vk-qr/src/index.js

"use strict";
/* eslint-disable */
var qrcodegen = new function() {

  /*---- QR Code symbol class ----*/
  this.qrBorder = 7;
  this.tileSize = 96;
  this.incTileSize = 96;
  this.minImageTiles = 5;
  /*
   * A class that represents a QR Code symbol, which is a type of two-dimension barcode.
   * Invented by Denso Wave and described in the ISO/IEC 18004 standard.
   * Instances of this class represent an immutable square grid of black and white cells.
   * The class provides static factory functions to create a QR Code from text or binary data.
   * The class covers the QR Code Model 2 specification, supporting all versions (sizes)
   * from 1 to 40, all 4 error correction levels, and 4 character encoding modes.
   *
   * Ways to create a QR Code object:
   * - High level: Take the payload data and call QrCode.encodeText() or QrCode.encodeBinary().
   * - Mid level: Custom-make the list of segments and call QrCode.encodeSegments().
   * - Low level: Custom-make the array of data codeword bytes (including
   *   segment headers and final padding, excluding error correction codewords),
   *   supply the appropriate version number, and call the QrCode() constructor.
   * (Note that all ways require supplying the desired error correction level.)
   *
   * This constructor creates a new QR Code with the given version number,
   * error correction level, data codeword bytes, and mask number.
   * This is a low-level API that most users should not use directly.
   * A mid-level API is the encodeSegments() function.
   */
  this.QrCode = function(version, errCorLvl, dataCodewords, mask) {

    /*---- Constructor (low level) ----*/

    // Check scalar arguments
    if (version < MIN_VERSION || version > MAX_VERSION)
      throw "Version value out of range";
    if (mask < -1 || mask > 7)
      throw "Mask value out of range";
    if (!(errCorLvl instanceof Ecc))
      throw "QrCode.Ecc expected";
    var size = version * 4 + 17;

    // Initialize both grids to be size*size arrays of Boolean false
    var row = [];
    for (var i = 0; i < size; i++)
      row.push(false);
    var modules = [];  // Initially all white
    var isFunction = [];
    for (var i = 0; i < size; i++) {
      modules.push(row.slice());
      isFunction.push(row.slice());
    }

    // Compute ECC, draw modules
    drawFunctionPatterns();
    var allCodewords = addEccAndInterleave(dataCodewords);
    drawCodewords(allCodewords);

    // Do masking
    if (mask == -1) {  // Automatically choose best mask
      var minPenalty = Infinity;
      for (var i = 0; i < 8; i++) {
        applyMask(i);
        drawFormatBits(i);
        var penalty = getPenaltyScore();
        if (penalty < minPenalty) {
          mask = i;
          minPenalty = penalty;
        }
        applyMask(i);  // Undoes the mask due to XOR
      }
    }
    if (mask < 0 || mask > 7)
      throw "Assertion error";
    applyMask(mask);  // Apply the final choice of mask
    drawFormatBits(mask);  // Overwrite old format bits

    isFunction = null;


    /*---- Read-only instance properties ----*/

    // The version number of this QR Code, which is between 1 and 40 (inclusive).
    // This determines the size of this barcode.
    Object.defineProperty(this, "version", {value: version});

    // The width and height of this QR Code, measured in modules, between
    // 21 and 177 (inclusive). This is equal to version * 4 + 17.
    Object.defineProperty(this, "size", {value: size});

    // The error correction level used in this QR Code.
    Object.defineProperty(this, "errorCorrectionLevel", {value: errCorLvl});

    // The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive).
    // Even if a QR Code is created with automatic masking requested (mask = -1),
    // the resulting object still has a mask value between 0 and 7.
    Object.defineProperty(this, "mask", {value: mask});


    /*---- Accessor methods ----*/

    // Returns the color of the module (pixel) at the given coordinates, which is false
    // for white or true for black. The top left corner has the coordinates (x=0, y=0).
    // If the given coordinates are out of bounds, then false (white) is returned.
    this.getPixel = function(x, y) {

      var imageTiles = (size - 13) / 2;
      if (imageTiles < qrcodegen.minImageTiles) {
        imageTiles = qrcodegen.minImageTiles;
      }

      var padding = (size - (qrcodegen.qrBorder * 2) - imageTiles);
      if (padding % 2 === 0) {
        padding++;
      }
      padding /= 2;
      padding--;

      if (x > qrcodegen.qrBorder + padding && y > qrcodegen.qrBorder + padding && x < size - padding - qrcodegen.qrBorder - 1 && y < size - padding - qrcodegen.qrBorder - 1) {
        return false;
      }

      return 0 <= x && x < size && 0 <= y && y < size && modules[y][x];
    };


    /*---- Public instance methods ----*/

    // Draws this QR Code, with the given module scale and border modules, onto the given HTML
    // canvas element. The canvas's width and height is resized to (this.size + border * 2) * scale.
    // The drawn image is be purely black and white, and fully opaque.
    // The scale must be a positive integer and the border must be a non-negative integer.
    this.drawCanvas = function(scale, border, canvas) {
      if (scale <= 0 || border < 0)
        throw "Value out of range";
      var width = (size + border * 2) * scale;
      canvas.width = width;
      canvas.height = width;
      var ctx = canvas.getContext("2d");
      for (var y = -border; y < size + border; y++) {
        for (var x = -border; x < size + border; x++) {
          ctx.fillStyle = this.getPixel(x, y) ? "#000000" : "#FFFFFF";
          ctx.fillRect((x + border) * scale, (y + border) * scale, scale, scale);
        }
      }
    };

