text: /*
   * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
   *
   * The MIT License
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <boost/multiprecision/integer.hpp>
  
  #include <fc/smart_ref_impl.hpp>
  #include <fc/uint128.hpp>
  
  #include <graphene/chain/database.hpp>
  #include <graphene/chain/fba_accumulator_id.hpp>
  #include <graphene/chain/hardfork.hpp>
  
  #include <graphene/chain/account_object.hpp>
  #include <graphene/chain/asset_object.hpp>
  #include <graphene/chain/budget_record_object.hpp>
  #include <graphene/chain/buyback_object.hpp>
  #include <graphene/chain/chain_property_object.hpp>
  #include <graphene/chain/committee_member_object.hpp>
  #include <graphene/chain/fba_object.hpp>
  #include <graphene/chain/global_property_object.hpp>
  #include <graphene/chain/market_object.hpp>
  #include <graphene/chain/special_authority_object.hpp>
  #include <graphene/chain/vesting_balance_object.hpp>
  #include <graphene/chain/vote_count.hpp>
  #include <graphene/chain/witness_object.hpp>
  #include <graphene/chain/worker_object.hpp>
  
  namespace graphene { namespace chain {
  
  template<class Index>
  vector<std::reference_wrapper<const typename Index::object_type>> database::sort_votable_objects(size_t count) const
  {
     using ObjectType = typename Index::object_type;
     const auto& all_objects = get_index_type<Index>().indices();
     count = std::min(count, all_objects.size());
     vector<std::reference_wrapper<const ObjectType>> refs;
     refs.reserve(all_objects.size());
     std::transform(all_objects.begin(), all_objects.end(),
                    std::back_inserter(refs),
                    [](const ObjectType& o) { return std::cref(o); });
     std::partial_sort(refs.begin(), refs.begin() + count, refs.end(),
                     [this](const ObjectType& a, const ObjectType& b)->bool {
        share_type oa_vote = _vote_tally_buffer[a.vote_id];
        share_type ob_vote = _vote_tally_buffer[b.vote_id];
        if( oa_vote != ob_vote )
           return oa_vote > ob_vote;
        return a.vote_id < b.vote_id;
     });
  
     refs.resize(count, refs.front());
     return refs;
  }
  
  template<class... Types>
  void database::perform_account_maintenance(std::tuple<Types...> helpers)
  {
     const auto& idx = get_index_type<account_index>().indices().get<by_name>();
     for( const account_object& a : idx )
        detail::for_each(helpers, a, detail::gen_seq<sizeof...(Types)>());
  }
  
  /// @brief A visitor for @ref worker_type which calls pay_worker on the worker within
  struct worker_pay_visitor
  {
     private:
        share_type pay;
        database& db;
  
     public:
        worker_pay_visitor(share_type pay, database& db)
           : pay(pay), db(db) {}
  
        typedef void result_type;
        template<typename W>
        void operator()(W& worker)const
        {
           worker.pay_worker(pay, db);
        }
  };
  void database::update_worker_votes()
  {
     auto& idx = get_index_type<worker_index>();
     auto itr = idx.indices().get<by_account>().begin();
     bool allow_negative_votes = (head_block_time() < HARDFORK_607_TIME);
     while( itr != idx.indices().get<by_account>().end() )
     {
        modify( *itr, [&]( worker_object& obj ){
           obj.total_votes_for = _vote_tally_buffer[obj.vote_for];
           obj.total_votes_against = allow_negative_votes ? _vote_tally_buffer[obj.vote_against] : 0;
        });
        ++itr;
     }
  }
  
  void database::pay_workers( share_type& budget )
  {
  //   ilog("Processing payroll! Available budget is ${b}", ("b", budget));
     vector<std::reference_wrapper<const worker_object>> active_workers;
     get_index_type<worker_index>().inspect_all_objects([this, &active_workers](const object& o) {
        const worker_object& w = static_cast<const worker_object&>(o);
        auto now = head_block_time();
        if( w.is_active(now) && w.approving_stake() > 0 )
           active_workers.emplace_back(w);
     });
  
     // worker with more votes is preferred
     // if two workers exactly tie for votes, worker with lower ID is preferred
     std::sort(active_workers.begin(), active_workers.end(), [](const worker_object& wa, const worker_object& wb) {
        share_type wa_vote = wa.approving_stake();
        share_type wb_vote = wb.approving_stake();
        if( wa_vote != wb_vote )
           return wa_vote > wb_vote;
        return wa.id < wb.id;
     });
  
     for( uint32_t i = 0; i < active_workers.size() && budget > 0; ++i )
     {
        const worker_object& active_worker = active_workers[i];
        share_type requested_pay = active_worker.daily_pay;
        if( head_block_time() - get_dynamic_global_properties().last_budget_time != fc::days(1) )
        {
           fc::uint128 pay(requested_pay.value);
           pay *= (head_block_time() - get_dynamic_global_properties().last_budget_time).count();
           pay /= fc::days(1).count();
           requested_pay = pay.to_uint64();
        }
  
        share_type actual_pay = std::min(budget, requested_pay);
        //ilog(" ==> Paying ${a} to worker ${w}", ("w", active_worker.id)("a", actual_pay));
        modify(active_worker, [&](worker_object& w) {
           w.worker.visit(worker_pay_visitor(actual_pay, *this));
        });
  
        budget -= actual_pay;
     }
  }
  
  void database::update_active_witnesses()
  { try {
     assert( _witness_count_histogram_buffer.size() > 0 );
     share_type stake_target = (_total_voting_stake-_witness_count_histogram_buffer[0]) / 2;
  
