package com.jsql.model.injection.strategy.blind.patch;
   
   import java.net.URLEncoder;
   import java.nio.charset.StandardCharsets;
   import java.util.LinkedList;
   
   /**
    * Class representing one patch operation.
    */
  public class Patch {
      
      private final LinkedList<Diff> diffs;
      private int start1;
      private int start2;
      private int length1;
      private int length2;
  
      /**
       * Constructor.  Initializes with an empty list of diffs.
       */
      public Patch() {
          this.diffs = new LinkedList<>();
      }
  
      /**
       * Emmulate GNU diff's format.
       * Header: @@ -382,8 +481,9 @@
       * Indicies are printed as 1-based, not 0-based.
       * @return The GNU diff string.
       */
      @Override
      public String toString() {
  
          String coords1;
          String coords2;
  
          if (this.length1 == 0) {
              coords1 = this.start1 + ",0";
          } else if (this.length1 == 1) {
              coords1 = Integer.toString(this.start1 + 1);
          } else {
              coords1 = (this.start1 + 1) + "," + this.length1;
          }
  
          if (this.length2 == 0) {
              coords2 = this.start2 + ",0";
          } else if (this.length2 == 1) {
              coords2 = Integer.toString(this.start2 + 1);
          } else {
              coords2 = (this.start2 + 1) + "," + this.length2;
          }
  
          StringBuilder text = new StringBuilder();
          text.append("@@ -").append(coords1).append(" +").append(coords2)
          .append(" @@\n");
  
          // Escape the body of the patch with %xx notation.
          for (Diff aDiff : this.diffs) {
              switch (aDiff.getOperation()) {
              case INSERT:
                  text.append('+');
                  break;
              case DELETE:
                  text.append('-');
                  break;
              case EQUAL:
                  text.append(' ');
                  break;
              }
              text.append(URLEncoder.encode(aDiff.getText(), StandardCharsets.UTF_8).replace('+', ' '))
              .append("\n");
          }
  
          return Patch.unescapeForEncodeUriCompatability(text.toString());
      }
      
      /**
       * Unescape selected chars for compatibility with JavaScript's encodeURI.
       * In speed critical applications this could be dropped since the
       * receiving application will certainly decode these fine.
       * Note that this function is case-sensitive. Thus, "%3f" would not be
       * unescaped.  But this is ok because it is only called with the output of
       * URLEncoder.encode() which returns uppercase hex.
       *
       * Example: "%3F" -> "?", "%24" -> "$", etc.
       *
       * @param str The string to escape.
       * @return The escaped string.
       */
      public static String unescapeForEncodeUriCompatability(String str) {
          return str.replace("%21", "!").replace("%7E", "~")
              .replace("%27", "'").replace("%28", "(").replace("%29", ")")
              .replace("%3B", ";").replace("%2F", "/").replace("%3F", "?")
              .replace("%3A", ":").replace("%40", "@").replace("%26", "&")
              .replace("%3D", "=").replace("%2B", "+").replace("%24", "$")
              .replace("%2C", ",").replace("%23", "#");
      }
      
      // Getter and setter
 
     public LinkedList<Diff> getDiffs() {
         return this.diffs;
     }
 
     public int getStart1() {
         return this.start1;
     }
 
     public void setStart1(int start1) {
         this.start1 = start1;
     }
 
     public int getStart2() {
         return this.start2;
     }
 
     public void setStart2(int start2) {
         this.start2 = start2;
     }
 
     public int getLength1() {
         return this.length1;
     }
 
     public void setLength1(int length1) {
         this.length1 = length1;
     }
 
     public int getLength2() {
         return this.length2;
     }
 
     public int setLength2(int length2) {
         this.length2 = length2;
         return length2;
     }
 }