qr-code.js

/*
 * QR Code generator library Javascript v1.8.0 ES6
 *
 * Copyright (c) Project Nayuki. (MIT License)
 * https://www.nayuki.io/page/qr-code-generator-library
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 * - The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 * - The Software is provided "as is", without warranty of any kind, express or
 *   implied, including but not limited to the warranties of merchantability,
 *   fitness for a particular purpose and noninfringement. In no event shall the
 *   authors or copyright holders be liable for any claim, damages or other
 *   liability, whether in an action of contract, tort or otherwise, arising from,
 *   out of or in connection with the Software or the use or other dealings in the
 *   Software.
 */

import { svg } from 'lit'

/**
 * Returns the number of Unicode code points in the given UTF-16 string.
 * @param {String} str - Input string
 * @returns {Number}
 */
const countUnicodeChars = (str) => {

    let result = 0
    for (const ch of str) {
        const cc = Number(ch.codePointAt(0))
        if (0xD800 <= cc && cc < 0xE000)
            throw new RangeError("Invalid UTF-16 string")
        result++
    }

    return result
}

/**
 * Appends the given number of low-order bits of the given value 
 * to the given buffer. Requires 0 <= len <= 31 and 0 <= val < 2^len.
 * @param {*} val 
 * @param {*} len
 * @param {*} bb 
 */
const appendBits = (val, len, bb) => {
    if (len < 0 || len > 31 || val >>> len != 0)
        throw new RangeError("Value out of range")
    for (let i = len - 1; i >= 0; i--) // Append bit by bit
        bb.push((val >>> i) & 1)
}
/**
 * Returns true iff the i'th bit of x is set to 1.
 * @param {*} x 
 * @param {*} i 
 * @returns 
 */
const getBit = (x, i) => {
    return ((x >>> i) & 1) != 0
}
/**
 * Throws an exception if the given condition is false.
 * @param {*} cond 
 */
const assert = (cond) => {
    if (!cond)
        throw new Error("Assertion error")
}

/* ---------------------------------- QrCode ------------------------------- */
class QrCode {
    /**
     * Constructor (low level) and fields.
     * Creates new QR Code with the given version number, error correction
     * level, data codeword bytes, and mask number. This is a low-level API
     * t most users should not use directly. A mid-level API is encodeSegments()
     * @param {number} version -    version number of this QR Code, between 1 and 40 (inclusive),
     *                              This determines the size of this barcode.
     * @param {*} errorCorrectionLevel - error correction level used in this QR Code.
     * @param {*} dataCodewords 
     * @param {*} msk 
     */
    constructor(
    version, 
    errorCorrectionLevel, dataCodewords, msk) {
        this.version = version
        this.errorCorrectionLevel = errorCorrectionLevel

        // The modules of this QR Code (false = light, true = dark).
        // Immutable after constructor finishes. Accessed through getModule().
        this.modules = []

        // Indicates function modules that are not subjected to masking.
        // Discarded when constructor finishes.
        this.isFunction = []

        // Check scalar arguments
        if (version < QrCode.MIN_VERSION || version > QrCode.MAX_VERSION)
            throw new RangeError("Version value out of range")

        if (msk < -1 || msk > 7)
            throw new RangeError("Mask value out of range")
        
        this.size = version * 4 + 17

        // Initialize both grids to be size*size arrays of Boolean false
        let row = []
        for (let i = 0; i < this.size; i++)
            row.push(false)
        for (let i = 0; i < this.size; i++) {
            this.modules.push(row.slice())   // Initially all light
            this.isFunction.push(row.slice())
        }
        // Compute ECC, draw modules
        this.drawFunctionPatterns()
        const allCodewords = this.addEccAndInterleave(dataCodewords)
        this.drawCodewords(allCodewords)
        // Do masking
        if (msk == -1) { // Automatically choose best mask
            let minPenalty = 1000000000
            for (let i = 0; i < 8; i++) {
                this.applyMask(i)
                this.drawFormatBits(i)
                const penalty = this.getPenaltyScore()
                if (penalty < minPenalty) {
                    msk = i
                    minPenalty = penalty
                }
                this.applyMask(i)    // Undoes the mask due to XOR
            }
        }
        assert(0 <= msk && msk <= 7)
        this.mask = msk
        this.applyMask(msk)     // Apply the final choice of mask
        this.drawFormatBits(msk)       // Overwrite old format bits
        this.isFunction = []
    }

