package net.sourceforge.jgeocoder.us;



import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Set;

import java.util.regex.Pattern;



import org.apache.commons.lang.StringUtils;

/**

 * Javadocs me

 * @author jliang

 *

 */

public class SpellingCorrector{

  private static final Map<Integer, Set<String>> STATE_TOKENS = new HashMap<Integer, Set<String>>();

  private static final Pattern DIGIT = Pattern.compile("^\\d+$");

  static{

    for(String s : Data.getSTATE_CODE_MAP().keySet()){

      int size = s.split("\\s+").length;

      Set<String> set = STATE_TOKENS.get(size);

      if(set == null){

        STATE_TOKENS.put(size, new HashSet<String>());

      }

      STATE_TOKENS.get(size).add(s);

    }

  }

  /**

   * Attempts to correct possible state mis-spellings

   * @param rawAddress

   * @return rawAddress or spelling corrected address if a state mis-spelling is found

   */

  public static String correctStateSpelling(String rawAddress){

    String[] originalTokens = rawAddress.split("\\s+");

    String[] tokens = rawAddress.toUpperCase().split("\\s+");

    int end = tokens.length -1;

    for(int i = end; i>0; i--){

      if(DIGIT.matcher(tokens[i]).matches()){

        end --;

      }else{

        break; //end is the index of the last non-all-digits token

      }

    }

    if(tokens[end].length()<=2){ //short word

      return rawAddress;  //this almost never works so just skip it

    }

    for(int i = 1; i<=4; i++){ 

      if(end >= i-1){

        for(String s : STATE_TOKENS.get(i)){

          StringBuilder sb = new StringBuilder();

          int newEnd = end - i+1;

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

            sb.append(tokens[newEnd+j]).append(" ");

          }

          float metrics = getNormalizedSimilarity(s, sb.toString().trim());

          if(metrics == 1f){

            return rawAddress;

          }else if(metrics >= 0.75f){ //assume mis-spelling

            if(i != 1){

              for(int j=0; j<i-1; j++){

                originalTokens[newEnd+j] = ""; 

              }

            }

            originalTokens[end] = s; 

            return StringUtils.join(originalTokens, " ");

          }          

        }

      }

    }

    return rawAddress;

  }

  private static float getNormalizedSimilarity(String s, String t){

    return 1f - StringUtils.getLevenshteinDistance(s, t)/(float)Math.max(s.length(), t.length());

  }

  

  public static void main(String[] args){

      String fulladdress="320 vairo blvd, state college, pennsylvaniaa 16803";//changed to PENNSYLVANIA

      System.out.println(correctStateSpelling(fulladdress));

  }

  

  

}