application/LinkDB.php

   1 <?php
   2 /**
   3  * Data storage for links.
   4  *
   5  * This object behaves like an associative array.
   6  *
   7  * Example:
   8  *    $myLinks = new LinkDB();
   9  *    echo $myLinks['20110826_161819']['title'];
  10  *    foreach ($myLinks as $link)
  11  *       echo $link['title'].' at url '.$link['url'].'; description:'.$link['description'];
  12  *
  13  * Available keys:
  14  *  - description: description of the entry
  15  *  - linkdate: date of the creation of this entry, in the form YYYYMMDD_HHMMSS
  16  *              (e.g.'20110914_192317')
  17  *  - private:  Is this link private? 0=no, other value=yes
  18  *  - tags:     tags attached to this entry (separated by spaces)
  19  *  - title     Title of the link
  20  *  - url       URL of the link. Can be absolute or relative.
  21  *              Relative URLs are permalinks (e.g.'?m-ukcw')
  22  *
  23  * Implements 3 interfaces:
  24  *  - ArrayAccess: behaves like an associative array;
  25  *  - Countable:   there is a count() method;
  26  *  - Iterator:    usable in foreach () loops.
  27  */
  28 class LinkDB implements Iterator, Countable, ArrayAccess
  29 {
  30     // Links are stored as a PHP serialized string
  31     private $_datastore;
  32
  33     // Datastore PHP prefix
  34     protected static $phpPrefix = '<?php /* ';
  35
  36     // Datastore PHP suffix
  37     protected static $phpSuffix = ' */ ?>';
  38
  39     // List of links (associative array)
  40     //  - key:   link date (e.g. "20110823_124546"),
  41     //  - value: associative array (keys: title, description...)
  42     private $_links;
  43
  44     // List of all recorded URLs (key=url, value=linkdate)
  45     // for fast reserve search (url-->linkdate)
  46     private $_urls;
  47
  48     // List of linkdate keys (for the Iterator interface implementation)
  49     private $_keys;
  50
  51     // Position in the $this->_keys array (for the Iterator interface)
  52     private $_position;
  53
  54     // Is the user logged in? (used to filter private links)
  55     private $_loggedIn;
  56
  57     // Hide public links
  58     private $_hidePublicLinks;
  59
  60     /**
  61      * Creates a new LinkDB
  62      *
  63      * Checks if the datastore exists; else, attempts to create a dummy one.
  64      *
  65      * @param $isLoggedIn is the user logged in?
  66      */
  67     function __construct($datastore, $isLoggedIn, $hidePublicLinks)
  68     {
  69         $this->_datastore = $datastore;
  70         $this->_loggedIn = $isLoggedIn;
  71         $this->_hidePublicLinks = $hidePublicLinks;
  72         $this->_checkDB();
  73         $this->_readDB();
  74     }
  75
  76     /**
  77      * Countable - Counts elements of an object
  78      */
  79     public function count()
  80     {
  81         return count($this->_links);
  82     }
  83
  84     /**
  85      * ArrayAccess - Assigns a value to the specified offset
  86      */
  87     public function offsetSet($offset, $value)
  88     {
  89         // TODO: use exceptions instead of "die"
  90         if (!$this->_loggedIn) {
  91             die('You are not authorized to add a link.');
  92         }
  93         if (empty($value['linkdate']) || empty($value['url'])) {
  94             die('Internal Error: A link should always have a linkdate and URL.');
  95         }
  96         if (empty($offset)) {
  97             die('You must specify a key.');
  98         }
  99         $this->_links[$offset] = $value;
 100         $this->_urls[$value['url']]=$offset;
 101     }
 102
 103     /**
 104      * ArrayAccess - Whether or not an offset exists
 105      */
 106     public function offsetExists($offset)
 107     {
 108         return array_key_exists($offset, $this->_links);
 109     }
 110
 111     /**
 112      * ArrayAccess - Unsets an offset
 113      */