     /// accounts that vote for 0 or 1 witness do not get to express an opinion on
     /// the number of witnesses to have (they abstain and are non-voting accounts)
  
     share_type stake_tally = 0; 
  
     size_t witness_count = 0;
     if( stake_target > 0 )
     {
        while( (witness_count < _witness_count_histogram_buffer.size() - 1)
               && (stake_tally <= stake_target) )
        {
           stake_tally += _witness_count_histogram_buffer[++witness_count];
        }
     }
  
     const chain_property_object& cpo = get_chain_properties();
     auto wits = sort_votable_objects<witness_index>(std::max(witness_count*2+1, (size_t)cpo.immutable_parameters.min_witness_count));
  
     const global_property_object& gpo = get_global_properties();
  
     const auto& all_witnesses = get_index_type<witness_index>().indices();
  
     for( const witness_object& wit : all_witnesses )
     {
        modify( wit, [&]( witness_object& obj ){
                obj.total_votes = _vote_tally_buffer[wit.vote_id];
                });
     }
  
     // Update witness authority
     modify( get(GRAPHENE_WITNESS_ACCOUNT), [&]( account_object& a )
     {
        if( head_block_time() < HARDFORK_533_TIME )
        {
           uint64_t total_votes = 0;
           map<account_id_type, uint64_t> weights;
           a.active.weight_threshold = 0;
           a.active.clear();
  
           for( const witness_object& wit : wits )
           {
              weights.emplace(wit.witness_account, _vote_tally_buffer[wit.vote_id]);
              total_votes += _vote_tally_buffer[wit.vote_id];
           }
  
           // total_votes is 64 bits. Subtract the number of leading low bits from 64 to get the number of useful bits,
           // then I want to keep the most significant 16 bits of what's left.
           int8_t bits_to_drop = std::max(int(boost::multiprecision::detail::find_msb(total_votes)) - 15, 0);
           for( const auto& weight : weights )
           {
              // Ensure that everyone has at least one vote. Zero weights aren't allowed.
              uint16_t votes = std::max((weight.second >> bits_to_drop), uint64_t(1) );
              a.active.account_auths[weight.first] += votes;
              a.active.weight_threshold += votes;
           }
  
           a.active.weight_threshold /= 2;
           a.active.weight_threshold += 1;
        }
        else
        {
           vote_counter vc;
           for( const witness_object& wit : wits )
              vc.add( wit.witness_account, _vote_tally_buffer[wit.vote_id] );
           vc.finish( a.active );
        }
     } );
  
     modify(gpo, [&]( global_property_object& gp ){
        gp.active_witnesses.clear();
        gp.active_witnesses.reserve(wits.size());
        std::transform(wits.begin(), wits.end(),
                       std::inserter(gp.active_witnesses, gp.active_witnesses.end()),
                       [](const witness_object& w) {
           return w.id;
        });
     });
  
  } FC_CAPTURE_AND_RETHROW() }
  
  void database::update_active_committee_members()
  { try {
     assert( _committee_count_histogram_buffer.size() > 0 );
     share_type stake_target = (_total_voting_stake-_committee_count_histogram_buffer[0]) / 2;
  
     /// accounts that vote for 0 or 1 witness do not get to express an opinion on
     /// the number of witnesses to have (they abstain and are non-voting accounts)
     uint64_t stake_tally = 0; // _committee_count_histogram_buffer[0];
     size_t committee_member_count = 0;
     if( stake_target > 0 )
        while( (committee_member_count < _committee_count_histogram_buffer.size() - 1)
               && (stake_tally <= stake_target) )
           stake_tally += _committee_count_histogram_buffer[++committee_member_count];
  
     const chain_property_object& cpo = get_chain_properties();
     auto committee_members = sort_votable_objects<committee_member_index>(std::max(committee_member_count*2+1, (size_t)cpo.immutable_parameters.min_committee_member_count));
  
     for( const committee_member_object& del : committee_members )
     {
        modify( del, [&]( committee_member_object& obj ){
                obj.total_votes = _vote_tally_buffer[del.vote_id];
                });
     }
  
     // Update committee authorities
     if( !committee_members.empty() )
     {
        modify(get(GRAPHENE_COMMITTEE_ACCOUNT), [&](account_object& a)
        {
           if( head_block_time() < HARDFORK_533_TIME )
           {
              uint64_t total_votes = 0;
              map<account_id_type, uint64_t> weights;
              a.active.weight_threshold = 0;
              a.active.clear();
  
              for( const committee_member_object& del : committee_members )
              {
                 weights.emplace(del.committee_member_account, _vote_tally_buffer[del.vote_id]);
                 total_votes += _vote_tally_buffer[del.vote_id];
              }
  
              // total_votes is 64 bits. Subtract the number of leading low bits from 64 to get the number of useful bits,
              // then I want to keep the most significant 16 bits of what's left.
              int8_t bits_to_drop = std::max(int(boost::multiprecision::detail::find_msb(total_votes)) - 15, 0);
              for( const auto& weight : weights )
              {
                 // Ensure that everyone has at least one vote. Zero weights aren't allowed.
                 uint16_t votes = std::max((weight.second >> bits_to_drop), uint64_t(1) );
                 a.active.account_auths[weight.first] += votes;
                 a.active.weight_threshold += votes;
              }
  
              a.active.weight_threshold /= 2;
              a.active.weight_threshold += 1;
           }
           else
           {
              vote_counter vc;
              for( const committee_member_object& cm : committee_members )
                 vc.add( cm.committee_member_account, _vote_tally_buffer[cm.vote_id] );
              vc.finish( a.active );
           }
        } );
        modify(get(GRAPHENE_RELAXED_COMMITTEE_ACCOUNT), [&](account_object& a) {
           a.active = get(GRAPHENE_COMMITTEE_ACCOUNT).active;
        });
     }
     modify(get_global_properties(), [&](global_property_object& gp) {
        gp.active_committee_members.clear();
        std::transform(committee_members.begin(), committee_members.end(),
                       std::inserter(gp.active_committee_members, gp.active_committee_members.begin()),
                       [](const committee_member_object& d) { return d.id; });
     });
  } FC_CAPTURE_AND_RETHROW() }
  