    this.getNeighbors = function(x, y) {
      return {
        l: this.getPixel(x - 1, y),
        r: this.getPixel(x + 1, y),
        t: this.getPixel(x, y - 1),
        b: this.getPixel(x, y + 1)
      };
    };

    this.toSvgString = function() {
      var parts = [];
      var leftPadding = 0;
      var topPadding = 0;
      var xCoord = 0;
      var yCoord = 0;
      for (var y = 0; y < size; y++) {
        leftPadding = 0;
        for (var x = 0; x < size; x++) {
          xCoord = x + leftPadding;
          leftPadding += qrcodegen.tileSize;
          yCoord = y + topPadding;
          var neighbors = this.getNeighbors(x, y);
          var path = '';
          if (this.getPixel(x, y)) {
            path = '';
            if (!neighbors.l && !neighbors.r && !neighbors.t && !neighbors.b) {
              path = '<path d="M0,28.6v42.9C0,87.3,12.8,100,28.6,100h42.9c15.9,0,28.6-12.8,28.6-28.6V28.6C100,12.7,87.2,0,71.4,0H28.6  C12.8,0,0,12.8,0,28.6z"/>';
            } else if (!neighbors.l && !neighbors.r && !neighbors.t && neighbors.b) {
              path = '<path d="M100,100V28.6C100,12.7,87.2,0,71.4,0H28.6C12.7,0,0,12.8,0,28.6V100H100z"/>';
            } else if (!neighbors.l && neighbors.r && !neighbors.t && !neighbors.b) {
              path = '<path d="M100,0H28.6C12.7,0,0,12.8,0,28.6v42.9C0,87.3,12.8,100,28.6,100H100V0z"/>';
            } else if (neighbors.l && !neighbors.r && !neighbors.t && !neighbors.b) {
              path = '<path d="M0,100h71.4c15.9,0,28.6-12.8,28.6-28.6V28.6C100,12.7,87.2,0,71.4,0H0V100z"/>';
            } else if (!neighbors.l && !neighbors.r && neighbors.t && !neighbors.b) {
              path = '<path d="M0,0v71.4C0,87.3,12.8,100,28.6,100h42.9c15.9,0,28.6-12.8,28.6-28.6V0H0z"/>';
            } else if (neighbors.l && !neighbors.r && !neighbors.t && neighbors.b) {
              path = '<path d="m0 100h100v-71.5c0-15.8-12.8-28.5-28.5-28.5h-71.5v100z"/>';
            } else if (neighbors.l && !neighbors.r && neighbors.t && !neighbors.b) {
              path = '<path d="m0 0v100h71.5c15.8 0 28.5-12.8 28.5-28.5v-71.5h-100z"/>';
            } else if (!neighbors.l && neighbors.r && !neighbors.t && neighbors.b) {
              path = '<path d="m100 100v-100h-71.5c-15.8 0-28.5 12.8-28.5 28.5v71.5h100z"/>';
            } else if (!neighbors.l && neighbors.r && neighbors.t && !neighbors.b) {
              path = '<path d="m100 0h-100v71.5c0 15.8 12.8 28.5 28.5 28.5h71.5v-100z"/>';
            } else {
              path = '<rect width="100" height="100"/>';
            }

            parts.push('<g transform="translate(' + xCoord + (yCoord !== 0 ? ',' + yCoord : '') + ')">' + path + '</g>');
          } else {
            if (neighbors.l && neighbors.t && this.getPixel(x - 1, y - 1)) {
              parts.push('<g transform="translate(' + xCoord + (yCoord !== 0 ? ',' + yCoord : '') + ')"><path d="M30.5,2V0H0v30.5h2C2,14.7,14.8,2,30.5,2z"/></g>');
            }
            if (neighbors.l && neighbors.b && this.getPixel(x - 1, y + 1)) {
              parts.push('<g transform="translate(' + xCoord + (yCoord !== 0 ? ',' + yCoord : '') + ')"><path d="M2,69.5H0V100h30.5v-2C14.7,98,2,85.2,2,69.5z"/></g>');
            }
            if (neighbors.r && neighbors.t && this.getPixel(x + 1, y - 1)) {
              parts.push('<g transform="translate(' + xCoord + (yCoord !== 0 ? ',' + yCoord : '') + ')"><path d="M98,30.5h2V0H69.5v2C85.3,2,98,14.8,98,30.5z"/></g>');
            }
            if (neighbors.r && neighbors.b && this.getPixel(x + 1, y + 1)) {
              parts.push('<g transform="translate(' + xCoord + (yCoord !== 0 ? ',' + yCoord : '') + ')"><path d="M69.5,98v2H100V69.5h-2C98,85.3,85.2,98,69.5,98z"/></g>');
            }
          }
        }
        topPadding += qrcodegen.tileSize;
      }

      var imgWidthInTiles = (size - ((qrcodegen.qrBorder * 2) - 1)) / 2;
      var width = (imgWidthInTiles * qrcodegen.incTileSize);
      var position = ((size - imgWidthInTiles) / 2) * qrcodegen.incTileSize + (qrcodegen.incTileSize / 4);
      parts.push('<image transform="translate(' + position + ',' + position + ')" width="' + width + '" height="' + width + '"  xlink:href="https://upload.wikimedia.org/wikipedia/commons/2/21/VK.com-logo.svg"/>');

      return '<?xml version="1.0" encoding="UTF-8"?>\n' +
        '<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">\n' +
        '<svg version="1.1" viewBox="0 0 ' + (size * qrcodegen.incTileSize + qrcodegen.incTileSize) + ' ' + (size * qrcodegen.incTileSize + qrcodegen.incTileSize) + '" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">\n' +
        '<g transform="translate(0,0)">\n' +
        parts.join("\n") +
        '</g>\n' +
        '</svg>\n';
    };