 114     public function offsetUnset($offset)
 115     {
 116         if (!$this->_loggedIn) {
 117             // TODO: raise an exception
 118             die('You are not authorized to delete a link.');
 119         }
 120         $url = $this->_links[$offset]['url'];
 121         unset($this->_urls[$url]);
 122         unset($this->_links[$offset]);
 123     }
 124
 125     /**
 126      * ArrayAccess - Returns the value at specified offset
 127      */
 128     public function offsetGet($offset)
 129     {
 130         return isset($this->_links[$offset]) ? $this->_links[$offset] : null;
 131     }
 132
 133     /**
 134      * Iterator - Returns the current element
 135      */
 136     function current()
 137     {
 138         return $this->_links[$this->_keys[$this->_position]];
 139     }
 140
 141     /**
 142      * Iterator - Returns the key of the current element
 143      */
 144     function key()
 145     {
 146         return $this->_keys[$this->_position];
 147     }
 148
 149     /**
 150      * Iterator - Moves forward to next element
 151      */
 152     function next()
 153     {
 154         ++$this->_position;
 155     }
 156
 157     /**
 158      * Iterator - Rewinds the Iterator to the first element
 159      *
 160      * Entries are sorted by date (latest first)
 161      */
 162     function rewind()
 163     {
 164         $this->_keys = array_keys($this->_links);
 165         rsort($this->_keys);
 166         $this->_position = 0;
 167     }
 168
 169     /**
 170      * Iterator - Checks if current position is valid
 171      */
 172     function valid()
 173     {
 174         return isset($this->_keys[$this->_position]);
 175     }
 176
 177     /**
 178      * Checks if the DB directory and file exist
 179      *
 180      * If no DB file is found, creates a dummy DB.
 181      */
 182     private function _checkDB()
 183     {
 184         if (file_exists($this->_datastore)) {
 185             return;
 186         }
 187
 188         // Create a dummy database for example
 189         $this->_links = array();
 190         $link = array(
 191             'title'=>' Shaarli: the personal, minimalist, super-fast, no-database delicious clone',
 192             'url'=>'https://github.com/shaarli/Shaarli/wiki',
 193             'description'=>'Welcome to Shaarli! This is your first public bookmark. To edit or delete me, you must first login.
 194
 195 To learn how to use Shaarli, consult the link "Help/documentation" at the bottom of this page.
 196
 197 You use the community supported version of the original Shaarli project, by Sebastien Sauvage.',
 198             'private'=>0,
 199             'linkdate'=> date('Ymd_His'),
 200             'tags'=>'opensource software'
 201         );
 202         $this->_links[$link['linkdate']] = $link;
 203
 204         $link = array(
 205             'title'=>'My secret stuff... - Pastebin.com',
 206             'url'=>'http://sebsauvage.net/paste/?8434b27936c09649#bR7XsXhoTiLcqCpQbmOpBi3rq2zzQUC5hBI7ZT1O3x8=',
 207             'description'=>'Shhhh! I\'m a private link only YOU can see. You can delete me too.',
 208             'private'=>1,
 209             'linkdate'=> date('Ymd_His', strtotime('-1 minute')),
 210             'tags'=>'secretstuff'
 211         );
 212         $this->_links[$link['linkdate']] = $link;
 213
 214         // Write database to disk
 215         $this->writeDB();
 216     }
 217
 218     /**
 219      * Reads database from disk to memory
 220      */
 221     private function _readDB()
 222     {
 223
 224         // Public links are hidden and user not logged in => nothing to show
 225         if ($this->_hidePublicLinks && !$this->_loggedIn) {
 226             $this->_links = array();
 227             return;
 228         }
 229
 230         // Read data
 231         // Note that gzinflate is faster than gzuncompress.
