Copyright (c) 2000, 2013 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.debug.internal.core.variables;

import java.io.File;
import java.net.URI;

import org.eclipse.core.filesystem.EFS;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.variables.IDynamicVariable;
import org.eclipse.core.variables.IDynamicVariableResolver;
import org.eclipse.core.variables.IStringVariableManager;
import org.eclipse.core.variables.VariablesPlugin;
import org.eclipse.debug.core.DebugPlugin;

import com.ibm.icu.text.MessageFormat;

Common function of variable resolvers.
Moved to debug core in 3.5, existed in debug.iu since 3.0.
Since:
3.5/**
 * Common function of variable resolvers.
 * Moved to debug core in 3.5, existed in debug.iu since 3.0.
 *
 * @since 3.5
 */
public class ResourceResolver implements IDynamicVariableResolver {

	@Override
	public String resolveValue(IDynamicVariable variable, String argument) throws CoreException {
		IResource resource = null;
		if (argument == null) {
			resource = getSelectedResource(variable);
		} else {
			resource = getWorkspaceRoot().findMember(new Path(argument));
		}
		if (resource != null && resource.exists()) {
			resource = translateSelectedResource(resource);
			if (resource != null && resource.exists()) {
				return translateToValue(resource, variable);
			}
		}
		abort(MessageFormat.format(Messages.ResourceResolver_0, new Object[] { getReferenceExpression(variable, argument) }), null);
		return null;
	}

	
Returns the resource applicable to this resolver, relative to the selected
resource. This method is called when no argument is present in a variable
expression. For, example, this method might return the project for the
selected resource.
Params:
resource – selected resource
Returns:
resource applicable to this variable resolver/**
	 * Returns the resource applicable to this resolver, relative to the selected
	 * resource. This method is called when no argument is present in a variable
	 * expression. For, example, this method might return the project for the
	 * selected resource.
	 *
	 * @param resource selected resource
	 * @return resource applicable to this variable resolver
	 */
	protected IResource translateSelectedResource(IResource resource) {
		return resource;
	}

	
Returns the workspace root
Returns:
workspace root/**
	 * Returns the workspace root
	 *
	 * @return workspace root
	 */
	protected IWorkspaceRoot getWorkspaceRoot() {
		return ResourcesPlugin.getWorkspace().getRoot();
	}

	
Returns an expression used to reference the given variable and optional argument.
For example, ${var_name:arg}.
Params:
variable – referenced variable
argument – referenced argument or null
Returns:
variable reference expression/**
	 * Returns an expression used to reference the given variable and optional argument.
	 * For example, <code>${var_name:arg}</code>.
	 *
	 * @param variable referenced variable
	 * @param argument referenced argument or <code>null</code>
	 * @return variable reference expression
	 */
	protected String getReferenceExpression(IDynamicVariable variable, String argument) {
		StringBuilder reference = new StringBuilder();
		reference.append("${"); //$NON-NLS-1$
		reference.append(variable.getName());
		if (argument != null) {
			reference.append(":"); //$NON-NLS-1$
			reference.append(argument);
		}
		reference.append("}"); //$NON-NLS-1$
		return reference.toString();
	}

	
Throws an exception with the given message and underlying exception.
Params:
message – exception message
exception – underlying exception or null
Throws:
CoreException – if a problem occurs/**
	 * Throws an exception with the given message and underlying exception.
	 *
	 * @param message exception message
	 * @param exception underlying exception or <code>null</code>
	 * @throws CoreException if a problem occurs
	 */
	protected void abort(String message, Throwable exception) throws CoreException {
		throw new CoreException(new Status(IStatus.ERROR, DebugPlugin.getUniqueIdentifier(), DebugPlugin.INTERNAL_ERROR, message, exception));
	}

	
Returns the selected resource. Uses the ${selected_resource_path} variable
to determine the selected resource. This variable is provided by the debug.ui
plug-in. Selected resource resolution is only available when the debug.ui
plug-in is present.
Params:
variable – variable referencing a resource
Throws:
CoreException – if there is no selection
Returns:
selected resource/**
	 * Returns the selected resource. Uses the ${selected_resource_path} variable
	 * to determine the selected resource. This variable is provided by the debug.ui
	 * plug-in. Selected resource resolution is only available when the debug.ui
	 * plug-in is present.
	 *
	 * @param variable variable referencing a resource
	 * @return selected resource
	 * @throws CoreException if there is no selection
	 */
	protected IResource getSelectedResource(IDynamicVariable variable) throws CoreException {
		IStringVariableManager manager = VariablesPlugin.getDefault().getStringVariableManager();
		try {
			String pathString = manager.performStringSubstitution("${selected_resource_path}"); //$NON-NLS-1$
			return ResourcesPlugin.getWorkspace().getRoot().findMember(new Path(pathString));
		} catch (CoreException e) {
			// unable to resolve a selection
		}
		abort(MessageFormat.format(Messages.ResourceResolver_1, new Object[] { getReferenceExpression(variable, null) }), null);
		return null;
	}

	
Translates the given resource into a value for this variable resolver.
Params:
resource – the resource applicable to this resolver's variable
variable – the variable being resolved
Throws:
CoreException – if the variable name is not recognized
Returns:
variable value/**
	 * Translates the given resource into a value for this variable resolver.
	 *
	 * @param resource the resource applicable to this resolver's variable
	 * @param variable the variable being resolved
	 * @return variable value
	 * @throws CoreException if the variable name is not recognized
	 */
	protected String translateToValue(IResource resource, IDynamicVariable variable) throws CoreException {
		String name = variable.getName();
		IPath path = null;
		URI uri = null;
		if (name.endsWith("_loc")) { //$NON-NLS-1$
			uri = resource.getLocationURI();
			if(uri != null) {
				File file = EFS.getStore(uri).toLocalFile(0, null);
				if(file != null) {
					return file.getAbsolutePath();
				}
			}
		} else if (name.endsWith("_path")) { //$NON-NLS-1$
			path = resource.getFullPath();
			if(path != null) {
				return path.toOSString();
			}
		} else if (name.endsWith("_name")) { //$NON-NLS-1$
			return resource.getName();
		}
		abort(MessageFormat.format(Messages.ResourceResolver_2, new Object[] { getReferenceExpression(variable, null) }), null);
		return null;
	}

}