package net.sourceforge.phpdt.externaltools.variable;

/**********************************************************************
Copyright (c) 2002 IBM Corp. and others. All rights reserved.
This file is made available under the terms of the Common Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v10.html
 
Contributors:
**********************************************************************/

import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IPath;
import net.sourceforge.phpdt.externaltools.model.IExternalToolConstants;

/**
 * Expands a resource type variable into the desired
 * result format.
 * <p>
 * This class is not intended to be extended by clients.
 * </p>
 */
public class ResourceExpander implements IVariableLocationExpander, IVariableResourceExpander, IVariableTextExpander {

	/**
	 * Create an instance
	 */
	public ResourceExpander() {
		super();
	}

	/**
	 * Expands the variable to a resource.
	 */
	/*package*/ IResource expand(String varValue, ExpandVariableContext context) {
		if (varValue != null && varValue.length() > 0) {
			return expandToMember(varValue);
		} else {
			return expandUsingContext(context);
		}
	}
	
	/**
	 * Expands using the current context information.
	 * By default, return the selected resource of the
	 * context.
	 */
	/*package*/ IResource expandUsingContext(ExpandVariableContext context) {
		return context.getSelectedResource();
	}
	
	/**
	 * Expands the variable value to a resource. The value
	 * will not be <code>null</code> nor empty. By default,
	 * lookup the member from the workspace root.
	 */
	/*package*/ IResource expandToMember(String varValue) {
		return getWorkspaceRoot().findMember(varValue);
	}
	
	/* (non-Javadoc)
	 * Method declared on IVariableLocationExpander.
	 */
	public IPath getPath(String varTag, String varValue, ExpandVariableContext context) {
		IResource resource = expand(varValue, context);
		if (resource != null) {
			if (isPathVariable(varTag)) {
				return resource.getFullPath();
			} else {
				return resource.getLocation();
			}
		} else {
			return null;
		}
	}
	
	/**
	 * Returns whether the given variable tag is a known path
	 * variable tag. Path variable tags represent variables that
	 * expand to paths relative to the workspace root.
	 */
	private boolean isPathVariable(String varTag) {
		return varTag.equals(IExternalToolConstants.VAR_CONTAINER_PATH) ||
				varTag.equals(IExternalToolConstants.VAR_PROJECT_PATH) ||
				varTag.equals(IExternalToolConstants.VAR_RESOURCE_PATH);
	}

	/* (non-Javadoc)
	 * Method declared on IVariableResourceExpander.
	 */
	public IResource[] getResources(String varTag, String varValue, ExpandVariableContext context) {
		IResource resource = expand(varValue, context);
		if (resource != null) {
			return new IResource[] {resource};
		} else {
			return null;
		}
	}
	
	/**
	 * Returns the workspace root resource.
	 */
	protected final IWorkspaceRoot getWorkspaceRoot() {
		return ResourcesPlugin.getWorkspace().getRoot();
	}
	
	/**
	 * Returns a string representation of the path to a file or directory
	 * for the given variable tag and value or <code>null</code>.
	 * 
	 * @see IVariableTextExpander#getText(String, String, ExpandVariableContext)
	 */
	public String getText(String varTag, String varValue, ExpandVariableContext context) {
		IPath path= getPath(varTag, varValue, context);
		if (path != null) {
			return path.toString();
		}
		return null;
	}

}