text: // Copyright (c) 2014-2017, The Monero Project
  //
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  //
  // 2. Redistributions in binary form must reproduce the above copyright notice, this list
  //    of conditions and the following disclaimer in the documentation and/or other
  //    materials provided with the distribution.
  //
  // 3. Neither the name of the copyright holder nor the names of its contributors may be
  //    used to endorse or promote products derived from this software without specific
  //    prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
  
  #pragma once
  #include <boost/asio/io_service.hpp>
  #include <boost/serialization/serialization.hpp>
  #include <boost/serialization/version.hpp>
  #include <boost/serialization/list.hpp>
  #include <boost/multi_index_container.hpp>
  #include <boost/multi_index/global_fun.hpp>
  #include <boost/multi_index/hashed_index.hpp>
  #include <boost/multi_index/member.hpp>
  #include <atomic>
  #include <unordered_map>
  #include <unordered_set>
  
  #include "syncobj.h"
  #include "string_tools.h"
  #include "cryptonote_basic/cryptonote_basic.h"
  #include "common/util.h"
  #include "cryptonote_protocol/cryptonote_protocol_defs.h"
  #include "rpc/core_rpc_server_commands_defs.h"
  #include "cryptonote_basic/difficulty.h"
  #include "cryptonote_tx_utils.h"
  #include "cryptonote_basic/verification_context.h"
  #include "crypto/hash.h"
  #include "checkpoints/checkpoints.h"
  #include "cryptonote_basic/hardfork.h"
  #include "blockchain_db/blockchain_db.h"
  
  namespace cryptonote
  {
    class tx_memory_pool;
    struct test_options;
  
    /** Declares ways in which the BlockchainDB backend should be told to sync
     *
     */
    enum blockchain_db_sync_mode
    {
      db_defaultsync, //!< user didn't specify, use db_async
      db_sync,  //!< handle syncing calls instead of the backing db, synchronously
      db_async, //!< handle syncing calls instead of the backing db, asynchronously
      db_nosync //!< Leave syncing up to the backing db (safest, but slowest because of disk I/O)
    };
  
    /************************************************************************/
    /*                                                                      */
    /************************************************************************/
    class Blockchain
    {
    public:
      /**
       * @brief Now-defunct (TODO: remove) struct from in-memory blockchain
       */
      struct transaction_chain_entry
      {
        transaction tx;
        uint64_t m_keeper_block_height;
        size_t m_blob_size;
        std::vector<uint64_t> m_global_output_indexes;
      };
  
      /**
       * @brief container for passing a block and metadata about it on the blockchain
       */
      struct block_extended_info
      {
        block   bl; //!< the block
        uint64_t height; //!< the height of the block in the blockchain
        size_t block_cumulative_size; //!< the size (in bytes) of the block
        difficulty_type cumulative_difficulty; //!< the accumulated difficulty after that block
        uint64_t already_generated_coins; //!< the total coins minted after that block
      };
  
      /**
       * @brief Blockchain constructor
       *
       * @param tx_pool a reference to the transaction pool to be kept by the Blockchain
       */
      Blockchain(tx_memory_pool& tx_pool);
  
      /**
       * @brief Initialize the Blockchain state
       *
       * @param db a pointer to the backing store to use for the blockchain
       * @param testnet true if on testnet, else false
       * @param offline true if running offline, else false
       * @param test_options test parameters
       *
       * @return true on success, false if any initialization steps fail
       */
      bool init(BlockchainDB* db, const bool testnet = false, bool offline = false, const cryptonote::test_options *test_options = NULL);
  
      /**
       * @brief Initialize the Blockchain state
       *
       * @param db a pointer to the backing store to use for the blockchain
       * @param hf a structure containing hardfork information
       * @param testnet true if on testnet, else false
       * @param offline true if running offline, else false
       *
       * @return true on success, false if any initialization steps fail
       */
      bool init(BlockchainDB* db, HardFork*& hf, const bool testnet = false, bool offline = false);
  
      /**
       * @brief Uninitializes the blockchain state
       *
       * Saves to disk any state that needs to be maintained
       *
       * @return true on success, false if any uninitialization steps fail
       */
      bool deinit();
  
      /**
       * @brief assign a set of blockchain checkpoint hashes
       *
       * @param chk_pts the set of checkpoints to assign
       */
      void set_checkpoints(checkpoints&& chk_pts) { m_checkpoints = chk_pts; }
  
      /**
       * @brief get blocks and transactions from blocks based on start height and count
       *
       * @param start_offset the height on the blockchain to start at
       * @param count the number of blocks to get, if there are as many after start_offset
       * @param blocks return-by-reference container to put result blocks in
       * @param txs return-by-reference container to put result transactions in
       *
       * @return false if start_offset > blockchain height, else true
       */
      bool get_blocks(uint64_t start_offset, size_t count, std::list<std::pair<cryptonote::blobdata,block>>& blocks, std::list<cryptonote::blobdata>& txs) const;
  
      /**
       * @brief get blocks from blocks based on start height and count
       *
       * @param start_offset the height on the blockchain to start at
       * @param count the number of blocks to get, if there are as many after start_offset
       * @param blocks return-by-reference container to put result blocks in
       *
       * @return false if start_offset > blockchain height, else true
       */
      bool get_blocks(uint64_t start_offset, size_t count, std::list<std::pair<cryptonote::blobdata,block>>& blocks) const;
  
      /**
       * @brief compiles a list of all blocks stored as alternative chains
       *
       * @param blocks return-by-reference container to put result blocks in
       *
       * @return true
       */
      bool get_alternative_blocks(std::list<block>& blocks) const;
  
      /**
       * @brief returns the number of alternative blocks stored
       *
       * @return the number of alternative blocks stored
       */
      size_t get_alternative_blocks_count() const;
  
      /**
       * @brief gets a block's hash given a height
       *
       * @param height the height of the block
       *
       * @return the hash of the block at the requested height, or a zeroed hash if there is no such block
       */
      crypto::hash get_block_id_by_height(uint64_t height) const;
  
