/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.artemis.cli.commands.messages.perf;

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.FieldPosition;

public class PaddingDecimalFormat extends DecimalFormat {

   private int minimumLength;
   private final StringBuilder pad;

   /**
    * Creates a PaddingDecimalFormat using the given pattern and minimum {@code minLength} and the symbols for the default
    * locale.
    */
   public PaddingDecimalFormat(String pattern, int minLength) {
      super(pattern);
      minimumLength = minLength;
      pad = new StringBuilder();
   }

   /**
    * Creates a PaddingDecimalFormat using the given pattern, symbols and minimum minimumLength.
    */
   public PaddingDecimalFormat(String pattern, DecimalFormatSymbols symbols, int minLength) {
      super(pattern, symbols);
      minimumLength = minLength;
      pad = new StringBuilder();
   }

   @Override
   public StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos) {
      int initLength = toAppendTo.length();
      super.format(number, toAppendTo, pos);
      return pad(toAppendTo, initLength);
   }

   @Override
   public StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos) {
      int initLength = toAppendTo.length();
      super.format(number, toAppendTo, pos);
      return pad(toAppendTo, initLength);
   }

   private StringBuffer pad(StringBuffer toAppendTo, int initLength) {
      int numLength = toAppendTo.length() - initLength;
      int padLength = minimumLength - numLength;
      if (padLength > 0) {
         final int initialPadLength = pad.length();
         for (int i = initialPadLength; i < padLength; i++) {
            pad.append(' ');
         }
         pad.setLength(padLength);
         toAppendTo.insert(initLength, pad);
      }
      return toAppendTo;
   }
}