    /*-- Static factory functions (high level) --*/
    // 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.
    static encodeText(text, ecl) {
        const segs = QrSegment.makeSegments(text)
        return QrCode.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.
    static encodeBinary(data, ecl) {
        const seg = QrSegment.makeBytes(data)
        return QrCode.encodeSegments([seg], ecl)
    }

    /*-- Static factory functions (mid level) --*/
    // 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().
    static encodeSegments(segs, ecl, minVersion = 1, maxVersion = 40, mask = -1, boostEcl = true) {
        if (!(QrCode.MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= QrCode.MAX_VERSION)
            || mask < -1 || mask > 7)
            throw new RangeError("Invalid value")

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

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

        // Concatenate all segments to create the data bit string
        let bb = []
        for (const seg of segs) {
            appendBits(seg.mode.modeBits, 4, bb)
            appendBits(seg.numChars, seg.mode.numCharCountBits(version), bb)
            for (const b of seg.getData())
                bb.push(b)
        }

        assert(bb.length == dataUsedBits)
        // Add terminator and pad up to a byte if applicable
        const dataCapacityBits = QrCode.getNumDataCodewords(version, ecl) * 8
        assert(bb.length <= dataCapacityBits)
        appendBits(0, Math.min(4, dataCapacityBits - bb.length), bb)
        appendBits(0, (8 - bb.length % 8) % 8, bb)
        assert(bb.length % 8 == 0)

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

        // Pack bits into bytes in big endian
        let dataCodewords = []
        while (dataCodewords.length * 8 < bb.length)
            dataCodewords.push(0)

        bb.forEach((b, i) => dataCodewords[i >>> 3] |= b << (7 - (i & 7)))

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

    /*-- Accessor methods --*/
    // Returns the color of the module (pixel) at the given coordinates, which is false
    // for light or true for dark. The top left corner has the coordinates (x=0, y=0).
    // If the given coordinates are out of bounds, then false (light) is returned.
    getModule(x, y) {
        return 0 <= x && x < this.size && 0 <= y && y < this.size && this.modules[y][x]
    }

    /*-- Private helper methods for constructor: Drawing function modules --*/
    // Reads this object's version field, and draws and marks all function modules.
    drawFunctionPatterns() {
        // Draw horizontal and vertical timing patterns
        for (let i = 0; i < this.size; i++) {
            this.setFunctionModule(6, i, i % 2 == 0)
            this.setFunctionModule(i, 6, i % 2 == 0)
        }

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

        // Draw numerous alignment patterns
        const alignPatPos = this.getAlignmentPatternPositions()
        const numAlign = alignPatPos.length

        for (let i = 0; i < numAlign; i++) {
            for (let 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))
                    this.drawAlignmentPattern(alignPatPos[i], alignPatPos[j])
            }
        }

        // Draw configuration data
        this.drawFormatBits(0)  // Dummy mask value; overwritten later in the constructor
        this.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.
    drawFormatBits(mask) {
        // Calculate error correction code and pack bits
        const data = this.errorCorrectionLevel.formatBits << 3 | mask   // errCorrLvl is uint2, mask is uint3
        let rem = data

        for (let i = 0; i < 10; i++)
            rem = (rem << 1) ^ ((rem >>> 9) * 0x537)

        const bits = (data << 10 | rem) ^ 0x5412    // uint15
        assert(bits >>> 15 == 0)

        // Draw first copy
        for (let i = 0; i <= 5; i++)
            this.setFunctionModule(8, i, getBit(bits, i))

        this.setFunctionModule(8, 7, getBit(bits, 6))
        this.setFunctionModule(8, 8, getBit(bits, 7))
        this.setFunctionModule(7, 8, getBit(bits, 8))

        for (let i = 9; i < 15; i++)
            this.setFunctionModule(14 - i, 8, getBit(bits, i))

