package aima.agents;
import java.util.*;

/** The basic environment: the world in which agents and other things exist. */
public abstract class Environment {

  /** Build an environment with a given set of agents */
  Environment(Agent[] agents) { 
    this.agents = new Vector();
    for(int i=0; i<agents.length; i++) this.agents.addElement(agents[i]);
  }
	public void p(Object x) {System.out.println(">>> "+x);} ///////////////
	
  /** Run the environment for numSteps time steps. */
  public Environment run(int numSteps) {
    for(; numSteps > 0 && !termination(); step++, numSteps--) {
      p("*** Step: " + step + "; "+agents.size()+" agents");
      for(int i=0; i<agents.size(); i++) {
	      Agent agent = agent(i);
	      Percept percept = presentPercept(agent);
	      p("Agent "+agent+" saw "+percept);
	      agent.setPercept(percept);
	      agent.setAction(agentManager.execute(agent.getProgram(), percept));
	      p(" and did "+agent.getAction());
      }
      update();
      for(int i=0; i<agents.size(); i++) {
	      Agent agent = agent(i);     
	      agent.setScore(performanceMeasure(agent));
	      p(agent+" scores "+agent.getScore());
      }
    }
    return this;
  }

  /** Return the percept that should be handed to this agent. */
  Percept presentPercept(Agent agent) { return null; }
	
  /** Modify the environment, based on agent actions, etc. */
  void update () { 
    // Execute each agent's action
    for(int i=0; i<agents.size(); i++) {
      Action action = agent(i).getAction();
      if (action != null) {execute(agent(i), action);}
    }
  }

  /** Execute the action chosen by the agent. Normally, an Environment designer
   * would override this method in the new Environment class. */
  public abstract void execute(Agent agent, Action action);
    
  /** Measure how well the agent is doing. */
  public float performanceMeasure(Agent agent) { return -step; }

  /** @returns true if the simulation should end now. */
  boolean termination() { return false; }
        	
  /** @returns the ith agent in the environment. */
  Agent agent(int i) { return (Agent)agents.elementAt(i); }
    
  public String toString () { return "[" + name + "]"; }
    
  /** A collection of all the agents in this environment */
  Vector agents = null;

  /** The number of time steps simulated so far. */
  int step = 0;
	
  /** A descriptive name for the environment; used only for printing. */
  static String name = "Environment";
  
  /** A thread manager for agents. */
  AgentManager agentManager = new AgentManager();
}