bookbrainz/bookbrainz-site

import {isNil as _isNil} from 'lodash';


function isEmpty(value) {
    return _isNil(value) || value === '';
}

export function dateValidator(dayObj, monthObj, yearObj) {
    const year = Number.parseInt(yearObj, 10);
    const month = Number.parseInt(monthObj, 10);
    const day = Number.parseInt(dayObj, 10);

    // Valid years are any integer value or, if month and day are also nil, nil
    if (isEmpty(yearObj)) {
        if (isEmpty(monthObj) && isEmpty(dayObj)) {
            return {errorMessage: '', isValid: true};
        }

        return {errorMessage: 'Year must be entered if month and day are entered', isValid: false};
    }
    else if (!Number.isInteger(year)) {
        return {errorMessage: 'Year is not valid', isValid: false};
    }

    // Valid months are 1 through 12 or, if day is also nil, nil
    if (isEmpty(monthObj)) {
        if (isEmpty(dayObj)) {
            return {errorMessage: '', isValid: true};
        }

        return {errorMessage: 'Month must be entered if day is entered', isValid: false};
    }
    else if (!Number.isInteger(month)) {
        return {errorMessage: 'Month is not valid', isValid: false};
    }
    else if (month < 1 || month > 12) {
        return {errorMessage: 'Month is not valid', isValid: false};
    }

    // Valid days are dependent on the month, but nil is also valid
    if (isEmpty(dayObj)) {
        return {errorMessage: '', isValid: true};
    }
    else if (!Number.isInteger(day)) {
        return {errorMessage: 'Day is not valid', isValid: false};
    }
    else if (day < 1 || day > 31) {
        return {errorMessage: 'Day is not valid', isValid: false};
    }
    else if ((month === 4 || month === 6 || month === 9 || month === 11) && day === 31) {
        return {errorMessage: 'Day is not valid for this month', isValid: false};
    }
    else if (month === 2) {
        const isLeapYear = year % 100 === 0 ? year % 400 === 0 : year % 4 === 0;

        if (day < 1 || day > 29) {
            return {errorMessage: 'Day is not valid for this month', isValid: false};
        }
        else if (day > 29 || (day === 29 && !isLeapYear)) {
            return {errorMessage: 'Year is not leap, invalid day', isValid: false};
        }
    }

    return {errorMessage: '', isValid: true};
}