        // Draw second copy
        for (let i = 0; i < 8; i++)
            this.setFunctionModule(this.size - 1 - i, 8, getBit(bits, i))

        for (let i = 8; i < 15; i++)
            this.setFunctionModule(8, this.size - 15 + i, getBit(bits, i))

        this.setFunctionModule(8, this.size - 8, true)  // Always dark
    }

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

        // Calculate error correction code and pack bits
        let rem = this.version  // version is uint6, in the range [7, 40]
        for (let i = 0; i < 12; i++)
            rem = (rem << 1) ^ ((rem >>> 11) * 0x1F25)

        const bits = this.version << 12 | rem   // uint18
        assert(bits >>> 18 == 0)

        // Draw two copies
        for (let i = 0; i < 18; i++) {
            const color = getBit(bits, i)
            const a = this.size - 11 + i % 3
            const b = Math.floor(i / 3)

            this.setFunctionModule(a, b, color)
            this.setFunctionModule(b, a, color)
        }
    }

    // Draws a 9*9 finder pattern including the border separator,
    // with the center module at (x, y). Modules can be out of bounds.
    drawFinderPattern(x, y) {
        for (let dy = -4; dy <= 4; dy++) {
            for (let dx = -4; dx <= 4; dx++) {
                const dist = Math.max(Math.abs(dx), Math.abs(dy))   // Chebyshev/infinity norm
                const xx = x + dx
                const yy = y + dy
                if (0 <= xx && xx < this.size && 0 <= yy && yy < this.size)
                    this.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.
    drawAlignmentPattern(x, y) {
        for (let dy = -2; dy <= 2; dy++) {
            for (let dx = -2; dx <= 2; dx++)
                this.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.
    setFunctionModule(x, y, isDark) {
        this.modules[y][x] = isDark
        this.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.
    addEccAndInterleave(data) {
        const ver = this.version
        const ecl = this.errorCorrectionLevel
        if (data.length != QrCode.getNumDataCodewords(ver, ecl))
            throw new RangeError("Invalid argument")

        // Calculate parameter numbers
        const numBlocks = QrCode.NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver]
        const blockEccLen = QrCode.ECC_CODEWORDS_PER_BLOCK[ecl.ordinal][ver]
        const rawCodewords = Math.floor(QrCode.getNumRawDataModules(ver) / 8)
        const numShortBlocks = numBlocks - rawCodewords % numBlocks
        const shortBlockLen = Math.floor(rawCodewords / numBlocks)

        // Split data into blocks and append ECC to each block
        let blocks = []
        const rsDiv = QrCode.reedSolomonComputeDivisor(blockEccLen)

        for (let i = 0, k = 0; i < numBlocks; i++) {
            let dat = data.slice(k, k + shortBlockLen - blockEccLen + (i < numShortBlocks ? 0 : 1))
            k += dat.length
            const ecc = QrCode.reedSolomonComputeRemainder(dat, rsDiv)

            if (i < numShortBlocks)
                dat.push(0)

            blocks.push(dat.concat(ecc))
        }

        // Interleave (not concatenate) the bytes from every block into a single sequence
        let result = []

        for (let i = 0; i < blocks[0].length; i++) {
            blocks.forEach((block, j) => {
                // Skip the padding byte in short blocks
                if (i != shortBlockLen - blockEccLen || j >= numShortBlocks)
                    result.push(block[i])
            })
        }

        assert(result.length == rawCodewords)
        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.
    drawCodewords(data) {
        if (data.length != Math.floor(QrCode.getNumRawDataModules(this.version) / 8))
            throw new RangeError("Invalid argument")

        let i = 0   // Bit index into the data

        // Do the funny zigzag scan
        for (let right = this.size - 1; right >= 1; right -= 2) { // Index of right column in each column pair
            if (right == 6)
                right = 5

            for (let vert = 0; vert < this.size; vert++) { // Vertical counter
                for (let j = 0; j < 2; j++) {

                    const x = right - j // Actual x coordinate
                    const upward = ((right + 1) & 2) == 0
                    const y = upward ? this.size - 1 - vert : vert  // Actual y coordinate

                    if (!this.isFunction[y][x] && i < data.length * 8) {
                        this.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/light by the constructor and are left unchanged by this method
                }
            }
        }
        assert(i == data.length * 8)
    }

