import lcm from './lcm'

class CharSet {

constructor(chars) {

this.chars = chars

this.len = chars.length

this.entropyPerChar = Math.floor(Math.log2(this.len))

if (this.entropyPerChar != Math.log2(this.len)) {

throw new Error('EntropyString only supports CharSets with a power of 2 characters')

}

this.charsPerChunk = lcm(this.entropyPerChar, 8) / this.entropyPerChar

}

use(chars) {

const len = chars.length

// Ensure correct number of characters

if (len != this.len) {

throw new Error('Invalid character count')

}

// Ensure no repeated characters

for (let i = 0; i < len; i++) {

let c = chars.charAt(i)

for (let j = i+1; j < len; j++) {

if (c === chars.charAt(j)) {

throw new Error('Characters not unique')

}

}

}

this.chars = chars

}

}

const charSet64 =

new CharSet("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")

const charSet32 =

new CharSet("2346789bdfghjmnpqrtBDFGHJLMNPQRT")

const charSet16 =

new CharSet("0123456789abcdef")

const charSet8 =

new CharSet("01234567")

const charSet4 =

new CharSet("ATCG")

const charSet2 =

new CharSet("01")

const isValid = (charSet) => {

return charSet instanceof CharSet

}

export default {

charSet64: charSet64,

charSet32: charSet32,

charSet16: charSet16,

charSet8: charSet8,

charSet4: charSet4,

charSet2: charSet2,

isValid: isValid

}