// Copyright (C) 2011, 2012  Strahinja Val Markovic  <val@markovic.io>
//
// This file is part of YouCompleteMe.
//
// YouCompleteMe is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// YouCompleteMe is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.

#include "IdentifierCompleter.h"
#include "standard.h"
#include "CandidateRepository.h"
#include "Candidate.h"
#include "Utils.h"
#include "IdentifierUtils.h"

#include <boost/unordered_set.hpp>
#include <boost/bind.hpp>
#include <boost/make_shared.hpp>
#include <algorithm>

using boost::packaged_task;
using boost::bind;
using boost::unique_future;
using boost::make_shared;
using boost::shared_ptr;
using boost::bind;
using boost::thread;

namespace YouCompleteMe
{

extern const unsigned int MAX_ASYNC_THREADS = 4;
extern const unsigned int MIN_ASYNC_THREADS = 2;

namespace
{

void QueryThreadMain( LatestQueryTask &latest_query_task )
{
  while ( true )
  {
    ( *latest_query_task.Get() )();
  }

}

void BufferIdentifiersThreadMain(
  BufferIdentifiersTaskStack &buffer_identifiers_task_stack )
{
  while ( true )
  {
    ( *buffer_identifiers_task_stack.Pop() )();
  }
}


} // unnamed namespace


IdentifierCompleter::IdentifierCompleter()
  : candidate_repository_( CandidateRepository::Instance() ),
    threading_enabled_( false )
{
}


IdentifierCompleter::IdentifierCompleter(
    const std::vector< std::string > &candidates )
  : candidate_repository_( CandidateRepository::Instance() ),
    threading_enabled_( false )
{
  AddCandidatesToDatabase( candidates, "", "" );
}


IdentifierCompleter::IdentifierCompleter(
    const std::vector< std::string > &candidates,
    const std::string &filetype,
    const std::string &filepath )
  : candidate_repository_( CandidateRepository::Instance() ),
    threading_enabled_( false )
{
  AddCandidatesToDatabase( candidates, filetype, filepath );
}


// We need this mostly so that we can not use it in tests. Apparently the
// GoogleTest framework goes apeshit on us if we enable threads by default.
void IdentifierCompleter::EnableThreading()
{
  threading_enabled_ = true;
  InitThreads();
}


void IdentifierCompleter::AddCandidatesToDatabase(
    const std::vector< std::string > &new_candidates,
    const std::string &filetype,
    const std::string &filepath )
{
  std::list< const Candidate *> &candidates =
    GetCandidateList( filetype, filepath );

  std::vector< const Candidate* > repository_candidates =
    candidate_repository_.GetCandidatesForStrings( new_candidates );

  candidates.insert( candidates.end(),
                     repository_candidates.begin(),
                     repository_candidates.end() );
}


void IdentifierCompleter::AddCandidatesToDatabaseFromBuffer(
    const std::string &buffer_contents,
    const std::string &filetype,
    const std::string &filepath )
{
  ClearCandidatesStoredForFile( filetype, filepath );

  AddCandidatesToDatabase(
      ExtractIdentifiersFromText( RemoveIdentifierFreeText( buffer_contents ) ),
      filetype,
      filepath );
}


void IdentifierCompleter::AddCandidatesToDatabaseFromBufferAsync(
    std::string buffer_contents,
    std::string filetype,
    std::string filepath )
{
  // TODO: throw exception when threading is not enabled and this is called
  if ( !threading_enabled_ )
    return;

  boost::function< void() > functor =
    bind( &IdentifierCompleter::AddCandidatesToDatabaseFromBuffer,
          boost::ref( *this ),
          boost::move( buffer_contents ),
          boost::move( filetype ),
          boost::move( filepath ) );

  buffer_identifiers_task_stack_.Push(
      make_shared< packaged_task< void > >( functor ) );
}


std::vector< std::string > IdentifierCompleter::CandidatesForQuery(
    const std::string &query ) const
{
  return CandidatesForQueryAndType( query, "" );
}


std::vector< std::string > IdentifierCompleter::CandidatesForQueryAndType(
    const std::string &query,
    const std::string &filetype ) const
{
  std::vector< Result > results;
  ResultsForQueryAndType( query, filetype, results );

  std::vector< std::string > candidates;
  candidates.reserve( results.size() );

  foreach ( const Result& result, results )
  {
    candidates.push_back( *result.Text() );
  }
  return candidates;
}


Future< AsyncResults > IdentifierCompleter::CandidatesForQueryAndTypeAsync(
    const std::string &query,
    const std::string &filetype ) const
{
  // TODO: throw exception when threading is not enabled and this is called
  if ( !threading_enabled_ )
    return Future< AsyncResults >();

  FunctionReturnsStringVector functor =
    bind( &IdentifierCompleter::CandidatesForQueryAndType,
          boost::cref( *this ),
          query,
          filetype );

  QueryTask task = make_shared< packaged_task< AsyncResults > >(
      bind( ReturnValueAsShared< std::vector< std::string > >,
            functor ) );

  unique_future< AsyncResults > future = task->get_future();

  latest_query_task_.Set( task );
  return Future< AsyncResults >( boost::move( future ) );
}


void IdentifierCompleter::ResultsForQueryAndType(
    const std::string &query,
    const std::string &filetype,
    std::vector< Result > &results ) const
{
  FiletypeMap::const_iterator it = filetype_map_.find( filetype );
  if ( it == filetype_map_.end() || query.empty() )
    return;

  Bitset query_bitset = LetterBitsetFromString( query );

  boost::unordered_set< const Candidate* > seen_candidates;
  seen_candidates.reserve( candidate_repository_.NumStoredCandidates() );

  foreach ( const FilepathToCandidates::value_type &path_and_candidates,
            *it->second )
  {
    foreach ( const Candidate* candidate, *path_and_candidates.second )
    {
      if ( ContainsKey( seen_candidates, candidate ) )
        continue;
      else
        seen_candidates.insert( candidate );

      if ( !candidate->MatchesQueryBitset( query_bitset ) )
        continue;

      Result result = candidate->QueryMatchResult( query );
      if ( result.IsSubsequence() )
        results.push_back( result );
    }
  }

  std::sort( results.begin(), results.end() );
}


void IdentifierCompleter::ClearCandidatesStoredForFile(
    const std::string &filetype,
    const std::string &filepath )
{
  GetCandidateList( filetype, filepath ).clear();
}


std::list< const Candidate* >& IdentifierCompleter::GetCandidateList(
    const std::string &filetype,
    const std::string &filepath )
{
  boost::shared_ptr< FilepathToCandidates > &path_to_candidates =
    filetype_map_[ filetype ];

  if ( !path_to_candidates )
    path_to_candidates.reset( new FilepathToCandidates() );

  boost::shared_ptr< std::list< const Candidate* > > &candidates =
    (*path_to_candidates)[ filepath ];

  if ( !candidates )
    candidates.reset( new std::list< const Candidate* >() );

  return *candidates;
}


void IdentifierCompleter::InitThreads()
{
  int query_threads_to_create =
    std::max( MIN_ASYNC_THREADS,
      std::min( MAX_ASYNC_THREADS, thread::hardware_concurrency() ) );

  for ( int i = 0; i < query_threads_to_create; ++i )
  {
    query_threads_.create_thread( bind( QueryThreadMain,
                                        boost::ref( latest_query_task_ ) ) );
  }

  buffer_identifiers_thread_ = boost::thread(
      BufferIdentifiersThreadMain,
      boost::ref( buffer_identifiers_task_stack_ ) );
}


} // namespace YouCompleteMe