source: trip-planner-front/node_modules/camelcase/index.js@ eed0bf8

'use strict';

const preserveCamelCase = string => {
        let isLastCharLower = false;
        let isLastCharUpper = false;
        let isLastLastCharUpper = false;

        for (let i = 0; i < string.length; i++) {
                const character = string[i];

                if (isLastCharLower && /[a-zA-Z]/.test(character) && character.toUpperCase() === character) {
                        string = string.slice(0, i) + '-' + string.slice(i);
                        isLastCharLower = false;
                        isLastLastCharUpper = isLastCharUpper;
                        isLastCharUpper = true;
                        i++;
                } else if (isLastCharUpper && isLastLastCharUpper && /[a-zA-Z]/.test(character) && character.toLowerCase() === character) {
                        string = string.slice(0, i - 1) + '-' + string.slice(i - 1);
                        isLastLastCharUpper = isLastCharUpper;
                        isLastCharUpper = false;
                        isLastCharLower = true;
                } else {
                        isLastCharLower = character.toLowerCase() === character && character.toUpperCase() !== character;
                        isLastLastCharUpper = isLastCharUpper;
                        isLastCharUpper = character.toUpperCase() === character && character.toLowerCase() !== character;
                }
        }

        return string;
};

const camelCase = (input, options) => {
        if (!(typeof input === 'string' || Array.isArray(input))) {
                throw new TypeError('Expected the input to be `string | string[]`');
        }

        options = Object.assign({
                pascalCase: false
        }, options);

        const postProcess = x => options.pascalCase ? x.charAt(0).toUpperCase() + x.slice(1) : x;

        if (Array.isArray(input)) {
                input = input.map(x => x.trim())
                        .filter(x => x.length)
                        .join('-');
        } else {
                input = input.trim();
        }

        if (input.length === 0) {
                return '';
        }

        if (input.length === 1) {
                return options.pascalCase ? input.toUpperCase() : input.toLowerCase();
        }

        const hasUpperCase = input !== input.toLowerCase();

        if (hasUpperCase) {
                input = preserveCamelCase(input);
        }

        input = input
                .replace(/^[_.\- ]+/, '')
                .toLowerCase()
                .replace(/[_.\- ]+(\w|$)/g, (_, p1) => p1.toUpperCase())
                .replace(/\d+(\w|$)/g, m => m.toUpperCase());

        return postProcess(input);
};

module.exports = camelCase;
// TODO: Remove this for the next major release
module.exports.default = camelCase;