      /**
       * @brief gets the block with a given hash
       *
       * @param h the hash to look for
       * @param blk return-by-reference variable to put result block in
       * @param orphan if non-NULL, will be set to true if not in the main chain, false otherwise
       *
       * @return true if the block was found, else false
       */
      bool get_block_by_hash(const crypto::hash &h, block &blk, bool *orphan = NULL) const;
  
      /**
       * @brief get all block hashes (main chain, alt chains, and invalid blocks)
       *
       * @param main return-by-reference container to put result main chain blocks' hashes in
       * @param alt return-by-reference container to put result alt chain blocks' hashes in
       * @param invalid return-by-reference container to put result invalid blocks' hashes in
       */
      void get_all_known_block_ids(std::list<crypto::hash> &main, std::list<crypto::hash> &alt, std::list<crypto::hash> &invalid) const;
  
      /**
       * @brief performs some preprocessing on a group of incoming blocks to speed up verification
       *
       * @param blocks a list of incoming blocks
       *
       * @return false on erroneous blocks, else true
       */
      bool prepare_handle_incoming_blocks(const std::list<block_complete_entry>  &blocks);
  
      /**
       * @brief incoming blocks post-processing, cleanup, and disk sync
       *
       * @param force_sync if true, and Blockchain is handling syncing to disk, always sync
       *
       * @return true
       */
      bool cleanup_handle_incoming_blocks(bool force_sync = false);
  
      /**
       * @brief search the blockchain for a transaction by hash
       *
       * @param id the hash to search for
       *
       * @return true if the tx exists, else false
       */
      bool have_tx(const crypto::hash &id) const;
  
      /**
       * @brief check if any key image in a transaction has already been spent
       *
       * @param tx the transaction to check
       *
       * @return true if any key image is already spent in the blockchain, else false
       */
      bool have_tx_keyimges_as_spent(const transaction &tx) const;
  
      /**
       * @brief check if a key image is already spent on the blockchain
       *
       * Whenever a transaction output is used as an input for another transaction
       * (a true input, not just one of a mixing set), a key image is generated
       * and stored in the transaction in order to prevent double spending.  If
       * this key image is seen again, the transaction using it is rejected.
       *
       * @param key_im the key image to search for
       *
       * @return true if the key image is already spent in the blockchain, else false
       */
      bool have_tx_keyimg_as_spent(const crypto::key_image &key_im) const;
  
      /**
       * @brief get the current height of the blockchain
       *
       * @return the height
       */
      uint64_t get_current_blockchain_height() const;
  
      /**
       * @brief get the hash of the most recent block on the blockchain
       *
       * @return the hash
       */
      crypto::hash get_tail_id() const;
  
      /**
       * @brief get the height and hash of the most recent block on the blockchain
       *
       * @param height return-by-reference variable to store the height in
       *
       * @return the hash
       */
      crypto::hash get_tail_id(uint64_t& height) const;
  
      /**
       * @brief returns the difficulty target the next block to be added must meet
       *
       * @return the target
       */
      difficulty_type get_difficulty_for_next_block();
  
      /**
       * @brief adds a block to the blockchain
       *
       * Adds a new block to the blockchain.  If the block's parent is not the
       * current top of the blockchain, the block may be added to an alternate
       * chain.  If the block does not belong, is already in the blockchain
       * or an alternate chain, or is invalid, return false.
       *
       * @param bl_ the block to be added
       * @param bvc metadata about the block addition's success/failure
       *
       * @return true on successful addition to the blockchain, else false
       */
      bool add_new_block(const block& bl_, block_verification_context& bvc);
  
      /**
       * @brief clears the blockchain and starts a new one
       *
       * @param b the first block in the new chain (the genesis block)
       *
       * @return true on success, else false
       */
      bool reset_and_set_genesis_block(const block& b);
  
      /**
       * @brief creates a new block to mine against
       *
       * @param b return-by-reference block to be filled in
       * @param miner_address address new coins for the block will go to
       * @param di return-by-reference tells the miner what the difficulty target is
       * @param height return-by-reference tells the miner what height it's mining against
       * @param expected_reward return-by-reference the total reward awarded to the miner finding this block, including transaction fees
       * @param ex_nonce extra data to be added to the miner transaction's extra
       *
       * @return true if block template filled in successfully, else false
       */
      bool create_block_template(block& b, const account_public_address& miner_address, difficulty_type& di, uint64_t& height, uint64_t& expected_reward, const blobdata& ex_nonce);
  
      /**
       * @brief checks if a block is known about with a given hash
       *
       * This function checks the main chain, alternate chains, and invalid blocks
       * for a block with the given hash
       *
       * @param id the hash to search for
       *
       * @return true if the block is known, else false
       */
      bool have_block(const crypto::hash& id) const;
  
      /**
       * @brief gets the total number of transactions on the main chain
       *
       * @return the number of transactions on the main chain
       */
      size_t get_total_transactions() const;
  
      /**
       * @brief gets the hashes for a subset of the blockchain
       *
       * puts into list <ids> a list of hashes representing certain blocks
       * from the blockchain in reverse chronological order
       *
       * the blocks chosen, at the time of this writing, are:
       *   the most recent 11
       *   powers of 2 less recent from there, so 13, 17, 25, etc...
       *
       * @param ids return-by-reference list to put the resulting hashes in
       *
       * @return true
       */
      bool get_short_chain_history(std::list<crypto::hash>& ids) const;
  
      /**
       * @brief get recent block hashes for a foreign chain
       *
       * Find the split point between us and foreign blockchain and return
       * (by reference) the most recent common block hash along with up to
       * BLOCKS_IDS_SYNCHRONIZING_DEFAULT_COUNT additional (more recent) hashes.
       *
       * @param qblock_ids the foreign chain's "short history" (see get_short_chain_history)
       * @param hashes the hashes to be returned, return-by-reference
       * @param start_height the start height, return-by-reference
       * @param current_height the current blockchain height, return-by-reference
       *
       * @return true if a block found in common, else false
       */
      bool find_blockchain_supplement(const std::list<crypto::hash>& qblock_ids, std::list<crypto::hash>& hashes, uint64_t& start_height, uint64_t& current_height) const;
  
