/*******************************************************************************
 * Copyright (c) 2006 Oracle Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Cameron Bateman/Oracle - initial API and implementation
 *    
 ********************************************************************************/

package org.eclipse.jst.jsf.designtime.symbols;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.jst.jsf.context.resolver.structureddocument.IStructuredDocumentContextResolverFactory;
import org.eclipse.jst.jsf.context.resolver.structureddocument.IWorkspaceContextResolver;
import org.eclipse.jst.jsf.context.structureddocument.IStructuredDocumentContext;

/**
 * Utility for deriving an IFile from an IAdaptable
 * 
 * @author cbateman
 *
 */
public final class FileContextUtil 
{
    /**
     * @param context
     * @return an IFile derived from context or null if not derivable
     */
    public static IFile deriveIFileFromContext(IAdaptable context)
    {
        // 
        if (context instanceof IFile)
        {
            return (IFile) context;
        }
        else if (context.getAdapter(IFile.class) != null)
        {
            return (IFile) context.getAdapter(IFile.class);
        }
        else if (context instanceof IStructuredDocumentContext)
        {
            return deriveIFileFromContext((IStructuredDocumentContext)context);
        }
        else
        {
            IStructuredDocumentContext  sdContext = 
                (IStructuredDocumentContext) context.getAdapter(IStructuredDocumentContext.class);
            
            if (sdContext != null)
            {
                return deriveIFileFromContext(sdContext);
            }
        }
 
        return null;
    }
    
    private static IFile deriveIFileFromContext(IStructuredDocumentContext context)
    {
        IWorkspaceContextResolver resolver = 
            IStructuredDocumentContextResolverFactory.
                INSTANCE.
                    getWorkspaceContextResolver(context);
        
        if (resolver != null)
        {
            IResource res = resolver.getResource();
            
            if (res instanceof IFile)
            {
                return (IFile) res;
            }
        }
        
        return null;
    }
    
    private FileContextUtil()
    {
        // no instantiation
    }
}