    // 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.
    applyMask(mask) {
        if (mask < 0 || mask > 7)
            throw new RangeError("Mask value out of range")
        for (let y = 0; y < this.size; y++) {
            for (let x = 0; x < this.size; x++) {
                let 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 new Error("Unreachable")
                }
                if (!this.isFunction[y][x] && invert)
                    this.modules[y][x] = !this.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.
    getPenaltyScore() {
        let result = 0
        // Adjacent modules in row having same color, and finder-like patterns
        for (let y = 0; y < this.size; y++) {

            let runColor = false
            let runX = 0
            let runHistory = [0, 0, 0, 0, 0, 0, 0]

            for (let x = 0; x < this.size; x++) {
                if (this.modules[y][x] == runColor) {
                    runX++

                    if (runX == 5)
                        result += QrCode.PENALTY_N1
                    else if (runX > 5)
                        result++

                } else {
                    this.finderPenaltyAddHistory(runX, runHistory)

                    if (!runColor)
                        result += this.finderPenaltyCountPatterns(runHistory) * QrCode.PENALTY_N3

                    runColor = this.modules[y][x]
                    runX = 1
                }
            }

            result += this.finderPenaltyTerminateAndCount(runColor, runX, runHistory) * QrCode.PENALTY_N3
        }

        // Adjacent modules in column having same color, and finder-like patterns
        for (let x = 0; x < this.size; x++) {

            let runColor = false
            let runY = 0
            let runHistory = [0, 0, 0, 0, 0, 0, 0]

            for (let y = 0; y < this.size; y++) {
                if (this.modules[y][x] == runColor) {
                    runY++
                    if (runY == 5)
                        result += QrCode.PENALTY_N1
                    else if (runY > 5)
                        result++
                } else {
                    this.finderPenaltyAddHistory(runY, runHistory)
                    if (!runColor)
                        result += this.finderPenaltyCountPatterns(runHistory) * QrCode.PENALTY_N3
                    runColor = this.modules[y][x]
                    runY = 1
                }
            }

            result += this.finderPenaltyTerminateAndCount(runColor, runY, runHistory) * QrCode.PENALTY_N3
        }

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

        // Balance of dark and light modules
        let dark = 0
        for (const row of this.modules)
            dark = row.reduce((sum, color) => sum + (color ? 1 : 0), dark)
        const total = this.size * this.size; // Note that size is odd, so dark/total != 1/2
        // Compute the smallest integer k >= 0 such that (45-5k)% <= dark/total <= (55+5k)%
        const k = Math.ceil(Math.abs(dark * 20 - total * 10) / total) - 1
        assert(0 <= k && k <= 9)
        result += k * QrCode.PENALTY_N4
        assert(0 <= result && result <= 2568888)    // Non-tight upper bound based on default values of PENALTY_N1, ..., N4
        return result
    }

    /*-- Private helper functions --*/
    // 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.
    getAlignmentPatternPositions() {
        if (this.version == 1)
            return []
        else {
            const numAlign = Math.floor(this.version / 7) + 2
            const step = (this.version == 32) ? 26 :
                Math.ceil((this.version * 4 + 4) / (numAlign * 2 - 2)) * 2

            let result = [6]

            for (let pos = this.size - 7; result.length < numAlign; pos -= step)
                result.splice(1, 0, pos)

            return result
        }
    }

    // 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.
    static getNumRawDataModules(ver) {
        if (ver < QrCode.MIN_VERSION || ver > QrCode.MAX_VERSION)
            throw new RangeError("Version number out of range")
        let result = (16 * ver + 128) * ver + 64
        if (ver >= 2) {
            const numAlign = Math.floor(ver / 7) + 2
            result -= (25 * numAlign - 10) * numAlign - 55
            if (ver >= 7)
                result -= 36
        }
        assert(208 <= result && result <= 29648)

        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.
    static getNumDataCodewords(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]
    }

    // Returns a Reed-Solomon ECC generator polynomial for the given degree. This could be
    // implemented as a lookup table over all possible parameter values, instead of as an algorithm.
    static reedSolomonComputeDivisor(degree) {
        if (degree < 1 || degree > 255)
            throw new RangeError("Degree out of range")
        // Polynomial coefficients are 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].
        let result = []
        for (let i = 0; i < degree - 1; i++)
            result.push(0)
        result.push(1)  // Start off with the monomial x^0

        // Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
        // and drop the highest monomial term which is always 1x^degree.
        // Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
        let root = 1

        for (let i = 0; i < degree; i++) {
            // Multiply the current product by (x - r^i)
            for (let j = 0; j < result.length; j++) {
                result[j] = QrCode.reedSolomonMultiply(result[j], root);
                if (j + 1 < result.length)
                    result[j] ^= result[j + 1]
            }

            root = QrCode.reedSolomonMultiply(root, 0x02)
        }
        return result
    }

    // Returns the Reed-Solomon error correction codeword for the given data and divisor polynomials.
    static reedSolomonComputeRemainder(data, divisor) {
        let result = divisor.map(_ => 0)
        for (const b of data) { // Polynomial division
            const factor = b ^ result.shift()
            result.push(0)
            divisor.forEach((coef, i) => result[i] ^= QrCode.reedSolomonMultiply(coef, factor))
        }
        return result
    }

    // 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.
    static reedSolomonMultiply(x, y) {
        if (x >>> 8 != 0 || y >>> 8 != 0)
            throw new RangeError("Byte out of range")
        // Russian peasant multiplication
        let z = 0
        for (let i = 7; i >= 0; i--) {
            z = (z << 1) ^ ((z >>> 7) * 0x11D)
            z ^= ((y >>> i) & 1) * x
        }
        assert(z >>> 8 == 0)
        return z
    }

    // Can only be called immediately after a light run is added, and
    // returns either 0, 1, or 2. A helper function for getPenaltyScore().
    finderPenaltyCountPatterns(runHistory) {
        const n = runHistory[1]
        assert(n <= this.size * 3)
        const core = n > 0 && runHistory[2] == n && runHistory[3] == n * 3 && runHistory[4] == n && runHistory[5] == n

        return (core && runHistory[0] >= n * 4 && runHistory[6] >= n ? 1 : 0)
            + (core && runHistory[6] >= n * 4 && runHistory[0] >= n ? 1 : 0)
    }

    // Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore().
    finderPenaltyTerminateAndCount(currentRunColor, currentRunLength, runHistory) {
        if (currentRunColor) { // Terminate dark run
            this.finderPenaltyAddHistory(currentRunLength, runHistory)
            currentRunLength = 0
        }

        currentRunLength += this.size   // Add light border to final run
        this.finderPenaltyAddHistory(currentRunLength, runHistory)
        return this.finderPenaltyCountPatterns(runHistory)
    }

    // Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore().
    finderPenaltyAddHistory(currentRunLength, runHistory) {
        if (runHistory[0] == 0)
            currentRunLength += this.size   // Add light border to initial run
        runHistory.pop()
        runHistory.unshift(currentRunLength)
    }
}

/* ----------------------------- QrCode Constants -------------------------- */
// The minimum version number supported in the QR Code Model 2 standard.
QrCode.MIN_VERSION = 1
// The maximum version number supported in the QR Code Model 2 standard.
QrCode.MAX_VERSION = 40
// 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
    [-1, 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],
    [-1, 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],
    [-1, 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],
    [-1, 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
    [-1, 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],
    [-1, 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],
    [-1, 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],
    [-1, 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
]


/* --------------------------------- QrSegment ----------------------------- */
/*
* 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.
*/
class QrSegment {
    /*-- Constructor (low level) and fields --*/
    // Creates a new 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.
    constructor(
    // The mode indicator of this segment.
    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.
    numChars, 
    // The data bits of this segment. Accessed through getData().
    bitData) {
        this.mode = mode
        this.numChars = numChars
        this.bitData = bitData
        if (numChars < 0)
            throw new RangeError("Invalid argument")
        this.bitData = bitData.slice()  // Make defensive copy
    }