  void database::initialize_budget_record( fc::time_point_sec now, budget_record& rec )const
  {
     const dynamic_global_property_object& dpo = get_dynamic_global_properties();
     const asset_object& core = asset_id_type(0)(*this);
     const asset_dynamic_data_object& core_dd = core.dynamic_asset_data_id(*this);
  
     rec.from_initial_reserve = core.reserved(*this);
     rec.from_accumulated_fees = core_dd.accumulated_fees;
     rec.from_unused_witness_budget = dpo.witness_budget;
  
     if(    (dpo.last_budget_time == fc::time_point_sec())
         || (now <= dpo.last_budget_time) )
     {
        rec.time_since_last_budget = 0;
        return;
     }
  
     int64_t dt = (now - dpo.last_budget_time).to_seconds();
     rec.time_since_last_budget = uint64_t( dt );
  
     // We'll consider accumulated_fees to be reserved at the BEGINNING
     // of the maintenance interval.  However, for speed we only
     // call modify() on the asset_dynamic_data_object once at the
     // end of the maintenance interval.  Thus the accumulated_fees
     // are available for the budget at this point, but not included
     // in core.reserved().
     share_type reserve = rec.from_initial_reserve + core_dd.accumulated_fees;
     // Similarly, we consider leftover witness_budget to be burned
     // at the BEGINNING of the maintenance interval.
     reserve += dpo.witness_budget;
  
     fc::uint128_t budget_u128 = reserve.value;
     budget_u128 *= uint64_t(dt);
     budget_u128 *= GRAPHENE_CORE_ASSET_CYCLE_RATE;
     //round up to the nearest satoshi -- this is necessary to ensure
     //   there isn't an "untouchable" reserve, and we will eventually
     //   be able to use the entire reserve
     budget_u128 += ((uint64_t(1) << GRAPHENE_CORE_ASSET_CYCLE_RATE_BITS) - 1);
     budget_u128 >>= GRAPHENE_CORE_ASSET_CYCLE_RATE_BITS;
     share_type budget;
     if( budget_u128 < reserve.value )
        rec.total_budget = share_type(budget_u128.to_uint64());
     else
        rec.total_budget = reserve;
  
     return;
  }
  
  /**
   * Update the budget for witnesses and workers.
   */
  void database::process_budget()
  {
     try
     {
        const global_property_object& gpo = get_global_properties();
        const dynamic_global_property_object& dpo = get_dynamic_global_properties();
        const asset_dynamic_data_object& core =
           asset_id_type(0)(*this).dynamic_asset_data_id(*this);
        fc::time_point_sec now = head_block_time();
  
        int64_t time_to_maint = (dpo.next_maintenance_time - now).to_seconds();
        //
        // The code that generates the next maintenance time should
        //    only produce a result in the future.  If this assert
        //    fails, then the next maintenance time algorithm is buggy.
        //
        assert( time_to_maint > 0 );
        //
        // Code for setting chain parameters should validate
        //    block_interval > 0 (as well as the humans proposing /
        //    voting on changes to block interval).
        //
        assert( gpo.parameters.block_interval > 0 );
        uint64_t blocks_to_maint = (uint64_t(time_to_maint) + gpo.parameters.block_interval - 1) / gpo.parameters.block_interval;
  
        // blocks_to_maint > 0 because time_to_maint > 0,
        // which means numerator is at least equal to block_interval
  
        budget_record rec;
        initialize_budget_record( now, rec );
        share_type available_funds = rec.total_budget;
  
        share_type witness_budget = gpo.parameters.witness_pay_per_block.value * blocks_to_maint;
        rec.requested_witness_budget = witness_budget;
        witness_budget = std::min(witness_budget, available_funds);
        rec.witness_budget = witness_budget;
        available_funds -= witness_budget;
  
        fc::uint128_t worker_budget_u128 = gpo.parameters.worker_budget_per_day.value;
        worker_budget_u128 *= uint64_t(time_to_maint);
        worker_budget_u128 /= 60*60*24;
  
        share_type worker_budget;
        if( worker_budget_u128 >= available_funds.value )
           worker_budget = available_funds;
        else
           worker_budget = worker_budget_u128.to_uint64();
        rec.worker_budget = worker_budget;
        available_funds -= worker_budget;
  
        share_type leftover_worker_funds = worker_budget;
        pay_workers(leftover_worker_funds);
        rec.leftover_worker_funds = leftover_worker_funds;
        available_funds += leftover_worker_funds;
  
        rec.supply_delta = rec.witness_budget
           + rec.worker_budget
           - rec.leftover_worker_funds
           - rec.from_accumulated_fees
           - rec.from_unused_witness_budget;
  
        modify(core, [&]( asset_dynamic_data_object& _core )
        {
           _core.current_supply = (_core.current_supply + rec.supply_delta );
  
           assert( rec.supply_delta ==
                                     witness_budget
                                   + worker_budget
                                   - leftover_worker_funds
                                   - _core.accumulated_fees
                                   - dpo.witness_budget
                                  );
           _core.accumulated_fees = 0;
        });
  
        modify(dpo, [&]( dynamic_global_property_object& _dpo )
        {
           // Since initial witness_budget was rolled into
           // available_funds, we replace it with witness_budget
           // instead of adding it.
           _dpo.witness_budget = witness_budget;
           _dpo.last_budget_time = now;
        });
  
        create< budget_record_object >( [&]( budget_record_object& _rec )
        {
           _rec.time = head_block_time();
           _rec.record = rec;
        });
  
