/*
 * Copyright (c) 2015, Cryptonomex, Inc.
 * All rights reserved.
 *
 * This source code is provided for evaluation in private test networks only, until September 8, 2015. After this date, this license expires and
 * the code may not be used, modified or distributed for any purpose. Redistribution and use in source and binary forms, with or without modification,
 * are permitted until September 8, 2015, provided that the following conditions are met:
 *
 * 1. The code and/or derivative works are used only for private test networks consisting of no more than 10 P2P nodes.
 *
 * 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.
 */

#include <graphene/chain/database.hpp>

#include <graphene/chain/block_summary_object.hpp>
#include <graphene/chain/global_property_object.hpp>
#include <graphene/chain/key_object.hpp>
#include <graphene/chain/operation_history_object.hpp>
#include <graphene/chain/proposal_object.hpp>
#include <graphene/chain/transaction_object.hpp>
#include <graphene/chain/witness_object.hpp>

namespace graphene { namespace chain {

bool database::is_known_block( const block_id_type& id )const
{
   return _fork_db.is_known_block(id) || _block_id_to_block.contains(id);
}
/**
 * Only return true *if* the transaction has not expired or been invalidated. If this
 * method is called with a VERY old transaction we will return false, they should
 * query things by blocks if they are that old.
 */
bool database::is_known_transaction( const transaction_id_type& id )const
{
   const auto& trx_idx = get_index_type<transaction_index>().indices().get<by_trx_id>();
   return trx_idx.find( id ) != trx_idx.end();
}

block_id_type  database::get_block_id_for_num( uint32_t block_num )const
{ try {
   return _block_id_to_block.fetch_block_id( block_num );
} FC_CAPTURE_AND_RETHROW( (block_num) ) }

optional<signed_block> database::fetch_block_by_id( const block_id_type& id )const
{
   auto b = _fork_db.fetch_block( id );
   if( !b )
      return _block_id_to_block.fetch_optional(id);
   return b->data;
}

optional<signed_block> database::fetch_block_by_number( uint32_t num )const
{
   auto results = _fork_db.fetch_block_by_number(num);
   if( results.size() == 1 )
      return results[0]->data;
   else
      return _block_id_to_block.fetch_by_number(num);
   return optional<signed_block>();
}

const signed_transaction& database::get_recent_transaction(const transaction_id_type& trx_id) const
{
   auto& index = get_index_type<transaction_index>().indices().get<by_trx_id>();
   auto itr = index.find(trx_id);
   FC_ASSERT(itr != index.end());
   return itr->trx;
}

/**
 * Push block "may fail" in which case every partial change is unwound.  After
 * push block is successful the block is appended to the chain database on disk.
 *
 * @return true if we switched forks as a result of this push.
 */
bool database::push_block( const signed_block& new_block, uint32_t skip )
{ try {
   if( !(skip&skip_fork_db) )
   {
      auto new_head = _fork_db.push_block( new_block );
      //If the head block from the longest chain does not build off of the current head, we need to switch forks.
      if( new_head->data.previous != head_block_id() )
      {
         edump((new_head->data.previous));
         //If the newly pushed block is the same height as head, we get head back in new_head
         //Only switch forks if new_head is actually higher than head
         if( new_head->data.block_num() > head_block_num() )
         {
            auto branches = _fork_db.fetch_branch_from( new_head->data.id(), _pending_block.previous );
            for( auto item : branches.first )
            {
               wdump( ("new")(item->id)(item->data.previous) );
            }
            for( auto item : branches.second )
            {
               wdump( ("old")(item->id)(item->data.previous) );
            }

            // pop blocks until we hit the forked block
            while( head_block_id() != branches.second.back()->data.previous )
               pop_block();

