source: frontend/node_modules/debug/src/node.js

/**
 * Module dependencies.
 */

const tty = require('tty');
const util = require('util');

/**
 * This is the Node.js implementation of `debug()`.
 */

exports.init = init;
exports.log = log;
exports.formatArgs = formatArgs;
exports.save = save;
exports.load = load;
exports.useColors = useColors;
exports.destroy = util.deprecate(
        () => {},
        'Instance method `debug.destroy()` is deprecated and no longer does anything. It will be removed in the next major version of `debug`.'
);

/**
 * Colors.
 */

exports.colors = [6, 2, 3, 4, 5, 1];

try {
        // Optional dependency (as in, doesn't need to be installed, NOT like optionalDependencies in package.json)
        // eslint-disable-next-line import/no-extraneous-dependencies
        const supportsColor = require('supports-color');

        if (supportsColor && (supportsColor.stderr || supportsColor).level >= 2) {
                exports.colors = [
                        20,
                        21,
                        26,
                        27,
                        32,
                        33,
                        38,
                        39,
                        40,
                        41,
                        42,
                        43,
                        44,
                        45,
                        56,
                        57,
                        62,
                        63,
                        68,
                        69,
                        74,
                        75,
                        76,
                        77,
                        78,
                        79,
                        80,
                        81,
                        92,
                        93,
                        98,
                        99,
                        112,
                        113,
                        128,
                        129,
                        134,
                        135,
                        148,
                        149,
                        160,
                        161,
                        162,
                        163,
                        164,
                        165,
                        166,
                        167,
                        168,
                        169,
                        170,
                        171,
                        172,
                        173,
                        178,
                        179,
                        184,
                        185,
                        196,
                        197,
                        198,
                        199,
                        200,
                        201,
                        202,
                        203,
                        204,
                        205,
                        206,
                        207,
                        208,
                        209,
                        214,
                        215,
                        220,
                        221
                ];
        }
} catch (error) {
        // Swallow - we only care if `supports-color` is available; it doesn't have to be.
}

/**
 * Build up the default `inspectOpts` object from the environment variables.
 *
 *   $ DEBUG_COLORS=no DEBUG_DEPTH=10 DEBUG_SHOW_HIDDEN=enabled node script.js
 */

exports.inspectOpts = Object.keys(process.env).filter(key => {
        return /^debug_/i.test(key);
}).reduce((obj, key) => {
        // Camel-case
        const prop = key
                .substring(6)
                .toLowerCase()
                .replace(/_([a-z])/g, (_, k) => {
                        return k.toUpperCase();
                });

        // Coerce string value into JS value
        let val = process.env[key];
        if (/^(yes|on|true|enabled)$/i.test(val)) {
                val = true;
        } else if (/^(no|off|false|disabled)$/i.test(val)) {
                val = false;
        } else if (val === 'null') {
                val = null;
        } else {
                val = Number(val);
        }

        obj[prop] = val;
        return obj;
}, {});

/**
 * Is stdout a TTY? Colored output is enabled when `true`.
 */

function useColors() {
        return 'colors' in exports.inspectOpts ?
                Boolean(exports.inspectOpts.colors) :
                tty.isatty(process.stderr.fd);
}

/**
 * Adds ANSI color escape codes if enabled.
 *
 * @api public
 */

function formatArgs(args) {
        const {namespace: name, useColors} = this;

        if (useColors) {
                const c = this.color;
                const colorCode = '\u001B[3' + (c < 8 ? c : '8;5;' + c);
                const prefix = `  ${colorCode};1m${name} \u001B[0m`;

                args[0] = prefix + args[0].split('\n').join('\n' + prefix);
                args.push(colorCode + 'm+' + module.exports.humanize(this.diff) + '\u001B[0m');
        } else {
                args[0] = getDate() + name + ' ' + args[0];
        }
}

function getDate() {
        if (exports.inspectOpts.hideDate) {
                return '';
        }
        return new Date().toISOString() + ' ';
}

/**
 * Invokes `util.formatWithOptions()` with the specified arguments and writes to stderr.
 */

function log(...args) {
        return process.stderr.write(util.formatWithOptions(exports.inspectOpts, ...args) + '\n');
}

/**
 * Save `namespaces`.
 *
 * @param {String} namespaces
 * @api private
 */
function save(namespaces) {
        if (namespaces) {
                process.env.DEBUG = namespaces;
        } else {
                // If you set a process.env field to null or undefined, it gets cast to the
                // string 'null' or 'undefined'. Just delete instead.
                delete process.env.DEBUG;
        }
}

/**
 * Load `namespaces`.
 *
 * @return {String} returns the previously persisted debug modes
 * @api private
 */

function load() {
        return process.env.DEBUG;
}

/**
 * Init logic for `debug` instances.
 *
 * Create a new `inspectOpts` object in case `useColors` is set
 * differently for a particular `debug` instance.
 */

function init(debug) {
        debug.inspectOpts = {};

        const keys = Object.keys(exports.inspectOpts);
        for (let i = 0; i < keys.length; i++) {
                debug.inspectOpts[keys[i]] = exports.inspectOpts[keys[i]];
        }
}

module.exports = require('./common')(exports);

const {formatters} = module.exports;

/**
 * Map %o to `util.inspect()`, all on a single line.
 */

formatters.o = function (v) {
        this.inspectOpts.colors = this.useColors;
        return util.inspect(v, this.inspectOpts)
                .split('\n')
                .map(str => str.trim())
                .join(' ');
};

/**
 * Map %O to `util.inspect()`, allowing multiple lines if needed.
 */

formatters.O = function (v) {
        this.inspectOpts.colors = this.useColors;
        return util.inspect(v, this.inspectOpts);
};