    /*---- Private helper methods for constructor: Drawing function modules ----*/

    // Reads this object's version field, and draws and marks all function modules.
    function drawFunctionPatterns() {
      // Draw horizontal and vertical timing patterns
      for (var i = 0; i < size; i++) {
        setFunctionModule(6, i, i % 2 == 0);
        setFunctionModule(i, 6, i % 2 == 0);
      }

      // Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules)
      drawFinderPattern(3, 3);
      drawFinderPattern(size - 4, 3);
      drawFinderPattern(3, size - 4);

      // Draw numerous alignment patterns
      var alignPatPos = getAlignmentPatternPositions();
      var numAlign = alignPatPos.length;
      for (var i = 0; i < numAlign; i++) {
        for (var j = 0; j < numAlign; j++) {
          // Don't draw on the three finder corners
          if (!(i == 0 && j == 0 || i == 0 && j == numAlign - 1 || i == numAlign - 1 && j == 0))
            drawAlignmentPattern(alignPatPos[i], alignPatPos[j]);
        }
      }

      // Draw configuration data
      drawFormatBits(0);  // Dummy mask value; overwritten later in the constructor
      drawVersion();
    }


    // Draws two copies of the format bits (with its own error correction code)
    // based on the given mask and this object's error correction level field.
    function drawFormatBits(mask) {
      // Calculate error correction code and pack bits
      var data = errCorLvl.formatBits << 3 | mask;  // errCorrLvl is uint2, mask is uint3
      var rem = data;
      for (var i = 0; i < 10; i++)
        rem = (rem << 1) ^ ((rem >>> 9) * 0x537);
      var bits = (data << 10 | rem) ^ 0x5412;  // uint15
      if (bits >>> 15 != 0)
        throw "Assertion error";

      // Draw first copy
      for (var i = 0; i <= 5; i++)
        setFunctionModule(8, i, getBit(bits, i));
      setFunctionModule(8, 7, getBit(bits, 6));
      setFunctionModule(8, 8, getBit(bits, 7));
      setFunctionModule(7, 8, getBit(bits, 8));
      for (var i = 9; i < 15; i++)
        setFunctionModule(14 - i, 8, getBit(bits, i));

      // Draw second copy
      for (var i = 0; i < 8; i++)
        setFunctionModule(size - 1 - i, 8, getBit(bits, i));
      for (var i = 8; i < 15; i++)
        setFunctionModule(8, size - 15 + i, getBit(bits, i));
      setFunctionModule(8, size - 8, true);  // Always black
    }


    // Draws two copies of the version bits (with its own error correction code),
    // based on this object's version field, iff 7 <= version <= 40.
    function drawVersion() {
      if (version < 7)
        return;

      // Calculate error correction code and pack bits
      var rem = version;  // version is uint6, in the range [7, 40]
      for (var i = 0; i < 12; i++)
        rem = (rem << 1) ^ ((rem >>> 11) * 0x1F25);
      var bits = version << 12 | rem;  // uint18
      if (bits >>> 18 != 0)
        throw "Assertion error";

      // Draw two copies
      for (var i = 0; i < 18; i++) {
        var bit = getBit(bits, i);
        var a = size - 11 + i % 3;
        var b = Math.floor(i / 3);
        setFunctionModule(a, b, bit);
        setFunctionModule(b, a, bit);
      }
    }


    // Draws a 9*9 finder pattern including the border separator,
    // with the center module at (x, y). Modules can be out of bounds.
    function drawFinderPattern(x, y) {
      for (var dy = -4; dy <= 4; dy++) {
        for (var dx = -4; dx <= 4; dx++) {
          var dist = Math.max(Math.abs(dx), Math.abs(dy));  // Chebyshev/infinity norm
          var xx = x + dx, yy = y + dy;
          if (0 <= xx && xx < size && 0 <= yy && yy < size)
            setFunctionModule(xx, yy, dist != 2 && dist != 4);
        }
      }
    }


    // Draws a 5*5 alignment pattern, with the center module
    // at (x, y). All modules must be in bounds.
    function drawAlignmentPattern(x, y) {
      for (var dy = -2; dy <= 2; dy++) {
        for (var dx = -2; dx <= 2; dx++)
          setFunctionModule(x + dx, y + dy, Math.max(Math.abs(dx), Math.abs(dy)) != 1);
      }
    }


    // Sets the color of a module and marks it as a function module.
    // Only used by the constructor. Coordinates must be in bounds.
    function setFunctionModule(x, y, isBlack) {
      modules[y][x] = isBlack;
      isFunction[y][x] = true;
    }


    /*---- Private helper methods for constructor: Codewords and masking ----*/

    // Returns a new byte string representing the given data with the appropriate error correction
    // codewords appended to it, based on this object's version and error correction level.
    function addEccAndInterleave(data) {
      if (data.length != QrCode.getNumDataCodewords(version, errCorLvl))
        throw "Invalid argument";