            // push all blocks on the new fork
            for( auto ritr = branches.first.rbegin(); ritr != branches.first.rend(); ++ritr )
            {
                optional<fc::exception> except;
                try {
                   auto session = _undo_db.start_undo_session();
                   apply_block( (*ritr)->data, skip );
                   _block_id_to_block.store( (*ritr)->id, (*ritr)->data );
                   session.commit();
                }
                catch ( const fc::exception& e ) { except = e; }
                if( except )
                {
                   wdump((except->to_detail_string()));
                   elog( "Encountered error when switching to a longer fork at id ${id}. Going back.",
                          ("id", (*ritr)->id) );
                   // remove the rest of branches.first from the fork_db, those blocks are invalid
                   while( ritr != branches.first.rend() )
                   {
                      _fork_db.remove( (*ritr)->data.id() );
                      ++ritr;
                   }
                   _fork_db.set_head( branches.second.front() );

                   // pop all blocks from the bad fork
                   while( head_block_id() != branches.second.back()->data.previous )
                      pop_block();

                   // restore all blocks from the good fork
                   for( auto ritr = branches.second.rbegin(); ritr != branches.second.rend(); ++ritr )
                   {
                      auto session = _undo_db.start_undo_session();
                      apply_block( (*ritr)->data, skip );
                      _block_id_to_block.store( new_block.id(), (*ritr)->data );
                      session.commit();
                   }
                   throw *except;
                }
            }
            return true;
         }
         else return false;
      }
   }

   // If there is a pending block session, then the database state is dirty with pending transactions.
   // Drop the pending session to reset the database to a clean head block state.
   // TODO: Preserve pending transactions, and re-apply any which weren't included in the new block.
   clear_pending();

   try {
      auto session = _undo_db.start_undo_session();
      apply_block( new_block, skip );
      _block_id_to_block.store( new_block.id(), new_block );
      session.commit();
   } catch ( const fc::exception& e ) {
      elog("Failed to push new block:\n${e}", ("e", e.to_detail_string()));
      _fork_db.remove(new_block.id());
      throw;
   }

   return false;
} FC_CAPTURE_AND_RETHROW( (new_block) ) }

/**
 * Attempts to push the transaction into the pending queue
 *
 * When called to push a locally generated transaction, set the skip_block_size_check bit on the skip argument. This
 * will allow the transaction to be pushed even if it causes the pending block size to exceed the maximum block size.
 * Although the transaction will probably not propagate further now, as the peers are likely to have their pending
 * queues full as well, it will be kept in the queue to be propagated later when a new block flushes out the pending
 * queues.
 */
processed_transaction database::push_transaction( const signed_transaction& trx, uint32_t skip )
{
   //wdump((trx.digest())(trx.id()));
   // If this is the first transaction pushed after applying a block, start a new undo session.
   // This allows us to quickly rewind to the clean state of the head block, in case a new block arrives.
   if( !_pending_block_session ) _pending_block_session = _undo_db.start_undo_session();
   auto session = _undo_db.start_undo_session();
   auto processed_trx = apply_transaction( trx, skip );
   _pending_block.transactions.push_back(processed_trx);

   FC_ASSERT( (skip & skip_block_size_check) ||
              fc::raw::pack_size(_pending_block) <= get_global_properties().parameters.maximum_block_size );

   // The transaction applied successfully. Merge its changes into the pending block session.
   session.merge();
   return processed_trx;
}

processed_transaction database::push_proposal(const proposal_object& proposal)
{
   transaction_evaluation_state eval_state(this);
   eval_state._is_proposed_trx = true;

   //Inject the approving authorities into the transaction eval state
   std::transform(proposal.required_active_approvals.begin(),
                  proposal.required_active_approvals.end(),
                  std::inserter(eval_state.approved_by, eval_state.approved_by.begin()),
                  []( account_id_type id ) {
                     return std::make_pair(id, authority::active);
                  });
   std::transform(proposal.required_owner_approvals.begin(),
                  proposal.required_owner_approvals.end(),
                  std::inserter(eval_state.approved_by, eval_state.approved_by.begin()),
                  []( account_id_type id ) {
                     return std::make_pair(id, authority::owner);
                  });

   ilog("Attempting to push proposal ${prop}", ("prop", proposal));
   idump((eval_state.approved_by));

   eval_state.operation_results.reserve(proposal.proposed_transaction.operations.size());
   processed_transaction ptrx(proposal.proposed_transaction);
   eval_state._trx = &ptrx;

