package sim.tsa;

import java.util.ArrayList;
import sim.tsa.TSAWorld.Path;
import java.util.Random;
import cern.jet.random.Uniform;

public class TravellingSalesAnt {

  private TSAWorld space;
  private TSAModel model;
  private double length; // Length of all paths travelled by ant
  private ArrayList visited;
  private ArrayList unvisited;
  private ArrayList allPaths;
  private ArrayList potentialPaths;
  private TSACity currCity;
  private TSACity prevCity;
  private boolean firstRun;

  public TravellingSalesAnt(TSAWorld ss, TSAModel model) {
    firstRun = true;
    space = ss;
    this.model = model;
    visited = new ArrayList<TSACity>();
    potentialPaths = new ArrayList();
    unvisited = (ArrayList) space.getCitiesList().clone();
    allPaths = (ArrayList) space.getCitiesList().clone();
    length = 0;
  }

  public ArrayList getPath() { //Returns list of visited cities by Ant
    return visited;
  }

  public double getLength() { // Returns length of all paths travelled by ant
    return length;
   }

  public void step(TSACity start) { // Start is the first city the ant is placed on randomly by TSAModel (?)

    // First step the ant takes
    if(firstRun) {
      currCity = start;
      firstRun = false;
    }

    // For all other steps after the first run

    prevCity = currCity; // Keep track of last city visited
    currCity = findCity(); // Find the next city to visit

    this.step2();
    if(currCity != null){
      step(currCity);
    }

  }

  public void step2() {
    // add your code for pheromone distribution here
    if(prevCity != null && currCity != null) {
      space.deposit(prevCity, currCity, length);
    }
  }

  public void addToVisited(TSACity lastCityVisited) {
    visited.add(lastCityVisited);
  }

  public TSACity findCity() { // Determines next city we can visit from our current city

    double alpha = model.getPheromoneWeight();
    double beta = model.getDistanceWeight();

    if(visited.size() < allPaths.size() - 1) { // Check to see if we still have cities to visit
      addToVisited(currCity); // add it our list of visited cities
      if(unvisited.size() > 0) {
        unvisited.remove(prevCity);
      }

    // for(int i=0; i < space.getPathsList().size(); i++) { //For each path in the world we see if the start is the same as our city and if we have visisted its destination. if not -> add to potential list of paths we can use
    //   if(((Path) space.getPathsList().get(i)).from == currCity && visited.contains(((Path)space.getPathsList().get(i)).to) == false){
    //     potentialPaths.add(((Path) space.getPathsList().get(i)));
    //   }
    // }

    //Calculate Probability using formula from notes
    double Bline = 0.0;
    for(int i=0; i< unvisited.size(); i++) { //Sum of...
      double tau = space.getPheromone(currCity, (TSACity) unvisited.get(i)); // pheromone level from current city to each unvistited city
      double eta = 1.0/(space.getDistance(currCity, (TSACity) unvisited.get(i))); // 1 over the distance between the current city and unvisited city
      Bline += Math.pow(tau, alpha)*Math.pow(eta, beta); // Cakculate bottom line of equation
    }

    int bestRouteIndex = 0;
        double bestProb = 0.0;
        //for current city work out Prob
        for(int j=0;j < unvisited.size(); j++)
        {
            double tau = space.getPheromone(currCity,(TSACity) unvisited.get(j));
            double eta  = 1.0/(space.getDistance(currCity,(TSACity) unvisited.get(j)));
            double prob = ( Math.pow(tau ,alpha)*Math.pow(eta, beta) )/ Bline;
            //if best, keep track
            if(prob>=bestProb)
            {
                bestRouteIndex = j;
                bestProb= prob;
            }
        }

    //move to this position
        if(unvisited.size()>0)
      // for(int i=0; i < space.getPathsList().size(); i++) { //Get path length and add to total path length
      //   if(((Path) space.getPathsList().get(i)).from == (TSACity) unvisited.get(bestroute)){
      //     double distance = space.getDistance(((Path)space.getPathsList().get(i)).from, ((Path)space.getPathsList().get(i)).to);
      //     length += distance;
      //   }
      // }
      // double distance = space.getDistance(((Path)unvisited.get(bestroute)).from, ((Path)unvisited.get(bestroute)).to);
      // length += distance;
      return (TSACity) unvisited.get(bestRouteIndex);

  //   Random rand = new Random();
  //   //Pick random path from list of potential paths we found
  //   int index = rand.nextInt((potentialPaths.size()-1 - 0) + 1) + 0;
   //
  //  return ((Path)potentialPaths.get(index)).to;
    }
   return null;
  }

}