package sim;



import prototrace.ProtoTrace.GenericMessage;

import prototrace.ProtoTrace.PingPongMessage;

import prototrace.ProtoTrace.Trace;

import com.google.protobuf.ByteString;

import java.io.FileOutputStream;

import java.util.Random;



class Simulator {

	static Random r = new Random();

	

	private static void printTypes(){

		System.err.println("\tTYPE=random #NODES #MESSAGES");

		System.err.println("\tTYPE=pingpong #NODES #PINGS ORDER{node | time | structure}");	

	}

	

	//Ask the user for the name of the tracefile to generate, and

	//the type of trace to simulate, and create the trace.

	public static void main(String[] args) throws Exception {

		if (args.length < 2) {

			System.err.println("Usage:  Simulator TRACE_FILE TYPE <ARGS>");

			printTypes();

			System.exit(-1);

	    }

	

	    Trace.Builder trace = Trace.newBuilder();

	    

	    if(args[1].equalsIgnoreCase("random")){

	    	generateRandom(Integer.parseInt(args[2]), Integer.parseInt(args[3]), trace);

	    } else if(args[1].equalsIgnoreCase("pingpong")){

	    	generatePingPong(Integer.parseInt(args[2]), Integer.parseInt(args[3]), trace);

	    	

	    	//re-order the trace if requested

		    if(args[4].equalsIgnoreCase("node")){

	    		trace = numericOrder(trace, "time");

	    		trace = numericOrder(trace, "src");

	    	}else if(args[4].equalsIgnoreCase("time")){

	    		trace = numericOrder(trace, "time");	

	    	}

	    } else{

	    	System.err.println("Unknown simulation type.  Available types:");

	    	printTypes();

	    	System.exit(-1);

	    }

	    

	   

	    /*

	    // Write the trace out to disk.

	    System.out.println("Writing the following trace to " + args[0] + ":");

	    for(GenericMessage m : trace.getGenericMessageList()){

	    	System.out.println("Src: " + m.getSrc() + "Dst: " + m.getDst() + 

	    			"Time: " + m.getTimestamp() + "PL: " + m.getPayload().toString());	

	    }

	    */

	    

	    // Write the trace out to disk.

	    FileOutputStream output = new FileOutputStream(args[0]);

	    trace.build().writeTo(output);

	    output.close();

	  }

	



	// This method creates a generic message given the input

	static GenericMessage createMessage(int src, int dst, long timestamp, byte[] payload){

                               

		GenericMessage.Builder message = GenericMessage.newBuilder();



	    //stdout.print("Building message...");

	    message.setSrc(src);

	    message.setDst(dst);

	    message.setTimestamp(timestamp);

	    

	    ByteString bytes = ByteString.copyFrom(payload);

	    message.setPayload(bytes);

	

	    return message.build();

	}

  

	//Generate a sequence of messages, with random lengths of random bytes

	//as the payload.  The only restrictions are that src != dest, and each

	//message increases in time.

	private static void generateRandom(int nodes, int times, Trace.Builder trace){

		

		for(int i = 0; i < times; i++){

			byte[] randomBytes = new byte[r.nextInt(10)];

			r.nextBytes(randomBytes);

			int[] pair = randomPair(nodes);

	    

			GenericMessage message = createMessage(pair[0], pair[1], i, randomBytes);

			trace.addGenericMessage(message);

		} 

	}

	

	// generates a trace of ping pong messages, sending a ping every second.  Each ping produces a pong 80% of the time

	// and when a pong is produced half of the time it is followed by a status message.

	// pings and pongs are separated by random intervals of 0-10 seconds.  pongs and status messages

	// are separated by random intervals of 0-2 seconds.

	// NOTE: trace will not be in time-order.

	private static void generatePingPong(int nodes, int pings, Trace.Builder trace){

		

		for(int i=0; i<pings; i++){

			int[] pair = randomPair(nodes);

			int delay = r.nextInt(11); //random delay between the ping and the pong, up to 10 seconds

			PingPongMessage ping = createPingPong(pair[0], pair[1], i, "ping");

			

			trace.addPingPongMessage(ping);

			

			if(r.nextDouble() <= 0.8){

				PingPongMessage pong = createPingPong(pair[1], pair[0], i+delay, "pong");

				trace.addPingPongMessage(pong);

				if(r.nextDouble() <= 0.5){

					int delay2 = r.nextInt(3);

					PingPongMessage status = createPingPong(pair[1], pair[0], i+delay+delay2, "status");

					trace.addPingPongMessage(status);

				}

			}

		}

		

	}

	

	// Construct a PingPong message

	private static PingPongMessage createPingPong(int src, int dst, long timestamp, String type){

		PingPongMessage.Builder message = PingPongMessage.newBuilder();



	    //stdout.print("Building message...");

	    message.setSrc(src);

	    message.setDst(dst);

	    message.setTimestamp(timestamp);

	    message.setType(type);

	  

	    return message.build();

		

	}

	

	//Orders a ping-pong trace by a numeric field and returns the new trace.

	//Not the most efficient sort, but it works.

	private static Trace.Builder numericOrder(Trace.Builder trace, String field){

		Trace.Builder trace2 = Trace.newBuilder();

		long lowest = Long.MAX_VALUE;

		boolean[] added = new boolean[trace.getPingPongMessageCount()];

		int lowestIndex = 0;

		while(trace2.getPingPongMessageCount() < trace.getPingPongMessageCount()){

			for(int i =0; i < trace.getPingPongMessageCount(); i++){

				PingPongMessage current = trace.getPingPongMessage(i);

				

				long currentField;

				if(field.equals("time")){

					currentField = current.getTimestamp();

				}else if(field.equals("src")){

					currentField = current.getSrc();

				} else {

					currentField = current.getDst();

				}

				

				if(currentField < lowest && !added[i]){

					lowestIndex = i;

					lowest = currentField;

				}

			}

			

			trace2.addPingPongMessage(trace.getPingPongMessage(lowestIndex));

			added[lowestIndex] = true;

			lowest = Long.MAX_VALUE;

		}

		

		return trace2;

	

	}

	

	

	// returns a 2 element array of a random distinct pair of nodes

	// (nodes numbered 0 .. nodes-1)

	private static int[] randomPair(int nodes){

		int node1 = r.nextInt(nodes);

		int node2 = r.nextInt(nodes);

		while(node1 == node2){

			node2 = r.nextInt(nodes);

		}

		int[] result = new int[2];

		result[0] = node1;

		result[1] = node2;

		

		return result;

	

	}

}