      /**
       * @brief get recent block hashes for a foreign chain
       *
       * Find the split point between us and foreign blockchain and return
       * (by reference) the most recent common block hash along with up to
       * BLOCKS_IDS_SYNCHRONIZING_DEFAULT_COUNT additional (more recent) hashes.
       *
       * @param qblock_ids the foreign chain's "short history" (see get_short_chain_history)
       * @param resp return-by-reference the split height and subsequent blocks' hashes
       *
       * @return true if a block found in common, else false
       */
      bool find_blockchain_supplement(const std::list<crypto::hash>& qblock_ids, NOTIFY_RESPONSE_CHAIN_ENTRY::request& resp) const;
  
      /**
       * @brief find the most recent common point between ours and a foreign chain
       *
       * This function takes a list of block hashes from another node
       * on the network to find where the split point is between us and them.
       * This is used to see what to send another node that needs to sync.
       *
       * @param qblock_ids the foreign chain's "short history" (see get_short_chain_history)
       * @param starter_offset return-by-reference the most recent common block's height
       *
       * @return true if a block found in common, else false
       */
      bool find_blockchain_supplement(const std::list<crypto::hash>& qblock_ids, uint64_t& starter_offset) const;
  
      /**
       * @brief get recent blocks for a foreign chain
       *
       * This function gets recent blocks relative to a foreign chain, starting either at
       * a requested height or whatever height is the most recent ours and the foreign
       * chain have in common.
       *
       * @param req_start_block if non-zero, specifies a start point (otherwise find most recent commonality)
       * @param qblock_ids the foreign chain's "short history" (see get_short_chain_history)
       * @param blocks return-by-reference the blocks and their transactions
       * @param total_height return-by-reference our current blockchain height
       * @param start_height return-by-reference the height of the first block returned
       * @param max_count the max number of blocks to get
       *
       * @return true if a block found in common or req_start_block specified, else false
       */
      bool find_blockchain_supplement(const uint64_t req_start_block, const std::list<crypto::hash>& qblock_ids, std::list<std::pair<cryptonote::blobdata, std::list<cryptonote::blobdata> > >& blocks, uint64_t& total_height, uint64_t& start_height, size_t max_count) const;
  
      /**
       * @brief retrieves a set of blocks and their transactions, and possibly other transactions
       *
       * the request object encapsulates a list of block hashes and a (possibly empty) list of
       * transaction hashes.  for each block hash, the block is fetched along with all of that
       * block's transactions.  Any transactions requested separately are fetched afterwards.
       *
       * @param arg the request
       * @param rsp return-by-reference the response to fill in
       *
       * @return true unless any blocks or transactions are missing
       */
      bool handle_get_objects(NOTIFY_REQUEST_GET_OBJECTS::request& arg, NOTIFY_RESPONSE_GET_OBJECTS::request& rsp);
  
      /**
       * @brief get number of outputs of an amount past the minimum spendable age
       *
       * @param amount the output amount
       *
       * @return the number of mature outputs
       */
      uint64_t get_num_mature_outputs(uint64_t amount) const;
  
      /**
       * @brief get random outputs (indices) for an amount
       *
       * @param amount the amount
       * @param count the number of random outputs to choose
       *
       * @return the outputs' amount-global indices
       */
      std::vector<uint64_t> get_random_outputs(uint64_t amount, uint64_t count) const;
  
      /**
       * @brief get the public key for an output
       *
       * @param amount the output amount
       * @param global_index the output amount-global index
       *
       * @return the public key
       */
      crypto::public_key get_output_key(uint64_t amount, uint64_t global_index) const;
  
      /**
       * @brief gets random outputs to mix with
       *
       * This function takes an RPC request for outputs to mix with
       * and creates an RPC response with the resultant output indices.
       *
       * Outputs to mix with are randomly selected from the utxo set
       * for each output amount in the request.
       *
       * @param req the output amounts and number of mixins to select
       * @param res return-by-reference the resultant output indices
       *
       * @return true
       */
      bool get_random_outs_for_amounts(const COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::request& req, COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::response& res) const;
  
      /**
       * @brief gets specific outputs to mix with
       *
       * This function takes an RPC request for outputs to mix with
       * and creates an RPC response with the resultant output indices.
       *
       * Outputs to mix with are specified in the request.
       *
       * @param req the outputs to return
       * @param res return-by-reference the resultant output indices and keys
       *
       * @return true
       */
      bool get_outs(const COMMAND_RPC_GET_OUTPUTS_BIN::request& req, COMMAND_RPC_GET_OUTPUTS_BIN::response& res) const;
  
      /**
       * @brief gets an output's key and unlocked state
       *
       * @param amount in - the output amount
       * @param index in - the output global amount index
       * @param mask out - the output's RingCT mask
       * @param key out - the output's key
       * @param unlocked out - the output's unlocked state
       */
      void get_output_key_mask_unlocked(const uint64_t& amount, const uint64_t& index, crypto::public_key& key, rct::key& mask, bool& unlocked) const;
  
      /**
       * @brief gets random ringct outputs to mix with
       *
       * This function takes an RPC request for outputs to mix with
       * and creates an RPC response with the resultant output indices
       * and the matching keys.
       *
       * Outputs to mix with are randomly selected from the utxo set
       * for each output amount in the request.
       *
       * @param req the output amounts and number of mixins to select
       * @param res return-by-reference the resultant output indices
       *
       * @return true
       */
      bool get_random_rct_outs(const COMMAND_RPC_GET_RANDOM_RCT_OUTPUTS::request& req, COMMAND_RPC_GET_RANDOM_RCT_OUTPUTS::response& res) const;
  
      /**
       * @brief gets the global indices for outputs from a given transaction
       *
       * This function gets the global indices for all outputs belonging
       * to a specific transaction.
       *
       * @param tx_id the hash of the transaction to fetch indices for
       * @param indexs return-by-reference the global indices for the transaction's outputs
       *
       * @return false if the transaction does not exist, or if no indices are found, otherwise true
       */
      bool get_tx_outputs_gindexs(const crypto::hash& tx_id, std::vector<uint64_t>& indexs) const;
  