        // available_funds is money we could spend, but don't want to.
        // we simply let it evaporate back into the reserve.
     }
     FC_CAPTURE_AND_RETHROW()
  }
  
  template< typename Visitor >
  void visit_special_authorities( const database& db, Visitor visit )
  {
     const auto& sa_idx = db.get_index_type< special_authority_index >().indices().get<by_id>();
  
     for( const special_authority_object& sao : sa_idx )
     {
        const account_object& acct = sao.account(db);
        if( acct.owner_special_authority.which() != special_authority::tag< no_special_authority >::value )
        {
           visit( acct, true, acct.owner_special_authority );
        }
        if( acct.active_special_authority.which() != special_authority::tag< no_special_authority >::value )
        {
           visit( acct, false, acct.active_special_authority );
        }
     }
  }
  
  void update_top_n_authorities( database& db )
  {
     visit_special_authorities( db,
     [&]( const account_object& acct, bool is_owner, const special_authority& auth )
     {
        if( auth.which() == special_authority::tag< top_holders_special_authority >::value )
        {
           // use index to grab the top N holders of the asset and vote_counter to obtain the weights
  
           const top_holders_special_authority& tha = auth.get< top_holders_special_authority >();
           vote_counter vc;
           const auto& bal_idx = db.get_index_type< account_balance_index >().indices().get< by_asset_balance >();
           uint8_t num_needed = tha.num_top_holders;
           if( num_needed == 0 )
              return;
  
           // find accounts
           const auto range = bal_idx.equal_range( boost::make_tuple( tha.asset ) );
           for( const account_balance_object& bal : boost::make_iterator_range( range.first, range.second ) )
           {
               assert( bal.asset_type == tha.asset );
               if( bal.owner == acct.id )
                  continue;
               vc.add( bal.owner, bal.balance.value );
               --num_needed;
               if( num_needed == 0 )
                  break;
           }
  
           db.modify( acct, [&]( account_object& a )
           {
              vc.finish( is_owner ? a.owner : a.active );
              if( !vc.is_empty() )
                 a.top_n_control_flags |= (is_owner ? account_object::top_n_control_owner : account_object::top_n_control_active);
           } );
        }
     } );
  }
  
  void split_fba_balance(
     database& db,
     uint64_t fba_id,
     uint16_t network_pct,
     uint16_t designated_asset_buyback_pct,
     uint16_t designated_asset_issuer_pct
  )
  {
     FC_ASSERT( uint32_t(network_pct) + uint32_t(designated_asset_buyback_pct) + uint32_t(designated_asset_issuer_pct) == GRAPHENE_100_PERCENT );
     const fba_accumulator_object& fba = fba_accumulator_id_type( fba_id )(db);
     if( fba.accumulated_fba_fees == 0 )
        return;
  
     const asset_object& core = asset_id_type(0)(db);
     const asset_dynamic_data_object& core_dd = core.dynamic_asset_data_id(db);
  
     if( !fba.is_configured(db) )
     {
        ilog( "${n} core given to network at block ${b} due to non-configured FBA", ("n", fba.accumulated_fba_fees)("b", db.head_block_time()) );
        db.modify( core_dd, [&]( asset_dynamic_data_object& _core_dd )
        {
           _core_dd.current_supply -= fba.accumulated_fba_fees;
        } );
        db.modify( fba, [&]( fba_accumulator_object& _fba )
        {
           _fba.accumulated_fba_fees = 0;
        } );
        return;
     }
  
     fc::uint128_t buyback_amount_128 = fba.accumulated_fba_fees.value;
     buyback_amount_128 *= designated_asset_buyback_pct;
     buyback_amount_128 /= GRAPHENE_100_PERCENT;
     share_type buyback_amount = buyback_amount_128.to_uint64();
  
     fc::uint128_t issuer_amount_128 = fba.accumulated_fba_fees.value;
     issuer_amount_128 *= designated_asset_issuer_pct;
     issuer_amount_128 /= GRAPHENE_100_PERCENT;
     share_type issuer_amount = issuer_amount_128.to_uint64();
  
     // this assert should never fail
     FC_ASSERT( buyback_amount + issuer_amount <= fba.accumulated_fba_fees );
  
     share_type network_amount = fba.accumulated_fba_fees - (buyback_amount + issuer_amount);
  
     const asset_object& designated_asset = (*fba.designated_asset)(db);
  
     if( network_amount != 0 )
     {
        db.modify( core_dd, [&]( asset_dynamic_data_object& _core_dd )
        {
           _core_dd.current_supply -= network_amount;
        } );
     }
  
     fba_distribute_operation vop;
     vop.account_id = *designated_asset.buyback_account;
     vop.fba_id = fba.id;
     vop.amount = buyback_amount;
     if( vop.amount != 0 )
     {
        db.adjust_balance( *designated_asset.buyback_account, asset(buyback_amount) );
        db.push_applied_operation(vop);
     }
  
     vop.account_id = designated_asset.issuer;
     vop.fba_id = fba.id;
     vop.amount = issuer_amount;
     if( vop.amount != 0 )
     {
        db.adjust_balance( designated_asset.issuer, asset(issuer_amount) );
        db.push_applied_operation(vop);
     }
  
     db.modify( fba, [&]( fba_accumulator_object& _fba )
     {
        _fba.accumulated_fba_fees = 0;
     } );
  }
  
  void distribute_fba_balances( database& db )
  {
     split_fba_balance( db, fba_accumulator_id_transfer_to_blind  , 20*GRAPHENE_1_PERCENT, 60*GRAPHENE_1_PERCENT, 20*GRAPHENE_1_PERCENT );
     split_fba_balance( db, fba_accumulator_id_blind_transfer     , 20*GRAPHENE_1_PERCENT, 60*GRAPHENE_1_PERCENT, 20*GRAPHENE_1_PERCENT );
     split_fba_balance( db, fba_accumulator_id_transfer_from_blind, 20*GRAPHENE_1_PERCENT, 60*GRAPHENE_1_PERCENT, 20*GRAPHENE_1_PERCENT );
  }
  
  void create_buyback_orders( database& db )
  {
     const auto& bbo_idx = db.get_index_type< buyback_index >().indices().get<by_id>();
     const auto& bal_idx = db.get_index_type< account_balance_index >().indices().get< by_account_asset >();
  
