/*******************************************************************************
 * 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.egovernment.moa.id.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 at.gv.egovernment.moa.id.auth.exception.BuildException;
import at.gv.egovernment.moa.id.data.Pair;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.Base64Utils;
import at.gv.egovernment.moa.util.Constants;
import at.gv.egovernment.moa.util.MiscUtil;

/**
 * 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>.
 *
 * @author Paul Schamberger
 * @version $Id$
 */
public class BPKBuilder {

    /**
     * Builds the bPK from the given parameters.
     *
     * @param identificationValue Base64 encoded "Stammzahl"
     * @param target              "Bereich lt. Verordnung des BKA"
     * @return bPK in a BASE64 encoding
     * @throws BuildException if an error occurs on building the bPK
     */
    public String buildBPK(String identificationValue, String target)
            throws BuildException {

        if ((identificationValue == null ||
                identificationValue.length() == 0 ||
                target == null ||
                target.length() == 0)) {
            throw new BuildException("builder.00",
                    new Object[]{"BPK", "Unvollständige Parameterangaben: identificationValue=" +
                            identificationValue + ",target=" + target});
        }
        String basisbegriff;
        if (target.startsWith(Constants.URN_PREFIX_CDID + "+"))
            basisbegriff = identificationValue + "+" + target;
        else
            basisbegriff = identificationValue + "+" + Constants.URN_PREFIX_CDID + "+" + target;

        return calculatebPKwbPK(basisbegriff);
    }

    /**
     * Builds the wbPK from the given parameters.
     *
     * @param identificationValue Base64 encoded "Stammzahl"
     * @param registerAndOrdNr    type of register + "+" + number in register.
     * @return wbPK in a BASE64 encoding
     * @throws BuildException if an error occurs on building the wbPK
     */
    public String buildWBPK(String identificationValue, String registerAndOrdNr)
            throws BuildException {

        if ((identificationValue == null ||
                identificationValue.length() == 0 ||
                registerAndOrdNr == null ||
                registerAndOrdNr.length() == 0)) {
            throw new BuildException("builder.00",
                    new Object[]{"wbPK", "Unvollständige Parameterangaben: identificationValue=" +
                            identificationValue + ",Register+Registernummer=" + registerAndOrdNr});
        }

        String basisbegriff;
        if (registerAndOrdNr.startsWith(Constants.URN_PREFIX_WBPK + "+"))
            basisbegriff = identificationValue + "+" + registerAndOrdNr;
        else
            basisbegriff = identificationValue + "+" + Constants.URN_PREFIX_WBPK + "+" + registerAndOrdNr;

        return calculatebPKwbPK(basisbegriff);
    }

    public String buildbPKorwbPK(String baseID, String bPKorwbPKTarget) throws BuildException {
    	if (MiscUtil.isEmpty(baseID) || 
    			!(bPKorwbPKTarget.startsWith(Constants.URN_PREFIX_CDID + "+") || 
    					bPKorwbPKTarget.startsWith(Constants.URN_PREFIX_WBPK + "+") || 
    					bPKorwbPKTarget.startsWith(Constants.URN_PREFIX_STORK + "+")) ) {
    		throw new BuildException("builder.00",
                    new Object[]{"bPK/wbPK", "bPK or wbPK target " + bPKorwbPKTarget 
    					+ " has an unkown prefix."});
    		
    	}
    	
    	return calculatebPKwbPK(baseID + "+" + bPKorwbPKTarget);
    	
    }
    
	public static String encryptBPK(String bpk, String target, PublicKey publicKey) throws BuildException {
		MiscUtil.assertNotNull(bpk, "BPK");
		MiscUtil.assertNotNull(publicKey, "publicKey");
		
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
		if (target.startsWith(Constants.URN_PREFIX_CDID + "+"))
			target = target.substring((Constants.URN_PREFIX_CDID + "+").length());
		