      /**
       * @brief stores the blockchain
       *
       * If Blockchain is handling storing of the blockchain (rather than BlockchainDB),
       * this initiates a blockchain save.
       *
       * @return true unless saving the blockchain fails
       */
      bool store_blockchain();
  
      /**
       * @brief validates a transaction's inputs
       *
       * validates a transaction's inputs as correctly used and not previously
       * spent.  also returns the hash and height of the most recent block
       * which contains an output that was used as an input to the transaction.
       * The transaction's rct signatures, if any, are expanded.
       *
       * @param tx the transaction to validate
       * @param pmax_used_block_height return-by-reference block height of most recent input
       * @param max_used_block_id return-by-reference block hash of most recent input
       * @param tvc returned information about tx verification
       * @param kept_by_block whether or not the transaction is from a previously-verified block
       *
       * @return false if any input is invalid, otherwise true
       */
      bool check_tx_inputs(transaction& tx, uint64_t& pmax_used_block_height, crypto::hash& max_used_block_id, tx_verification_context &tvc, bool kept_by_block = false);
  
      /**
       * @brief get dynamic per kB fee for a given block size
       *
       * The dynamic fee is based on the block size in a past window, and
       * the current block reward. It is expressed by kB.
       *
       * @param block_reward the current block reward
       * @param median_block_size the median blob's size in the past window
       * @param version hard fork version for rules and constants to use
       *
       * @return the per kB fee
       */
      static uint64_t get_dynamic_per_kb_fee(uint64_t block_reward, size_t median_block_size, uint8_t version);
  
      /**
       * @brief get dynamic per kB fee estimate for the next few blocks
       *
       * The dynamic fee is based on the block size in a past window, and
       * the current block reward. It is expressed by kB. This function
       * calculates an estimate for a dynamic fee which will be valid for
       * the next grace_blocks
       *
       * @param grace_blocks number of blocks we want the fee to be valid for
       *
       * @return the per kB fee estimate
       */
      uint64_t get_dynamic_per_kb_fee_estimate(uint64_t grace_blocks) const;
  
      /**
       * @brief validate a transaction's fee
       *
       * This function validates the fee is enough for the transaction.
       * This is based on the size of the transaction blob, and, after a
       * height threshold, on the average size of transaction in a past window
       *
       * @param blob_size the transaction blob's size
       * @param fee the fee
       *
       * @return true if the fee is enough, false otherwise
       */
      bool check_fee(size_t blob_size, uint64_t fee) const;
  
      /**
       * @brief check that a transaction's outputs conform to current standards
       *
       * This function checks, for example at the time of this writing, that
       * each output is of the form a * 10^b (phrased differently, that if
       * written out would have only one non-zero digit in base 10).
       *
       * @param tx the transaction to check the outputs of
       * @param tvc returned info about tx verification
       *
       * @return false if any outputs do not conform, otherwise true
       */
      bool check_tx_outputs(const transaction& tx, tx_verification_context &tvc);
  
      /**
       * @brief gets the blocksize limit based on recent blocks
       *
       * @return the limit
       */
      uint64_t get_current_cumulative_blocksize_limit() const;
  
      /**
       * @brief gets the difficulty of the block with a given height
       *
       * @param i the height
       *
       * @return the difficulty
       */
      uint64_t block_difficulty(uint64_t i) const;
  
      /**
       * @brief gets blocks based on a list of block hashes
       *
       * @tparam t_ids_container a standard-iterable container
       * @tparam t_blocks_container a standard-iterable container
       * @tparam t_missed_container a standard-iterable container
       * @param block_ids a container of block hashes for which to get the corresponding blocks
       * @param blocks return-by-reference a container to store result blocks in
       * @param missed_bs return-by-reference a container to store missed blocks in
       *
       * @return false if an unexpected exception occurs, else true
       */
      template<class t_ids_container, class t_blocks_container, class t_missed_container>
      bool get_blocks(const t_ids_container& block_ids, t_blocks_container& blocks, t_missed_container& missed_bs) const;
  
      /**
       * @brief gets transactions based on a list of transaction hashes
       *
       * @tparam t_ids_container a standard-iterable container
       * @tparam t_tx_container a standard-iterable container
       * @tparam t_missed_container a standard-iterable container
       * @param txs_ids a container of hashes for which to get the corresponding transactions
       * @param txs return-by-reference a container to store result transactions in
       * @param missed_txs return-by-reference a container to store missed transactions in
       *
       * @return false if an unexpected exception occurs, else true
       */
      template<class t_ids_container, class t_tx_container, class t_missed_container>
      bool get_transactions_blobs(const t_ids_container& txs_ids, t_tx_container& txs, t_missed_container& missed_txs) const;
      template<class t_ids_container, class t_tx_container, class t_missed_container>
      bool get_transactions(const t_ids_container& txs_ids, t_tx_container& txs, t_missed_container& missed_txs) const;
  
      //debug functions
  
      /**
       * @brief prints data about a snippet of the blockchain
       *
       * if start_index is greater than the blockchain height, do nothing
       *
       * @param start_index height on chain to start at
       * @param end_index height on chain to end at
       */
      void print_blockchain(uint64_t start_index, uint64_t end_index) const;
  
      /**
       * @brief prints every block's hash
       *
       * WARNING: This function will absolutely crush a terminal in prints, so
       * it is recommended to redirect this output to a log file (or null sink
       * if a log file is already set up, as should be the default)
       */
      void print_blockchain_index() const;
  
      /**
       * @brief currently does nothing, candidate for removal
       *
       * @param file
       */
      void print_blockchain_outs(const std::string& file) const;
  
      /**
       * @brief check the blockchain against a set of checkpoints
       *
       * If a block fails a checkpoint and enforce is enabled, the blockchain
       * will be rolled back to two blocks prior to that block.  If enforce
       * is disabled, as is currently the default case with DNS-based checkpoints,
       * an error will be printed to the user but no other action will be taken.
       *
       * @param points the checkpoints to check against
       * @param enforce whether or not to take action on failure
       */
      void check_against_checkpoints(const checkpoints& points, bool enforce);
  