     for( const buyback_object& bbo : bbo_idx )
     {
        const asset_object& asset_to_buy = bbo.asset_to_buy(db);
        assert( asset_to_buy.buyback_account.valid() );
  
        const account_object& buyback_account = (*(asset_to_buy.buyback_account))(db);
        asset_id_type next_asset = asset_id_type();
  
        if( !buyback_account.allowed_assets.valid() )
        {
           wlog( "skipping buyback account ${b} at block ${n} because allowed_assets does not exist", ("b", buyback_account)("n", db.head_block_num()) );
           continue;
        }
  
        while( true )
        {
           auto it = bal_idx.lower_bound( boost::make_tuple( buyback_account.id, next_asset ) );
           if( it == bal_idx.end() )
              break;
           if( it->owner != buyback_account.id )
              break;
           asset_id_type asset_to_sell = it->asset_type;
           share_type amount_to_sell = it->balance;
           next_asset = asset_to_sell + 1;
           if( asset_to_sell == asset_to_buy.id )
              continue;
           if( amount_to_sell == 0 )
              continue;
           if( buyback_account.allowed_assets->find( asset_to_sell ) == buyback_account.allowed_assets->end() )
           {
              wlog( "buyback account ${b} not selling disallowed holdings of asset ${a} at block ${n}", ("b", buyback_account)("a", asset_to_sell)("n", db.head_block_num()) );
              continue;
           }
  
           try
           {
              transaction_evaluation_state buyback_context(&db);
              buyback_context.skip_fee_schedule_check = true;
  
              limit_order_create_operation create_vop;
              create_vop.fee = asset( 0, asset_id_type() );
              create_vop.seller = buyback_account.id;
              create_vop.amount_to_sell = asset( amount_to_sell, asset_to_sell );
              create_vop.min_to_receive = asset( 1, asset_to_buy.id );
              create_vop.expiration = time_point_sec::maximum();
              create_vop.fill_or_kill = false;
  
              limit_order_id_type order_id = db.apply_operation( buyback_context, create_vop ).get< object_id_type >();
  
              if( db.find( order_id ) != nullptr )
              {
                 limit_order_cancel_operation cancel_vop;
                 cancel_vop.fee = asset( 0, asset_id_type() );
                 cancel_vop.order = order_id;
                 cancel_vop.fee_paying_account = buyback_account.id;
  
                 db.apply_operation( buyback_context, cancel_vop );
              }
           }
           catch( const fc::exception& e )
           {
              // we can in fact get here, e.g. if asset issuer of buy/sell asset blacklists/whitelists the buyback account
              wlog( "Skipping buyback processing selling ${as} for ${ab} for buyback account ${b} at block ${n}; exception was ${e}",
                    ("as", asset_to_sell)("ab", asset_to_buy)("b", buyback_account)("n", db.head_block_num())("e", e.to_detail_string()) );
              continue;
           }
        }
     }
     return;
  }
  
  void deprecate_annual_members( database& db )
  {
     const auto& account_idx = db.get_index_type<account_index>().indices().get<by_id>();
     fc::time_point_sec now = db.head_block_time();
     for( const account_object& acct : account_idx )
     {
        try
        {
           transaction_evaluation_state upgrade_context(&db);
           upgrade_context.skip_fee_schedule_check = true;
  
           if( acct.is_annual_member( now ) )
           {
              account_upgrade_operation upgrade_vop;
              upgrade_vop.fee = asset( 0, asset_id_type() );
              upgrade_vop.account_to_upgrade = acct.id;
              upgrade_vop.upgrade_to_lifetime_member = true;
              db.apply_operation( upgrade_context, upgrade_vop );
           }
        }
        catch( const fc::exception& e )
        {
           // we can in fact get here, e.g. if asset issuer of buy/sell asset blacklists/whitelists the buyback account
           wlog( "Skipping annual member deprecate processing for account ${a} (${an}) at block ${n}; exception was ${e}",
                 ("a", acct.id)("an", acct.name)("n", db.head_block_num())("e", e.to_detail_string()) );
           continue;
        }
     }
     return;
  }
  
  void database::process_bids( const asset_bitasset_data_object& bad )
  {
     if( bad.is_prediction_market ) return;
     if( bad.current_feed.settlement_price.is_null() ) return;
  
     asset_id_type to_revive_id = (asset( 0, bad.options.short_backing_asset ) * bad.settlement_price).asset_id;
     const asset_object& to_revive = to_revive_id( *this );
     const asset_dynamic_data_object& bdd = to_revive.dynamic_data( *this );
  
     const auto& bid_idx = get_index_type< collateral_bid_index >().indices().get<by_price>();
     const auto start = bid_idx.lower_bound( boost::make_tuple( to_revive_id, price::max( bad.options.short_backing_asset, to_revive_id ), collateral_bid_id_type() ) );
  
     share_type covered = 0;
     auto itr = start;
     while( covered < bdd.current_supply && itr != bid_idx.end() && itr->inv_swan_price.quote.asset_id == to_revive_id )
     {
        const collateral_bid_object& bid = *itr;
        asset total_collateral = bid.inv_swan_price.quote * bad.settlement_price;
        total_collateral += bid.inv_swan_price.base;
        price call_price = price::call_price( bid.inv_swan_price.quote, total_collateral, bad.current_feed.maintenance_collateral_ratio );
        if( ~call_price >= bad.current_feed.settlement_price ) break;
        covered += bid.inv_swan_price.quote.amount;
        ++itr;
     }
     if( covered < bdd.current_supply ) return;
  
     const auto end = itr;
     share_type to_cover = bdd.current_supply;
     share_type remaining_fund = bad.settlement_fund;
     for( itr = start; itr != end; )
     {
        const collateral_bid_object& bid = *itr;
        ++itr;
        share_type debt = bid.inv_swan_price.quote.amount;
        share_type collateral = (bid.inv_swan_price.quote * bad.settlement_price).amount;
        if( bid.inv_swan_price.quote.amount >= to_cover )
        {
           debt = to_cover;
           collateral = remaining_fund;
        }
        to_cover -= debt;
        remaining_fund -= collateral;
        execute_bid( bid, debt, collateral, bad.current_feed );
     }
     FC_ASSERT( remaining_fund == 0 );
     FC_ASSERT( to_cover == 0 );
  