      // Calculate parameter numbers
      var numBlocks = QrCode.NUM_ERROR_CORRECTION_BLOCKS[errCorLvl.ordinal][version];
      var blockEccLen = QrCode.ECC_CODEWORDS_PER_BLOCK  [errCorLvl.ordinal][version];
      var rawCodewords = Math.floor(QrCode.getNumRawDataModules(version) / 8);
      var numShortBlocks = numBlocks - rawCodewords % numBlocks;
      var shortBlockLen = Math.floor(rawCodewords / numBlocks);

      // Split data into blocks and append ECC to each block
      var blocks = [];
      var rs = new ReedSolomonGenerator(blockEccLen);
      for (var i = 0, k = 0; i < numBlocks; i++) {
        var dat = data.slice(k, k + shortBlockLen - blockEccLen + (i < numShortBlocks ? 0 : 1));
        k += dat.length;
        var ecc = rs.getRemainder(dat);
        if (i < numShortBlocks)
          dat.push(0);
        blocks.push(dat.concat(ecc));
      }

      // Interleave (not concatenate) the bytes from every block into a single sequence
      var result = [];
      for (var i = 0; i < blocks[0].length; i++) {
        for (var j = 0; j < blocks.length; j++) {
          // Skip the padding byte in short blocks
          if (i != shortBlockLen - blockEccLen || j >= numShortBlocks)
            result.push(blocks[j][i]);
        }
      }
      if (result.length != rawCodewords)
        throw "Assertion error";
      return result;
    }


    // Draws the given sequence of 8-bit codewords (data and error correction) onto the entire
    // data area of this QR Code. Function modules need to be marked off before this is called.
    function drawCodewords(data) {
      if (data.length != Math.floor(QrCode.getNumRawDataModules(version) / 8))
        throw "Invalid argument";
      var i = 0;  // Bit index into the data
      // Do the funny zigzag scan
      for (var right = size - 1; right >= 1; right -= 2) {  // Index of right column in each column pair
        if (right == 6)
          right = 5;
        for (var vert = 0; vert < size; vert++) {  // Vertical counter
          for (var j = 0; j < 2; j++) {
            var x = right - j;  // Actual x coordinate
            var upward = ((right + 1) & 2) == 0;
            var y = upward ? size - 1 - vert : vert;  // Actual y coordinate
            if (!isFunction[y][x] && i < data.length * 8) {
              modules[y][x] = getBit(data[i >>> 3], 7 - (i & 7));
              i++;
            }
            // If this QR Code has any remainder bits (0 to 7), they were assigned as
            // 0/false/white by the constructor and are left unchanged by this method
          }
        }
      }
      if (i != data.length * 8)
        throw "Assertion error";
    }


    // XORs the codeword modules in this QR Code with the given mask pattern.
    // The function modules must be marked and the codeword bits must be drawn
    // before masking. Due to the arithmetic of XOR, calling applyMask() with
    // the same mask value a second time will undo the mask. A final well-formed
    // QR Code needs exactly one (not zero, two, etc.) mask applied.
    function applyMask(mask) {
      if (mask < 0 || mask > 7)
        throw "Mask value out of range";
      for (var y = 0; y < size; y++) {
        for (var x = 0; x < size; x++) {
          var invert;
          switch (mask) {
            case 0:
              invert = (x + y) % 2 == 0;
              break;
            case 1:
              invert = y % 2 == 0;
              break;
            case 2:
              invert = x % 3 == 0;
              break;
            case 3:
              invert = (x + y) % 3 == 0;
              break;
            case 4:
              invert = (Math.floor(x / 3) + Math.floor(y / 2)) % 2 == 0;
              break;
            case 5:
              invert = x * y % 2 + x * y % 3 == 0;
              break;
            case 6:
              invert = (x * y % 2 + x * y % 3) % 2 == 0;
              break;
            case 7:
              invert = ((x + y) % 2 + x * y % 3) % 2 == 0;
              break;
            default:
              throw "Assertion error";
          }
          if (!isFunction[y][x] && invert)
            modules[y][x] = !modules[y][x];
        }
      }
    }


    // Calculates and returns the penalty score based on state of this QR Code's current modules.
    // This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
    function getPenaltyScore() {
      var result = 0;

      // Adjacent modules in row having same color, and finder-like patterns
      for (var y = 0; y < size; y++) {
        var runHistory = [0, 0, 0, 0, 0, 0, 0];
        var color = false;
        var runX = 0;
        for (var x = 0; x < size; x++) {
          if (modules[y][x] == color) {
            runX++;
            if (runX == 5)
              result += QrCode.PENALTY_N1;
            else if (runX > 5)
              result++;
          } else {
            QrCode.addRunToHistory(runX, runHistory);
            if (!color && QrCode.hasFinderLikePattern(runHistory))
              result += QrCode.PENALTY_N3;
            color = modules[y][x];
            runX = 1;
          }
        }
        QrCode.addRunToHistory(runX, runHistory);
        if (color)
          QrCode.addRunToHistory(0, runHistory);  // Dummy run of white
        if (QrCode.hasFinderLikePattern(runHistory))
          result += QrCode.PENALTY_N3;
      }
      // Adjacent modules in column having same color, and finder-like patterns
      for (var x = 0; x < size; x++) {
        var runHistory = [0, 0, 0, 0, 0, 0, 0];
        var color = false;
        var runY = 0;
        for (var y = 0; y < size; y++) {
          if (modules[y][x] == color) {
            runY++;
            if (runY == 5)
              result += QrCode.PENALTY_N1;
            else if (runY > 5)
              result++;
          } else {
            QrCode.addRunToHistory(runY, runHistory);
            if (!color && QrCode.hasFinderLikePattern(runHistory))
              result += QrCode.PENALTY_N3;
            color = modules[y][x];
            runY = 1;
          }
        }
        QrCode.addRunToHistory(runY, runHistory);
        if (color)
          QrCode.addRunToHistory(0, runHistory);  // Dummy run of white
        if (QrCode.hasFinderLikePattern(runHistory))
          result += QrCode.PENALTY_N3;
      }

