// Copyright 1999 Regents of The University of Michigan
// This makes all public classes defined for the simulator package available to this class
import umich.coabs.simulator.*;

/**
   This class is a decision maker that controls the single transport
   in its entities list.  The transport explores the network by
   avoiding locations it has already visited, moving randomly
   otherwise, and stopping at each location to allow evacuees to
   embark or disembark.  It has a very simple state machine and can
   get stuck if one of its actions fails.
   @author Brad Clement, bradc@umich.edu 
*/
public class SmarterTransportDM extends DecisionMaker {
  int state = 0;  // the state of the state machine
  Location destination;  // global variable for keeping track of where 
                         // it wants to go
  LinkedList visitedLocations;

  /**
     Just passes basics up to the costructor of the parent class, 
     <tt>DecisionMaker</tt>
  */
  public SmarterTransportDM(String i, LinkedList e, Control c) {
    super(i, e, c);
    visitedLocations = new LinkedList();
  }

  /**
     This is the method that is called on each decision cycle by the
     Control object of the simulator.  It controls the behavior of the
     transport in its <tt>entities</tt> list.  Sometimes the
     transports will not successfully move to a location.  The results
     of these action failures are defined in the Transport class.  The
     default is nothing changes, and a message is printed.
     Additionally, this decision maker often winds up in the wrong
     state and gets stuck when an action fails.  For example, this can
     happen when two transports try to go opposite ways on a one-lane
     road or when a transport tries to traverse a route that has been
     destroyed.
  */
  public void TakeStep() {
    ListElement elem, elem1;  // for stepping through lists
    LinkedList candidates = new LinkedList();  // candidate routes to take
    int i, n;
    Route r;  // the chosen route to traverse
    Route tr;  // temporary route var
    double time = 0.0;  // used to wait for a specified time
    Transport me = (Transport)entities.head.data;  // get the transport at 
                                                   // the front of the 
                                                   // entities list

    // Take step for state 0
    if (state == 0) {
      visitedLocations.Add(me.getCurLocation());
      // Every route that has not been traveled before is a candidate
      for (elem=me.getCurLocation().getRoutes().head; elem!=null; 
	   elem=elem.next) {
	tr = (Route)elem.data;
	if (tr.getEndpt1() == me.getCurLocation()) {
	  if (visitedLocations.Find(tr.getEndpt2()) == null)
	    candidates.Add(tr);
	} else if (visitedLocations.Find(tr.getEndpt1()) == null)
	  candidates.Add(tr);
      }
      // If have been to all surrounding locations, all routes are candidates
      if (candidates.size == 0) {
	candidates = me.getCurLocation().getRoutes();
      }
      // Pick a random route to traverse; assign it to r
      n = (int) (candidates.size * java.lang.Math.random());
      if (n == candidates.size)
	--n;
      elem = candidates.head;
      for (i = 0; i < n; i++)
	elem = elem.next;
      r = (Route) elem.data;
      // Get the location at the other end of the route
      if (r.getEndpt1() == me.getCurLocation())
	destination = r.getEndpt2();
      else
	destination = r.getEndpt1();
      // Move the transport along the chosen route; additionally destroy 
      // the route with 0.0 probability
      if (java.lang.Math.random() < 1.0)
	me.Move(destination, r);
      else
	me.MoveAndDestroy(destination, r);
      // Go to next state
      state = 1;
    } else
      // Take step for state 1
      if (state == 1) {
	// If transport has arrived at its destination, set a timer to 
	// wait at the current location to let evacuees embark or disembark
	if (me.getCurLocation() == destination) {
	  time = ctrl.getTime();
	  state = 2;
	}
      } else
	// Take step for state 2
	if (state == 2) {
	  // If time is up go back to state 0 to move to another location
	  if (ctrl.getTime() - time >= 4.0)
	    state = 0;
	}
  }
}