     _cancel_bids_and_revive_mpa( to_revive, bad );
  }
  
  void update_and_match_call_orders( database& db )
  {
     // Update call_price
     wlog( "Updating all call orders for hardfork core-343 at block ${n}", ("n",db.head_block_num()) );
     asset_id_type current_asset;
     const asset_bitasset_data_object* abd = nullptr;
     // by_collateral index won't change after call_price updated, so it's safe to iterate
     for( const auto& call_obj : db.get_index_type<call_order_index>().indices().get<by_collateral>() )
     {
        if( current_asset != call_obj.debt_type() ) // debt type won't be asset_id_type(), abd will always get initialized
        {
           current_asset = call_obj.debt_type();
           abd = &current_asset(db).bitasset_data(db);
        }
        if( !abd || abd->is_prediction_market ) // nothing to do with PM's; check !abd just to be safe
           continue;
        db.modify( call_obj, [abd]( call_order_object& call ) {
           call.call_price  =  price::call_price( call.get_debt(), call.get_collateral(),
                                                  abd->current_feed.maintenance_collateral_ratio );
        });
     }
     // Match call orders
     const auto& asset_idx = db.get_index_type<asset_index>().indices().get<by_type>();
     auto itr = asset_idx.lower_bound( true /** market issued */ );
     while( itr != asset_idx.end() )
     {
        const asset_object& a = *itr;
        ++itr;
        // be here, next_maintenance_time should have been updated already
        db.check_call_orders( a, true, false ); // allow black swan, and call orders are taker
     }
     wlog( "Done updating all call orders for hardfork core-343 at block ${n}", ("n",db.head_block_num()) );
  }
  
  void database::process_bitassets()
  {
     time_point_sec head_time = head_block_time();
     uint32_t head_epoch_seconds = head_time.sec_since_epoch();
     bool after_hf_core_518 = ( head_time >= HARDFORK_CORE_518_TIME ); // clear expired feeds
  
     const auto update_bitasset = [this,head_time,head_epoch_seconds,after_hf_core_518]( asset_bitasset_data_object &o )
     {
        o.force_settled_volume = 0; // Reset all BitAsset force settlement volumes to zero
  
        // clear expired feeds
        if( after_hf_core_518 )
        {
           const auto &asset = get( o.asset_id );
           auto flags = asset.options.flags;
           if ( ( flags & ( witness_fed_asset | committee_fed_asset ) ) &&
                o.options.feed_lifetime_sec < head_epoch_seconds ) // if smartcoin && check overflow
           {
              fc::time_point_sec calculated = head_time - o.options.feed_lifetime_sec;
              for( auto itr = o.feeds.rbegin(); itr != o.feeds.rend(); ) // loop feeds
              {
                 auto feed_time = itr->second.first;
                 std::advance( itr, 1 );
                 if( feed_time < calculated )
                    o.feeds.erase( itr.base() ); // delete expired feed
              }
           }
        }
     };
  
     for( const auto& d : get_index_type<asset_bitasset_data_index>().indices() )
     {
        modify( d, update_bitasset );
        if( d.has_settlement() )
           process_bids(d);
     }
  }
  
  /******
   * @brief one-time data process for hard fork core-868-890
   *
   * Prior to hardfork 868, switching a bitasset's shorting asset would not reset its
   * feeds. This method will run at the hardfork time, and erase (or nullify) feeds
   * that have incorrect backing assets.
   * https://github.com/bitshares/bitshares-core/issues/868
   *
   * Prior to hardfork 890, changing a bitasset's feed expiration time would not
   * trigger a median feed update. This method will run at the hardfork time, and
   * correct all median feed data.
   * https://github.com/bitshares/bitshares-core/issues/890
   *
   * @param db the database
   * @param skip_check_call_orders true if check_call_orders() should not be called
   */
  // TODO: for better performance, this function can be removed if it actually updated nothing at hf time.
  //       * Also need to update related test cases
  //       * NOTE: the removal can't be applied to testnet
  void process_hf_868_890( database& db, bool skip_check_call_orders )
  {
     const auto head_time = db.head_block_time();
     const auto head_num = db.head_block_num();
     wlog( "Processing hard fork core-868-890 at block ${n}", ("n",head_num) );
     // for each market issued asset
     const auto& asset_idx = db.get_index_type<asset_index>().indices().get<by_type>();
     for( auto asset_itr = asset_idx.lower_bound(true); asset_itr != asset_idx.end(); ++asset_itr )
     {
        const auto& current_asset = *asset_itr;
        // Incorrect witness & committee feeds can simply be removed.
        // For non-witness-fed and non-committee-fed assets, set incorrect
        // feeds to price(), since we can't simply remove them. For more information:
        // https://github.com/bitshares/bitshares-core/pull/832#issuecomment-384112633
        bool is_witness_or_committee_fed = false;
        if ( current_asset.options.flags & ( witness_fed_asset | committee_fed_asset ) )
           is_witness_or_committee_fed = true;
  
