package at.gv.util.client.mis.usp_v2;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Base64;
import java.util.Date;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import at.gv.util.MiscUtil;
import at.gv.util.client.szr.IRoleGenerationStrategy;
import at.gv.util.ex.EgovUtilException;

public class VDDSRoleGenerationStrategy implements IRoleGenerationStrategy {
	private static final Logger log = LoggerFactory.getLogger(VDDSRoleGenerationStrategy.class);

	public static final String ROLE_CONSTANT_PARTNERNAME = "partner-name=";
	public static final String ROLE_CONSTANT_SECRET = "secret=";
	public static final String ROLE_CONSTANT_CREATIONTS = "creation-ts=";
	
	public static final String TS_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSSXXX";
	private static final SimpleDateFormat tsFormat = new SimpleDateFormat(TS_PATTERN);
	
	private String participant;
	private String authData;
	
	public VDDSRoleGenerationStrategy(String participant, String authData) throws EgovUtilException {
		if (MiscUtil.isEmpty(authData)) {
			log.error("Secret to generate VDDS role is 'null or 'empty''");
			throw new EgovUtilException("Secret to generate VDDS role is 'null or 'empty'");
			
		}
		this.authData = authData;
		
		if (MiscUtil.isEmpty(participant)) {
			log.error("Participant to generate VDDS role is 'null or 'empty''");
			throw new EgovUtilException("Secret to generate VDDS role is 'null or 'empty'");
			
		}
		this.participant = participant;
				
		log.trace("VDDSRoleGenerationStrategy uses participant: " + this.participant + " and secret: " + this.authData);
		
	}

	@Override
	public String generateRoleString(String roleString) throws EgovUtilException {
		
		 try {
			 String currentTS = tsFormat.format(new Date());
			 log.trace("Generate VDDS role at: " + currentTS);
		     MessageDigest md = MessageDigest.getInstance("SHA-1");
		     byte[] digistInput = (currentTS + authData).getBytes("UTF-8");		     
		     log.trace("DigistInput: " + new String(digistInput, "UTF-8"));
		     byte[] digistOutput = md.digest(digistInput);
		     String secret = Base64.getEncoder().encodeToString(digistOutput);
		     
		     StringBuilder sBuilder = new StringBuilder(roleString);
		     sBuilder.append("(");
		     sBuilder.append(ROLE_CONSTANT_PARTNERNAME);
		     sBuilder.append(participant);
		     sBuilder.append(",");
		     sBuilder.append(ROLE_CONSTANT_SECRET);
		     sBuilder.append(secret);
		     sBuilder.append(",");
		     sBuilder.append(ROLE_CONSTANT_CREATIONTS);
		     sBuilder.append(currentTS);
		     sBuilder.append(")");
		     
		     log.trace("Finale VDDS Role: " + sBuilder.toString());		     
		     return sBuilder.toString();
		        
		 } catch(NoSuchAlgorithmException | UnsupportedEncodingException e) {
		     log.error("VDDSRoleGeneration FAILED with error: " + e.getMessage(), e);
		     throw new EgovUtilException("VDDSRoleGeneration FAILED", e);
		        
		 } 		
	}

}