text: // Copyright (c) 2019-2021 WAZN Project
  // Copyright (c) 2014-2020, The Monero Project
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  #pragma once
  
  #include "syncobj.h"
  #include "hardforks/hardforks.h"
  #include "cryptonote_basic/cryptonote_basic.h"
  
  namespace cryptonote
  {
    class BlockchainDB;
  
    class HardFork
    {
    public:
      typedef enum {
        LikelyForked,
        UpdateNeeded,
        Ready,
      } State;
  
      static const uint64_t DEFAULT_ORIGINAL_VERSION_TILL_HEIGHT = 0; // <= actual height
      static const time_t DEFAULT_FORKED_TIME = 31557600; // a year in seconds
      static const time_t DEFAULT_UPDATE_TIME = 31557600 / 2;
      static const uint64_t DEFAULT_WINDOW_SIZE = 10080; // supermajority window check length - a week
      static const uint8_t DEFAULT_THRESHOLD_PERCENT = 80;
  
      /**
       * @brief creates a new HardFork object
       *
       * @param original_version the block version for blocks 0 through to the first fork
       * @param forked_time the time in seconds before thinking we're forked
       * @param update_time the time in seconds before thinking we need to update
       * @param window_size the size of the window in blocks to consider for version voting
       * @param default_threshold_percent the size of the majority in percents
       */
      HardFork(cryptonote::BlockchainDB &db, uint8_t original_version = 1, uint64_t original_version_till_height = DEFAULT_ORIGINAL_VERSION_TILL_HEIGHT, time_t forked_time = DEFAULT_FORKED_TIME, time_t update_time = DEFAULT_UPDATE_TIME, uint64_t window_size = DEFAULT_WINDOW_SIZE, uint8_t default_threshold_percent = DEFAULT_THRESHOLD_PERCENT);
  
      /**
       * @brief add a new hardfork height
       *
       * returns true if no error, false otherwise
       *
       * @param version the major block version for the fork
       * @param height The height the hardfork takes effect
       * @param threshold The threshold of votes needed for this fork (0-100)
       * @param time Approximate time of the hardfork (seconds since epoch)
       */
      bool add_fork(uint8_t version, uint64_t height, uint8_t threshold, time_t time);
  
      /**
       * @brief add a new hardfork height
       *
       * returns true if no error, false otherwise
       *
       * @param version the major block version for the fork
       * @param height The height the hardfork takes effect
       * @param time Approximate time of the hardfork (seconds since epoch)
       */
      bool add_fork(uint8_t version, uint64_t height, time_t time);
  
      /**
       * @brief initialize the object
       *
       * Must be done after adding all the required hardforks via add above
       */
      void init();
  
      /**
       * @brief check whether a new block would be accepted
       *
       * returns true if the block is accepted, false otherwise
       *
       * @param block the new block
       *
       * This check is made by add. It is exposed publicly to allow
       * the caller to inexpensively check whether a block would be
       * accepted or rejected by its version number. Indeed, if this
       * check could only be done as part of add, the caller would
       * either have to add the block to the blockchain first, then
       * call add, then have to pop the block from the blockchain if
       * its version did not satisfy the hard fork requirements, or
       * call add first, then, if the hard fork requirements are met,
       * add the block to the blockchain, upon which a failure (the
       * block being invalid, double spending, etc) would cause the
       * hardfork object to reorganize.
       */
      bool check(const cryptonote::block &block) const;
  
      /**
       * @brief same as check, but for a particular height, rather than the top
       *
       * NOTE: this does not play well with voting, and relies on voting to be
       * disabled (that is, forks happen on the scheduled date, whether or not
       * enough blocks have voted for the fork).
       *
       * returns true if no error, false otherwise
       *
       * @param block the new block
       * @param height which height to check for
       */
      bool check_for_height(const cryptonote::block &block, uint64_t height) const;
  
