root/trunk/system/libraries/Calendar_Event.php

<?php defined('SYSPATH') or die('No direct script access.');
/**
 * Calendar event observer class.
 *
 * $Id$
 *
 * @package    Calendar
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class Calendar_Event_Core extends Event_Observer {

    // Boolean conditions
    protected $booleans = array
    (
        'current',
        'weekend',
        'first_day',
        'last_day',
        'last_occurrence',
        'easter',
    );

    // Rendering conditions
    protected $conditions = array();

    // Cell classes
    protected $classes = array();

    // Cell output
    protected $output = '';

    /**
     * Adds a condition to the event. The condition can be one of the following:
     *
     * timestamp       - UNIX timestamp
     * day             - day number (1-31)
     * week            - week number (1-5)
     * month           - month number (1-12)
     * year            - year number (4 digits)
     * day_of_week     - day of week (1-7)
     * current         - active month (boolean) (only show data for the month being rendered)
     * weekend         - weekend day (boolean)
     * first_day       - first day of month (boolean)
     * last_day        - last day of month (boolean)
     * occurrence      - occurrence of the week day (1-5) (use with "day_of_week")
     * last_occurrence - last occurrence of week day (boolean) (use with "day_of_week")
     * easter          - Easter day (boolean)
     * callback        - callback test (boolean)
     *
     * To unset a condition, call condition with a value of NULL.
     *
     * @chainable
     * @param   string  condition key
     * @param   mixed   condition value
     * @return  object
     */
    public function condition($key, $value)
    {
        if ($value === NULL)
        {
            unset($this->conditions[$key]);
        }
        else
        {
            if ($key === 'callback')
            {
                // Do nothing
            }
            elseif (in_array($key, $this->booleans))
            {
                // Make the value boolean
                $value = (bool) $value;
            }
            else
            {
                // Make the value an int
                $value = (int) $value;
            }

            $this->conditions[$key] = $value;
        }

        return $this;
    }

    /**
     * Add a CSS class for this event. This can be called multiple times.
     *
     * @chainable
     * @param   string  CSS class name
     * @return  object
     */
    public function add_class($class)
    {
        $this->classes[$class] = $class;

        return $this;
    }

    /**
     * Remove a CSS class for this event. This can be called multiple times.
     *
     * @chainable
     * @param   string  CSS class name
     * @return  object
     */
    public function remove_class($class)
    {
        unset($this->classes[$class]);

        return $this;
    }

    /**
     * Set HTML output for this event.
     *
     * @chainable
     * @param   string  HTML output
     * @return  object
     */
    public function output($str)
    {
        $this->output = $str;

        return $this;
    }

    /**
     * Add a CSS class for this event. This can be called multiple times.
     *
     * @chainable
     * @param   string  CSS class name
     * @return  object
     */
    public function notify($data)
    {
        // Split the date and current status
        list ($month, $day, $year, $week, $current) = $data;

        // Get a timestamp for the day
        $timestamp = mktime(0, 0, 0, $month, $day, $year);

        // Date conditionals
        $condition = array
        (
            'timestamp'   => (int) $timestamp,
            'day'         => (int) date('j', $timestamp),
            'week'        => (int) $week,
            'month'       => (int) date('n', $timestamp),
            'year'        => (int) date('Y', $timestamp),
            'day_of_week' => (int) date('w', $timestamp),
            'current'     => (bool) $current,
        );

        // Tested conditions
        $tested = array();

        foreach ($condition as $key => $value)
        {
            // Test basic conditions first
            if (isset($this->conditions[$key]) AND $this->conditions[$key] !== $value)
                return FALSE;

            // Condition has been tested
            $tested[$key] = TRUE;
        }

        if (isset($this->conditions['weekend']))
        {
            // Weekday vs Weekend
            $condition['weekend'] = ($condition['day_of_week'] === 0 OR $condition['day_of_week'] === 6);
        }

        if (isset($this->conditions['first_day']))
        {
            // First day of month
            $condition['first_day'] = ($condition['day'] === 1);
        }

        if (isset($this->conditions['last_day']))
        {
            // Last day of month
            $condition['last_day'] = ($condition['day'] === (int) date('t', $timestamp));
        }

        if (isset($this->conditions['occurrence']))
        {
            // Get the occurance of the current day
            $condition['occurrence'] = $this->day_occurrence($timestamp);
        }

        if (isset($this->conditions['last_occurrence']))
        {
            // Test if the next occurance of this date is next month
            $condition['last_occurrence'] = ((int) date('n', $timestamp + 604800) !== $condition['month']);
        }

        if (isset($this->conditions['easter']))
        {
            if ($condition['month'] === 3 OR $condition['month'] === 4)
            {
                // This algorithm is from Practical Astronomy With Your Calculator, 2nd Edition by Peter
                // Duffett-Smith. It was originally from Butcher's Ecclesiastical Calendar, published in
                // 1876. This algorithm has also been published in the 1922 book General Astronomy by
                // Spencer Jones; in The Journal of the British Astronomical Association (Vol.88, page
                // 91, December 1977); and in Astronomical Algorithms (1991) by Jean Meeus.

                $a = $condition['year'] % 19;
                $b = (int) ($condition['year'] / 100);
                $c = $condition['year'] % 100;
                $d = (int) ($b / 4);
                $e = $b % 4;
                $f = (int) (($b + 8) / 25);
                $g = (int) (($b - $f + 1) / 3);
                $h = (19 * $a + $b - $d - $g + 15) % 30;
                $i = (int) ($c / 4);
                $k = $c % 4;
                $l = (32 + 2 * $e + 2 * $i - $h - $k) % 7;
                $m = (int) (($a + 11 * $h + 22 * $l) / 451);
                $p = ($h + $l - 7 * $m + 114) % 31;

                $month = (int) (($h + $l - 7 * $m + 114) / 31);
                $day = $p + 1;

                $condition['easter'] = ($condition['month'] === $month AND $condition['day'] === $day);
            }
            else
            {
                // Easter can only happen in March or April
                $condition['easter'] = FALSE;
            }
        }

        if (isset($this->conditions['callback']))
        {
            // Use a callback to determine validity
            $condition['callback'] = call_user_func($this->conditions['callback'], $condition, $this);
        }

        $conditions = array_diff_key($this->conditions, $tested);

        foreach ($conditions as $key => $value)
        {
            if ($key === 'callback')
            {
                // Callbacks are tested on a TRUE/FALSE basis
                $value = TRUE;
            }

            // Test advanced conditions
            if ($condition[$key] !== $value)
                return FALSE;
        }

        $this->caller->add_data(array
        (
            'classes' => $this->classes,
            'output'  => $this->output,
        ));
    }

    /**
     * Find the week day occurrence for a specific timestamp. The occurrence is
     * relative to the current month. For example, the second Saturday of any
     * given month will return "2" as the occurrence. This is used in combination
     * with the "occurrence" condition.
     *
     * @param   integer  UNIX timestamp
     * @return  integer
     */
    protected function day_occurrence($timestamp)
    {
        // Get the current month for the timestamp
        $month = date('m', $timestamp);

        // Default occurrence is one
        $occurrence = 1;

        // Reduce the timestamp by one week for each loop. This has the added
        // benefit of preventing an infinite loop.
        while ($timestamp -= 604800)
        {
            if (date('m', $timestamp) !== $month)
            {
                // Once the timestamp has gone into the previous month, the
                // proper occurrence has been found.
                return $occurrence;
            }

            // Increment the occurrence
            $occurrence++;
        }
    }

} // End Calendar Event