import crypto from 'crypto'
import { urlAlphabet } from '../url-alphabet/index.js'
let random = bytes =>
new Promise((resolve, reject) => {
crypto.randomFill(Buffer.allocUnsafe(bytes), (err, buf) => {
if (err) {
reject(err)
} else {
resolve(buf)
}
})
})
let customAlphabet = (alphabet, defaultSize = 21) => {
let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
let tick = (id, size = defaultSize) =>
random(step).then(bytes => {
let i = step
while (i--) {
id += alphabet[bytes[i] & mask] || ''
if (id.length === size) return id
}
return tick(id, size)
})
return size => tick('', size)
}
let nanoid = (size = 21) =>
random(size).then(bytes => {
let id = ''
while (size--) {
id += urlAlphabet[bytes[size] & 63]
}
return id
})
export { nanoid, customAlphabet, random }