const VersionCheck = require('./version-check')
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const Regex = require('./regex')
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/**
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* Numeric mode encodes data from the decimal digit set (0 - 9)
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* (byte values 30HEX to 39HEX).
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* Normally, 3 data characters are represented by 10 bits.
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*
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* @type {Object}
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*/
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exports.NUMERIC = {
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id: 'Numeric',
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bit: 1 << 0,
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ccBits: [10, 12, 14]
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}
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/**
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* Alphanumeric mode encodes data from a set of 45 characters,
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* i.e. 10 numeric digits (0 - 9),
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* 26 alphabetic characters (A - Z),
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* and 9 symbols (SP, $, %, *, +, -, ., /, :).
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* Normally, two input characters are represented by 11 bits.
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*
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* @type {Object}
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*/
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exports.ALPHANUMERIC = {
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id: 'Alphanumeric',
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bit: 1 << 1,
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ccBits: [9, 11, 13]
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}
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/**
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* In byte mode, data is encoded at 8 bits per character.
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*
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* @type {Object}
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*/
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exports.BYTE = {
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id: 'Byte',
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bit: 1 << 2,
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ccBits: [8, 16, 16]
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}
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/**
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* The Kanji mode efficiently encodes Kanji characters in accordance with
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* the Shift JIS system based on JIS X 0208.
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* The Shift JIS values are shifted from the JIS X 0208 values.
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* JIS X 0208 gives details of the shift coded representation.
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* Each two-byte character value is compacted to a 13-bit binary codeword.
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*
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* @type {Object}
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*/
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exports.KANJI = {
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id: 'Kanji',
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bit: 1 << 3,
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ccBits: [8, 10, 12]
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}
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/**
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* Mixed mode will contain a sequences of data in a combination of any of
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* the modes described above
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*
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* @type {Object}
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*/
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exports.MIXED = {
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bit: -1
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}
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/**
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* Returns the number of bits needed to store the data length
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* according to QR Code specifications.
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*
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* @param {Mode} mode Data mode
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* @param {Number} version QR Code version
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* @return {Number} Number of bits
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*/
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exports.getCharCountIndicator = function getCharCountIndicator (mode, version) {
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if (!mode.ccBits) throw new Error('Invalid mode: ' + mode)
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if (!VersionCheck.isValid(version)) {
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throw new Error('Invalid version: ' + version)
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}
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if (version >= 1 && version < 10) return mode.ccBits[0]
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else if (version < 27) return mode.ccBits[1]
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return mode.ccBits[2]
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}
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/**
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* Returns the most efficient mode to store the specified data
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*
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* @param {String} dataStr Input data string
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* @return {Mode} Best mode
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*/
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exports.getBestModeForData = function getBestModeForData (dataStr) {
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if (Regex.testNumeric(dataStr)) return exports.NUMERIC
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else if (Regex.testAlphanumeric(dataStr)) return exports.ALPHANUMERIC
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else if (Regex.testKanji(dataStr)) return exports.KANJI
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else return exports.BYTE
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}
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/**
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* Return mode name as string
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*
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* @param {Mode} mode Mode object
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* @returns {String} Mode name
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*/
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exports.toString = function toString (mode) {
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if (mode && mode.id) return mode.id
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throw new Error('Invalid mode')
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}
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/**
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* Check if input param is a valid mode object
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*
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* @param {Mode} mode Mode object
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* @returns {Boolean} True if valid mode, false otherwise
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*/
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exports.isValid = function isValid (mode) {
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return mode && mode.bit && mode.ccBits
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}
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/**
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* Get mode object from its name
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*
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* @param {String} string Mode name
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* @returns {Mode} Mode object
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*/
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function fromString (string) {
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if (typeof string !== 'string') {
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throw new Error('Param is not a string')
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}
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const lcStr = string.toLowerCase()
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switch (lcStr) {
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case 'numeric':
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return exports.NUMERIC
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case 'alphanumeric':
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return exports.ALPHANUMERIC
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case 'kanji':
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return exports.KANJI
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case 'byte':
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return exports.BYTE
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default:
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throw new Error('Unknown mode: ' + string)
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}
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}
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/**
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* Returns mode from a value.
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* If value is not a valid mode, returns defaultValue
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*
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* @param {Mode|String} value Encoding mode
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* @param {Mode} defaultValue Fallback value
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* @return {Mode} Encoding mode
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*/
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exports.from = function from (value, defaultValue) {
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if (exports.isValid(value)) {
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return value
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}
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try {
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return fromString(value)
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} catch (e) {
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return defaultValue
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}
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}
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