/*******************************************************************************
 * Copyright (c) 2009 Elliott Baron
 * 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:
 *    Elliott Baron - initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.codan.checkers;

import java.text.MessageFormat;

import org.eclipse.cdt.codan.core.model.AbstractIndexAstChecker;
import org.eclipse.cdt.core.dom.ast.ASTVisitor;
import org.eclipse.cdt.core.dom.ast.IASTDeclarator;
import org.eclipse.cdt.core.dom.ast.IASTExpression;
import org.eclipse.cdt.core.dom.ast.IASTFunctionCallExpression;
import org.eclipse.cdt.core.dom.ast.IASTIdExpression;
import org.eclipse.cdt.core.dom.ast.IASTInitializer;
import org.eclipse.cdt.core.dom.ast.IASTName;
import org.eclipse.cdt.core.dom.ast.IASTNode;
import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
import org.eclipse.cdt.core.dom.ast.IBinding;

public class CloseOpenedFilesChecker extends AbstractIndexAstChecker {
	private static final String ERR_ID = Activator.PLUGIN_ID + ".CloseOpenedFilesProblem";

	public void processAst(IASTTranslationUnit ast) {
		// traverse the AST using the visitor pattern
		CloseOpenedFilesVisitor visitor = new CloseOpenedFilesVisitor();
		ast.accept(visitor);
		
		IASTName closeFD = visitor.getCloseFD();
		if (closeFD != null) {
			IASTName openFD = visitor.getOpenFD();
			if (openFD == null || !matchingFileDescriptors(closeFD.getBinding(), openFD.getBinding())) {
				String message = MessageFormat.format("File descriptor \"{0}\" has not been opened", closeFD.toString());
				reportProblem(ERR_ID, closeFD, message);
			}
		}
	}

	private boolean matchingFileDescriptors(IBinding closeFD, IBinding openFD) {
		// FIXME elaborate
		return closeFD.equals(openFD);
	}
	
	class CloseOpenedFilesVisitor extends ASTVisitor {
		
		public static final String OPEN = "open";
		public static final String CLOSE = "close";
		
		private IASTName openFD;
		private IASTName closeFD;

		public CloseOpenedFilesVisitor() {
			shouldVisitExpressions = true;
		}
		
		@Override
		public int visit(IASTExpression expression) {
			if (expression instanceof IASTFunctionCallExpression) {
				IASTFunctionCallExpression callExpression = (IASTFunctionCallExpression) expression;
				IASTExpression funcName = callExpression.getFunctionNameExpression();
				if (funcName instanceof IASTIdExpression) {
					IASTName name = ((IASTIdExpression) funcName).getName();
					String simpleName = String.valueOf(name.getSimpleID());
					if (simpleName.equals(OPEN)) {
						IASTNode parent = callExpression.getParent();
						if (parent instanceof IASTInitializer) {
							parent = parent.getParent();
							if (parent instanceof IASTDeclarator) {
								openFD = ((IASTDeclarator) parent).getName();
							}
						}
					}
					else if (simpleName.equals(CLOSE)) {
						IASTExpression paramExpression = callExpression.getParameterExpression();
						if (paramExpression instanceof IASTIdExpression) {
							closeFD = ((IASTIdExpression) paramExpression).getName();
						}						
					}
				}
				
				return PROCESS_SKIP;
			}
			else {
				return PROCESS_CONTINUE;
			}
		}
		
		public IASTName getOpenFD() {
			return openFD;
		}
		
		public IASTName getCloseFD() {
			return closeFD;
		}
	}

}