   auto session = _undo_db.start_undo_session();
   for( auto& op : proposal.proposed_transaction.operations )
      eval_state.operation_results.emplace_back(apply_operation(eval_state, op));
   remove(proposal);
   session.merge();

   ptrx.operation_results = std::move(eval_state.operation_results);
   return ptrx;
}

signed_block database::generate_block(
   fc::time_point_sec when,
   witness_id_type witness_id,
   const fc::ecc::private_key& block_signing_private_key,
   uint32_t skip /* = 0 */
   )
{
   try {
   uint32_t slot_num = get_slot_at_time( when );
   witness_id_type scheduled_witness = get_scheduled_witness( slot_num ).first;
   FC_ASSERT( scheduled_witness == witness_id );

   const auto& witness_obj = witness_id(*this);

   if( !(skip & skip_delegate_signature) )
      FC_ASSERT( witness_obj.signing_key(*this).key() == block_signing_private_key.get_public_key() );

   _pending_block.timestamp = when;

   secret_hash_type::encoder last_enc;
   fc::raw::pack( last_enc, block_signing_private_key );
   fc::raw::pack( last_enc, witness_obj.last_secret );
   _pending_block.previous_secret = last_enc.result();

   secret_hash_type::encoder next_enc;
   fc::raw::pack( next_enc, block_signing_private_key );
   fc::raw::pack( next_enc, _pending_block.previous_secret );
   _pending_block.next_secret_hash = secret_hash_type::hash(next_enc.result());

   _pending_block.transaction_merkle_root = _pending_block.calculate_merkle_root();

   _pending_block.witness = witness_id;
   if( !(skip & skip_delegate_signature) ) _pending_block.sign( block_signing_private_key );

   FC_ASSERT( fc::raw::pack_size(_pending_block) <= get_global_properties().parameters.maximum_block_size );
   //This line used to std::move(_pending_block) but this is unsafe as _pending_block is later referenced without being
   //reinitialized. Future optimization could be to move it, then reinitialize it with the values we need to preserve.
   signed_block tmp = _pending_block;
   tmp.transaction_merkle_root = tmp.calculate_merkle_root();
   _pending_block.transactions.clear();
   push_block( tmp, skip );
   return tmp;
} FC_CAPTURE_AND_RETHROW( (witness_id) ) }

/**
 * Removes the most recent block from the database and
 * undoes any changes it made.
 */
void database::pop_block()
{ try {
   _pending_block_session.reset();
   _block_id_to_block.remove( _pending_block.previous );
   pop_undo();
   _pending_block.previous  = head_block_id();
   _pending_block.timestamp = head_block_time();
   _fork_db.pop_block();
} FC_CAPTURE_AND_RETHROW() }

void database::clear_pending()
{ try {
   _pending_block.transactions.clear();
   _pending_block_session.reset();
} FC_CAPTURE_AND_RETHROW() }

uint32_t database::push_applied_operation( const operation& op )
{
   _applied_ops.emplace_back(op);
   auto& oh = _applied_ops.back();
   oh.block_num    = _current_block_num;
   oh.trx_in_block = _current_trx_in_block;
   oh.op_in_trx    = _current_op_in_trx;
   oh.virtual_op   = _current_virtual_op++;
   return _applied_ops.size() - 1;
}
void database::set_applied_operation_result( uint32_t op_id, const operation_result& result )
{
   assert( op_id < _applied_ops.size() );
   _applied_ops[op_id].result = result;
}

const vector<operation_history_object>& database::get_applied_operations() const
{
   return _applied_ops;
}

//////////////////// private methods ////////////////////

void database::apply_block( const signed_block& next_block, uint32_t skip )
{ try {
   _applied_ops.clear();

   FC_ASSERT( (skip & skip_merkle_check) || next_block.transaction_merkle_root == next_block.calculate_merkle_root(), "", ("next_block.transaction_merkle_root",next_block.transaction_merkle_root)("calc",next_block.calculate_merkle_root())("next_block",next_block)("id",next_block.id()) );

   const witness_object& signing_witness = validate_block_header(skip, next_block);
   const auto& global_props = get_global_properties();
   const auto& dynamic_global_props = get<dynamic_global_property_object>(dynamic_global_property_id_type());