        // for each feed
        const asset_bitasset_data_object& bitasset_data = current_asset.bitasset_data(db);
        // NOTE: We'll only need old_feed if HF343 hasn't rolled out yet
        auto old_feed = bitasset_data.current_feed;
        bool feeds_changed = false; // did any feed change
        auto itr = bitasset_data.feeds.begin();
        while( itr != bitasset_data.feeds.end() )
        {
           // If the feed is invalid
           if ( itr->second.second.settlement_price.quote.asset_id != bitasset_data.options.short_backing_asset
                 && ( is_witness_or_committee_fed || itr->second.second.settlement_price != price() ) )
           {
              feeds_changed = true;
              db.modify( bitasset_data, [&itr, is_witness_or_committee_fed]( asset_bitasset_data_object& obj )
              {
                 if( is_witness_or_committee_fed )
                 {
                    // erase the invalid feed
                    itr = obj.feeds.erase(itr);
                 }
                 else
                 {
                    // nullify the invalid feed
                    obj.feeds[itr->first].second.settlement_price = price();
                    ++itr;
                 }
              });
           }
           else
           {
              // Feed is valid. Skip it.
              ++itr;
           }
        } // end loop of each feed
  
        // if any feed was modified, print a warning message
        if( feeds_changed )
        {
           wlog( "Found invalid feed for asset ${asset_sym} (${asset_id}) during hardfork core-868-890",
                 ("asset_sym", current_asset.symbol)("asset_id", current_asset.id) );
        }
  
        // always update the median feed due to https://github.com/bitshares/bitshares-core/issues/890
        db.modify( bitasset_data, [&head_time]( asset_bitasset_data_object &obj ) {
           obj.update_median_feeds( head_time );
        });
  
        bool median_changed = ( old_feed.settlement_price != bitasset_data.current_feed.settlement_price );
        bool median_feed_changed = ( !( old_feed == bitasset_data.current_feed ) );
        if( median_feed_changed )
        {
           wlog( "Median feed for asset ${asset_sym} (${asset_id}) changed during hardfork core-868-890",
                 ("asset_sym", current_asset.symbol)("asset_id", current_asset.id) );
        }
  
        // Note: due to bitshares-core issue #935, the check below (using median_changed) is incorrect.
        //       However, `skip_check_call_orders` will likely be true in both testnet and mainnet,
        //         so effectively the incorrect code won't make a difference.
        //       Additionally, we have code to update all call orders again during hardfork core-935
        // TODO cleanup after hard fork
        if( !skip_check_call_orders && median_changed ) // check_call_orders should be called
        {
           db.check_call_orders( current_asset );
        }
        else if( !skip_check_call_orders && median_feed_changed )
        {
           wlog( "Incorrectly skipped check_call_orders for asset ${asset_sym} (${asset_id}) during hardfork core-868-890",
                 ("asset_sym", current_asset.symbol)("asset_id", current_asset.id) );
        }
     } // for each market issued asset
     wlog( "Done processing hard fork core-868-890 at block ${n}", ("n",head_num) );
  }
  
  /******
   * @brief one-time data process for hard fork core-935
   *
   * Prior to hardfork 935, `check_call_orders` may be unintendedly skipped when
   * median price feed has changed. This method will run at the hardfork time, and
   * call `check_call_orders` for all markets.
   * https://github.com/bitshares/bitshares-core/issues/935
   *
   * @param db the database
   */
  // TODO: for better performance, this function can be removed if it actually updated nothing at hf time.
  //       * Also need to update related test cases
  //       * NOTE: perhaps the removal can't be applied to testnet
  void process_hf_935( database& db )
  {
     bool changed_something = false;
     const asset_bitasset_data_object* bitasset = nullptr;
     bool settled_before_check_call;
     bool settled_after_check_call;
     // for each market issued asset
     const auto& asset_idx = db.get_index_type<asset_index>().indices().get<by_type>();
     for( auto asset_itr = asset_idx.lower_bound(true); asset_itr != asset_idx.end(); ++asset_itr )
     {
        const auto& current_asset = *asset_itr;
  
        if( !changed_something )
        {
           bitasset = &current_asset.bitasset_data( db );
           settled_before_check_call = bitasset->has_settlement(); // whether already force settled
        }
  
        bool called_some = db.check_call_orders( current_asset );
  
        if( !changed_something )
        {
           settled_after_check_call = bitasset->has_settlement(); // whether already force settled
  
           if( settled_before_check_call != settled_after_check_call || called_some )
           {
              changed_something = true;
              wlog( "process_hf_935 changed something" );
           }
        }
     }
  }
  
  void database::perform_chain_maintenance(const signed_block& next_block, const global_property_object& global_props)
  {
     const auto& gpo = get_global_properties();
  
     distribute_fba_balances(*this);
     create_buyback_orders(*this);
  
     struct vote_tally_helper {
        database& d;
        const global_property_object& props;
  
        vote_tally_helper(database& d, const global_property_object& gpo)
           : d(d), props(gpo)
        {
           d._vote_tally_buffer.resize(props.next_available_vote_id);
           d._witness_count_histogram_buffer.resize(props.parameters.maximum_witness_count / 2 + 1);
           d._committee_count_histogram_buffer.resize(props.parameters.maximum_committee_count / 2 + 1);
           d._total_voting_stake = 0;
        }
  
        void operator()(const account_object& stake_account) {
           if( props.parameters.count_non_member_votes || stake_account.is_member(d.head_block_time()) )
           {
              // There may be a difference between the account whose stake is voting and the one specifying opinions.
              // Usually they're the same, but if the stake account has specified a voting_account, that account is the one
              // specifying the opinions.
              const account_object& opinion_account =
                    (stake_account.options.voting_account ==
                     GRAPHENE_PROXY_TO_SELF_ACCOUNT)? stake_account
                                       : d.get(stake_account.options.voting_account);
  
              const auto& stats = stake_account.statistics(d);
              uint64_t voting_stake = stats.total_core_in_orders.value
                    + (stake_account.cashback_vb.valid() ? (*stake_account.cashback_vb)(d).balance.amount.value: 0)
                    + d.get_balance(stake_account.get_id(), asset_id_type()).amount.value;
  
