/*!
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* This program 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 Lesser General Public License for more details.
*
* Copyright (c) 2002-2013 Pentaho Corporation..  All rights reserved.
*/

package org.pentaho.reporting.engine.classic.extensions.datasources.mondrian;

import mondrian.olap.Util;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemManager;
import org.apache.commons.vfs2.VFS;
import org.pentaho.reporting.libraries.resourceloader.ResourceKey;
import org.pentaho.reporting.libraries.resourceloader.ResourceManager;

import java.io.File;
import java.io.IOException;

/**
 * This class emulates Mondrian's schema resolving and allows us to find a string that correctly represents a valid VFS
 * path for use in mondrian.
 *
 * @author Thomas Morgner.
 */
public class SchemaResolver {
  private static final Log logger = LogFactory.getLog( SchemaResolver.class );

  private SchemaResolver() {
  }

  public static String resolveSchema( final ResourceManager resourceManager,
                                      final ResourceKey contextKey,
                                      String catalogUrl )
    throws FileSystemException {
    final FileSystemManager fsManager = VFS.getManager();
    if ( fsManager == null ) {
      throw Util.newError( "Cannot get virtual file system manager" );
    }

    // Workaround VFS bug.
    if ( catalogUrl.startsWith( "file://localhost" ) ) {
      catalogUrl = catalogUrl.substring( "file://localhost".length() );
    }
    if ( catalogUrl.startsWith( "file:" ) ) {
      catalogUrl = catalogUrl.substring( "file:".length() );
    }

    try {
      final File catalogFile = new File( catalogUrl ).getCanonicalFile();
      final FileObject file = fsManager.toFileObject( catalogFile );
      if ( file.isReadable() ) {
        return catalogFile.getPath();
      }
    } catch ( FileSystemException fse ) {
      logger.info( "Failed to resolve schema file '" + catalogUrl + "' as local file. Treating file as non-readable.",
        fse );
    } catch ( IOException e ) {
      logger
        .info( "Failed to resolve schema file '" + catalogUrl + "' as local file. Treating file as non-readable.", e );
    }

    if ( contextKey == null ) {
      return catalogUrl;
    }

    final File contextAsFile = getContextAsFile( contextKey );
    if ( contextAsFile == null ) {
      return catalogUrl;
    }

    final File resolvedFile = new File( contextAsFile.getParentFile(), catalogUrl );
    if ( resolvedFile.isFile() && resolvedFile.canRead() ) {
      return resolvedFile.getAbsolutePath();
    }

    return catalogUrl;
  }

  private static File getContextAsFile( ResourceKey key ) {
    while ( key != null ) {
      final Object identifier = key.getIdentifier();
      if ( identifier instanceof File ) {
        return (File) identifier;
      }

      key = key.getParent();
    }
    return null;
  }

}