/*******************************************************************************
 * 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.
 ******************************************************************************/
/*
 * Copyright 2003 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.egiz.eaaf.core.impl.idp.auth.builder;

import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Base64Utils;

import at.gv.egiz.eaaf.core.api.data.EAAFConstants;
import at.gv.egiz.eaaf.core.exceptions.EAAFBuilderException;
import at.gv.egiz.eaaf.core.impl.data.Pair;

/**
 * Builder for the bPK, as defined in
 * <code>&quot;Ableitung f&uml;r die bereichsspezifische Personenkennzeichnung&quot;</code>
 * version <code>1.0.1</code> from <code>&quot;reference.e-government.gv.at&quot;</code>.
 *
 */
public class BPKBuilder {
	private static final Logger log = LoggerFactory.getLogger(BPKBuilder.class);
	
	/**
	 * Calculates an area specific unique person-identifier from a baseID
	 * 
	 * @param baseID baseId from user but never null
	 * @param targetIdentifier target identifier for area specific identifier calculation but never null
	 * @return Pair consists of (unique person identifier for this target, targetArea) but never null
	 * @throws EAAFBuilderException if some input data are not valid 
	 */
	public static Pair<String, String> generateAreaSpecificPersonIdentifier(String baseID, String targetIdentifier) throws EAAFBuilderException {
		return generateAreaSpecificPersonIdentifier(baseID, EAAFConstants.URN_PREFIX_BASEID, targetIdentifier);
		
	}
	
	/**
	 * Calculates an area specific unique person-identifier from an unique identifier with a specific type
	 * 
	 * @param baseID baseId from user but never null
	 * @param baseIdType Type of the baseID but never null
	 * @param targetIdentifier target identifier for area specific identifier calculation but never null
	 * @return Pair consists of (unique person identifier for this target, targetArea) but never null
	 * @throws EAAFBuilderException if some input data are not valid 
	 */
	public static Pair<String, String> generateAreaSpecificPersonIdentifier(String baseID, String baseIdType, String targetIdentifier) throws EAAFBuilderException{
		if (StringUtils.isEmpty(baseID))
			throw new EAAFBuilderException("builder.00", new Object[]{"baseID is empty or null"},
					"BaseId is empty or null");

		if (StringUtils.isEmpty(baseIdType))
			throw new EAAFBuilderException("builder.00", new Object[]{"the type of baseID is empty or null"},
					"Type of baseId is empty or null");
		
		if (StringUtils.isEmpty(targetIdentifier)) 
			throw new EAAFBuilderException("builder.00", new Object[]{"SP specific target identifier is empty or null"},
					"SP specific target identifier is empty or null");

		if (baseIdType.equals(EAAFConstants.URN_PREFIX_BASEID)) {
			log.trace("Find baseID. Starting unique identifier caluclation for this target");
			
			if (targetIdentifier.startsWith(EAAFConstants.URN_PREFIX_CDID) || 
					targetIdentifier.startsWith(EAAFConstants.URN_PREFIX_WBPK)) {
				log.trace("Calculate bPK, wbPK, or STORK identifier for target: " + targetIdentifier);
				return Pair.newInstance(calculatebPKwbPK(baseID + "+" + targetIdentifier), targetIdentifier);
													
			} else if (targetIdentifier.startsWith(EAAFConstants.URN_PREFIX_EIDAS)) {
				log.trace("Calculate eIDAS identifier for target: " + targetIdentifier);
				final String[] splittedTarget = targetIdentifier.split("\\+");
				final String cititzenCountryCode = splittedTarget[1];
				final String eIDASOutboundCountry = splittedTarget[2];				 
				 
				if (cititzenCountryCode.equalsIgnoreCase(eIDASOutboundCountry)) {
					log.warn("Suspect configuration FOUND!!! CitizenCountry equals DestinationCountry");
					 
				}
				return buildeIDASIdentifer(baseID, baseIdType, cititzenCountryCode, eIDASOutboundCountry);
				
				
			} else
				throw new EAAFBuilderException("builder.00", 
						new Object[]{"Target identifier: " + targetIdentifier + " is NOT allowed or unknown"},
						"Target identifier: " + targetIdentifier + " is NOT allowed or unknown");
		
		} else {
			log.trace("BaseID is not of type " + EAAFConstants.URN_PREFIX_BASEID + ". Check type against requested target ...");
			if (baseIdType.equals(targetIdentifier)) {
				log.debug("Unique identifier is already area specific. Is nothing todo");
				return Pair.newInstance(baseID, targetIdentifier);
				
			} else {
				log.warn("Get unique identifier for target: " + baseIdType + " but target: " + targetIdentifier + " is required!");
				throw new EAAFBuilderException("builder.00", 
						new Object[]{"Get unique identifier for target: " + baseIdType + " but target: " + targetIdentifier + " is required"},
						"Get unique identifier for target: " + baseIdType + " but target: " + targetIdentifier + " is required");
				
			}			
		}						
	}
	
	
    /**
     * Builds the eIDAS from the given parameters.
     *
     * @param baseID baseID of the citizen
     * @param baseIDType Type of the baseID
     * @param sourceCountry CountryCode of that country, which build the eIDAs ID
     * @param destinationCountry CountryCode of that country, which receives the eIDAs ID
     * 
     * @return Pair<eIDAs, bPKType> in a BASE64 encoding
     * @throws EAAFBuilderException if some input data are not valid 
     */
    private static Pair<String, String> buildeIDASIdentifer(String baseID, String baseIDType, String sourceCountry, String destinationCountry)
            throws EAAFBuilderException {        
        String bPK = null;
        String bPKType = null;
        
