/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.sysds.utils;

import static org.junit.Assert.fail;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.sysds.runtime.io.IOUtilFunctions;

/**
 * Class to help setting variables in a script. 
 */
public class ParameterBuilder 
{
	
	/** String used to replace variables in scripts */
	private static String _RS = "\\$\\$";

	/**
	 * <p>
	 * Replaces variables in a DML or R script with the specified values. A
	 * variable of format $$name$$ will be replaced where the name is used to
	 * identify the variable in the hashmap containing the belonging value.
	 * </p>
	 * 
	 * @param strScriptPathName
	 *            filename of the DML script
	 * @param variables
	 *            hashmap containing all the variables and their replacements
	 */
	public static void setVariablesInScript(String strScriptPathName, HashMap<String, String> variables) {
		try {
			String strScript = strScriptPathName;
			String strTmpScript = strScript + "t";

			BufferedReader in = null;
			PrintWriter pw = null;
			
			try {
				in = new BufferedReader(new InputStreamReader(new FileInputStream(strScript)));
				pw = new PrintWriter(new FileOutputStream(strTmpScript));
				
				String content;
				Pattern unresolvedVars = Pattern.compile(_RS + ".*" + _RS);
				/*
				 * so that variables, which were not assigned, are replaced by an
				 * empty string
				 */
				while ((content = in.readLine()) != null) {
					for (Entry<String, String> e : variables.entrySet() ) {
						String variable = e.getKey();
						String val = e.getValue();
						Pattern pattern = Pattern.compile(_RS + variable + _RS);
						Matcher matcher = pattern.matcher(content);
						while (matcher.find()) {
							content = content.replaceFirst(matcher.group().replace("$", "\\$"), val);
						}
					}
					Matcher matcher = unresolvedVars.matcher(content);
					content = matcher.replaceAll("");
					pw.println(content);
				}
			}
			finally {
				IOUtilFunctions.closeSilently(pw);
				IOUtilFunctions.closeSilently(in);
			}
		} 
		catch (IOException e) {
			fail("unable to set variables in dml script: " + e.getMessage());
		}
	}

	/**
	 * <p>
	 * Replaces variables in a DML or R script with the specified values. A
	 * variable of format $$name$$ will be replaced where the name is used to
	 * identify the variable in the hashmap containing the belonging value.
	 * </p>
	 * 
	 * @param strScriptDirectory
	 *            directory which contains the DML script
	 * @param strScriptFile
	 *            filename of the DML script
	 * @param variables
	 *            hashmap containing all the variables and their replacements
	 */
	public static void setVariablesInScript(String strScriptDirectory, String strScriptFile,
			HashMap<String, String> variables) {

		String strScript = strScriptDirectory + strScriptFile;
		setVariablesInScript(strScript, variables);
	}
}