/**

* Divide two numbers and get the result of floor division and remainder

* @param {number} dividend

* @param {number} divisor

* @returns {[result: number, remainder: number]}

*/

const floorDiv = (dividend, divisor) => {

const remainder = dividend % divisor

const result = Math.floor(dividend / divisor)

return [result, remainder]

}

/**

* Converts a string from one base to other. Loses accuracy above the value of `Number.MAX_SAFE_INTEGER`.

* @param {string} stringInBaseOne String in input base

* @param {string} baseOneCharacters Character set for the input base

* @param {string} baseTwoCharacters Character set for the output base

* @returns {string}

*/

const convertArbitraryBase = (

stringInBaseOne,

baseOneCharacterString,

baseTwoCharacterString

) => {

if (

[stringInBaseOne, baseOneCharacterString, baseTwoCharacterString]

.map((arg) => typeof arg)

.some((type) => type !== 'string')

) {

throw new TypeError('Only string arguments are allowed')

}

const baseOneCharacters = [...baseOneCharacterString]

const baseTwoCharacters = [...baseTwoCharacterString]

for (const charactersInBase of [baseOneCharacters, baseTwoCharacters]) {

if (charactersInBase.length !== new Set(charactersInBase).size) {

throw new TypeError(

'Duplicate characters in character set are not allowed'

)

}

}

const reversedStringOneChars = [...stringInBaseOne].reverse()

const stringOneBase = baseOneCharacters.length

let value = 0

let placeValue = 1

for (const digit of reversedStringOneChars) {

const digitNumber = baseOneCharacters.indexOf(digit)

if (digitNumber === -1) {

throw new TypeError(`Not a valid character: ${digit}`)

}

value += digitNumber * placeValue

placeValue *= stringOneBase

}

const outputChars = []

const stringTwoBase = baseTwoCharacters.length

while (value > 0) {

const [divisionResult, remainder] = floorDiv(value, stringTwoBase)

outputChars.push(baseTwoCharacters[remainder])

value = divisionResult

}

return outputChars.reverse().join('') || baseTwoCharacters[0]

}

/**

* Converts a arbitrary-length string from one base to other. Doesn't lose accuracy.

* @param {string} stringInBaseOne String in input base

* @param {string} baseOneCharacters Character set for the input base

* @param {string} baseTwoCharacters Character set for the output base

* @returns {string}

*/

const convertArbitraryBaseBigIntVersion = (

stringInBaseOne,

baseOneCharacterString,

baseTwoCharacterString

) => {

if (

[stringInBaseOne, baseOneCharacterString, baseTwoCharacterString]

.map((arg) => typeof arg)

.some((type) => type !== 'string')

) {

throw new TypeError('Only string arguments are allowed')

}

const baseOneCharacters = [...baseOneCharacterString]

const baseTwoCharacters = [...baseTwoCharacterString]

for (const charactersInBase of [baseOneCharacters, baseTwoCharacters]) {

if (charactersInBase.length !== new Set(charactersInBase).size) {

throw new TypeError(

'Duplicate characters in character set are not allowed'

)

}

}

const reversedStringOneChars = [...stringInBaseOne].reverse()

const stringOneBase = BigInt(baseOneCharacters.length)

let value = 0n

let placeValue = 1n

for (const digit of reversedStringOneChars) {

const digitNumber = BigInt(baseOneCharacters.indexOf(digit))

if (digitNumber === -1n) {

throw new TypeError(`Not a valid character: ${digit}`)

}

value += digitNumber * placeValue

placeValue *= stringOneBase

}

const outputChars = []

const stringTwoBase = BigInt(baseTwoCharacters.length)

while (value > 0n) {

const divisionResult = value / stringTwoBase

const remainder = value % stringTwoBase

outputChars.push(baseTwoCharacters[remainder])

value = divisionResult

}

return outputChars.reverse().join('') || baseTwoCharacters[0]

}

export { convertArbitraryBase, convertArbitraryBaseBigIntVersion }