        // check if we have been called by public sector application
        if (baseIDType.startsWith(EAAFConstants.URN_PREFIX_BASEID)) {
        	bPKType = EAAFConstants.URN_PREFIX_EIDAS + sourceCountry + "+" + destinationCountry;
            log.debug("Building eIDAS identification from: [identValue]+" + bPKType);         
            bPK = calculatebPKwbPK(baseID + "+"  + bPKType);
            
        } else { // if not, sector identification value is already calculated by BKU
            log.debug("eIDAS eIdentifier already provided by BKU");
            bPK = baseID;
        }

        if ((StringUtils.isEmpty(bPK) ||
                StringUtils.isEmpty(sourceCountry) ||
                	StringUtils.isEmpty(destinationCountry))) {
            throw new EAAFBuilderException("builder.00",
                    new Object[]{"eIDAS-ID", "Unvollständige Parameterangaben: identificationValue=" +
                            bPK + ", Zielland=" + destinationCountry + ", Ursprungsland=" + sourceCountry}
                    ,"eIDAS-ID: Unvollständige Parameterangaben: identificationValue=" +
                            bPK + ", Zielland=" + destinationCountry + ", Ursprungsland=" + sourceCountry);
        }
        
        log.trace("eIDAS pseudonym generation finished. ");
        final String eIdentifier = sourceCountry + "/" + destinationCountry + "/" + bPK;
        
        return Pair.newInstance(eIdentifier, bPKType);
    }
	    
	public static String encryptBPK(String bpk, String target, PublicKey publicKey) throws EAAFBuilderException {		
		final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
		if (target.startsWith(EAAFConstants.URN_PREFIX_CDID))
			target = target.substring((EAAFConstants.URN_PREFIX_CDID).length());
		
		final String input = "V1::urn:publicid:gv.at:cdid+" + target + "::"
		    + bpk + "::"
		    + sdf.format(new Date());
		System.out.println(input);
		byte[] result;
		try {
			final byte[] inputBytes = input.getBytes("ISO-8859-1");
			result = encrypt(inputBytes, publicKey);
			return new String(Base64Utils.encode(result), "ISO-8859-1").replaceAll("\r\n", "");
			//return new String(Base64Utils.encode(result, "ISO-8859-1")).replaceAll("\r\n", "");
			
			
		} catch (final Exception e) {
			throw new EAAFBuilderException("bPK encryption FAILED", null,
					e.getMessage(), e);
			
		}		
	}

	public static String decryptBPK(String encryptedBpk, String target, PrivateKey privateKey) throws EAAFBuilderException {
		String decryptedString;
		try {
			//byte[] encryptedBytes = Base64Utils.decode(encryptedBpk, false, "ISO-8859-1");
			final byte[] encryptedBytes = Base64Utils.decode(encryptedBpk.getBytes("ISO-8859-1")); 
			final byte[] decryptedBytes = decrypt(encryptedBytes, privateKey);
			decryptedString = new String(decryptedBytes, "ISO-8859-1");
			
		} catch (final Exception e) {
			throw new EAAFBuilderException("bPK decryption FAILED", null, 
					e.getMessage(), e);
			
		}
		
		String tmp = decryptedString.substring(decryptedString.indexOf('+') + 1);
		final String sector = tmp.substring(0, tmp.indexOf("::"));
		tmp = tmp.substring(tmp.indexOf("::") + 2);
		final String bPK = tmp.substring(0, tmp.indexOf("::"));

		if (target.startsWith(EAAFConstants.URN_PREFIX_CDID + "+"))
			target = target.substring((EAAFConstants.URN_PREFIX_CDID + "+").length());
		
		if (target.equals(sector))
			return bPK;
		
		else {
			log.error("Decrypted bPK does not match to request bPK target.");
			return null;
		}		
	}
        
    private static String calculatebPKwbPK(String basisbegriff) throws EAAFBuilderException {
    	try {
            final MessageDigest md = MessageDigest.getInstance("SHA-1");
            final byte[] hash = md.digest(basisbegriff.getBytes("ISO-8859-1"));
            final String hashBase64 = new String(Base64Utils.encode(hash), "ISO-8859-1").replaceAll("\r\n", ""); //Base64Utils.encode(hash);
            return hashBase64;
            
        } catch (final Exception ex) {
            throw new EAAFBuilderException("builder.00", new Object[]{"bPK/wbPK", ex.toString()}, 
            		ex.getMessage(), ex);
            
        }
    	
    }
    
	private static byte[] encrypt(byte[] inputBytes, PublicKey publicKey) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		byte[] result;
		Cipher cipher = null;
		try {
			cipher = Cipher.getInstance("RSA/ECB/OAEPPadding"); // try with bouncycastle
			
		} catch(final NoSuchAlgorithmException e) {
			cipher = Cipher.getInstance("RSA/ECB/OAEP"); // try with iaik provider
		}
		cipher.init(Cipher.ENCRYPT_MODE, publicKey);
		result = cipher.doFinal(inputBytes);
		
		return result;
	}

	private static byte[] decrypt(byte[] encryptedBytes, PrivateKey privateKey) 
			throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{
		byte[] result;
		Cipher cipher = null;
		try {
			cipher = Cipher.getInstance("RSA/ECB/OAEPPadding"); // try with bouncycastle
			
		} catch(final NoSuchAlgorithmException e) {
			cipher = Cipher.getInstance("RSA/ECB/OAEP"); // try with iaik provider
			
		}
		cipher.init(Cipher.DECRYPT_MODE, privateKey);
		result = cipher.doFinal(encryptedBytes);
		return result;
		
	}
}