omni-tools/src/pages/string/create-palindrome/service.ts

import { reverseString } from 'utils/string'

export function createPalindrome(
    input: string,
    lastChar: boolean  // only checkbox is need here to handle it [instead of two combo boxes]
) {
    if (!input) return '';
    let result: string;
    let reversedString: string;

    // reverse the whole input if lastChar enabled
    reversedString = lastChar ? reverseString(input) : reverseString(input.slice(0, -1));
    result = input.concat(reversedString);
    return result;
}

export function createPalindromeList(
    input: string,
    lastChar: boolean,
    multiLine: boolean
): string {
    if (!input) return '';
    let array: string[];
    let result: string[] = [];

    if (!multiLine) return createPalindrome(input, lastChar);
    else {
        array = input.split('\n');
        for (const word of array) {
            result.push(createPalindrome(word, lastChar));
        }
    }
    return result.join('\n');
    
}