      // 2*2 blocks of modules having same color
      for (var y = 0; y < size - 1; y++) {
        for (var x = 0; x < size - 1; x++) {
          var color = modules[y][x];
          if (color == modules[y][x + 1] &&
            color == modules[y + 1][x] &&
            color == modules[y + 1][x + 1])
            result += QrCode.PENALTY_N2;
        }
      }

      // Balance of black and white modules
      var black = 0;
      modules.forEach(function(row) {
        row.forEach(function(color) {
          if (color)
            black++;
        });
      });
      var total = size * size;  // Note that size is odd, so black/total != 1/2
      // Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)%
      var k = Math.ceil(Math.abs(black * 20 - total * 10) / total) - 1;
      result += k * QrCode.PENALTY_N4;
      return result;
    }


    // Returns an ascending list of positions of alignment patterns for this version number.
    // Each position is in the range [0,177), and are used on both the x and y axes.
    // This could be implemented as lookup table of 40 variable-length lists of integers.
    function getAlignmentPatternPositions() {
      if (version == 1)
        return [];
      else {
        var numAlign = Math.floor(version / 7) + 2;
        var step = (version == 32) ? 26 :
          Math.ceil((size - 13) / (numAlign * 2 - 2)) * 2;
        var result = [6];
        for (var pos = size - 7; result.length < numAlign; pos -= step)
          result.splice(1, 0, pos);
        return result;
      }
    }


    // Returns true iff the i'th bit of x is set to 1.
    function getBit(x, i) {
      return ((x >>> i) & 1) != 0;
    }
  };


  /*---- Static factory functions (high level) for QrCode ----*/

  /*
   * Returns a QR Code representing the given Unicode text string at the given error correction level.
   * As a conservative upper bound, this function is guaranteed to succeed for strings that have 738 or fewer
   * Unicode code points (not UTF-16 code units) if the low error correction level is used. The smallest possible
   * QR Code version is automatically chosen for the output. The ECC level of the result may be higher than the
   * ecl argument if it can be done without increasing the version.
   */
  this.QrCode.encodeText = function(text, ecl) {
    var segs = qrcodegen.QrSegment.makeSegments(text);
    return this.encodeSegments(segs, ecl);
  };


  /*
   * Returns a QR Code representing the given binary data at the given error correction level.
   * This function always encodes using the binary segment mode, not any text mode. The maximum number of
   * bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output.
   * The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version.
   */
  this.QrCode.encodeBinary = function(data, ecl) {
    var seg = qrcodegen.QrSegment.makeBytes(data);
    return this.encodeSegments([seg], ecl);
  };


  /*---- Static factory functions (mid level) for QrCode ----*/

  /*
   * Returns a QR Code representing the given segments with the given encoding parameters.
   * The smallest possible QR Code version within the given range is automatically
   * chosen for the output. Iff boostEcl is true, then the ECC level of the result
   * may be higher than the ecl argument if it can be done without increasing the
   * version. The mask number is either between 0 to 7 (inclusive) to force that
   * mask, or -1 to automatically choose an appropriate mask (which may be slow).
   * This function allows the user to create a custom sequence of segments that switches
   * between modes (such as alphanumeric and byte) to encode text in less space.
   * This is a mid-level API; the high-level API is encodeText() and encodeBinary().
   */
  this.QrCode.encodeSegments = function(segs, ecl, minVersion, maxVersion, mask, boostEcl) {
    if (minVersion == undefined) minVersion = MIN_VERSION;
    if (maxVersion == undefined) maxVersion = MAX_VERSION;
    if (mask == undefined) mask = -1;
    if (boostEcl == undefined) boostEcl = true;
    if (!(MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= MAX_VERSION) || mask < -1 || mask > 7)
      throw "Invalid value";

    // Find the minimal version number to use
    var version, dataUsedBits;
    for (version = minVersion; ; version++) {
      var dataCapacityBits = QrCode.getNumDataCodewords(version, ecl) * 8;  // Number of data bits available
      dataUsedBits = qrcodegen.QrSegment.getTotalBits(segs, version);
      if (dataUsedBits <= dataCapacityBits)
        break;  // This version number is found to be suitable
      if (version >= maxVersion)  // All versions in the range could not fit the given data
        throw "Data too long";
    }

    // Increase the error correction level while the data still fits in the current version number
    [this.Ecc.MEDIUM, this.Ecc.QUARTILE, this.Ecc.HIGH].forEach(function(newEcl) {  // From low to high
      if (boostEcl && dataUsedBits <= QrCode.getNumDataCodewords(version, newEcl) * 8)
        ecl = newEcl;
    });

    // Concatenate all segments to create the data bit string
    var bb = new BitBuffer();
    segs.forEach(function(seg) {
      bb.appendBits(seg.mode.modeBits, 4);
      bb.appendBits(seg.numChars, seg.mode.numCharCountBits(version));
      seg.getData().forEach(function(bit) {
        bb.push(bit);
      });
    });
    if (bb.length != dataUsedBits)
      throw "Assertion error";