   _current_block_num    = next_block.block_num();
   _current_trx_in_block = 0;

   for( const auto& trx : next_block.transactions )
   {
      /* We do not need to push the undo state for each transaction
       * because they either all apply and are valid or the
       * entire block fails to apply.  We only need an "undo" state
       * for transactions when validating broadcast transactions or
       * when building a block.
       */
      apply_transaction( trx, skip | skip_transaction_signatures );
      ++_current_trx_in_block;
   }

   update_witness_schedule(next_block);
   update_global_dynamic_data(next_block);
   update_signing_witness(signing_witness, next_block);

   auto current_block_interval = global_props.parameters.block_interval;

   // Are we at the maintenance interval?
   if( dynamic_global_props.next_maintenance_time <= next_block.timestamp )
      // This will update _pending_block.timestamp if the block interval has changed
      perform_chain_maintenance(next_block, global_props);

   create_block_summary(next_block);
   clear_expired_transactions();
   clear_expired_proposals();
   clear_expired_orders();
   update_expired_feeds();
   update_withdraw_permissions();

   // notify observers that the block has been applied
   applied_block( next_block ); //emit
   _applied_ops.clear();

   const auto& head_undo = _undo_db.head();
   vector<object_id_type> changed_ids;  changed_ids.reserve(head_undo.old_values.size());
   for( const auto& item : head_undo.old_values ) changed_ids.push_back(item.first);
   changed_objects(changed_ids);


   update_pending_block(next_block, current_block_interval);
} FC_CAPTURE_AND_RETHROW( (next_block.block_num())(skip) )  }

processed_transaction database::apply_transaction( const signed_transaction& trx, uint32_t skip )
{ try {
   trx.validate();
   auto& trx_idx = get_mutable_index_type<transaction_index>();
   auto trx_id = trx.id();
   FC_ASSERT( (skip & skip_transaction_dupe_check) ||
              trx_idx.indices().get<by_trx_id>().find(trx_id) == trx_idx.indices().get<by_trx_id>().end() );
   transaction_evaluation_state eval_state(this, skip&skip_authority_check );
   const chain_parameters& chain_parameters = get_global_properties().parameters;
   eval_state._trx = &trx;

   //This check is used only if this transaction has an absolute expiration time.
   if( !(skip & skip_transaction_signatures) && trx.relative_expiration == 0 )
   {
      for( const auto& sig : trx.signatures )
      {
         FC_ASSERT( sig.first(*this).key_address() == fc::ecc::public_key( sig.second, trx.digest() ), "",
                    ("trx",trx)
                    ("digest",trx.digest())
                    ("sig.first",sig.first)
                    ("key_address",sig.first(*this).key_address())
                    ("addr", address(fc::ecc::public_key( sig.second, trx.digest() ))) );
      }
   }

   //If we're skipping tapos check, but not dupe check, assume all transactions have maximum expiration time.
   fc::time_point_sec trx_expiration = _pending_block.timestamp + chain_parameters.maximum_time_until_expiration;

   //Skip all manner of expiration and TaPoS checking if we're on block 1; It's impossible that the transaction is
   //expired, and TaPoS makes no sense as no blocks exist.
   if( BOOST_LIKELY(head_block_num() > 0) )
   {
      if( !(skip & skip_tapos_check) && trx.relative_expiration != 0 )
      {
         //Check the TaPoS reference and expiration time
         //Remember that the TaPoS block number is abbreviated; it contains only the lower 16 bits.
         //Lookup TaPoS block summary by block number (remember block summary instances are the block numbers)
         const block_summary_object& tapos_block_summary
               = static_cast<const block_summary_object&>(get_index<block_summary_object>()
                                                          .get(block_summary_id_type((head_block_num() & ~0xffff)
                                                                                     + trx.ref_block_num)));

