qgspathresolver.cpp

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/***************************************************************************
  qgspathresolver.cpp
  --------------------------------------
  Date                 : February 2017
  Copyright            : (C) 2017 by Martin Dobias
  Email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program 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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "qgspathresolver.h"

#include "qgis.h"

#include <QFileInfo>


QgsPathResolver::QgsPathResolver( const QString &baseFileName )
  : mBaseFileName( baseFileName )
{
}


QString QgsPathResolver::readPath( const QString &filename ) const
{
  if ( filename.isEmpty() )
    return QString();

  QString src = filename;

  if ( mBaseFileName.isNull() )
  {
    return src;
  }

  // if this is a VSIFILE, remove the VSI prefix and append to final result
  QString vsiPrefix = qgsVsiPrefix( src );
  if ( ! vsiPrefix.isEmpty() )
  {
    // unfortunately qgsVsiPrefix returns prefix also for files like "/x/y/z.gz"
    // so we need to check if we really have the prefix
    if ( src.startsWith( QLatin1String( "/vsi" ), Qt::CaseInsensitive ) )
      src.remove( 0, vsiPrefix.size() );
    else
      vsiPrefix.clear();
  }

  // relative path should always start with ./ or ../
  if ( !src.startsWith( QLatin1String( "./" ) ) && !src.startsWith( QLatin1String( "../" ) ) )
  {
#if defined(Q_OS_WIN)
    if ( src.startsWith( "\\\\" ) ||
         src.startsWith( "//" ) ||
         ( src[0].isLetter() && src[1] == ':' ) )
    {
      // UNC or absolute path
      return vsiPrefix + src;
    }
#else
    if ( src[0] == '/' )
    {
      // absolute path
      return vsiPrefix + src;
    }
#endif

    // so this one isn't absolute, but also doesn't start // with ./ or ../.
    // That means that it was saved with an earlier version of "relative path support",
    // where the source file had to exist and only the project directory was stripped
    // from the filename.

    QFileInfo pfi( mBaseFileName );
    QString home = pfi.absolutePath();
    if ( home.isEmpty() )
      return vsiPrefix + src;

    QFileInfo fi( home + '/' + src );

    if ( !fi.exists() )
    {
      return vsiPrefix + src;
    }
    else
    {
      return vsiPrefix + fi.canonicalFilePath();
    }
  }

  QString srcPath = src;
  QString projPath = mBaseFileName;

  if ( projPath.isEmpty() )
  {
    return vsiPrefix + src;
  }

#if defined(Q_OS_WIN)
  srcPath.replace( '\\', '/' );
  projPath.replace( '\\', '/' );

  bool uncPath = projPath.startsWith( "//" );
#endif

  QStringList srcElems = srcPath.split( '/', QString::SkipEmptyParts );
  QStringList projElems = projPath.split( '/', QString::SkipEmptyParts );

#if defined(Q_OS_WIN)
  if ( uncPath )
  {
    projElems.insert( 0, "" );
    projElems.insert( 0, "" );
  }
#endif

  // remove project file element
  projElems.removeLast();

  // append source path elements
  projElems << srcElems;
  projElems.removeAll( QStringLiteral( "." ) );

  // resolve ..
  int pos;
  while ( ( pos = projElems.indexOf( QStringLiteral( ".." ) ) ) > 0 )
  {
    // remove preceding element and ..
    projElems.removeAt( pos - 1 );
    projElems.removeAt( pos - 1 );
  }

#if !defined(Q_OS_WIN)
  // make path absolute
  projElems.prepend( QString() );
#endif

  return vsiPrefix + projElems.join( QStringLiteral( "/" ) );
}


QString QgsPathResolver::writePath( const QString &src ) const
{
  if ( mBaseFileName.isEmpty() || src.isEmpty() )
  {
    return src;
  }

  // Get projPath even if project has not been created yet
  QFileInfo pfi( QFileInfo( mBaseFileName ).path() );
  QString projPath = pfi.canonicalFilePath();

  // If project directory doesn't exit, fallback to absoluteFilePath : symbolic
  // links won't be handled correctly, but that's OK as the path is "virtual".
  if ( projPath.isEmpty() )
    projPath = pfi.absoluteFilePath();

  if ( projPath.isEmpty() )
  {
    return src;
  }

  // Strip "file://"
  QFileInfo srcFileInfo( src.startsWith( QStringLiteral( "file://" ) ) ? src.mid( 7 ) : src );
  QString srcPath = srcFileInfo.exists() ? srcFileInfo.canonicalFilePath() : src;

  // if this is a VSIFILE, remove the VSI prefix and append to final result
  QString vsiPrefix = qgsVsiPrefix( src );
  if ( ! vsiPrefix.isEmpty() )
  {
    srcPath.remove( 0, vsiPrefix.size() );
  }

#if defined( Q_OS_WIN )
  const Qt::CaseSensitivity cs = Qt::CaseInsensitive;

  srcPath.replace( '\\', '/' );

  if ( srcPath.startsWith( "//" ) )
  {
    // keep UNC prefix
    srcPath = "\\\\" + srcPath.mid( 2 );
  }

  projPath.replace( '\\', '/' );
  if ( projPath.startsWith( "//" ) )
  {
    // keep UNC prefix
    projPath = "\\\\" + projPath.mid( 2 );
  }
#else
  const Qt::CaseSensitivity cs = Qt::CaseSensitive;
#endif

  QStringList projElems = projPath.split( '/', QString::SkipEmptyParts );
  QStringList srcElems = srcPath.split( '/', QString::SkipEmptyParts );

  projElems.removeAll( QStringLiteral( "." ) );
  srcElems.removeAll( QStringLiteral( "." ) );

  // remove common part
  int n = 0;
  while ( !srcElems.isEmpty() &&
          !projElems.isEmpty() &&
          srcElems[0].compare( projElems[0], cs ) == 0 )
  {
    srcElems.removeFirst();
    projElems.removeFirst();
    n++;
  }

  if ( n == 0 )
  {
    // no common parts; might not even be a file
    return src;
  }

  if ( !projElems.isEmpty() )
  {
    // go up to the common directory
    for ( int i = 0; i < projElems.size(); i++ )
    {
      srcElems.insert( 0, QStringLiteral( ".." ) );
    }
  }
  else
  {
    // let it start with . nevertheless,
    // so relative path always start with either ./ or ../
    srcElems.insert( 0, QStringLiteral( "." ) );
  }

  return vsiPrefix + srcElems.join( QStringLiteral( "/" ) );
}