/bonfire/helpers/BF_date_helper.php

<?php defined('BASEPATH') || exit('No direct script access allowed');
/**
 * Bonfire
 *
 * An open source project to allow developers to jumpstart their development of
 * CodeIgniter applications.
 *
 * @package   Bonfire
 * @author    Bonfire Dev Team
 * @copyright Copyright (c) 2011 - 2018, Bonfire Dev Team
 * @license   http://opensource.org/licenses/MIT The MIT License
 * @link      http://cibonfire.com
 * @since     Version 1.0
 * @filesource
 */

/**
 * Date helper functions.
 *
 * Includes additional date-related functions helpful in Bonfire development.
 *
 * @package Bonfire\Helpers\BF_date_helper
 * @author  Bonfire Dev Team
 * @link    http://cibonfire.com/docs/developer
 */

if (! function_exists('date_difference')) {
    /**
     * Return the difference between two dates.
     *
     * @todo Consider updating this to use date_diff() and/or DateInterval.
     *
     * @param mixed  $start    The start date as a unix timestamp or in a format
     * which can be used within strtotime().
     * @param mixed  $end      The ending date as a unix timestamp or in a
     * format which can be used within strtotime().
     * @param string $interval A string with the interval to use. Valid values
     * are 'week', 'day', 'hour', or 'minute'.
     * @param bool   $reformat If TRUE, will reformat the time using strtotime().
     *
     * @return int A number representing the difference between the two dates in
     * the interval desired.
     */
    function date_difference($start = null, $end = null, $interval = 'day', $reformat = false)
    {
        if (is_null($start)) {
            return false;
        }

        if (is_null($end)) {
            $end = date('Y-m-d H:i:s');
        }

        $times = array(
            'week'   => 604800,
            'day'    => 86400,
            'hour'   => 3600,
            'minute' => 60,
        );

        if ($reformat === true) {
            $start = strtotime($start);
            $end   = strtotime($end);
        }

        $diff = $end - $start;

        return round($diff / $times[$interval]);
    }
}

if (! function_exists('relative_time')) {
    /**
     * Return a string representing how long ago a given UNIX timestamp was,
     * e.g. "moments ago", "2 weeks ago", etc.
     *
     * @todo Consider updating this to use date_diff() and/or DateInterval.
     * @todo Internationalization.
     *
     * @param int $timestamp A UNIX timestamp.
     *
     * @return string A human-readable amount of time 'ago'.
     */
    function relative_time($timestamp)
    {
        if ($timestamp != '' && ! is_int($timestamp)) {
            $timestamp = strtotime($timestamp);
        }

        if (! is_int($timestamp)) {
            return "never";
        }

        $difference = time() - $timestamp;

        $periods = array('moment', 'min', 'hour', 'day', 'week', 'month', 'year', 'decade');
        $lengths = array('60', '60', '24', '7', '4.35', '12', '10', '10');

        if ($difference >= 0) {
            // This was in the past
            $ending = "ago";
        } else {
            // This is in the future
            $difference = -$difference;
            $ending = "to go";
        }

        for ($j = 0; $difference >= $lengths[$j]; $j++) {
            $difference /= $lengths[$j];
        }

        $difference = round($difference);
        if ($difference != 1) {
            $periods[$j] .= "s";
        }

        if ($difference < 60 && $j == 0) {
            return "{$periods[$j]} {$ending}";
        }

        return "{$difference} {$periods[$j]} {$ending}";
    }
}

if (! function_exists('standard_timezone')) {
    /**
     * Convert CodeIgniter's time zone strings to standard PHP time zone strings.
     *
     * @param string $ciTimezone A time zone string generated by CodeIgniter.
     *
     * @return string    A PHP time zone string.
     */
    function standard_timezone($ciTimezone)
    {
        switch ($ciTimezone) {
            case 'UM12':
                return 'Pacific/Kwajalein';
            case 'UM11':
                return 'Pacific/Midway';
            case 'UM10':
                return 'Pacific/Honolulu';
            case 'UM95':
                return 'Pacific/Marquesas';
            case 'UM9':
                return 'Pacific/Gambier';
            case 'UM8':
                return 'America/Los_Angeles';
            case 'UM7':
                return 'America/Boise';
            case 'UM6':
                return 'America/Chicago';
            case 'UM5':
                return 'America/New_York';
            case 'UM45':
                return 'America/Caracas';
            case 'UM4':
                return 'America/Sao_Paulo';
            case 'UM35':
                return 'America/St_Johns';
            case 'UM3':
                return 'America/Buenos_Aires';
            case 'UM2':
                return 'Atlantic/St_Helena';
            case 'UM1':
                return 'Atlantic/Azores';
            case 'UP1':
                return 'Europe/Berlin';
            case 'UP2':
                return 'Europe/Kaliningrad';
            case 'UP3':
                return 'Asia/Baghdad';
            case 'UP35':
                return 'Asia/Tehran';
            case 'UP4':
                return 'Asia/Baku';
            case 'UP45':
                return 'Asia/Kabul';
            case 'UP5':
                return 'Asia/Karachi';
            case 'UP55':
                return 'Asia/Calcutta';
            case 'UP575':
                return 'Asia/Kathmandu';
            case 'UP6':
                return 'Asia/Almaty';
            case 'UP65':
                return 'Asia/Rangoon';
            case 'UP7':
                return 'Asia/Bangkok';
            case 'UP8':
                return 'Asia/Hong_Kong';
            case 'UP875':
                return 'Australia/Eucla';
            case 'UP9':
                return 'Asia/Tokyo';
            case 'UP95':
                return 'Australia/Darwin';
            case 'UP10':
                return 'Australia/Melbourne';
            case 'UP105':
                return 'Australia/LHI';
            case 'UP11':
                return 'Asia/Magadan';
            case 'UP115':
                return 'Pacific/Norfolk';
            case 'UP12':
                return 'Pacific/Fiji';
            case 'UP1275':
                return 'Pacific/Chatham';
            case 'UP13':
                return 'Pacific/Samoa';
            case 'UP14':
                return 'Pacific/Kiritimati';
            case 'UTC':
                // no break;
            default:
                return 'UTC';
        }
    }
}

if (! function_exists('user_time')) {
    /**
     * Convert unix time to a human readable time in the user's timezone or in a
     * given timezone.
     *
     * For supported timezones visit - http://php.net/manual/timezones.php
     * For accepted formats visit - http://php.net/manual/function.date.php
     *
     * @example echo user_time();
     * @example echo user_time($timestamp, 'EET', 'l jS \of F Y h:i:s A');
     *
     * @param int    $timestamp A UNIX timestamp. If none is given, current time
     * will be used.
     * @param string $timezone  The destination timezone for the conversion. If
     * none is given, the current user's configured timezone will be used.
     * @param string $format    The format string to apply to the converted
     * timestamp.
     *
     * @return string A string containing the timestamp in the requested format.
     */
    function user_time($timestamp = null, $timezone = null, $format = 'r')
    {
        if (! $timezone) {
            $CI =& get_instance();
            $CI->load->library('users/auth');
            if ($CI->auth->is_logged_in()) {
                $timezone = standard_timezone($CI->auth->user()->timezone);
            }
        }

        if (empty($timestamp)) {
            $dtime = new DateTime(null, new DateTimeZone($timezone));
            return $dtime->format($format);
        }

        $dtime = new DateTime();
        if (is_int($timestamp)) {
            $dtime->setTimestamp($timestamp);
        } elseif ($timestamp != 'now') {
            $dtime->modify($timestamp);
        }

        return $dtime->setTimezone(new DateTimeZone($timezone))->format($format);
    }
}