import { randomBytes } from 'crypto';

/**

* convert a string to a utf-8 encoded base64 string

*

* @param source the source string to encode

* @returns the base64 encoded string

*/

export function base64Encode(source: string): string {

return Buffer.from(new TextEncoder().encode(source)).toString('base64');

}

/**

* convert a utf-8 encoded base64 string to a string

*

* @param source the source base64 string to decode

* @returns the decoded string

*/

export function base64Decode(source: string): string {

return new TextDecoder('utf8').decode(Buffer.from(source, 'base64'));

}

/**

* create a new random string.

* the string will only contain alphanumerical characters ([A-Za-z0-9])

*

* @param length the length of the string.

* if not even, the length is shortened by one character

* @returns a random string

*/

export function getRandomString(length: number): string {

return randomBytes(length / 2).toString('hex');

}

/**

* get the parameter names of a function or method

*

* @param fn the function to get the parameter names of

* @returns a array containing the parameter names of the function, in order

*/

// eslint-disable-next-line @typescript-eslint/ban-types

export function getFunctionParameterNames(fn: Function): string[] {

// convert method body to a string, reduce to a single line

const methodDefinition = fn.toString().replace(/\r?\n/g, '');

// prepare regex with method name embedded

const regex = new RegExp(`^(?:async\\s)?(?:function\\s)?(?:${fn.name})?\\s*\\(([\\w\\s,_]*)\\)\\s*{`);

// get the parameter list of the method

const parameterListMatch = methodDefinition.match(regex);

if (!parameterListMatch || parameterListMatch.length != 2) {

throw new Error('failed to parse method parameter list');

}

// split parameter list on commas and trim the resulting parameter names

return parameterListMatch[1]

.split(',')

.map((p) => p.trim())

.filter((p) => p);

}