusParams);
bool ReadRawBlockFromDisk(std::vector<uint8_t>& block, const FlatFilePos& pos, const CMessageHeader::MessageStartChars& message_start);
// ELEMENTS:

bool UndoReadFromDisk(CBlockUndo& blockundo, const CBlockIndex* pindex);

void ThreadImport(ChainstateManager& chainman, std::vector<fs::path> vImportFiles, const ArgsManager& args);
} // namespace node

#endif // BITCOIN_NODE_BLOCKSTORAGE_H
