src/variants.js

import {enumerate} from '@iterable-iterator/zip';

import {toObject, inverse} from '@iterable-iterator/mapping';

const variants = {
	// Standard ``base32''
	RFC4648: {
		alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567',
		padding: '=',
	},

	// Also RFC4648 (used by NSEC3)
	// ``encoded data maintains its sort order when the encoded data is compared bit-wise''
	base32hex: {
		alphabet: '0123456789ABCDEFGHIJKLMNOPQRSTUV',
		padding: '=',
	},

	// ``easier for human use and more compact''
	'z-base-32': {
		alphabet: 'ybndrfg8ejkmcpqxot1uwisza345h769',
		padding: false,
	},

	// It excludes the letters I, L, and O to avoid confusion with digits. It
	// also excludes the letter U to reduce the likelihood of accidental
	// obscenity.
	// See http://www.crockford.com/wrmg/base32.html
	crockford: {
		alphabet: '0123456789ABCDEFGHJKMNPQRSTVWXYZ',
		padding: false,
		index: {
			0: 0,
			o: 0,
			O: 0,
			1: 1,
			i: 1,
			I: 1,
			l: 1,
			L: 1,
			2: 2,
			3: 3,
			4: 4,
			5: 5,
			6: 6,
			7: 7,
			8: 8,
			9: 9,
			a: 10,
			A: 10,
			b: 11,
			B: 11,
			c: 12,
			C: 12,
			d: 13,
			D: 13,
			e: 14,
			E: 14,
			f: 15,
			F: 15,
			g: 16,
			G: 16,
			h: 17,
			H: 17,
			j: 18,
			J: 18,
			k: 19,
			K: 19,
			m: 20,
			M: 20,
			n: 21,
			N: 21,
			p: 22,
			P: 22,
			q: 23,
			Q: 23,
			r: 24,
			R: 24,
			s: 25,
			S: 25,
			t: 26,
			T: 26,
			v: 27,
			V: 27,
			w: 28,
			W: 28,
			x: 29,
			X: 29,
			y: 30,
			Y: 30,
			z: 31,
			Z: 31,
		},
	},
};

for (const variant in variants) {
	if (variants[variant].index) continue;
	variants[variant].index = toObject(
		inverse(enumerate(variants[variant].alphabet)),
	);
}

// eslint-disable-next-line no-multi-assign
variants.default = variants.base32 = variants.RFC3548 = variants.RFC4648;
variants.RFC2938 = variants.base32hex;
variants.Crockford = variants.crockford;

export default variants;