/**
 * Choose between singular or plural form based on the number of elements.
 *
 * @example
 * > choosePlural(1, 'example', '.s')
 * 'example'
 * > choosePlural(4, 'example', '.s')
 * 'examples'
 * > choosePlural(0, 'radius', 'radii')
 * 'radii'
 *
 * @param count Number of elements.
 * @param singular Singular form.
 * @param plural Plural form. An initial dot will be replaced by `singular`.
 * @return Appropriate form.
 */
const choosePlural = (count, singular, plural) =>
{
    if (count === 1)
    {
        return singular;
    }
    else
    {
        return plural.replace(/^\./, singular);
    }
};

exports.choosePlural = choosePlural;

/**
 * Join elements with the given separator and a special separator for the last
 * element.
 *
 * @example
 * > joinSentence(['apple', 'orange', 'banana'], ', ', ' and ')
 * 'apple, orange and banana'
 * > joinSentence(['apple', 'banana'], ', ', ' and ')
 * 'apple and banana'
 * > joinSentence(['banana'], ', ', ' and ')
 * 'banana'
 *
 * @param array Sequence of strings to join.
 * @param separator Separator for all elements but the last one.
 * @param lastSeparator Separator for the last element.
 * @return Joined string.
 */
const joinSentence = (array, separator, lastSeparator) =>
{
    if (array.length <= 2)
    {
        return array.join(lastSeparator);
    }

    return (
        array.slice(0, -1).join(separator)
            + lastSeparator
            + array[array.length - 1]
    );
};

exports.joinSentence = joinSentence;

/**
 * Check if a value is a JS object.
 *
 * @param value Value to check.
 * @return True iff. `value` is a JS object.
 */
const isObject = value => value !== null && typeof value === 'object';

exports.isObject = isObject;

/**
 * Check if two arrays are equal in a shallow manner.
 *
 * @param array1 First array.
 * @param array2 Second array.
 * @return True iff. the two arrays are equal.
 */
const arraysEqual = (array1, array2) => (
    array1.length === array2.length
    && array1.every((elt1, index) => elt1 === array2[index])
);

exports.arraysEqual = arraysEqual;