/**
The contents of this file are subject to the Mozilla Public License Version 1.1 
(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.mozilla.org/MPL/ 
Software distributed under the License is distributed on an "AS IS" basis, 
WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the 
specific language governing rights and limitations under the License. 

The Original Code is "Initiator.java".  Description: 
"Performs the initiation role of a message exchange accorging to HL7's original 
 mode rules." 

The Initial Developer of the Original Code is University Health Network. Copyright (C) 
2002.  All Rights Reserved. 

Contributor(s): ______________________________________. 

Alternatively, the contents of this file may be used under the terms of the 
GNU General Public License (the  �GPL�), in which case the provisions of the GPL are 
applicable instead of those above.  If you wish to allow use of your version of this 
file only under the terms of the GPL and not to allow others to use your version 
of this file under the MPL, indicate your decision by deleting  the provisions above 
and replace  them with the notice and other provisions required by the GPL License.  
If you do not delete the provisions above, a recipient may use your version of 
this file under either the MPL or the GPL. 

*/

package ca.uhn.hl7v2.app;

import java.io.IOException;
import java.net.Socket;

import ca.uhn.hl7v2.HL7Exception;
import ca.uhn.hl7v2.llp.HL7Reader;
import ca.uhn.hl7v2.llp.HL7Writer;
import ca.uhn.hl7v2.llp.LLPException;
import ca.uhn.hl7v2.llp.LowerLayerProtocol;
import ca.uhn.hl7v2.model.Message;
import ca.uhn.hl7v2.parser.Parser;
import ca.uhn.hl7v2.parser.PipeParser;
import ca.uhn.hl7v2.util.MessageIDGenerator;
import ca.uhn.hl7v2.util.Terser;
import ca.uhn.log.HapiLog;
import ca.uhn.log.HapiLogFactory;

/**
 * <p>Performs the initiation role of a message exchange (i.e sender of the first message; 
 * analagous to the client in a client-server interaction), according to HL7's original 
 * mode processing rules.</p>
 * <p>The <code>sendAndReceive(...)</code> method blocks until either a response is received 
 * with the matching message ID, or until a timeout period has passed.  The timeout defaults to 
 * 10000 ms (10 sec) but can be configured by setting the system property "ca.uhn.hl7v2.app.initiator.timeout"
 * to an integer value representing the number of ms after which to time out.</p>
 * <p>At the time of writing, enhanced mode, two-phase reply, continuation messages, and 
 * batch processing are unsupported. </p>
 * @author  Bryan Tripp
 */
public class Initiator {
    
    private static final HapiLog log = HapiLogFactory.getHapiLog(Initiator.class); 

    //private Parser parser;
    private HL7Reader in;
    private HL7Writer out;
    private Connection conn;
    //private boolean keepListening;    
    private int timeoutMillis = 10000;

    /** 
     * Creates a new instance of Initiator.  
     * @param conn the Connection associated with this Initiator.   
     */
    protected Initiator(Connection conn) throws LLPException {
        this.conn = conn;

        //see if timeout has been set
        String timeout = System.getProperty("ca.uhn.hl7v2.app.initiator.timeout");
        if (timeout != null) {
            try {
                timeoutMillis = Integer.parseInt(timeout);
                log.debug("Setting Initiator timeout to " + timeout + " ms");
            }
            catch (NumberFormatException e) {
                log.warn(timeout + " is not a valid integer - Initiator is using default timeout");
            }
        }
    }

    /**
     * Sends a message to a responder system, receives the reply, and 
     * returns the reply as a Message object.  This method is thread-safe - multiple  
     * threads can share an Initiator and call this method.  Responses are returned to 
     * the calling thread on the basis of message ID.  
     */
    public Message sendAndReceive(Message out) throws HL7Exception, LLPException, IOException {
        HapiLog rawOutbound = HapiLogFactory.getHapiLog("ca.uhn.hl7v2.raw.outbound");
        HapiLog rawInbound = HapiLogFactory.getHapiLog("ca.uhn.hl7v2.raw.inbound");
        
        if (out == null) {
            throw new HL7Exception("Can't encode null message", HL7Exception.REQUIRED_FIELD_MISSING);
		}

        //register message with response Receiver(s) (by message ID)
        Terser t = new Terser(out);
        String messID = t.get("/MSH-10");

		if (messID == null || messID.length() == 0) {
			throw new HL7Exception("MSH segment missing required field Control ID (MSH-10)", HL7Exception.REQUIRED_FIELD_MISSING);
		}

        MessageReceipt mr = this.conn.reserveResponse(messID);

        //log and send message 
        String outbound = conn.getParser().encode(out);
        log.info("Initiator sending message: " + outbound);
        rawOutbound.info(outbound);
        
        try {
            this.conn.getSendWriter().writeMessage(outbound);
        }
        catch (IOException e) {
            conn.close();
            throw e;
        }

