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import { Either, type Mapper, type IEither } from '@emprespresso/pengueno';
export const isArgKey = <K extends string>(k: string): k is K => k.startsWith('--');
interface ArgHandler<V> {
absent?: V;
unspecified?: V;
present: Mapper<string, V>;
}
export const getArg = <K extends string, V>(
arg: K,
argv: Array<string>,
whenValue: ArgHandler<V>,
): IEither<Error, V> => {
const value =
argv
.filter((_argv) => isArgKey(_argv) && _argv.split('=')[0] === arg)
.map((_argv, i) => {
const next = _argv.includes('=') ? _argv.split('=')[1] : argv.at(i + 1);
if (next) {
if (isArgKey(next)) return whenValue.unspecified;
return whenValue.present(next);
}
return whenValue.unspecified;
})
.find((x) => x) ?? whenValue.absent;
if (value === undefined) {
return Either.left(new Error('no value specified for ' + arg));
}
return Either.right(value);
};
type MappedArgs<
Args extends ReadonlyArray<string>,
Handlers extends Partial<Record<Args[number], ArgHandler<unknown>>>,
> = {
[K in Args[number]]: K extends keyof Handlers ? (Handlers[K] extends ArgHandler<infer T> ? T : string) : string;
};
export const argv = <
const Args extends ReadonlyArray<string>,
const Handlers extends Partial<Record<Args[number], ArgHandler<unknown>>>,
>(
args: Args,
handlers?: Handlers,
argv = process.argv.slice(2),
): IEither<Error, MappedArgs<Args, Handlers>> => {
type Result = MappedArgs<Args, Handlers>;
const defaultHandler: ArgHandler<string> = { present: (value: string) => value };
const processArg = (arg: Args[number]): IEither<Error, [Args[number], unknown]> => {
const handler = handlers?.[arg] ?? defaultHandler;
return getArg(arg, argv, handler).mapRight((value) => [arg, value] as const);
};
return args
.map(processArg)
.reduce(
(acc: IEither<Error, Partial<Result>>, current: IEither<Error, readonly [Args[number], unknown]>) =>
acc.flatMap((accValue) =>
current.mapRight(([key, value]) => ({
...accValue,
[key]: value,
})),
),
Either.right(<Partial<Result>>{}),
)
.mapRight((result) => <Result>result);
};
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