      /**
       * @brief configure whether or not to enforce DNS-based checkpoints
       *
       * @param enforce the new enforcement setting
       */
      void set_enforce_dns_checkpoints(bool enforce);
  
      /**
       * @brief loads new checkpoints from a file and optionally from DNS
       *
       * @param file_path the path of the file to look for and load checkpoints from
       * @param check_dns whether or not to check for new DNS-based checkpoints
       *
       * @return false if any enforced checkpoint type fails to load, otherwise true
       */
      bool update_checkpoints(const std::string& file_path, bool check_dns);
  
  
      // user options, must be called before calling init()
  
      /**
       * @brief sets various performance options
       *
       * @param maxthreads max number of threads when preparing blocks for addition
       * @param blocks_per_sync number of blocks to cache before syncing to database
       * @param sync_mode the ::blockchain_db_sync_mode to use
       * @param fast_sync sync using built-in block hashes as trusted
       */
      void set_user_options(uint64_t maxthreads, uint64_t blocks_per_sync,
          blockchain_db_sync_mode sync_mode, bool fast_sync);
  
      /**
       * @brief Put DB in safe sync mode
       */
      void safesyncmode(const bool onoff);
  
      /**
       * @brief set whether or not to show/print time statistics
       *
       * @param stats the new time stats setting
       */
      void set_show_time_stats(bool stats) { m_show_time_stats = stats; }
  
      /**
       * @brief gets the hardfork voting state object
       *
       * @return the HardFork object
       */
      HardFork::State get_hard_fork_state() const;
  
      /**
       * @brief gets the current hardfork version in use/voted for
       *
       * @return the version
       */
      uint8_t get_current_hard_fork_version() const { return m_hardfork->get_current_version(); }
  
      /**
       * @brief returns the newest hardfork version known to the blockchain
       *
       * @return the version
       */
      uint8_t get_ideal_hard_fork_version() const { return m_hardfork->get_ideal_version(); }
  
      /**
       * @brief returns the next hardfork version
       *
       * @return the version
       */
      uint8_t get_next_hard_fork_version() const { return m_hardfork->get_next_version(); }
  
      /**
       * @brief returns the newest hardfork version voted to be enabled
       * as of a certain height
       *
       * @param height the height for which to check version info
       *
       * @return the version
       */
      uint8_t get_ideal_hard_fork_version(uint64_t height) const { return m_hardfork->get_ideal_version(height); }
  
      /**
       * @brief returns the actual hardfork version for a given block height
       *
       * @param height the height for which to check version info
       *
       * @return the version
       */
      uint8_t get_hard_fork_version(uint64_t height) const { return m_hardfork->get(height); }
  
      /**
       * @brief get information about hardfork voting for a version
       *
       * @param version the version in question
       * @param window the size of the voting window
       * @param votes the number of votes to enable <version>
       * @param threshold the number of votes required to enable <version>
       * @param earliest_height the earliest height at which <version> is allowed
       * @param voting which version this node is voting for/using
       *
       * @return whether the version queried is enabled 
       */
      bool get_hard_fork_voting_info(uint8_t version, uint32_t &window, uint32_t &votes, uint32_t &threshold, uint64_t &earliest_height, uint8_t &voting) const;
  
      /**
       * @brief get difficulty target based on chain and hardfork version
       *
       * @return difficulty target
       */
      uint64_t get_difficulty_target() const;
  
      /**
       * @brief remove transactions from the transaction pool (if present)
       *
       * @param txids a list of hashes of transactions to be removed
       *
       * @return false if any removals fail, otherwise true
       */
      bool flush_txes_from_pool(const std::list<crypto::hash> &txids);
  
      /**
       * @brief return a histogram of outputs on the blockchain
       *
       * @param amounts optional set of amounts to lookup
       * @param unlocked whether to restrict instances to unlocked ones
       * @param recent_cutoff timestamp to consider outputs as recent
       *
       * @return a set of amount/instances
       */
      std::map<uint64_t, std::tuple<uint64_t, uint64_t, uint64_t>> get_output_histogram(const std::vector<uint64_t> &amounts, bool unlocked, uint64_t recent_cutoff) const;
  
      /**
       * @brief perform a check on all key images in the blockchain
       *
       * @param std::function the check to perform, pass/fail
       *
       * @return false if any key image fails the check, otherwise true
       */
      bool for_all_key_images(std::function<bool(const crypto::key_image&)>) const;
  
      /**
       * @brief perform a check on all blocks in the blockchain in the given range
       *
       * @param h1 the start height
       * @param h2 the end height
       * @param std::function the check to perform, pass/fail
       *
       * @return false if any block fails the check, otherwise true
       */
      bool for_blocks_range(const uint64_t& h1, const uint64_t& h2, std::function<bool(uint64_t, const crypto::hash&, const block&)>) const;
  
      /**
       * @brief perform a check on all transactions in the blockchain
       *
       * @param std::function the check to perform, pass/fail
       *
       * @return false if any transaction fails the check, otherwise true
       */
      bool for_all_transactions(std::function<bool(const crypto::hash&, const cryptonote::transaction&)>) const;
  
      /**
       * @brief perform a check on all outputs in the blockchain
       *
       * @param std::function the check to perform, pass/fail
       *
       * @return false if any output fails the check, otherwise true
       */
      bool for_all_outputs(std::function<bool(uint64_t amount, const crypto::hash &tx_hash, size_t tx_idx)>) const;
  
      /**
       * @brief get a reference to the BlockchainDB in use by Blockchain
       *
       * @return a reference to the BlockchainDB instance
       */
      const BlockchainDB& get_db() const
      {
        return *m_db;
      }
  
      /**
       * @brief get a reference to the BlockchainDB in use by Blockchain
       *
       * @return a reference to the BlockchainDB instance
       */
      BlockchainDB& get_db()
      {
        return *m_db;
      }
  
      /**
       * @brief get a number of outputs of a specific amount
       *
       * @param amount the amount
       * @param offsets the indices (indexed to the amount) of the outputs
       * @param outputs return-by-reference the outputs collected
       * @param txs unused, candidate for removal
       */
      void output_scan_worker(const uint64_t amount,const std::vector<uint64_t> &offsets,
          std::vector<output_data_t> &outputs, std::unordered_map<crypto::hash,
          cryptonote::transaction> &txs) const;
  