        //wait for response
        boolean done = false;
        Message response = null;
        long startTime = System.currentTimeMillis();
        while (!done) {
            synchronized (mr) {
                try {
                    mr.wait(500); //if it comes, notifyAll() will be called
                }
                catch (InterruptedException e) {
                }

                if (mr.getMessage() != null) {
                    //get message from receipt 
                    String inbound = mr.getMessage();
                    
                    //log that we got the message
                    log.info( "Initiator received message: " + inbound );
                    rawInbound.info(inbound);
                    
                    //parse message
                    response = conn.getParser().parse(inbound);
                    log.debug("response parsed");
                    done = true;
                }

                if (System.currentTimeMillis() > startTime + timeoutMillis)
                    throw new HL7Exception("Timeout waiting for response to message with control ID '" + messID);
            }
        }

        return response;
    }
    
    
    
    /**
     * Sends a message to a responder system, receives the reply, and 
     * returns the reply as a String.  This method is thread-safe - multiple  
     * threads can share an Initiator and call this method.  Responses are returned to 
     * the calling thread on the basis of message ID.  
     */
    public String sendAndReceiveAsString(Message out) throws HL7Exception, LLPException, IOException {
        HapiLog rawOutbound = HapiLogFactory.getHapiLog("ca.uhn.hl7v2.raw.outbound");
        HapiLog rawInbound = HapiLogFactory.getHapiLog("ca.uhn.hl7v2.raw.inbound");
        
        if (out == null) {
            throw new HL7Exception("Can't encode null message", HL7Exception.REQUIRED_FIELD_MISSING);
		}

        //register message with response Receiver(s) (by message ID)
        Terser t = new Terser(out);
        String messID = t.get("/MSH-10");

		if (messID == null || messID.length() == 0) {
			throw new HL7Exception("MSH segment missing required field Control ID (MSH-10)", HL7Exception.REQUIRED_FIELD_MISSING);
		}

        MessageReceipt mr = this.conn.reserveResponse(messID);

        //log and send message 
        String outbound = conn.getParser().encode(out);
        log.info("Initiator sending message: " + outbound);
        rawOutbound.info(outbound);
        
        try {
            this.conn.getSendWriter().writeMessage(outbound);
        }
        catch (IOException e) {
            conn.close();
            throw e;
        }

        String inbound = "";
        
        //wait for response
        boolean done = false;
        //Message response = null;
        long startTime = System.currentTimeMillis();
        while (!done) {
            synchronized (mr) {
                try {
                    mr.wait(500); //if it comes, notifyAll() will be called
                }
                catch (InterruptedException e) {
                }

                if (mr.getMessage() != null) {
                    //get message from receipt 
                    inbound = mr.getMessage();
                    
                    //log that we got the message
                    log.info( "Initiator received message: " + inbound );
                    rawInbound.info(inbound);
                    
                    //parse message
//                    response = conn.getParser().parse(inbound);
//                    log.debug("response parsed");
                    done = true;
                }

                if (System.currentTimeMillis() > startTime + timeoutMillis)
                    throw new HL7Exception("Timeout waiting for response to message with control ID '" + messID);
            }
        }

        return inbound;
    }

    /**
     * Sets the time (in milliseconds) that the initiator will wait for a response 
     * for a given message before timing out and throwing an exception (default 
     * is 10 seconds). 
     */
    public void setTimeoutMillis(int timeout) {
        this.timeoutMillis = timeout;
    }

    /**
     * Test harness
     */
    public static void main(String args[]) {
        if (args.length != 2) {
            System.out.println("Usage: ca.uhn.hl7v2.app.Initiator host port");
        }

        try {

            //set up connection to server
            String host = args[0];
            int port = Integer.parseInt(args[1]);

            final Parser parser = new PipeParser();
            LowerLayerProtocol llp = LowerLayerProtocol.makeLLP();
            Connection connection = new Connection(parser, llp, new Socket(host, port));
            final Initiator initiator = connection.getInitiator();
            final String outText = "MSH|^~\\&|||||||ACK^^ACK|||R|2.4|\rMSA|AA";

            //get a bunch of threads to send messages
            for (int i = 0; i < 1000; i++) {
                Thread sender = new Thread(new Runnable() {
                    public void run() {
                        try {
                                //get message ID
    String ID = MessageIDGenerator.getInstance().getNewID();
                            Message out = parser.parse(outText);
                            Terser tOut = new Terser(out);
                            tOut.set("/MSH-10", ID);

                            //send, get response
                            Message in = initiator.sendAndReceive(out);

                            //get ACK ID
                            Terser tIn = new Terser(in);
                            String ackID = tIn.get("/MSA-2");
                            if (ID.equals(ackID)) {
                                System.out.println("OK - ack ID matches");
                            }
                            else {
                                throw new RuntimeException("Ack ID for message " + ID + " is " + ackID);
                            }

                        }
                        catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                });
                sender.start();
            }

        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

}