    // Add terminator and pad up to a byte if applicable
    var dataCapacityBits = QrCode.getNumDataCodewords(version, ecl) * 8;
    if (bb.length > dataCapacityBits)
      throw "Assertion error";
    bb.appendBits(0, Math.min(4, dataCapacityBits - bb.length));
    bb.appendBits(0, (8 - bb.length % 8) % 8);
    if (bb.length % 8 != 0)
      throw "Assertion error";

    // Pad with alternating bytes until data capacity is reached
    for (var padByte = 0xEC; bb.length < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
      bb.appendBits(padByte, 8);

    // Pack bits into bytes in big endian
    var dataCodewords = [];
    while (dataCodewords.length * 8 < bb.length)
      dataCodewords.push(0);
    bb.forEach(function(bit, i) {
      dataCodewords[i >>> 3] |= bit << (7 - (i & 7));
    });

    // Create the QR Code object
    return new this(version, ecl, dataCodewords, mask);
  };


  /*---- Private static helper functions for QrCode ----*/

  var QrCode = {};  // Private object to assign properties to. Not the same object as 'this.QrCode'.


  // Returns the number of data bits that can be stored in a QR Code of the given version number, after
  // all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8.
  // The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table.
  QrCode.getNumRawDataModules = function(ver) {
    if (ver < MIN_VERSION || ver > MAX_VERSION)
      throw "Version number out of range";
    var result = (16 * ver + 128) * ver + 64;
    if (ver >= 2) {
      var numAlign = Math.floor(ver / 7) + 2;
      result -= (25 * numAlign - 10) * numAlign - 55;
      if (ver >= 7)
        result -= 36;
    }
    return result;
  };


  // Returns the number of 8-bit data (i.e. not error correction) codewords contained in any
  // QR Code of the given version number and error correction level, with remainder bits discarded.
  // This stateless pure function could be implemented as a (40*4)-cell lookup table.
  QrCode.getNumDataCodewords = function(ver, ecl) {
    return Math.floor(QrCode.getNumRawDataModules(ver) / 8) -
      QrCode.ECC_CODEWORDS_PER_BLOCK    [ecl.ordinal][ver] *
      QrCode.NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver];
  };


  // Inserts the given value to the front of the given array, which shifts over the
  // existing values and deletes the last value. A helper function for getPenaltyScore().
  QrCode.addRunToHistory = function(run, history) {
    history.pop();
    history.unshift(run);
  };


  // Tests whether the given run history has the pattern of ratio 1:1:3:1:1 in the middle, and
  // surrounded by at least 4 on either or both ends. A helper function for getPenaltyScore().
  // Must only be called immediately after a run of white modules has ended.
  QrCode.hasFinderLikePattern = function(runHistory) {
    var n = runHistory[1];
    return n > 0 && runHistory[2] == n && runHistory[4] == n && runHistory[5] == n
      && runHistory[3] == n * 3 && Math.max(runHistory[0], runHistory[6]) >= n * 4;
  };


  /*---- Constants and tables for QrCode ----*/

  var MIN_VERSION = 1;  // The minimum version number supported in the QR Code Model 2 standard
  var MAX_VERSION = 40;  // The maximum version number supported in the QR Code Model 2 standard
  Object.defineProperty(this.QrCode, "MIN_VERSION", {value: MIN_VERSION});
  Object.defineProperty(this.QrCode, "MAX_VERSION", {value: MAX_VERSION});

  // For use in getPenaltyScore(), when evaluating which mask is best.
  QrCode.PENALTY_N1 = 3;
  QrCode.PENALTY_N2 = 3;
  QrCode.PENALTY_N3 = 40;
  QrCode.PENALTY_N4 = 10;

  QrCode.ECC_CODEWORDS_PER_BLOCK = [
    // Version: (note that index 0 is for padding, and is set to an illegal value)
    //  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
    [null, 7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30],  // Low
    [null, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28],  // Medium
    [null, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30],  // Quartile
    [null, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30],  // High
  ];

  QrCode.NUM_ERROR_CORRECTION_BLOCKS = [
    // Version: (note that index 0 is for padding, and is set to an illegal value)
    //  0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40    Error correction level
    [null, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 7, 8, 8, 9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25],  // Low
    [null, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5, 5, 8, 9, 9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49],  // Medium
    [null, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68],  // Quartile
    [null, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81],  // High
  ];


  /*---- Public helper enumeration ----*/

  /*
   * The error correction level in a QR Code symbol. Immutable.
   */
  this.QrCode.Ecc = {
    LOW: new Ecc(0, 1),  // The QR Code can tolerate about  7% erroneous codewords
    MEDIUM: new Ecc(1, 0),  // The QR Code can tolerate about 15% erroneous codewords
    QUARTILE: new Ecc(2, 3),  // The QR Code can tolerate about 25% erroneous codewords
    HIGH: new Ecc(3, 2),  // The QR Code can tolerate about 30% erroneous codewords
  };


  // Private constructor.
  function Ecc(ord, fb) {
    // (Public) In the range 0 to 3 (unsigned 2-bit integer)
    Object.defineProperty(this, "ordinal", {value: ord});

    // (Package-private) In the range 0 to 3 (unsigned 2-bit integer)
    Object.defineProperty(this, "formatBits", {value: fb});
  }


