/*
   Copyright (C) 2005-2012, by the President and Fellows of Harvard College.

   Licensed 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.

   Dataverse Network - A web application to share, preserve and analyze research data.
   Developed at the Institute for Quantitative Social Science, Harvard University.
   Version 3.0.
*/

package edu.harvard.iq.dataverse;

import edu.harvard.iq.dataverse.settings.SettingsServiceBean;

import java.io.File;
import java.io.FileInputStream;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.ejb.EJB;
import javax.ejb.Stateless;
import java.security.PrivateKey;

/* Handlenet imports: */
import net.handle.hdllib.AbstractMessage;
import net.handle.hdllib.AbstractResponse;
import net.handle.hdllib.AdminRecord;
import net.handle.hdllib.ClientSessionTracker;
import net.handle.hdllib.CreateHandleRequest;
import net.handle.hdllib.DeleteHandleRequest;
import net.handle.hdllib.Encoder;
import net.handle.hdllib.HandleException;
import net.handle.hdllib.HandleResolver;
import net.handle.hdllib.HandleValue;
import net.handle.hdllib.ModifyValueRequest;
import net.handle.hdllib.PublicKeyAuthenticationInfo;
import net.handle.hdllib.ResolutionRequest;
import net.handle.hdllib.ResolutionResponse;
import net.handle.hdllib.Util;

/**
 *
 * @author Leonid Andreev
 * 
 * This is a *partial* implementation of the Handles global id 
 * service. 
 * As of now, it only does the registration updates, to accommodate 
 * the modifyRegistration datasets API sub-command.
 */
@Stateless
public class HandlenetServiceBean {
    @EJB
    DataverseServiceBean dataverseService;
    @EJB 
    SettingsServiceBean settingsService;    
    private static final Logger logger = Logger.getLogger("edu.harvard.iq.dataverse.HandlenetServiceBean");
    
    private static final String HANDLE_PROTOCOL_TAG = "hdl";
    
    public HandlenetServiceBean() {
    }
    
    public void reRegisterHandle(Dataset dataset) {
        if (!HANDLE_PROTOCOL_TAG.equals(dataset.getProtocol())) {
            logger.warning("reRegisterHandle called on a dataset with the non-handle global id: "+dataset.getId());
        }
        
        String handle = getDatasetHandle(dataset);

        boolean handleRegistered = isHandleRegistered(handle);
        
        if (handleRegistered) {
            // Rebuild/Modify an existing handle
            
            logger.info("Re-registering an existing handle id "+handle);
            
            String authHandle = getHandleAuthority(dataset);

            HandleResolver resolver = new HandleResolver();

            String datasetUrl = getRegistrationUrl(dataset);
            
            logger.info("New registration URL: "+datasetUrl);

            PublicKeyAuthenticationInfo auth = getAuthInfo(dataset.getAuthority());
            
            try {

                AdminRecord admin = new AdminRecord(authHandle.getBytes("UTF8"), 300,
                        true, true, true, true, true, true,
                        true, true, true, true, true, true);

                int timestamp = (int) (System.currentTimeMillis() / 1000);

                HandleValue[] val = {new HandleValue(100, "HS_ADMIN".getBytes("UTF8"),
                    Encoder.encodeAdminRecord(admin),
                    HandleValue.TTL_TYPE_RELATIVE, 86400,
                    timestamp, null, true, true, true, false), new HandleValue(1, "URL".getBytes("UTF8"),
                    datasetUrl.getBytes(),
                    HandleValue.TTL_TYPE_RELATIVE, 86400,
                    timestamp, null, true, true, true, false)};

                ModifyValueRequest req = new ModifyValueRequest(handle.getBytes("UTF8"), val, auth);

                resolver.traceMessages = true;
                AbstractResponse response = resolver.processRequest(req);
                if (response.responseCode == AbstractMessage.RC_SUCCESS) {
                    logger.info("\nGot Response: \n" + response);
                } else {
                    logger.info("\nGot Error: \n" + response);
                }
            } catch (Throwable t) {
                logger.fine("\nError: " + t);
            }
        } else {
            // Create a new handle from scratch:
            logger.info("Handle " + handle + " not registered. Registering (creating) from scratch.");
            registerNewHandle(dataset);
        }
    }
    
    public void registerNewHandle(Dataset dataset) {
        String handlePrefix = dataset.getAuthority();
        String handle = getDatasetHandle(dataset);
        String datasetUrl = getRegistrationUrl(dataset);

        logger.info("Creating NEW handle " + handle);

        String authHandle = getHandleAuthority(dataset);

