// @flow

import _ from 'lodash';

const AVATAR_COLORS = [
    '#6A50D3',
    '#FF9B42',
    '#DF486F',
    '#73348C',
    '#B23683',
    '#F96E57',
    '#4380E2',
    '#2AA076',
    '#00A8B3'
];

/**
 * Generates the background color of an initials based avatar.
 *
 * @param {string?} initials - The initials of the avatar.
 * @param {Array<strig>} customAvatarBackgrounds - Custom avatar background values.
 * @returns {string}
 */
export function getAvatarColor(initials: ?string, customAvatarBackgrounds: Array<string>) {
    const hasCustomAvatarBackgronds = customAvatarBackgrounds && customAvatarBackgrounds.length;
    const colorsBase = hasCustomAvatarBackgronds ? customAvatarBackgrounds : AVATAR_COLORS;

    let colorIndex = 0;

    if (initials) {
        let nameHash = 0;

        for (const s of initials) {
            nameHash += s.codePointAt(0);
        }

        colorIndex = nameHash % colorsBase.length;
    }

    return colorsBase[colorIndex];
}

/**
 * Generates initials for a simple string.
 *
 * @param {string?} s - The string to generate initials for.
 * @returns {string?}
 */
export function getInitials(s: ?string) {
    // We don't want to use the domain part of an email address, if it is one
    const initialsBasis = _.split(s, '@')[0];
    const words = _.words(initialsBasis);
    let initials = '';

    for (const w of words) {
        (initials.length < 2) && (initials += w.substr(0, 1).toUpperCase());
    }

    return initials;
}