  /*---- Data segment class ----*/

  /*
   * A segment of character/binary/control data in a QR Code symbol.
   * Instances of this class are immutable.
   * The mid-level way to create a segment is to take the payload data
   * and call a static factory function such as QrSegment.makeNumeric().
   * The low-level way to create a segment is to custom-make the bit buffer
   * and call the QrSegment() constructor with appropriate values.
   * This segment class imposes no length restrictions, but QR Codes have restrictions.
   * Even in the most favorable conditions, a QR Code can only hold 7089 characters of data.
   * Any segment longer than this is meaningless for the purpose of generating QR Codes.
   * This constructor creates a QR Code segment with the given attributes and data.
   * The character count (numChars) must agree with the mode and the bit buffer length,
   * but the constraint isn't checked. The given bit buffer is cloned and stored.
   */
  this.QrSegment = function(mode, numChars, bitData) {
    /*---- Constructor (low level) ----*/
    if (numChars < 0 || !(mode instanceof Mode))
      throw "Invalid argument";

    // The data bits of this segment. Accessed through getData().
    bitData = bitData.slice();  // Make defensive copy

    // The mode indicator of this segment.
    Object.defineProperty(this, "mode", {value: mode});

    // The length of this segment's unencoded data. Measured in characters for
    // numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
    // Always zero or positive. Not the same as the data's bit length.
    Object.defineProperty(this, "numChars", {value: numChars});

    // Returns a new copy of the data bits of this segment.
    this.getData = function() {
      return bitData.slice();  // Make defensive copy
    };
  };


  /*---- Static factory functions (mid level) for QrSegment ----*/

  /*
   * Returns a segment representing the given binary data encoded in
   * byte mode. All input byte arrays are acceptable. Any text string
   * can be converted to UTF-8 bytes and encoded as a byte mode segment.
   */
  this.QrSegment.makeBytes = function(data) {
    var bb = new BitBuffer();
    data.forEach(function(b) {
      bb.appendBits(b, 8);
    });
    return new this(this.Mode.BYTE, data.length, bb);
  };


  /*
   * Returns a segment representing the given string of decimal digits encoded in numeric mode.
   */
  this.QrSegment.makeNumeric = function(digits) {
    if (!this.NUMERIC_REGEX.test(digits))
      throw "String contains non-numeric characters";
    var bb = new BitBuffer();
    for (var i = 0; i < digits.length;) {  // Consume up to 3 digits per iteration
      var n = Math.min(digits.length - i, 3);
      bb.appendBits(parseInt(digits.substring(i, i + n), 10), n * 3 + 1);
      i += n;
    }
    return new this(this.Mode.NUMERIC, digits.length, bb);
  };


  /*
   * Returns a segment representing the given text string encoded in alphanumeric mode.
   * The characters allowed are: 0 to 9, A to Z (uppercase only), space,
   * dollar, percent, asterisk, plus, hyphen, period, slash, colon.
   */
  this.QrSegment.makeAlphanumeric = function(text) {
    if (!this.ALPHANUMERIC_REGEX.test(text))
      throw "String contains unencodable characters in alphanumeric mode";
    var bb = new BitBuffer();
    var i;
    for (i = 0; i + 2 <= text.length; i += 2) {  // Process groups of 2
      var temp = QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)) * 45;
      temp += QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i + 1));
      bb.appendBits(temp, 11);
    }
    if (i < text.length)  // 1 character remaining
      bb.appendBits(QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)), 6);
    return new this(this.Mode.ALPHANUMERIC, text.length, bb);
  };


  /*
   * Returns a new mutable list of zero or more segments to represent the given Unicode text string.
   * The result may use various segment modes and switch modes to optimize the length of the bit stream.
   */
  this.QrSegment.makeSegments = function(text) {
    // Select the most efficient segment encoding automatically
    if (text == "")
      return [];
    else if (this.NUMERIC_REGEX.test(text))
      return [this.makeNumeric(text)];
    else if (this.ALPHANUMERIC_REGEX.test(text))
      return [this.makeAlphanumeric(text)];
    else
      return [this.makeBytes(toUtf8ByteArray(text))];
  };


  /*
   * Returns a segment representing an Extended Channel Interpretation
   * (ECI) designator with the given assignment value.
   */
  this.QrSegment.makeEci = function(assignVal) {
    var bb = new BitBuffer();
    if (assignVal < 0)
      throw "ECI assignment value out of range";
    else if (assignVal < (1 << 7))
      bb.appendBits(assignVal, 8);
    else if (assignVal < (1 << 14)) {
      bb.appendBits(2, 2);
      bb.appendBits(assignVal, 14);
    } else if (assignVal < 1000000) {
      bb.appendBits(6, 3);
      bb.appendBits(assignVal, 21);
    } else
      throw "ECI assignment value out of range";
    return new this(this.Mode.ECI, 0, bb);
  };


  // (Package-private) Calculates and returns the number of bits needed to encode the given segments at the
  // given version. The result is infinity if a segment has too many characters to fit its length field.
  this.QrSegment.getTotalBits = function(segs, version) {
    var result = 0;
    for (var i = 0; i < segs.length; i++) {
      var seg = segs[i];
      var ccbits = seg.mode.numCharCountBits(version);
      if (seg.numChars >= (1 << ccbits))
        return Infinity;  // The segment's length doesn't fit the field's bit width
      result += 4 + ccbits + seg.getData().length;
    }
    return result;
  };


  /*---- Constants for QrSegment ----*/

  var QrSegment = {};  // Private object to assign properties to. Not the same object as 'this.QrSegment'.

