/**
    * This source code file is part of a direct port of Stan Birchfield's implementation
    * of a Kanade-Lucas-Tomasi feature tracker. The original implementation can be found
    * here: http://www.ces.clemson.edu/~stb/klt/
    *
    * As per the original code, the source code is in the public domain, available
    * for both commercial and non-commercial use.
    */
   package org.openimaj.video.tracking.klt;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  
  /**
   * The history of a set of tracked features through time
   * 
   * @author Stan Birchfield
   * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
   */
  public class FeatureHistory {
  	Map<Integer, List<List<Feature>>> history = new TreeMap<Integer, List<List<Feature>>>();
  	
  	/**
  	 * The feature history. Each element is a list over time.
  	 */
  	public List<Feature> [] currentState;
  	
  	/**
  	 * Default constructor with given number of features
  	 * @param nFeatures
  	 */
  	@SuppressWarnings("unchecked")
  	public FeatureHistory(int nFeatures) {
  		currentState = new List[nFeatures];
  	}
  	
  	/**
  	 * Record a list of features at a given time
  	 * @param fl
  	 * @param frame
  	 */
  	public void record(FeatureList fl, int frame) {
  		for (int i=0; i<fl.features.length; i++) {
  			Feature f = fl.features[i];
  			
  			if (f.val>=0) {
  				//was tracked
  				if (currentState[i] == null) {
  					List<Feature> ff = new ArrayList<Feature>();
  					List<List<Feature>> hist;
  					if (history.containsKey(frame)) {
  						hist = history.get(frame);
  					} else {
  						hist = new ArrayList<List<Feature>>();
  						history.put(frame, hist);
  					}
  					hist.add(ff);
  					currentState[i] = ff;
  				}
  				if (currentState[i].size() == 0 || !currentState[i].get(currentState[i].size()-1).equals(f))
  					currentState[i].add(f.clone());
  			} else {
  				//was lost
  				currentState[i] = null;
  			}
  		}
  	}
  	
  	@Override
  	public String toString() {
  		String s = "FeatureHistory[\n";
  		for (int startframe : history.keySet()) {
  			List<List<Feature>> tracks = history.get(startframe);
  			s += "Starting frame: " + startframe + ":\n";
  			for (int i=0; i<tracks.size(); i++) {
  				s += "\t" + i +" " + tracks.get(i) + "\n";
  			}
  		}
  		return s+"]";
  	}
  }