         //This is the signature check for transactions with relative expiration.
         if( !(skip & skip_transaction_signatures) )
         {
            for( const auto& sig : trx.signatures )
            {
               address trx_addr = fc::ecc::public_key(sig.second, trx.digest(tapos_block_summary.block_id));
               FC_ASSERT(sig.first(*this).key_address() == trx_addr,
                          "",
                          ("sig.first",sig.first)
                          ("key_address",sig.first(*this).key_address())
                          ("addr", trx_addr));
            }
         }

         //Verify TaPoS block summary has correct ID prefix, and that this block's time is not past the expiration
         FC_ASSERT( trx.ref_block_prefix == tapos_block_summary.block_id._hash[1] );
         trx_expiration = tapos_block_summary.timestamp + chain_parameters.block_interval*trx.relative_expiration;
      } else if( trx.relative_expiration == 0 ) {
         trx_expiration = fc::time_point_sec(trx.ref_block_prefix);
         FC_ASSERT( trx_expiration <= _pending_block.timestamp + chain_parameters.maximum_time_until_expiration );
      }
      FC_ASSERT( _pending_block.timestamp <= trx_expiration );
   } else if( !(skip & skip_transaction_signatures) ) {
      FC_ASSERT(trx.relative_expiration == 0, "May not use transactions with a reference block in block 1!");
   }

   //Insert transaction into unique transactions database.
   if( !(skip & skip_transaction_dupe_check) )
   {
      create<transaction_object>([&](transaction_object& transaction) {
         transaction.expiration = trx_expiration;
         transaction.trx_id = trx_id;
         transaction.trx = trx;
      });
   }

   eval_state.operation_results.reserve( trx.operations.size() );

   processed_transaction ptrx(trx);
   _current_op_in_trx = 0;
   for( const auto& op : ptrx.operations )
   {
      eval_state.operation_results.emplace_back(apply_operation(eval_state, op));
      ++_current_op_in_trx;
   }
   ptrx.operation_results = std::move( eval_state.operation_results );

   return ptrx;
} FC_CAPTURE_AND_RETHROW( (trx) ) }

operation_result database::apply_operation(transaction_evaluation_state& eval_state, const operation& op)
{
   int i_which = op.which();
   uint64_t u_which = uint64_t( i_which );
   if( i_which < 0 )
      assert( "Negative operation tag" && false );
   if( u_which >= _operation_evaluators.size() )
      assert( "No registered evaluator for this operation" && false );
   unique_ptr<op_evaluator>& eval = _operation_evaluators[ u_which ];
   if( !eval )
      assert( "No registered evaluator for this operation" && false );
   auto op_id = push_applied_operation( op );
   auto result = eval->evaluate( eval_state, op, true );
   set_applied_operation_result( op_id, result );
   return result;
}

const witness_object& database::validate_block_header( uint32_t skip, const signed_block& next_block )const
{
   FC_ASSERT( _pending_block.previous == next_block.previous, "", ("pending.prev",_pending_block.previous)("next.prev",next_block.previous) );
   FC_ASSERT( _pending_block.timestamp <= next_block.timestamp, "", ("_pending_block.timestamp",_pending_block.timestamp)("next",next_block.timestamp)("blocknum",next_block.block_num()) );
   const witness_object& witness = next_block.witness(*this);
   FC_ASSERT( secret_hash_type::hash(next_block.previous_secret) == witness.next_secret, "",
              ("previous_secret", next_block.previous_secret)("next_secret", witness.next_secret));
   if( !(skip&skip_delegate_signature) ) FC_ASSERT( next_block.validate_signee( witness.signing_key(*this).key() ) );

   uint32_t slot_num = get_slot_at_time( next_block.timestamp );
   FC_ASSERT( slot_num > 0 );

   witness_id_type scheduled_witness = get_scheduled_witness( slot_num ).first;
   FC_ASSERT( next_block.witness == scheduled_witness );

   return witness;
}

void database::create_block_summary(const signed_block& next_block)
{
   const auto& sum = create<block_summary_object>( [&](block_summary_object& p) {
         p.block_id = next_block.id();
         p.timestamp = next_block.timestamp;
   });
   FC_ASSERT( sum.id.instance() == next_block.block_num(), "", ("summary.id",sum.id)("next.block_num",next_block.block_num()) );
}

} }