    /*-- Static factory functions (mid level) --*/
    // 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.
    static makeBytes(data) {
        let bb = []
        for (const b of data)
            appendBits(b, 8, bb)

        return new QrSegment(Mode.BYTE, data.length, bb)
    }

    // Returns a segment representing the given string of decimal digits encoded in numeric mode.
    static makeNumeric(digits) {
        if (!QrSegment.isNumeric(digits))
            throw new RangeError("String contains non-numeric characters")

        let bb = []

        for (let i = 0; i < digits.length;) { // Consume up to 3 digits per iteration
            const n = Math.min(digits.length - i, 3)
            appendBits(parseInt(digits.substr(i, n), 10), n * 3 + 1, bb)
            i += n
        }

        return new QrSegment(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.
    static makeAlphanumeric(text) {
        if (!QrSegment.isAlphanumeric(text))
            throw new RangeError("String contains unencodable characters in alphanumeric mode")

        let bb = []
        let i

        for (i = 0; i + 2 <= text.length; i += 2) { // Process groups of 2
            let temp = QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)) * 45
            temp += QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i + 1))
            appendBits(temp, 11, bb)
        }

        if (i < text.length) // 1 character remaining
            appendBits(QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)), 6, bb)
        return new QrSegment(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.
    static makeSegments(text) {
        // Select the most efficient segment encoding automatically
        if (text == "")
            return []
        else if (QrSegment.isNumeric(text))
            return [QrSegment.makeNumeric(text)]
        else if (QrSegment.isAlphanumeric(text))
            return [QrSegment.makeAlphanumeric(text)]
        else
            return [QrSegment.makeBytes(QrSegment.toUtf8ByteArray(text))]
    }

    // Returns a segment representing an Extended Channel Interpretation
    // (ECI) designator with the given assignment value.
    static makeEci(assignVal) {
        let bb = [];
        if (assignVal < 0)
            throw new RangeError("ECI assignment value out of range")
        else if (assignVal < (1 << 7))
            appendBits(assignVal, 8, bb)
        else if (assignVal < (1 << 14)) {
            appendBits(0b10, 2, bb)
            appendBits(assignVal, 14, bb)
        }
        else if (assignVal < 1000000) {
            appendBits(0b110, 3, bb)
            appendBits(assignVal, 21, bb)
        }
        else
            throw new RangeError("ECI assignment value out of range")
        return new QrSegment(QrSegment.Mode.ECI, 0, bb)
    }

    // Tests whether the given string can be encoded as a segment in numeric mode.
    // A string is encodable iff each character is in the range 0 to 9.
    static isNumeric(text) {
        return QrSegment.NUMERIC_REGEX.test(text)
    }

    // Tests whether the given string can be encoded as a segment in alphanumeric mode.
    // 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.
    static isAlphanumeric(text) {
        return QrSegment.ALPHANUMERIC_REGEX.test(text)
    }

    /*-- Methods --*/
    // Returns a new copy of the data bits of this segment.
    getData() {
        return this.bitData.slice() // Make defensive copy
    }

    // (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.
    static getTotalBits(segs, version) {

        let result = 0

        for (const seg of segs) {
            const 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.bitData.length
        }
        return result
    }

    // Returns a new array of bytes representing the given string encoded in UTF-8.
    static toUtf8ByteArray(str) {

        str = encodeURI(str)
        let result = []

        for (let i = 0; i < str.length; i++) {
            if (str.charAt(i) != "%")
                result.push(str.charCodeAt(i))
            else {
                result.push(parseInt(str.substr(i + 1, 2), 16))
                i += 2
            }
        }
        return result
    }

}

/* ---------------------------- QrSegment Constants ------------------------ */
// Describes precisely all strings that are encodable in numeric mode.
QrSegment.NUMERIC_REGEX = /^[0-9]*$/;
// Describes precisely all strings that are encodable in alphanumeric mode.
QrSegment.ALPHANUMERIC_REGEX = /^[A-Z0-9 $%*+.\/:-]*$/;
// The set of all legal characters in alphanumeric mode,
// where each character value maps to the index in the string.
QrSegment.ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"

/* ---------------------------------- Ecc ---------------------------------- */
/*
* The error correction level in a QR Code symbol. Immutable.
*/
class Ecc {
    /*-- Constructor and fields --*/
    constructor(
    // In the range 0 to 3 (unsigned 2-bit integer).
    ordinal, 
    // (Package-private) In the range 0 to 3 (unsigned 2-bit integer).
    formatBits) {
        this.ordinal = ordinal
        this.formatBits = formatBits
    }
}