              for( vote_id_type id : opinion_account.options.votes )
              {
                 uint32_t offset = id.instance();
                 // if they somehow managed to specify an illegal offset, ignore it.
                 if( offset < d._vote_tally_buffer.size() )
                    d._vote_tally_buffer[offset] += voting_stake;
              }
  
              if( opinion_account.options.num_witness <= props.parameters.maximum_witness_count )
              {
                 uint16_t offset = std::min(size_t(opinion_account.options.num_witness/2),
                                            d._witness_count_histogram_buffer.size() - 1);
                 // votes for a number greater than maximum_witness_count
                 // are turned into votes for maximum_witness_count.
                 //
                 // in particular, this takes care of the case where a
                 // member was voting for a high number, then the
                 // parameter was lowered.
                 d._witness_count_histogram_buffer[offset] += voting_stake;
              }
              if( opinion_account.options.num_committee <= props.parameters.maximum_committee_count )
              {
                 uint16_t offset = std::min(size_t(opinion_account.options.num_committee/2),
                                            d._committee_count_histogram_buffer.size() - 1);
                 // votes for a number greater than maximum_committee_count
                 // are turned into votes for maximum_committee_count.
                 //
                 // same rationale as for witnesses
                 d._committee_count_histogram_buffer[offset] += voting_stake;
              }
  
              d._total_voting_stake += voting_stake;
           }
        }
     } tally_helper(*this, gpo);
     struct process_fees_helper {
        database& d;
        const global_property_object& props;
  
        process_fees_helper(database& d, const global_property_object& gpo)
           : d(d), props(gpo) {}
  
        void operator()(const account_object& a) {
           a.statistics(d).process_fees(a, d);
        }
     } fee_helper(*this, gpo);
  
     perform_account_maintenance(std::tie(
        tally_helper,
        fee_helper
        ));
  
     struct clear_canary {
        clear_canary(vector<uint64_t>& target): target(target){}
        ~clear_canary() { target.clear(); }
     private:
        vector<uint64_t>& target;
     };
     clear_canary a(_witness_count_histogram_buffer),
                  b(_committee_count_histogram_buffer),
                  c(_vote_tally_buffer);
  
     update_top_n_authorities(*this);
     update_active_witnesses();
     update_active_committee_members();
     update_worker_votes();
  
     modify(gpo, [this](global_property_object& p) {
        // Remove scaling of account registration fee
        const auto& dgpo = get_dynamic_global_properties();
        p.parameters.current_fees->get<account_create_operation>().basic_fee >>= p.parameters.account_fee_scale_bitshifts *
              (dgpo.accounts_registered_this_interval / p.parameters.accounts_per_fee_scale);
  
        if( p.pending_parameters )
        {
           p.parameters = std::move(*p.pending_parameters);
           p.pending_parameters.reset();
        }
     });
  
     auto next_maintenance_time = get<dynamic_global_property_object>(dynamic_global_property_id_type()).next_maintenance_time;
     auto maintenance_interval = gpo.parameters.maintenance_interval;
  
     if( next_maintenance_time <= next_block.timestamp )
     {
        if( next_block.block_num() == 1 )
           next_maintenance_time = time_point_sec() +
                 (((next_block.timestamp.sec_since_epoch() / maintenance_interval) + 1) * maintenance_interval);
        else
        {
           // We want to find the smallest k such that next_maintenance_time + k * maintenance_interval > head_block_time()
           //  This implies k > ( head_block_time() - next_maintenance_time ) / maintenance_interval
           //
           // Let y be the right-hand side of this inequality, i.e.
           // y = ( head_block_time() - next_maintenance_time ) / maintenance_interval
           //
           // and let the fractional part f be y-floor(y).  Clearly 0 <= f < 1.
           // We can rewrite f = y-floor(y) as floor(y) = y-f.
           //
           // Clearly k = floor(y)+1 has k > y as desired.  Now we must
           // show that this is the least such k, i.e. k-1 <= y.
           //
           // But k-1 = floor(y)+1-1 = floor(y) = y-f <= y.
           // So this k suffices.
           //
           auto y = (head_block_time() - next_maintenance_time).to_seconds() / maintenance_interval;
           next_maintenance_time += (y+1) * maintenance_interval;
        }
     }
  
     const dynamic_global_property_object& dgpo = get_dynamic_global_properties();
  
     if( (dgpo.next_maintenance_time < HARDFORK_613_TIME) && (next_maintenance_time >= HARDFORK_613_TIME) )
        deprecate_annual_members(*this);
  
     // To reset call_price of all call orders, then match by new rule
     bool to_update_and_match_call_orders = false;
     if( (dgpo.next_maintenance_time <= HARDFORK_CORE_343_TIME) && (next_maintenance_time > HARDFORK_CORE_343_TIME) )
        to_update_and_match_call_orders = true;
  
     // Process inconsistent price feeds
     if( (dgpo.next_maintenance_time <= HARDFORK_CORE_868_890_TIME) && (next_maintenance_time > HARDFORK_CORE_868_890_TIME) )
        process_hf_868_890( *this, to_update_and_match_call_orders );
  
     // Explicitly call check_call_orders of all markets
     if( (dgpo.next_maintenance_time <= HARDFORK_CORE_935_TIME) && (next_maintenance_time > HARDFORK_CORE_935_TIME)
           && !to_update_and_match_call_orders )
        process_hf_935( *this );
  
     modify(dgpo, [next_maintenance_time](dynamic_global_property_object& d) {
        d.next_maintenance_time = next_maintenance_time;
        d.accounts_registered_this_interval = 0;
     });
  
     // We need to do it after updated next_maintenance_time, to apply new rules here
     if( to_update_and_match_call_orders )
        update_and_match_call_orders(*this);
  
     process_bitassets();
  
     // process_budget needs to run at the bottom because
     //   it needs to know the next_maintenance_time
     process_budget();
  }
  
  } }
  