classes/visibility.php

   1 <?php
   2 /***************************************************************************
   3  *  Copyright (C) 2003-2014 Polytechnique.org                              *
   4  *  http://opensource.polytechnique.org/                                   *
   5  *                                                                         *
   6  *  This program is free software; you can redistribute it and/or modify   *
   7  *  it under the terms of the GNU General Public License as published by   *
   8  *  the Free Software Foundation; either version 2 of the License, or      *
   9  *  (at your option) any later version.                                    *
  10  *                                                                         *
  11  *  This program is distributed in the hope that it will be useful,        *
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
  14  *  GNU General Public License for more details.                           *
  15  *                                                                         *
  16  *  You should have received a copy of the GNU General Public License      *
  17  *  along with this program; if not, write to the Free Software            *
  18  *  Foundation, Inc.,                                                      *
  19  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                *
  20  ***************************************************************************/
  21
  22 class Visibility
  23 {
  24     /** Visibility levels.
  25      * The VIEW_* constants describe the access level
  26      * The EXPORT_* constants describe the degree of confidentiality of the data.
  27      */
  28     const VIEW_NONE = 'none';
  29     const VIEW_PUBLIC = 'public';
  30     const VIEW_AX = 'ax';
  31     const VIEW_PRIVATE = 'private';
  32     const VIEW_ADMIN = 'admin';
  33
  34     const EXPORT_PUBLIC = 'public';
  35     const EXPORT_AX = 'ax';
  36     const EXPORT_PRIVATE = 'private';
  37     const EXPORT_HIDDEN = 'hidden';
  38
  39     /** Map each VIEW_ level to the list of EXPORT_ levels it can view.
  40      */
  41     static private $view_levels = array(
  42         self::VIEW_NONE    => array(),
  43         self::VIEW_PUBLIC  => array(self::EXPORT_PUBLIC),
  44         self::VIEW_AX      => array(self::EXPORT_AX, self::EXPORT_PUBLIC),
  45         self::VIEW_PRIVATE => array(self::EXPORT_PRIVATE, self::EXPORT_AX, self::EXPORT_PUBLIC),
  46         self::VIEW_ADMIN   => array(self::EXPORT_HIDDEN, self::EXPORT_PRIVATE, self::EXPORT_AX, self::EXPORT_PUBLIC),
  47     );
  48
  49     static private $display_levels = array(
  50         self::EXPORT_PUBLIC => 0,
  51         self::EXPORT_AX => 1,
  52         self::EXPORT_PRIVATE => 2,
  53         self::EXPORT_HIDDEN => 3,
  54     );
  55
  56     private $level;
  57
  58     private function __construct($level)
  59     {
  60         $this->level = $level;
  61     }
  62
  63     static private $vis_list = array();
  64     public static function get($level)
  65     {
  66         Platal::assert(array_key_exists($level, self::$view_levels), "Invalid visibility access level $level.");
  67         if (!array_key_exists($level, self::$vis_list)) {
  68             self::$vis_list[$level] = new Visibility($level);
  69         }
  70         return self::$vis_list[$level];
  71     }
  72
  73     public function level()
  74     {
  75         return $this->level;
  76     }
  77
  78     public static function defaultForRead($max_level = null)
  79     {
  80         if (!S::logged()) {
  81             $vis = self::get(self::VIEW_PUBLIC);
  82         } else {
  83             $vis = S::user()->readVisibility();
  84         }
  85         if ($max_level != null) {
  86             return $vis->restrict($max_level);
  87         } else {
  88             return $vis;
  89         }
  90     }
  91
  92     public static function defaultForEdit($max_level = null)
  93     {
  94         if (!S::logged()) {
  95             $vis = self::get(self::VIEW_NONE);
  96         } else {
  97             $vis = S::user()->editVisibility();
  98         }
  99         if ($max_level != null) {
 100             return $vis->restrict($max_level);
 101         } else {
 102             return $vis;
 103         }
 104     }
 105
 106     /** Retrieve a 'restricted' version of the current Visibility.
 107      *
 108      * @param $level The visibility level to restrict to
 109      * @return A new Visibility instance, whose level is min($this->level, $level)
 110      */
 111     public function restrict($level = null)
 112     {
 113         if ($level != null && !$this->isVisible($level)) {
 114             $level = $this->level();
 115         }
 116
 117         return self::get($level);
 118     }
 119
 120     public function isVisible($visibility)
 121     {
 122         return in_array($visibility, self::$view_levels[$this->level()]);
 123     }
 124
 125     public function equals($visibility)
 126     {
 127         return $visibility !== null && $this->level() == $visibility->level();
 128     }
 129
 130     static public function isLessRestrictive($level_a, $level_b)
 131     {
 132         // self::$display_levels is order from least restrictive
 133         // to most restrictive.
 134         return self::$display_levels[$level_a] >= self::$display_levels[$level_b];
 135     }
 136
 137     /** Compare the visibility of two fields.
 138      * Returns:
 139      *   >0 if $a is less restrictive than $b,
 140      *   <0 if $a is more restrictive than $b,
 141      *   0  if $a is equal to $b.
 142      */
 143     static public function cmpLessRestrictive($a, $b)
 144     {
 145         $a_pub = self::$display_levels[$a];
 146         $b_pub = self::$display_levels[$b];
 147         /* self::$display_levels is ordered from least restrictive to
 148          * most restrictive.
 149          * This will be 0 if both levels are equal, < 0 if $b_pub is less
 150          * than $a_pub, thus less restrictive, which means that $a comes
 151          * before $b in descending restrictiveness order.
 152          */
 153         return $b_pub - $a_pub;
 154     }
 155
 156     static public function comparePublicity($a, $b)
 157     {
 158         return self::cmpLessRestrictive($a['pub'], $b['pub']);
 159     }
 160 }
 161
 162 // vim:set et sw=4 sts=4 sws=4 foldmethod=marker fenc=utf-8:
 163 ?>