        PublicKeyAuthenticationInfo auth = getAuthInfo(handlePrefix);
        HandleResolver resolver = new HandleResolver();

        int index = 300;

        try {

            AdminRecord admin = new AdminRecord(authHandle.getBytes("UTF8"), 300,
                    true, true, true, true, true, true,
                    true, true, true, true, true, true);

            int timestamp = (int) (System.currentTimeMillis() / 1000);

            HandleValue[] val = {new HandleValue(100, "HS_ADMIN".getBytes("UTF8"),
                Encoder.encodeAdminRecord(admin),
                HandleValue.TTL_TYPE_RELATIVE, 86400,
                timestamp, null, true, true, true, false), new HandleValue(1, "URL".getBytes("UTF8"),
                datasetUrl.getBytes(),
                HandleValue.TTL_TYPE_RELATIVE, 86400,
                timestamp, null, true, true, true, false)};

            CreateHandleRequest req
                    = new CreateHandleRequest(handle.getBytes("UTF8"), val, auth);

            resolver.traceMessages = true;
            AbstractResponse response = resolver.processRequest(req);
            if (response.responseCode == AbstractMessage.RC_SUCCESS) {
                logger.info("Success! Response: \n" + response);
            } else {
                logger.warning("Error response: \n" + response);
            }
        } catch (Throwable t) {
            logger.warning("\nError (caught exception): " + t);
        }
    }
    
    public boolean isHandleRegistered(String handle){
        boolean handleRegistered = false;
        ResolutionRequest req = buildResolutionRequest(handle);
        AbstractResponse response = null;
        HandleResolver resolver = new HandleResolver();
        try {
            response = resolver.processRequest(req);
        } catch (HandleException ex) {
            logger.info("Caught exception trying to process lookup request");
            ex.printStackTrace();
        }
        if((response!=null && response.responseCode==AbstractMessage.RC_SUCCESS)) {
            logger.info("Handle "+handle+" registered.");
            handleRegistered = true;
        } 
        return handleRegistered;
    }
    
    private ResolutionRequest buildResolutionRequest(final String handle) {
        String handlePrefix = handle.substring(0,handle.indexOf("/"));
        
        PublicKeyAuthenticationInfo auth = getAuthInfo(handlePrefix);
        
        byte[][] types = null;
        int[] indexes = null;
        ResolutionRequest req =
                new ResolutionRequest(Util.encodeString(handle),
                types, indexes,
                auth);
        req.certify = false;
        req.cacheCertify = true;
        req.authoritative = false;
        req.ignoreRestrictedValues = true;
        return req;
    }
    
    private PublicKeyAuthenticationInfo getAuthInfo(String handlePrefix) {
        byte[] key = null;
        String adminCredFile = System.getProperty("dataverse.handlenet.admcredfile");

        key = readKey(adminCredFile);        
        PrivateKey privkey = null;
        privkey = readPrivKey(key, adminCredFile);
        String authHandle =  getHandleAuthority(handlePrefix);
        PublicKeyAuthenticationInfo auth =
                new PublicKeyAuthenticationInfo(Util.encodeString(authHandle), 300, privkey);
        return auth;
    }
    private String getRegistrationUrl(Dataset dataset) {
       
        
        String targetUrl = "/dataset.xhtml?persistentId=hdl:" + dataset.getAuthority() 
                + "/" + dataset.getIdentifier();       
        return targetUrl;
    }
    
   
    
    private byte[] readKey(final String file) {
        byte[] key = null;
        try {
            File f = new File(file);
            FileInputStream fs = new FileInputStream(f);
            key = new byte[(int)f.length()];
            int n=0;
            while(n<key.length) {
                key[n++] = (byte)fs.read();
            }
        } catch (Throwable t){
            logger.severe("Cannot read private key " + file +": " + t);
        }
        return key;
    }
    
    private PrivateKey readPrivKey(byte[] key, final String file) {
        PrivateKey privkey=null;
        
        String secret = System.getProperty("dataverse.handlenet.admprivphrase");
        byte secKey[] = null;
        try {
            if(Util.requiresSecretKey(key)){
                secKey = secret.getBytes();
            }
            key = Util.decrypt(key, secKey);
            privkey = Util.getPrivateKeyFromBytes(key, 0);
        } catch (Throwable t){
            logger.severe("Can't load private key in " + file +": " + t);
        }
        return privkey;
    }
    
    private String getDatasetHandle(Dataset dataset) {
        /* 
         * This is different from dataset.getGlobalId() in that we don't 
         * need the "hdl:" prefix.
         */
        String handle = dataset.getAuthority() + "/" + dataset.getIdentifier();
        return handle;
    }
    
    private String getHandleAuthority(Dataset dataset){
        return getHandleAuthority(dataset.getAuthority());
    }
    
    private String getHandleAuthority(String handlePrefix) {
        return "0.NA/" + handlePrefix;
    }
}