packages/util-crypto/src/base32/helpers.ts
// Copyright 2017-2024 @polkadot/util-crypto authors & contributors
// SPDX-License-Identifier: Apache-2.0
import type { U8aLike } from '@polkadot/util/types';
import { u8aToU8a } from '@polkadot/util';
// re-export the type so *.d.ts files don't have ../src imports
export type { U8aLike } from '@polkadot/util/types';
interface Coder {
decode: (value: string) => Uint8Array;
encode: (value: Uint8Array) => string;
}
interface Config {
chars: string;
coder: Coder;
ipfs?: string;
regex?: RegExp;
type: string;
withPadding?: boolean;
}
type DecodeFn = (value: string, ipfsCompat?: boolean) => Uint8Array;
type EncodeFn = (value: U8aLike, ipfsCompat?: boolean) => string;
type ValidateFn = (value?: unknown, ipfsCompat?: boolean) => value is string;
/** @internal */
export function createDecode ({ coder, ipfs }: Config, validate: ValidateFn): DecodeFn {
return (value: string, ipfsCompat?: boolean): Uint8Array => {
validate(value, ipfsCompat);
return coder.decode(
ipfs && ipfsCompat
? value.substring(1)
: value
);
};
}
/** @internal */
export function createEncode ({ coder, ipfs }: Config): EncodeFn {
return (value: U8aLike, ipfsCompat?: boolean): string => {
const out = coder.encode(u8aToU8a(value));
return ipfs && ipfsCompat
? `${ipfs}${out}`
: out;
};
}
/** @internal */
export function createIs (validate: ValidateFn): ValidateFn {
return (value?: unknown, ipfsCompat?: boolean): value is string => {
try {
return validate(value, ipfsCompat);
} catch {
return false;
}
};
}
/** @internal */
export function createValidate ({ chars, ipfs, type, withPadding }: Config): ValidateFn {
return (value?: unknown, ipfsCompat?: boolean): value is string => {
if (typeof value !== 'string') {
throw new Error(`Expected ${type} string input`);
} else if (ipfs && ipfsCompat && !value.startsWith(ipfs)) {
throw new Error(`Expected ipfs-compatible ${type} to start with '${ipfs}'`);
}
for (let i = (ipfsCompat ? 1 : 0), count = value.length; i < count; i++) {
if (chars.includes(value[i])) {
// all ok, character found
} else if (withPadding && value[i] === '=') {
if (i === count - 1) {
// last character, everything ok
} else if (value[i + 1] === '=') {
// next one is also padding, sequence ok
} else {
throw new Error(`Invalid ${type} padding sequence "${value[i]}${value[i + 1]}" at index ${i}`);
}
} else {
throw new Error(`Invalid ${type} character "${value[i]}" (0x${value.charCodeAt(i).toString(16)}) at index ${i}`);
}
}
return true;
};
}