package media;
   
   import java.io.FilterInputStream;
   import java.io.IOException;
   import java.io.InputStream;
   
   /**
    * <p>Stream che permette la lettura di byte fino a un limite arbitrario.</p>
    * <p>Se il limite fissato viene superato, un ulteriore tentativo di lettura provoca il lancio di una {@link ReadLimitExceededException}</p>
   */
  public class LimitedInputStream extends FilterInputStream {
      private final long byteLimit;
      private long byteRead = 0;
  
  
      public LimitedInputStream(InputStream in, long byteLimit){
          super(in);
          this.byteLimit = byteLimit;
      }
  
      @Override
      public int read() throws IOException {
          int bite = super.read();
          this.byteRead++;
          if(this.byteRead > byteLimit)
              throw new ReadLimitExceededException();
          return bite;
      }
  
      @Override
      public int read(byte[] b) throws IOException {
          return super.read(b);
      }
  
      @Override
      public int read(byte[] b, int off, int len) throws IOException {
          int byteRead = super.read(b,off,len);
          this.byteRead += byteRead;
          if(this.byteRead > byteLimit)
              throw new ReadLimitExceededException();
          return byteRead;
      }
  }