Chart.js Zoom Plugin Utils

chartjs-plugin-zoom-utils.js

// https://github.com/chartjs/chartjs-plugin-zoom/blob/master/docs/scripts/utils.js

import { addDays, addHours, startOfWeek, endOfWeek, isWeekend, nextMonday, getHours, setHours } from "https://cdn.jsdelivr.net/

function valueOrDefault(value, defaultValue) {
    return typeof value === 'undefined' ? defaultValue : value;
}

// Adapted from http://indiegamr.com/generate-repeatable-random-numbers-in-js/
let _seed = Date.now();

function srand(seed) {
    _seed = seed;
}

function rand(min, max) {
    min = valueOrDefault(min, 0);
    max = valueOrDefault(max, 0);
    _seed = (_seed * 9301 + 49297) % 233280;
    return min + (_seed / 233280) * (max - min);
}

function numbers(config) {
    const cfg = config || {};
    const min = valueOrDefault(cfg.min, 0);
    const max = valueOrDefault(cfg.max, 100);
    const from = valueOrDefault(cfg.from, []);
    const count = valueOrDefault(cfg.count, 8);
    const decimals = valueOrDefault(cfg.decimals, 8);
    const continuity = valueOrDefault(cfg.continuity, 1);
    const dfactor = Math.pow(10, decimals) || 0;
    const data = [];
    let i, value;

    for (i = 0; i < count; ++i) {
        value = (from[i] || 0) + rand(min, max);
        if (rand() <= continuity) {
            data.push(Math.round(dfactor * value) / dfactor);
        } else {
            data.push(null);
        }
    }

    return data;
}

function points(config) {
    const xs = numbers(config);
    const ys = numbers(config);
    return xs.map((x, i) => ({x, y: ys[i]}));
}

const rand255 = () => Math.round(Math.random() * 255);

function randomColor(alpha) {
    return 'rgba(' + rand255() + ',' + rand255() + ',' + rand255() + ',' + (alpha || '.3') + ')';
}

const MONTHS = [
    'January',
    'February',
    'March',
    'April',
    'May',
    'June',
    'July',
    'August',
    'September',
    'October',
    'November',
    'December'
];

function months(config) {
    const cfg = config || {};
    const count = cfg.count || 12;
    const section = cfg.section;
    const values = [];
    let i, value;

    for (i = 0; i < count; ++i) {
        value = MONTHS[Math.ceil(i) % 12];
        values.push(value.substring(0, section));
    }

    return values;
}

function hourlyPoints(config) {
    const ys = numbers(config);
    const start = new Date().valueOf();
    return ys.map((y, i) => ({x: addHours(start, i), y}));
}

function nextOfficeHour(time) {
    if (getHours(time) > 17) {
        time = setHours(addDays(time, 1), 8);
    }
    if (getHours(time) < 9) {
        time = setHours(time, 9);
    } else {
        time = addHours(time, 1);
    }
    if (isWeekend(time)) {
        time = setHours(nextMonday(time), 9);
    }
    return time;
}

function officeHourPoints(config) {
    const ys = numbers(config);
    let time = new Date().valueOf();
    return ys.map(y => {
        time = nextOfficeHour(time);
        return {x: +time, y};
    });
}

function nextWeek() {
    const now = new Date().valueOf();
    const min = startOfWeek(addHours(endOfWeek(now), 24));
    return {
        min: +min,
        max: +endOfWeek(min)
    };
}