/* ---------------------------- Ecc Constants ------------------------------ */
Ecc.LOW = new Ecc(0, 1) // The QR Code can tolerate about  7% erroneous codewords
Ecc.MEDIUM = new Ecc(1, 0)  // The QR Code can tolerate about 15% erroneous codewords
Ecc.QUARTILE = new Ecc(2, 3)    // The QR Code can tolerate about 25% erroneous codewords
Ecc.HIGH = new Ecc(3, 2)    // The QR Code can tolerate about 30% erroneous codewords

/* --------------------------------- Mode ---------------------------------- */
/*
* Describes how a segment's data bits are interpreted. Immutable.
*/
class Mode {
    /*-- Constructor and fields --*/
    constructor(
    // The mode indicator bits, which is a uint4 value (range 0 to 15).
    modeBits, 
    // Number of character count bits for three different version ranges.
    numBitsCharCount) {
        this.modeBits = modeBits
        this.numBitsCharCount = numBitsCharCount
    }
    /*-- Method --*/
    // (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].
    numCharCountBits(ver) {
        return this.numBitsCharCount[Math.floor((ver + 7) / 17)]
    }
}

/* -------------------------- Mode Constants ------------------------------- */
Mode.NUMERIC = new Mode(0x1, [10, 12, 14])
Mode.ALPHANUMERIC = new Mode(0x2, [9, 11, 13])
Mode.BYTE = new Mode(0x4, [8, 16, 16])
Mode.KANJI = new Mode(0x8, [8, 10, 12])
Mode.ECI = new Mode(0x7, [0, 0, 0])

/**
 * 
 * @param {QrCode} qr - QrCode object get from eg. QrCode.encodeText
 * @param {Number} scale - Number of the scale of qr, handling the size
 * @param {Number} border - Number >= 0, thickness of the border of Qr
 * @param {String} lightColor - Color for QrCode background
 * @param {String} darkColor - Color fot tiles of QrCode
 * @param {HTMLCanvasElement} canvas - The Canvas that will be draw with QrCode
 */
const drawOnCanvas = (
    qr,
    scale,
    border,
    lightColor,
    darkColor,
    canvas
    ) => {

    if (scale <= 0 || border < 0) {
        throw new RangeError('@RangeError >> scale or border values')
    }

    const width = (qr.size + border * 2) * scale
    canvas.width = width
    canvas.height = width

    const ctx = canvas.getContext('2d')

    for(let y = -border; y < qr.size + border; y++) {
        for (let x = -border; x < qr.size + border; x++) {
        ctx.fillStyle = qr.getModule(x, y) ? darkColor : lightColor
        ctx.fillRect((x + border) * scale, (y + border) * scale, scale, scale)
        }
    }

}

// Returns a string of SVG code for an image depicting the given QR Code, with the given number
	// of border modules. The string always uses Unix newlines (\n), regardless of the platform.

/**
 * 
 * @param {QrCode} qr - QrCode Object get from eg. QrCode.encodeText
 * @param {Number} border - Number >= 0, thickness of the border of Qr
 * @param {String} lightColor - Color for QrCode background
 * @param {String} darkColor - Color for QrCode background
 * @returns {String} - String with the SVG code of the QrCode
 */
const toSvgString = (
    qr,
    border,
    lightColor,
    darkColor
    ) => {

    if (border < 0)
        throw new RangeError('@BORDER >> must be non-negative')

    let parts = []
    for (let y = 0; y < qr.size; y++) {
        for (let x = 0; x < qr.size; x++) {

            if (qr.getModule(x, y)) {
                parts.push(`M${x + border},${y + border}h1v1h-1z`)
            }

        }
    }
    
    return svg`<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0 0 ${qr.size + border * 2} ${qr.size + border * 2}" stroke="none">
<rect width="100%" height="100%" fill="${lightColor}"/>
<path d="${parts.join(" ")}" fill="${darkColor}"/>
</svg>
`
}

export { QrCode, QrSegment, Ecc, countUnicodeChars, drawOnCanvas, toSvgString }