      /**
       * @brief add a new block
       *
       * returns true if no error, false otherwise
       *
       * @param block the new block
       */
      bool add(const cryptonote::block &block, uint64_t height);
  
      /**
       * @brief called when the blockchain is reorganized
       *
       * This will rescan the blockchain to determine which hard forks
       * have been triggered
       *
       * returns true if no error, false otherwise
       *
       * @param blockchain the blockchain
       * @param height of the last block kept from the previous blockchain
       */
      bool reorganize_from_block_height(uint64_t height);
      bool reorganize_from_chain_height(uint64_t height);
  
      /**
       * @brief called when one or more blocks are popped from the blockchain
       *
       * The current fork will be updated by looking up the db,
       * which is much cheaper than recomputing everything
       *
       * @param new_chain_height the height of the chain after popping
       */
      void on_block_popped(uint64_t new_chain_height);
  
      /**
       * @brief returns current state at the given time
       *
       * Based on the approximate time of the last known hard fork,
       * estimate whether we need to update, or if we're way behind
       *
       * @param t the time to consider
       */
      State get_state(time_t t) const;
      State get_state() const;
  
      /**
       * @brief returns the hard fork version for the given block height
       *
       * @param height height of the block to check
       */
      uint8_t get(uint64_t height) const;
  
      /**
       * @brief returns the latest "ideal" version
       *
       * This is the latest version that's been scheduled
       */
      uint8_t get_ideal_version() const;
  
      /**
       * @brief returns the "ideal" version for a given height
       *
       * @param height height of the block to check
       */
      uint8_t get_ideal_version(uint64_t height) const;
  
      /**
       * @brief returns the next version
       *
       * This is the version which will we fork to next
       */
      uint8_t get_next_version() const;
  
      /**
       * @brief returns the current version
       *
       * This is the latest version that's past its trigger date and had enough votes
       * at one point in the past.
       */
      uint8_t get_current_version() const;
  
      /**
       * @brief returns the earliest block a given version may activate
       */
      uint64_t get_earliest_ideal_height_for_version(uint8_t version) const;
  
      /**
       * @brief returns information about current voting state
       *
       * returns true if the given version is enabled (ie, the current version
       * is at least the passed version), false otherwise
       *
       * @param version the version to check voting for
       * @param window the number of blocks considered in voting
       * @param votes number of votes for next version
       * @param threshold number of votes needed to switch to next version
       * @param earliest_height earliest height at which the version can take effect
       */
      bool get_voting_info(uint8_t version, uint32_t &window, uint32_t &votes, uint32_t &threshold, uint64_t &earliest_height, uint8_t &voting) const;
  
      /**
       * @brief returns the size of the voting window in blocks
       */
      uint64_t get_window_size() const { return window_size; }
  
    private:
  
      uint8_t get_block_version(uint64_t height) const;
      bool do_check(uint8_t block_version, uint8_t voting_version) const;
      bool do_check_for_height(uint8_t block_version, uint8_t voting_version, uint64_t height) const;
      int get_voted_fork_index(uint64_t height) const;
      uint8_t get_effective_version(uint8_t voting_version) const;
      bool add(uint8_t block_version, uint8_t voting_version, uint64_t height);
  
      bool rescan_from_block_height(uint64_t height);
      bool rescan_from_chain_height(uint64_t height);
  
    private:
  
      BlockchainDB &db;
  
      time_t forked_time;
      time_t update_time;
      uint64_t window_size;
      uint8_t default_threshold_percent;
  
      uint8_t original_version;
      uint64_t original_version_till_height;
  
      std::vector<hardfork_t> heights;
  
      std::deque<uint8_t> versions; /* rolling window of the last N blocks' versions */
      unsigned int last_versions[256]; /* count of the block versions in the last N blocks */
      uint32_t current_fork_index;
  
      mutable epee::critical_section lock;
    };
  
  }  // namespace cryptonote
  