<?php

/**
 * FeedDate is an internal class that stores a date for a feed or feed item.
 * Usually, you won't need to use this.
 */
class FeedDate
{
    protected $unix;

    /**
     * Creates a new instance of FeedDate representing a given date.
     * Accepts RFC 822, ISO 8601 date formats as well as unix time stamps.
     *
     * @param mixed $dateString optional the date this FeedDate will represent. If not specified, the current date and
     *                          time is used.
     */
    public function __construct($dateString = "")
    {
        if ($dateString == "") {
            $dateString = date("r");
        }

        if (is_integer($dateString)) {
            $this->unix = $dateString;

            return;
        }
        $tzOffset = 0;
        if (preg_match(
            "~(?:(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun),\\s+)?(\\d{1,2})\\s+([a-zA-Z]{3})\\s+(\\d{4})\\s+(\\d{2}):(\\d{2}):(\\d{2})\\s+(.*)~",
            $dateString,
            $matches
        )) {
            $months = Array(
                "Jan" => 1,
                "Feb" => 2,
                "Mar" => 3,
                "Apr" => 4,
                "May" => 5,
                "Jun" => 6,
                "Jul" => 7,
                "Aug" => 8,
                "Sep" => 9,
                "Oct" => 10,
                "Nov" => 11,
                "Dec" => 12,
            );
            $this->unix = mktime($matches[4], $matches[5], $matches[6], $months[$matches[2]], $matches[1], $matches[3]);
            if (substr($matches[7], 0, 1) == '+' OR substr($matches[7], 0, 1) == '-') {
                $tzOffset = (((int)substr($matches[7], 0, 3) * 60) + (int)substr($matches[7], -2)) * 60;
            } else {
                if (strlen($matches[7]) == 1) {
                    $oneHour = 3600;
                    $ord = ord($matches[7]);
                    if ($ord < ord("M")) {
                        $tzOffset = (ord("A") - $ord - 1) * $oneHour;
                    } elseif ($ord >= ord("M") AND $matches[7] != "Z") {
                        $tzOffset = ($ord - ord("M")) * $oneHour;
                    } elseif ($matches[7] == "Z") {
                        $tzOffset = 0;
                    }
                }
                switch ($matches[7]) {
                    case "UT":
                    case "GMT":
                        $tzOffset = 0;
                }
            }
            $this->unix += $tzOffset;

            return;
        }
        if (preg_match("~(\\d{4})-(\\d{2})-(\\d{2})T(\\d{2}):(\\d{2}):(\\d{2})(.*)~", $dateString, $matches)) {
            $this->unix = mktime($matches[4], $matches[5], $matches[6], $matches[2], $matches[3], $matches[1]);
            if (substr($matches[7], 0, 1) == '+' OR substr($matches[7], 0, 1) == '-') {
                $tzOffset = (((int)substr($matches[7], 0, 3) * 60) + (int)substr($matches[7], -2)) * 60;
            } else {
                if ($matches[7] == "Z") {
                    $tzOffset = 0;
                }
            }
            $this->unix += $tzOffset;

            return;
        }
        $this->unix = 0;
    }

    /**
     * Gets the date stored in this FeedDate as an RFC 822 date.
     *
     * @return string a date in RFC 822 format
     */
    public function rfc822()
    {
        //return gmdate("r",$this->unix);
        $date = gmdate("D, d M Y H:i:s O", $this->unix);

        return $date;
    }

    /**
     * Gets the date stored in this FeedDate as an ISO 8601 date.
     *
     * @return string a date in ISO 8601 format
     */
    public function iso8601()
    {
        $date = gmdate("Y-m-d\TH:i:sP", $this->unix);

        return $date;
    }

    /**
     * Gets the date stored in this FeedDate as unix time stamp.
     *
     * @return int a date as a unix time stamp
     */
    public function unix()
    {
        return $this->unix;
    }
}