  // (Public) Describes precisely all strings that are encodable in numeric mode.
  // To test whether a string s is encodable: var ok = NUMERIC_REGEX.test(s);
  // A string is encodable iff each character is in the range 0 to 9.
  this.QrSegment.NUMERIC_REGEX = /^[0-9]*$/;

  // (Public) Describes precisely all strings that are encodable in alphanumeric mode.
  // To test whether a string s is encodable: var ok = ALPHANUMERIC_REGEX.test(s);
  // A string is encodable iff each character is in the following set: 0 to 9, A to Z
  // (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
  this.QrSegment.ALPHANUMERIC_REGEX = /^[A-Z0-9 $%*+.\/:-]*$/;

  // (Private) The set of all legal characters in alphanumeric mode,
  // where each character value maps to the index in the string.
  QrSegment.ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";


  /*---- Public helper enumeration ----*/

  /*
   * Describes how a segment's data bits are interpreted. Immutable.
   */
  this.QrSegment.Mode = {  // Constants
    NUMERIC: new Mode(0x1, [10, 12, 14]),
    ALPHANUMERIC: new Mode(0x2, [9, 11, 13]),
    BYTE: new Mode(0x4, [8, 16, 16]),
    KANJI: new Mode(0x8, [8, 10, 12]),
    ECI: new Mode(0x7, [0, 0, 0]),
  };


  // Private constructor.
  function Mode(mode, ccbits) {
    // (Package-private) The mode indicator bits, which is a uint4 value (range 0 to 15).
    Object.defineProperty(this, "modeBits", {value: mode});

    // (Package-private) Returns the bit width of the character count field for a segment in
    // this mode in a QR Code at the given version number. The result is in the range [0, 16].
    this.numCharCountBits = function(ver) {
      return ccbits[Math.floor((ver + 7) / 17)];
    };
  }


  /*---- Private helper functions and classes ----*/

  // Returns a new array of bytes representing the given string encoded in UTF-8.
  function toUtf8ByteArray(str) {
    str = encodeURI(str);
    var result = [];
    for (var i = 0; i < str.length; i++) {
      if (str.charAt(i) != "%")
        result.push(str.charCodeAt(i));
      else {
        result.push(parseInt(str.substring(i + 1, i + 3), 16));
        i += 2;
      }
    }
    return result;
  }


  /*
   * A private helper class that computes the Reed-Solomon error correction codewords for a sequence of
   * data codewords at a given degree. Objects are immutable, and the state only depends on the degree.
   * This class exists because each data block in a QR Code shares the same the divisor polynomial.
   * This constructor creates a Reed-Solomon ECC generator for the given degree. This could be implemented
   * as a lookup table over all possible parameter values, instead of as an algorithm.
   */
  function ReedSolomonGenerator(degree) {
    if (degree < 1 || degree > 255)
      throw "Degree out of range";

    // Coefficients of the divisor polynomial, stored from highest to lowest power, excluding the leading term which
    // is always 1. For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array {255, 8, 93}.
    var coefficients = [];

    // Start with the monomial x^0
    for (var i = 0; i < degree - 1; i++)
      coefficients.push(0);
    coefficients.push(1);

    // Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
    // drop the highest term, and store the rest of the coefficients in order of descending powers.
    // Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
    var root = 1;
    for (var i = 0; i < degree; i++) {
      // Multiply the current product by (x - r^i)
      for (var j = 0; j < coefficients.length; j++) {
        coefficients[j] = ReedSolomonGenerator.multiply(coefficients[j], root);
        if (j + 1 < coefficients.length)
          coefficients[j] ^= coefficients[j + 1];
      }
      root = ReedSolomonGenerator.multiply(root, 0x02);
    }

    // Computes and returns the Reed-Solomon error correction codewords for the given
    // sequence of data codewords. The returned object is always a new byte array.
    // This method does not alter this object's state (because it is immutable).
    this.getRemainder = function(data) {
      // Compute the remainder by performing polynomial division
      var result = coefficients.map(function() { return 0; });
      data.forEach(function(b) {
        var factor = b ^ result.shift();
        result.push(0);
        coefficients.forEach(function(coef, i) {
          result[i] ^= ReedSolomonGenerator.multiply(coef, factor);
        });
      });
      return result;
    };
  }

  // This static function returns the product of the two given field elements modulo GF(2^8/0x11D). The arguments and
  // result are unsigned 8-bit integers. This could be implemented as a lookup table of 256*256 entries of uint8.
  ReedSolomonGenerator.multiply = function(x, y) {
    if (x >>> 8 != 0 || y >>> 8 != 0)
      throw "Byte out of range";
    // Russian peasant multiplication
    var z = 0;
    for (var i = 7; i >= 0; i--) {
      z = (z << 1) ^ ((z >>> 7) * 0x11D);
      z ^= ((y >>> i) & 1) * x;
    }
    if (z >>> 8 != 0)
      throw "Assertion error";
    return z;
  };


  /*
   * A private helper class that represents an appendable sequence of bits (0s and 1s).
   * Mainly used by QrSegment. This constructor creates an empty bit buffer (length 0).
   */
  function BitBuffer() {
    Array.call(this);

    // Appends the given number of low-order bits of the given value
    // to this buffer. Requires 0 <= len <= 31 and 0 <= val < 2^len.
    this.appendBits = function(val, len) {
      if (len < 0 || len > 31 || val >>> len != 0)
        throw "Value out of range";
      for (var i = len - 1; i >= 0; i--)  // Append bit by bit
        this.push((val >>> i) & 1);
    };
  }

  BitBuffer.prototype = Object.create(Array.prototype);
  BitBuffer.prototype.constructor = BitBuffer;

};

export default qrcodegen;