      /**
       * @brief computes the "short" and "long" hashes for a set of blocks
       *
       * @param height the height of the first block
       * @param blocks the blocks to be hashed
       * @param map return-by-reference the hashes for each block
       */
      void block_longhash_worker(uint64_t height, const std::vector<block> &blocks,
          std::unordered_map<crypto::hash, crypto::hash> &map) const;
  
      /**
       * @brief returns a set of known alternate chains
       *
       * @return a list of chains
       */
      std::list<std::pair<block_extended_info,uint64_t>> get_alternative_chains() const;
  
      void add_txpool_tx(transaction &tx, const txpool_tx_meta_t &meta);
      void update_txpool_tx(const crypto::hash &txid, const txpool_tx_meta_t &meta);
      void remove_txpool_tx(const crypto::hash &txid);
      uint64_t get_txpool_tx_count(bool include_unrelayed_txes = true) const;
      txpool_tx_meta_t get_txpool_tx_meta(const crypto::hash& txid) const;
      bool get_txpool_tx_blob(const crypto::hash& txid, cryptonote::blobdata &bd) const;
      cryptonote::blobdata get_txpool_tx_blob(const crypto::hash& txid) const;
      bool for_all_txpool_txes(std::function<bool(const crypto::hash&, const txpool_tx_meta_t&, const cryptonote::blobdata*)>, bool include_blob = false, bool include_unrelayed_txes = true) const;
  
      bool is_within_compiled_block_hash_area(uint64_t height) const;
      bool is_within_compiled_block_hash_area() const { return is_within_compiled_block_hash_area(m_db->height()); }
      uint64_t prevalidate_block_hashes(uint64_t height, const std::list<crypto::hash> &hashes);
  
      void lock();
      void unlock();
  
      void cancel();
  
      /**
       * @brief called when we see a tx originating from a block
       *
       * Used for handling txes from historical blocks in a fast way
       */
      void on_new_tx_from_block(const cryptonote::transaction &tx);
  
    private:
  
      // TODO: evaluate whether or not each of these typedefs are left over from blockchain_storage
      typedef std::unordered_map<crypto::hash, size_t> blocks_by_id_index;
  
      typedef std::unordered_map<crypto::hash, transaction_chain_entry> transactions_container;
  
      typedef std::unordered_set<crypto::key_image> key_images_container;
  
      typedef std::vector<block_extended_info> blocks_container;
  
      typedef std::unordered_map<crypto::hash, block_extended_info> blocks_ext_by_hash;
  
      typedef std::unordered_map<crypto::hash, block> blocks_by_hash;
  
      typedef std::map<uint64_t, std::vector<std::pair<crypto::hash, size_t>>> outputs_container; //crypto::hash - tx hash, size_t - index of out in transaction
  
  
      BlockchainDB* m_db;
  
      tx_memory_pool& m_tx_pool;
  
      mutable epee::critical_section m_blockchain_lock; // TODO: add here reader/writer lock
  
      // main chain
      transactions_container m_transactions;
      size_t m_current_block_cumul_sz_limit;
  
      // metadata containers
      std::unordered_map<crypto::hash, std::unordered_map<crypto::key_image, std::vector<output_data_t>>> m_scan_table;
      std::unordered_map<crypto::hash, crypto::hash> m_blocks_longhash_table;
      std::unordered_map<crypto::hash, std::unordered_map<crypto::key_image, bool>> m_check_txin_table;
  
      // SHA-3 hashes for each block and for fast pow checking
      std::vector<crypto::hash> m_blocks_hash_of_hashes;
      std::vector<crypto::hash> m_blocks_hash_check;
      std::vector<crypto::hash> m_blocks_txs_check;
  
      blockchain_db_sync_mode m_db_sync_mode;
      bool m_fast_sync;
      bool m_show_time_stats;
      bool m_db_default_sync;
      uint64_t m_db_blocks_per_sync;
      uint64_t m_max_prepare_blocks_threads;
      uint64_t m_fake_pow_calc_time;
      uint64_t m_fake_scan_time;
      uint64_t m_sync_counter;
      std::vector<uint64_t> m_timestamps;
      std::vector<difficulty_type> m_difficulties;
      uint64_t m_timestamps_and_difficulties_height;
  
      boost::asio::io_service m_async_service;
      boost::thread_group m_async_pool;
      std::unique_ptr<boost::asio::io_service::work> m_async_work_idle;
  
      // all alternative chains
      blocks_ext_by_hash m_alternative_chains; // crypto::hash -> block_extended_info
  
      // some invalid blocks
      blocks_ext_by_hash m_invalid_blocks;     // crypto::hash -> block_extended_info
  
  
      checkpoints m_checkpoints;
      bool m_enforce_dns_checkpoints;
  
      HardFork *m_hardfork;
  
      bool m_testnet;
      bool m_offline;
  
      std::atomic<bool> m_cancel;
  
      /**
       * @brief collects the keys for all outputs being "spent" as an input
       *
       * This function makes sure that each "input" in an input (mixins) exists
       * and collects the public key for each from the transaction it was included in
       * via the visitor passed to it.
       *
       * If pmax_related_block_height is not NULL, its value is set to the height
       * of the most recent block which contains an output used in the input set
       *
       * @tparam visitor_t a class encapsulating tx is unlocked and collect tx key
       * @param tx_in_to_key a transaction input instance
       * @param vis an instance of the visitor to use
       * @param tx_prefix_hash the hash of the associated transaction_prefix
       * @param pmax_related_block_height return-by-pointer the height of the most recent block in the input set
       * @param tx_version version of the tx, if > 1 we also get commitments
       *
       * @return false if any keys are not found or any inputs are not unlocked, otherwise true
       */
      template<class visitor_t>
      inline bool scan_outputkeys_for_indexes(size_t tx_version, const txin_to_key& tx_in_to_key, visitor_t &vis, const crypto::hash &tx_prefix_hash, uint64_t* pmax_related_block_height = NULL) const;
  
