using System.Collections;
using System.Text;

/*
 * Copyright 2008 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.
 */

namespace com.google.zxing.oned
{

	using BarcodeFormat = com.google.zxing.BarcodeFormat;
	using NotFoundException = com.google.zxing.NotFoundException;
	using BitArray = com.google.zxing.common.BitArray;

	/// <summary>
	/// <p>Implements decoding of the EAN-13 format.</p>
	/// 
	/// @author dswitkin@google.com (Daniel Switkin)
	/// @author Sean Owen
	/// @author alasdair@google.com (Alasdair Mackintosh)
	/// </summary>
	public sealed class EAN13Reader : UPCEANReader
	{

	  // For an EAN-13 barcode, the first digit is represented by the parities used
	  // to encode the next six digits, according to the table below. For example,
	  // if the barcode is 5 123456 789012 then the value of the first digit is
	  // signified by using odd for '1', even for '2', even for '3', odd for '4',
	  // odd for '5', and even for '6'. See http://en.wikipedia.org/wiki/EAN-13
	  //
	  //                Parity of next 6 digits
	  //    Digit   0     1     2     3     4     5
	  //       0    Odd   Odd   Odd   Odd   Odd   Odd
	  //       1    Odd   Odd   Even  Odd   Even  Even
	  //       2    Odd   Odd   Even  Even  Odd   Even
	  //       3    Odd   Odd   Even  Even  Even  Odd
	  //       4    Odd   Even  Odd   Odd   Even  Even
	  //       5    Odd   Even  Even  Odd   Odd   Even
	  //       6    Odd   Even  Even  Even  Odd   Odd
	  //       7    Odd   Even  Odd   Even  Odd   Even
	  //       8    Odd   Even  Odd   Even  Even  Odd
	  //       9    Odd   Even  Even  Odd   Even  Odd
	  //
	  // Note that the encoding for '0' uses the same parity as a UPC barcode. Hence
	  // a UPC barcode can be converted to an EAN-13 barcode by prepending a 0.
	  //
	  // The encoding is represented by the following array, which is a bit pattern
	  // using Odd = 0 and Even = 1. For example, 5 is represented by:
	  //
	  //              Odd Even Even Odd Odd Even
	  // in binary:
	  //                0    1    1   0   0    1   == 0x19
	  //
	  internal static readonly int[] FIRST_DIGIT_ENCODINGS = {0x00, 0x0B, 0x0D, 0xE, 0x13, 0x19, 0x1C, 0x15, 0x16, 0x1A};

	  private readonly int[] decodeMiddleCounters;

	  public EAN13Reader()
	  {
		decodeMiddleCounters = new int[4];
	  }

//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: protected int decodeMiddle(com.google.zxing.common.BitArray row, int[] startRange, StringBuilder resultString) throws com.google.zxing.NotFoundException
	  protected internal override int decodeMiddle(BitArray row, int[] startRange, StringBuilder resultString)
	  {
		int[] counters = decodeMiddleCounters;
		counters[0] = 0;
		counters[1] = 0;
		counters[2] = 0;
		counters[3] = 0;
		int end = row.Size;
		int rowOffset = startRange[1];

		int lgPatternFound = 0;

		for (int x = 0; x < 6 && rowOffset < end; x++)
		{
		  int bestMatch = decodeDigit(row, counters, rowOffset, L_AND_G_PATTERNS);
		  resultString.Append((char)('0' + bestMatch % 10));
		  foreach (int counter in counters)
		  {
			rowOffset += counter;
		  }
		  if (bestMatch >= 10)
		  {
			lgPatternFound |= 1 << (5 - x);
		  }
		}

		determineFirstDigit(resultString, lgPatternFound);

		int[] middleRange = findGuardPattern(row, rowOffset, true, MIDDLE_PATTERN);
		rowOffset = middleRange[1];

		for (int x = 0; x < 6 && rowOffset < end; x++)
		{
		  int bestMatch = decodeDigit(row, counters, rowOffset, L_PATTERNS);
		  resultString.Append((char)('0' + bestMatch));
		  foreach (int counter in counters)
		  {
			rowOffset += counter;
		  }
		}

		return rowOffset;
	  }

	  internal override BarcodeFormat BarcodeFormat
	  {
		  get
		  {
			return BarcodeFormat.EAN_13;
		  }
	  }

	  /// <summary>
	  /// Based on pattern of odd-even ('L' and 'G') patterns used to encoded the explicitly-encoded
	  /// digits in a barcode, determines the implicitly encoded first digit and adds it to the
	  /// result string.
	  /// </summary>
	  /// <param name="resultString"> string to insert decoded first digit into </param>
	  /// <param name="lgPatternFound"> int whose bits indicates the pattern of odd/even L/G patterns used to
	  ///  encode digits </param>
	  /// <exception cref="NotFoundException"> if first digit cannot be determined </exception>
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: private static void determineFirstDigit(StringBuilder resultString, int lgPatternFound) throws com.google.zxing.NotFoundException
	  private static void determineFirstDigit(StringBuilder resultString, int lgPatternFound)
	  {
		for (int d = 0; d < 10; d++)
		{
		  if (lgPatternFound == FIRST_DIGIT_ENCODINGS[d])
		  {
			resultString.Insert(0, (char)('0' + d));
			return;
		  }
		}
		throw NotFoundException.NotFoundInstance;
	  }

	}

}