/*
 * Copyright (C) 2010 ZXing authors
 *
 * Licensed 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.
 */

/*
 * These authors would like to acknowledge the Spanish Ministry of Industry,
 * Tourism and Trade, for the support in the project TSI020301-2008-2
 * "PIRAmIDE: Personalizable Interactions with Resources on AmI-enabled
 * Mobile Dynamic Environments", led by Treelogic
 * ( http://www.treelogic.com/ ):
 *
 *   http://www.piramidepse.com/
 */

package com.google.zxing.oned.rss.expanded.decoders;

import com.google.zxing.common.BitArray;

/**
 * @author Pablo Orduña, University of Deusto (pablo.orduna@deusto.es)
 * @author Eduardo Castillejo, University of Deusto (eduardo.castillejo@deusto.es)
 */
abstract class AI01decoder extends AbstractExpandedDecoder {

  protected static final int gtinSize   = 40;

  AI01decoder(BitArray information) {
    super(information);
  }

  protected void encodeCompressedGtin(StringBuffer buf, int currentPos) {
    buf.append("(01)");
    int initialPosition = buf.length();
    buf.append('9');

    encodeCompressedGtinWithoutAI(buf, currentPos, initialPosition);
  }

  protected void encodeCompressedGtinWithoutAI(StringBuffer buf, int currentPos, int initialBufferPosition) {
    for(int i = 0; i < 4; ++i){
      int currentBlock = this.generalDecoder.extractNumericValueFromBitArray(currentPos + 10 * i, 10);
      if (currentBlock / 100 == 0) {
        buf.append('0');
      }
      if (currentBlock / 10 == 0) {
        buf.append('0');
      }
      buf.append(currentBlock);
    }

      appendCheckDigit(buf, initialBufferPosition);
  }

  private static void appendCheckDigit(StringBuffer buf, int currentPos){
    int checkDigit = 0;
    for (int i = 0; i < 13; i++) {
      int digit = buf.charAt(i + currentPos) - '0';
      checkDigit += (i & 0x01) == 0 ? 3 * digit : digit;
    }

    checkDigit = 10 - (checkDigit % 10);
    if (checkDigit == 10) {
      checkDigit = 0;
    }

    buf.append(checkDigit);
  }

}
