/*
 * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
 * 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. Any modified source or binaries are used only with the BitShares network.
 *
 * 2. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 *
 * 3. 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.
 *
 * 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/db/object_database.hpp>
#include <graphene/db/undo_database.hpp>
#include <fc/reflect/variant.hpp>

namespace graphene { namespace db {

void undo_database::enable()  { _disabled = false; }
void undo_database::disable() { _disabled = true; }

undo_database::session undo_database::start_undo_session( bool force_enable )
{
   if( _disabled && !force_enable ) return session(*this);
   bool disable_on_exit = _disabled  && force_enable;
   if( force_enable ) 
      _disabled = false;

   while( size() > max_size() )
      _stack.pop_front();

   _stack.emplace_back();
   ++_active_sessions;
   return session(*this, disable_on_exit );
}
void undo_database::on_create( const object& obj )
{
   if( _disabled ) return;

   if( _stack.empty() )
      _stack.emplace_back();
   auto& state = _stack.back();
   auto index_id = object_id_type( obj.id.space(), obj.id.type(), 0 );
   auto itr = state.old_index_next_ids.find( index_id );
   if( itr == state.old_index_next_ids.end() )
      state.old_index_next_ids[index_id] = obj.id;
   state.new_ids.insert(obj.id);
}
void undo_database::on_modify( const object& obj )
{
   if( _disabled ) return;

   if( _stack.empty() )
      _stack.emplace_back();
   auto& state = _stack.back();
   if( state.new_ids.find(obj.id) != state.new_ids.end() )
      return;
   auto itr =  state.old_values.find(obj.id);
   if( itr != state.old_values.end() ) return;
   state.old_values[obj.id] = obj.clone();
}
void undo_database::on_remove( const object& obj )
{
   if( _disabled ) return;

   if( _stack.empty() )
      _stack.emplace_back();
   undo_state& state = _stack.back();
   if( state.new_ids.count(obj.id) )
   {
      state.new_ids.erase(obj.id);
      return;
   }
   if( state.old_values.count(obj.id) )
   {
      state.removed[obj.id] = std::move(state.old_values[obj.id]);
      state.old_values.erase(obj.id);
      return;
   }
   if( state.removed.count(obj.id) ) return;
   state.removed[obj.id] = obj.clone();
}

void undo_database::undo()
{ try {
   FC_ASSERT( !_disabled );
   FC_ASSERT( _active_sessions > 0 );
   disable();

   auto& state = _stack.back();
   for( auto& item : state.old_values )
   {
      _db.modify( _db.get_object( item.second->id ), [&]( object& obj ){ obj.move_from( *item.second ); } );
   }

   for( auto ritr = state.new_ids.begin(); ritr != state.new_ids.end(); ++ritr  )
   {
      _db.remove( _db.get_object(*ritr) );
   }

   for( auto& item : state.old_index_next_ids )
   {
      _db.get_mutable_index( item.first.space(), item.first.type() ).set_next_id( item.second );
   }

   for( auto& item : state.removed )
      _db.insert( std::move(*item.second) );

   _stack.pop_back();
   if( _stack.empty() )
      _stack.emplace_back();
   enable();
   --_active_sessions;
} FC_CAPTURE_AND_RETHROW() }

void undo_database::merge()
{
   FC_ASSERT( _active_sessions > 0 );
   FC_ASSERT( _stack.size() >=2 );
   auto& state = _stack.back();
   auto& prev_state = _stack[_stack.size()-2];
   for( auto& obj : state.old_values )
   {
      if( prev_state.new_ids.find(obj.second->id) != prev_state.new_ids.end() )
         continue;
      if( prev_state.old_values.find(obj.second->id) == prev_state.old_values.end() )
         prev_state.old_values[obj.second->id] = std::move(obj.second);
   }
   for( auto id : state.new_ids )
      prev_state.new_ids.insert(id);
   for( auto& item : state.old_index_next_ids )
   {
      if( prev_state.old_index_next_ids.find( item.first ) == prev_state.old_index_next_ids.end() )
         prev_state.old_index_next_ids[item.first] = item.second;
   }
   for( auto& obj : state.removed )
      if( prev_state.new_ids.find(obj.second->id) == prev_state.new_ids.end() )
         prev_state.removed[obj.second->id] = std::move(obj.second);
      else
         prev_state.new_ids.erase(obj.second->id);
   _stack.pop_back();
   --_active_sessions;
}
void undo_database::commit()
{
   FC_ASSERT( _active_sessions > 0 );
   --_active_sessions;
}

void undo_database::pop_commit()
{
   FC_ASSERT( _active_sessions == 0 );
   FC_ASSERT( !_stack.empty() );

   disable();
   try {
      auto& state = _stack.back();

      for( auto& item : state.old_values )
      {
         _db.modify( _db.get_object( item.second->id ), [&]( object& obj ){ obj.move_from( *item.second ); } );
      }

      for( auto ritr = state.new_ids.begin(); ritr != state.new_ids.end(); ++ritr  )
      {
         _db.remove( _db.get_object(*ritr) );
      }

      for( auto& item : state.old_index_next_ids )
      {
         _db.get_mutable_index( item.first.space(), item.first.type() ).set_next_id( item.second );
      }

      for( auto& item : state.removed )
         _db.insert( std::move(*item.second) );

      _stack.pop_back();
   }
   catch ( const fc::exception& e )
   {
      elog( "error popping commit ${e}", ("e", e.to_detail_string() )  );
      enable();
      throw;
   }
   enable();
}
const undo_state& undo_database::head()const
{
   FC_ASSERT( !_stack.empty() );
   return _stack.back();
}

} } // graphene::db