/*
 * Copyright 2014 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.gv.egovernment.moa.id.auth.modules.eidas.utils;

import java.util.regex.Pattern;

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang.StringUtils;

import com.google.common.collect.ImmutableSet;

import at.gv.egiz.eaaf.core.impl.utils.KeyValueUtils;

/**
 * @author tlenz
 *
 */
public class MOAWhiteListConfigurator  {
	 private static final Pattern WHITE_LIST_SPLITTER = Pattern.compile("[;,]");

	    
	    public static ImmutableSet<String> getAllowedAlgorithms( ImmutableSet<String> defaultWhiteList,
	                                                             ImmutableSet<String> allowedValues,
	                                                            String algorithmWhiteListValue) {
	        if (StringUtils.isBlank(algorithmWhiteListValue)) {
	            return defaultWhiteList;
	        }
	        ImmutableSet.Builder<String> allowed = ImmutableSet.builder();
	        String[] wlAlgorithms = WHITE_LIST_SPLITTER.split(algorithmWhiteListValue);
	        
	        //BugFix: remove newlines from configuration
	        for (int i=0; i<wlAlgorithms.length; i++)
	        	wlAlgorithms[i] = StringUtils.trimToNull(KeyValueUtils.removeAllNewlineFromString(wlAlgorithms[i]));
 	        
	        if (null != wlAlgorithms && wlAlgorithms.length > 0) {
	            return getAllowedAlgorithms(defaultWhiteList, allowedValues, ImmutableSet.<String>copyOf(wlAlgorithms));
	        }
	        return defaultWhiteList;
	    }


	    public static ImmutableSet<String> getAllowedAlgorithms( ImmutableSet<String> defaultWhiteList,
	                                                             ImmutableSet<String> allowedValues,
	                                                            ImmutableSet<String> candidateValues) {
	        if (CollectionUtils.isEmpty(candidateValues)) {
	            return defaultWhiteList;
	        }
	        ImmutableSet.Builder<String> allowed = ImmutableSet.builder();
	        boolean modified = false;
	        for (String candidateValue : candidateValues) {

	    	    /**FIX:
	    	     * fix problem with lowerCase and MGF1 signature algorithms  
	    	     * 
	    	     */
	            candidateValue = StringUtils.trimToNull(
	            		KeyValueUtils.removeAllNewlineFromString(candidateValue));
	            if (StringUtils.isNotBlank(candidateValue)) {
	            	
	            	//BUGFIX: eIDAS SAML-engine MPF1 signature schemes problem 
	            	String candidateAlgorithm = candidateValue;
	            	//String candidateAlgorithm = StringUtils.lowerCase(candidateValue, Locale.ENGLISH);
	            	
	                if (allowedValues.contains(candidateAlgorithm)) {
	                    allowed.add(candidateValue);
	                    if (!modified && !candidateAlgorithm.equals(candidateValue)) {
	                        modified = true;
	                    }
	                } else {
	                    modified = true;
	                }
	            }
	        }
	        if (!modified) {
	            return candidateValues;
	        }
	        ImmutableSet<String> set = allowed.build();
	        if (set.isEmpty()) {
	            return defaultWhiteList;
	        }
	        return set;
	    }

}