      /**
       * @brief collect output public keys of a transaction input set
       *
       * This function locates all outputs associated with a given input set (mixins)
       * and validates that they exist and are usable
       * (unlocked, unspent is checked elsewhere).
       *
       * If pmax_related_block_height is not NULL, its value is set to the height
       * of the most recent block which contains an output used in the input set
       *
       * @param tx_version the transaction version
       * @param txin the transaction input
       * @param tx_prefix_hash the transaction prefix hash, for caching organization
       * @param sig the input signature
       * @param output_keys return-by-reference the public keys of the outputs in the input set
       * @param rct_signatures the ringCT signatures, which are only valid if tx version > 1
       * @param pmax_related_block_height return-by-pointer the height of the most recent block in the input set
       *
       * @return false if any output is not yet unlocked, or is missing, otherwise true
       */
      bool check_tx_input(size_t tx_version,const txin_to_key& txin, const crypto::hash& tx_prefix_hash, const std::vector<crypto::signature>& sig, const rct::rctSig &rct_signatures, std::vector<rct::ctkey> &output_keys, uint64_t* pmax_related_block_height);
  
      /**
       * @brief validate a transaction's inputs and their keys
       *
       * This function validates transaction inputs and their keys.  Previously
       * it also performed double spend checking, but that has been moved to its
       * own function.
       * The transaction's rct signatures, if any, are expanded.
       *
       * If pmax_related_block_height is not NULL, its value is set to the height
       * of the most recent block which contains an output used in any input set
       *
       * Currently this function calls ring signature validation for each
       * transaction.
       *
       * @param tx the transaction to validate
       * @param tvc returned information about tx verification
       * @param pmax_related_block_height return-by-pointer the height of the most recent block in the input set
       *
       * @return false if any validation step fails, otherwise true
       */
      bool check_tx_inputs(transaction& tx, tx_verification_context &tvc, uint64_t* pmax_used_block_height = NULL);
  
      /**
       * @brief performs a blockchain reorganization according to the longest chain rule
       *
       * This function aggregates all the actions necessary to switch to a
       * newly-longer chain.  If any step in the reorganization process fails,
       * the blockchain is reverted to its previous state.
       *
       * @param alt_chain the chain to switch to
       * @param discard_disconnected_chain whether or not to keep the old chain as an alternate
       *
       * @return false if the reorganization fails, otherwise true
       */
      bool switch_to_alternative_blockchain(std::list<blocks_ext_by_hash::iterator>& alt_chain, bool discard_disconnected_chain);
  
      /**
       * @brief removes the most recent block from the blockchain
       *
       * @return the block removed
       */
      block pop_block_from_blockchain();
  
      /**
       * @brief validate and add a new block to the end of the blockchain
       *
       * This function is merely a convenience wrapper around the other
       * of the same name.  This one passes the block's hash to the other
       * as well as the block and verification context.
       *
       * @param bl the block to be added
       * @param bvc metadata concerning the block's validity
       *
       * @return true if the block was added successfully, otherwise false
       */
      bool handle_block_to_main_chain(const block& bl, block_verification_context& bvc);
  
      /**
       * @brief validate and add a new block to the end of the blockchain
       *
       * When a block is given to Blockchain to be added to the blockchain, it
       * is passed here if it is determined to belong at the end of the current
       * chain.
       *
       * @param bl the block to be added
       * @param id the hash of the block
       * @param bvc metadata concerning the block's validity
       *
       * @return true if the block was added successfully, otherwise false
       */
      bool handle_block_to_main_chain(const block& bl, const crypto::hash& id, block_verification_context& bvc);
  
      /**
       * @brief validate and add a new block to an alternate blockchain
       *
       * If a block to be added does not belong to the main chain, but there
       * is an alternate chain to which it should be added, that is handled
       * here.
       *
       * @param b the block to be added
       * @param id the hash of the block
       * @param bvc metadata concerning the block's validity
       *
       * @return true if the block was added successfully, otherwise false
       */
      bool handle_alternative_block(const block& b, const crypto::hash& id, block_verification_context& bvc);
  
      /**
       * @brief gets the difficulty requirement for a new block on an alternate chain
       *
       * @param alt_chain the chain to be added to
       * @param bei the block being added (and metadata, see ::block_extended_info)
       *
       * @return the difficulty requirement
       */
      difficulty_type get_next_difficulty_for_alternative_chain(const std::list<blocks_ext_by_hash::iterator>& alt_chain, block_extended_info& bei) const;
  
      /**
       * @brief sanity checks a miner transaction before validating an entire block
       *
       * This function merely checks basic things like the structure of the miner
       * transaction, the unlock time, and that the amount doesn't overflow.
       *
       * @param b the block containing the miner transaction
       * @param height the height at which the block will be added
       *
       * @return false if anything is found wrong with the miner transaction, otherwise true
       */
      bool prevalidate_miner_transaction(const block& b, uint64_t height);
  
      /**
       * @brief validates a miner (coinbase) transaction
       *
       * This function makes sure that the miner calculated his reward correctly
       * and that his miner transaction totals reward + fee.
       *
       * @param b the block containing the miner transaction to be validated
       * @param cumulative_block_size the block's size
       * @param fee the total fees collected in the block
       * @param base_reward return-by-reference the new block's generated coins
       * @param already_generated_coins the amount of currency generated prior to this block
       * @param partial_block_reward return-by-reference true if miner accepted only partial reward
       * @param version hard fork version for that transaction
       *
       * @return false if anything is found wrong with the miner transaction, otherwise true
       */
      bool validate_miner_transaction(const block& b, size_t cumulative_block_size, uint64_t fee, uint64_t& base_reward, uint64_t already_generated_coins, bool &partial_block_reward, uint8_t version);
  
      /**
       * @brief reverts the blockchain to its previous state following a failed switch
       *
       * If Blockchain fails to switch to an alternate chain when it means
       * to do so, this function reverts the blockchain to how it was before
       * the attempted switch.
       *
       * @param original_chain the chain to switch back to
       * @param rollback_height the height to revert to before appending the original chain
       *
       * @return false if something goes wrong with reverting (very bad), otherwise true
       */
      bool rollback_blockchain_switching(std::list<block>& original_chain, uint64_t rollback_height);
  
