numerica/packages/core/src/converter.ts

import { enUS } from './systems';
import { StringifySystem } from './common';

type StringifyValue = string | number | bigint;

export interface StringifyOptions {
	system?: StringifySystem;
	makeGroupOptions?: Record<string, unknown>;
}

export const stringify = (
	valueRaw: StringifyValue,
	options = {} as StringifyOptions
): string => {
	if (!(['bigint', 'number', 'string'].includes(typeof (valueRaw as unknown)))) {
		throw new TypeError('value must be a string, number, or bigint');
	}

	const value = valueRaw.toString().replace(/\s/g, '');
	const { system = enUS, makeGroupOptions} = options;

	if (value.startsWith('-')) {
		return system.makeNegative(stringify(value.slice(1), options));
	}

	const groups = system
		.group(value)
		.map(([group, place]) => (
			system.makeGroup(group, place, makeGroupOptions)
		));

	return system.finalize(groups);
};

type ParseType = 'string' | 'number' | 'bigint';

export interface ParseOptions {
	system?: StringifySystem;
	type?: ParseType;
}

export const parse = (value: string, options = {} as ParseOptions) => {
	const { system = enUS, type = 'string' } = options;

	const tokens = system.tokenize(value);
	const groups = system.parseGroups(tokens);
	const stringValue = system.combineGroups(groups);

	switch (type) {
		case 'number':
			return Number(stringValue);
		case 'bigint':
			return BigInt(stringValue);
		default:
			break;
	}

	return stringValue;
};