		String input = "V1::urn:publicid:gv.at:cdid+" + target + "::"
		    + bpk + "::"
		    + sdf.format(new Date());
		System.out.println(input);
		byte[] result;
		try {
			byte[] inputBytes = input.getBytes("ISO-8859-1");
			result = encrypt(inputBytes, publicKey);
			return new String(Base64Utils.encode(result, "ISO-8859-1")).replaceAll("\r\n", "");
			
		} catch (Exception e) {
			throw new BuildException("bPK encryption FAILED", null, e);
		}		
	}

	public static String decryptBPK(String encryptedBpk, String target, PrivateKey privateKey) throws BuildException {
		MiscUtil.assertNotEmpty(encryptedBpk, "Encrypted BPK");
		MiscUtil.assertNotNull(privateKey, "Private key");
		String decryptedString;
		try {
			byte[] encryptedBytes = Base64Utils.decode(encryptedBpk, false, "ISO-8859-1");
			byte[] decryptedBytes = decrypt(encryptedBytes, privateKey);
			decryptedString = new String(decryptedBytes, "ISO-8859-1");
			
		} catch (Exception e) {
			throw new BuildException("bPK decryption FAILED", null, e);
		}
		String tmp = decryptedString.substring(decryptedString.indexOf('+') + 1);
		String sector = tmp.substring(0, tmp.indexOf("::"));
		tmp = tmp.substring(tmp.indexOf("::") + 2);
		String bPK = tmp.substring(0, tmp.indexOf("::"));

		if (target.startsWith(Constants.URN_PREFIX_CDID + "+"))
			target = target.substring((Constants.URN_PREFIX_CDID + "+").length());
		
		if (target.equals(sector))
			return bPK;
		
		else {
			Logger.error("Decrypted bPK does not match to request bPK target.");
			return null;
		}		
	}
    
    /**
     * Builds the storkeid 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 BuildException if an error occurs on building the wbPK
     */
    public Pair<String, String> buildeIDASIdentifer(String baseID, String baseIDType, String sourceCountry, String destinationCountry)
            throws BuildException {        
        String bPK = null;
        String bPKType = null;
        
        // check if we have been called by public sector application
        if (baseIDType.startsWith(Constants.URN_PREFIX_BASEID)) {
        	bPKType = Constants.URN_PREFIX_EIDAS + "+" + sourceCountry + "+" + destinationCountry;
            Logger.debug("Building eIDAS identification from: [identValue]+" + bPKType);         
            bPK = calculatebPKwbPK(baseID + "+"  + bPKType);
            
        } else { // if not, sector identification value is already calculated by BKU
            Logger.debug("eIDAS eIdentifier already provided by BKU");
            bPK = baseID;
        }

        if ((MiscUtil.isEmpty(bPK) ||
                MiscUtil.isEmpty(sourceCountry) ||
                	MiscUtil.isEmpty(destinationCountry))) {
            throw new BuildException("builder.00",
                    new Object[]{"eIDAS-ID", "Unvollständige Parameterangaben: identificationValue=" +
                            bPK + ", Zielland=" + destinationCountry + ", Ursprungsland=" + sourceCountry});
        }
        
        Logger.debug("Building eIDAS identification from: " + sourceCountry+"/"+destinationCountry+"/" + "[identValue]");
        String eIdentifier = sourceCountry + "/" + destinationCountry + "/" + bPK;
        
        return Pair.newInstance(eIdentifier, baseIDType);
    }
    
    private String calculatebPKwbPK(String basisbegriff) throws BuildException {
    	try {
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            byte[] hash = md.digest(basisbegriff.getBytes("ISO-8859-1"));
            String hashBase64 = Base64Utils.encode(hash);
            return hashBase64;
            
        } catch (Exception ex) {
            throw new BuildException("builder.00", new Object[]{"bPK/wbPK", ex.toString()}, 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(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(NoSuchAlgorithmException e) {
			cipher = Cipher.getInstance("RSA/ECB/OAEP"); // try with iaik provider
		}
		cipher.init(Cipher.DECRYPT_MODE, privateKey);
		result = cipher.doFinal(encryptedBytes);
		return result;
	}


}