/*
  Ported to JavaScript by Lazar Laszlo 2011

  lazarsoft@gmail.com, www.lazarsoft.info

*/

/*
*
* Copyright 2007 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.
*/

import {URShift} from './qrcode';
import ErrorCorrectionLevel from './errorlevel';

var FORMAT_INFO_MASK_QR = 0x5412;
var FORMAT_INFO_DECODE_LOOKUP = [
  [0x5412, 0x00],
  [0x5125, 0x01],
  [0x5E7C, 0x02],
  [0x5B4B, 0x03],
  [0x45F9, 0x04],
  [0x40CE, 0x05],
  [0x4F97, 0x06],
  [0x4AA0, 0x07],
  [0x77C4, 0x08],
  [0x72F3, 0x09],
  [0x7DAA, 0x0A],
  [0x789D, 0x0B],
  [0x662F, 0x0C],
  [0x6318, 0x0D],
  [0x6C41, 0x0E],
  [0x6976, 0x0F],
  [0x1689, 0x10],
  [0x13BE, 0x11],
  [0x1CE7, 0x12],
  [0x19D0, 0x13],
  [0x0762, 0x14],
  [0x0255, 0x15],
  [0x0D0C, 0x16],
  [0x083B, 0x17],
  [0x355F, 0x18],
  [0x3068, 0x19],
  [0x3F31, 0x1A],
  [0x3A06, 0x1B],
  [0x24B4, 0x1C],
  [0x2183, 0x1D],
  [0x2EDA, 0x1E],
  [0x2BED, 0x1F],
];
var BITS_SET_IN_HALF_BYTE = [0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4];


export default function FormatInformation(formatInfo) {
  this.errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
  this.dataMask =  (formatInfo & 0x07);
}

FormatInformation.prototype.GetHashCode = function() {
  return (this.errorCorrectionLevel.ordinal() << 3) |  this.dataMask;
};

FormatInformation.prototype.Equals = function(o) {
  var other =  o;
  return this.errorCorrectionLevel == other.errorCorrectionLevel && this.dataMask == other.dataMask;
};

FormatInformation.numBitsDiffering = function(a,  b) {
  a ^= b; // a now has a 1 bit exactly where its bit differs with b's
  // Count bits set quickly with a series of lookups:
  return BITS_SET_IN_HALF_BYTE[a & 0x0F] + BITS_SET_IN_HALF_BYTE[(URShift(a, 4) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 8) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 12) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 16) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 20) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 24) & 0x0F)] + BITS_SET_IN_HALF_BYTE[(URShift(a, 28) & 0x0F)];
};

FormatInformation.decodeFormatInformation = function(maskedFormatInfo) {
  var formatInfo = FormatInformation.doDecodeFormatInformation(maskedFormatInfo);
  if (formatInfo != null) {
    return formatInfo;
  }
  // Should return null, but, some QR codes apparently
  // do not mask this info. Try again by actually masking the pattern
  // first
  return FormatInformation.doDecodeFormatInformation(maskedFormatInfo ^ FORMAT_INFO_MASK_QR);
};
FormatInformation.doDecodeFormatInformation = function(maskedFormatInfo) {
  // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
  var bestDifference = 0xffffffff;
  var bestFormatInfo = 0;
  for (var i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
    var decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
    var targetInfo = decodeInfo[0];
    if (targetInfo == maskedFormatInfo) {
      // Found an exact match
      return new FormatInformation(decodeInfo[1]);
    }
    var bitsDifference = this.numBitsDiffering(maskedFormatInfo, targetInfo);
    if (bitsDifference < bestDifference) {
      bestFormatInfo = decodeInfo[1];
      bestDifference = bitsDifference;
    }
  }
  // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
  // differing means we found a match
  if (bestDifference <= 3) {
    return new FormatInformation(bestFormatInfo);
  }
  return null;
};