/*
   Copyright 2008 David Nolden <david.nolden.kdevelop@art-master.de>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License version 2 as published by the Free Software Foundation.

   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "modificationrevision.h"

#include <QString>
#include <QFileInfo>

#include <ktexteditor/document.h>

#include "../duchain/indexedstring.h"
#include "modificationrevisionset.h"
#include <sys/time.h>

/// @todo Listen to filesystem changes (together with the project manager)
/// and call fileModificationCache().clear(...) when a file has changed

namespace KDevelop {

const int cacheModificationTimesForSeconds = 30;

QMutex fileModificationTimeCacheMutex(QMutex::Recursive);

struct FileModificationCache
{
  timeval m_readTime;
  QDateTime m_modificationTime;
};

typedef QHash<KDevelop::IndexedString, FileModificationCache> FileModificationMap;

FileModificationMap& fileModificationCache()
{
  static FileModificationMap cache;
  return cache;
}

typedef QHash<KDevelop::IndexedString, int> OpenDocumentRevisionsMap;

OpenDocumentRevisionsMap& openDocumentsRevisionMap()
{
  static OpenDocumentRevisionsMap map;
  return map;
}

QDateTime fileModificationTimeCached( const IndexedString& fileName )
{
  timeval currentTime;
  gettimeofday(&currentTime, 0);

  FileModificationMap::const_iterator it = fileModificationCache().constFind( fileName );
  if ( it != fileModificationCache().constEnd() ) {
    ///Use the cache for X seconds
    timeval age;
    timersub(&currentTime, &it.value().m_readTime, &age);
    if ( age.tv_sec < cacheModificationTimesForSeconds ) {
      return it.value().m_modificationTime;
    }
  }

  QFileInfo fileInfo( fileName.str() );
  FileModificationCache data = {currentTime, fileInfo.lastModified()};
  fileModificationCache().insert(fileName, data);
  return data.m_modificationTime;
}

void ModificationRevision::clearModificationCache(const IndexedString& fileName)
{
  ///@todo Make the cache management more clever (don't clear the whole)
  ModificationRevisionSet::clearCache();

  QMutexLocker lock(&fileModificationTimeCacheMutex);

  fileModificationCache().remove(fileName);
}

ModificationRevision ModificationRevision::revisionForFile(const IndexedString& url)
{
  QMutexLocker lock(&fileModificationTimeCacheMutex);

  ModificationRevision ret(fileModificationTimeCached(url));

  OpenDocumentRevisionsMap::const_iterator it = openDocumentsRevisionMap().constFind(url);
  if(it != openDocumentsRevisionMap().constEnd()) {
    ret.revision = it.value();
  }

  return ret;
}

void ModificationRevision::clearEditorRevisionForFile(const KDevelop::IndexedString& url)
{
  ModificationRevisionSet::clearCache(); ///@todo Make the cache management more clever (don't clear the whole)

  QMutexLocker lock(&fileModificationTimeCacheMutex);
  openDocumentsRevisionMap().remove(url);
}

void ModificationRevision::setEditorRevisionForFile(const KDevelop::IndexedString& url, int revision)
{
  ModificationRevisionSet::clearCache(); ///@todo Make the cache management more clever (don't clear the whole)

  QMutexLocker lock(&fileModificationTimeCacheMutex);
  openDocumentsRevisionMap().insert(url, revision);
  Q_ASSERT(revisionForFile(url).revision == revision);
}

ModificationRevision::ModificationRevision( const QDateTime& modTime , int revision_ )
: modificationTime(modTime.toTime_t())
, revision(revision_)
{
}

bool ModificationRevision::operator <( const ModificationRevision& rhs ) const
{
  return modificationTime < rhs.modificationTime || (modificationTime == rhs.modificationTime && revision < rhs.revision);
}

bool ModificationRevision::operator ==( const ModificationRevision& rhs ) const
{
  return modificationTime == rhs.modificationTime && revision == rhs.revision;
}

bool ModificationRevision::operator !=( const ModificationRevision& rhs ) const
{
  return modificationTime != rhs.modificationTime || revision != rhs.revision;
}

QString ModificationRevision::toString() const
{
  return QString("%1 (rev %2)").arg(QDateTime::fromTime_t(modificationTime).time().toString()).arg(revision);
}

}

/*
kdbgstream& operator<< (kdbgstream& s, const KDevelop::ModificationRevision& rev)
{
  s << rev.toString();
  return s;
}
*/