      /**
       * @brief gets recent block sizes for median calculation
       *
       * get the block sizes of the last <count> blocks, and return by reference <sz>.
       *
       * @param sz return-by-reference the list of sizes
       * @param count the number of blocks to get sizes for
       */
      void get_last_n_blocks_sizes(std::vector<size_t>& sz, size_t count) const;
  
      /**
       * @brief adds the given output to the requested set of random outputs
       *
       * @param result_outs return-by-reference the set the output is to be added to
       * @param amount the output amount
       * @param i the output index (indexed to amount)
       */
      void add_out_to_get_random_outs(COMMAND_RPC_GET_RANDOM_OUTPUTS_FOR_AMOUNTS::outs_for_amount& result_outs, uint64_t amount, size_t i) const;
  
      /**
       * @brief adds the given output to the requested set of random ringct outputs
       *
       * @param outs return-by-reference the set the output is to be added to
       * @param amount the output amount (0 for rct inputs)
       * @param i the rct output index
       */
      void add_out_to_get_rct_random_outs(std::list<COMMAND_RPC_GET_RANDOM_RCT_OUTPUTS::out_entry>& outs, uint64_t amount, size_t i) const;
  
      /**
       * @brief checks if a transaction is unlocked (its outputs spendable)
       *
       * This function checks to see if a transaction is unlocked.
       * unlock_time is either a block index or a unix time.
       *
       * @param unlock_time the unlock parameter (height or time)
       *
       * @return true if spendable, otherwise false
       */
      bool is_tx_spendtime_unlocked(uint64_t unlock_time) const;
  
      /**
       * @brief stores an invalid block in a separate container
       *
       * Storing invalid blocks allows quick dismissal of the same block
       * if it is seen again.
       *
       * @param bl the invalid block
       * @param h the block's hash
       *
       * @return false if the block cannot be stored for some reason, otherwise true
       */
      bool add_block_as_invalid(const block& bl, const crypto::hash& h);
  
      /**
       * @brief stores an invalid block in a separate container
       *
       * Storing invalid blocks allows quick dismissal of the same block
       * if it is seen again.
       *
       * @param bei the invalid block (see ::block_extended_info)
       * @param h the block's hash
       *
       * @return false if the block cannot be stored for some reason, otherwise true
       */
      bool add_block_as_invalid(const block_extended_info& bei, const crypto::hash& h);
  
      /**
       * @brief checks a block's timestamp
       *
       * This function grabs the timestamps from the most recent <n> blocks,
       * where n = BLOCKCHAIN_TIMESTAMP_CHECK_WINDOW.  If there are not those many
       * blocks in the blockchain, the timestap is assumed to be valid.  If there
       * are, this function returns:
       *   true if the block's timestamp is not less than the timestamp of the
       *       median of the selected blocks
       *   false otherwise
       *
       * @param b the block to be checked
       *
       * @return true if the block's timestamp is valid, otherwise false
       */
      bool check_block_timestamp(const block& b) const;
  
      /**
       * @brief checks a block's timestamp
       *
       * If the block is not more recent than the median of the recent
       * timestamps passed here, it is considered invalid.
       *
       * @param timestamps a list of the most recent timestamps to check against
       * @param b the block to be checked
       *
       * @return true if the block's timestamp is valid, otherwise false
       */
      bool check_block_timestamp(std::vector<uint64_t>& timestamps, const block& b) const;
  
      /**
       * @brief get the "adjusted time"
       *
       * Currently this simply returns the current time according to the
       * user's machine.
       *
       * @return the current time
       */
      uint64_t get_adjusted_time() const;
  
      /**
       * @brief finish an alternate chain's timestamp window from the main chain
       *
       * for an alternate chain, get the timestamps from the main chain to complete
       * the needed number of timestamps for the BLOCKCHAIN_TIMESTAMP_CHECK_WINDOW.
       *
       * @param start_height the alternate chain's attachment height to the main chain
       * @param timestamps return-by-value the timestamps set to be populated
       *
       * @return true unless start_height is greater than the current blockchain height
       */
      bool complete_timestamps_vector(uint64_t start_height, std::vector<uint64_t>& timestamps);
  
      /**
       * @brief calculate the block size limit for the next block to be added
       *
       * @return true
       */
      bool update_next_cumulative_size_limit();
      void return_tx_to_pool(std::vector<transaction> &txs);
  
      /**
       * @brief make sure a transaction isn't attempting a double-spend
       *
       * @param tx the transaction to check
       * @param keys_this_block a cumulative list of spent keys for the current block
       *
       * @return false if a double spend was detected, otherwise true
       */
      bool check_for_double_spend(const transaction& tx, key_images_container& keys_this_block) const;
  
      /**
       * @brief validates a transaction input's ring signature
       *
       * @param tx_prefix_hash the transaction prefix' hash
       * @param key_image the key image generated from the true input
       * @param pubkeys the public keys for each input in the ring signature
       * @param sig the signature generated for each input in the ring signature
       * @param result false if the ring signature is invalid, otherwise true
       */
      void check_ring_signature(const crypto::hash &tx_prefix_hash, const crypto::key_image &key_image,
          const std::vector<rct::ctkey> &pubkeys, const std::vector<crypto::signature> &sig, uint64_t &result);
  
      /**
       * @brief loads block hashes from compiled-in data set
       *
       * A (possibly empty) set of block hashes can be compiled into the
       * monero daemon binary.  This function loads those hashes into
       * a useful state.
       */
      void load_compiled_in_block_hashes();
  
      /**
       * @brief expands v2 transaction data from blockchain
       *
       * RingCT transactions do not transmit some of their data if it
       * can be reconstituted by the receiver. This function expands
       * that implicit data.
       */
      bool expand_transaction_2(transaction &tx, const crypto::hash &tx_prefix_hash, const std::vector<std::vector<rct::ctkey>> &pubkeys);
    };
  }  // namespace cryptonote
  