 232         // See: http://www.php.net/manual/en/function.gzdeflate.php#96439
 233         $this->_links = array();
 234
 235         if (file_exists($this->_datastore)) {
 236             $this->_links = unserialize(gzinflate(base64_decode(
 237                 substr(file_get_contents($this->_datastore),
 238                        strlen(self::$phpPrefix), -strlen(self::$phpSuffix)))));
 239         }
 240
 241         // If user is not logged in, filter private links.
 242         if (!$this->_loggedIn) {
 243             $toremove = array();
 244             foreach ($this->_links as $link) {
 245                 if ($link['private'] != 0) {
 246                     $toremove[] = $link['linkdate'];
 247                 }
 248             }
 249             foreach ($toremove as $linkdate) {
 250                 unset($this->_links[$linkdate]);
 251             }
 252         }
 253
 254         // Keep the list of the mapping URLs-->linkdate up-to-date.
 255         $this->_urls = array();
 256         foreach ($this->_links as $link) {
 257             $this->_urls[$link['url']] = $link['linkdate'];
 258         }
 259
 260         // Escape links data
 261         foreach($this->_links as &$link) {
 262             sanitizeLink($link);
 263         }
 264     }
 265
 266     /**
 267      * Saves the database from memory to disk
 268      *
 269      * @throws IOException the datastore is not writable
 270      */
 271     private function writeDB()
 272     {
 273         if (is_file($this->_datastore) && !is_writeable($this->_datastore)) {
 274             // The datastore exists but is not writeable
 275             throw new IOException($this->_datastore);
 276         } else if (!is_file($this->_datastore) && !is_writeable(dirname($this->_datastore))) {
 277             // The datastore does not exist and its parent directory is not writeable
 278             throw new IOException(dirname($this->_datastore));
 279         }
 280
 281         file_put_contents(
 282             $this->_datastore,
 283             self::$phpPrefix.base64_encode(gzdeflate(serialize($this->_links))).self::$phpSuffix
 284         );
 285
 286     }
 287
 288     /**
 289      * Saves the database from memory to disk
 290      *
 291      * @param string $pageCacheDir page cache directory
 292      */
 293     public function savedb($pageCacheDir)
 294     {
 295         if (!$this->_loggedIn) {
 296             // TODO: raise an Exception instead
 297             die('You are not authorized to change the database.');
 298         }
 299
 300         $this->writeDB();
 301
 302         invalidateCaches($pageCacheDir);
 303     }
 304
 305     /**
 306      * Returns the link for a given URL, or False if it does not exist.
 307      *
 308      * @param string $url URL to search for
 309      *
 310      * @return mixed the existing link if it exists, else 'false'
 311      */
 312     public function getLinkFromUrl($url)
 313     {
 314         if (isset($this->_urls[$url])) {
 315             return $this->_links[$this->_urls[$url]];
 316         }
 317         return false;
 318     }
 319
 320     /**
 321      * Returns the list of links corresponding to a full-text search
 322      *
 323      * Searches:
 324      *  - in the URLs, title and description;
 325      *  - are case-insensitive.
 326      *
 327      * Example:
 328      *    print_r($mydb->filterFulltext('hollandais'));
 329      *
 330      * mb_convert_case($val, MB_CASE_LOWER, 'UTF-8')
 331      *  - allows to perform searches on Unicode text
 332      *  - see https://github.com/shaarli/Shaarli/issues/75 for examples
 333      */
 334     public function filterFulltext($searchterms)
 335     {
 336         // FIXME: explode(' ',$searchterms) and perform a AND search.
 337         // FIXME: accept double-quotes to search for a string "as is"?
 338         $filtered = array();
 339         $search = mb_convert_case($searchterms, MB_CASE_LOWER, 'UTF-8');
 340         $keys = array('title', 'description', 'url', 'tags');
 341
 342         foreach ($this->_links as $link) {
 343             $found = false;
 344
 345             foreach ($keys as $key) {
 346                 if (strpos(mb_convert_case($link[$key], MB_CASE_LOWER, 'UTF-8'),
 347                            $search) !== false) {
 348                     $found = true;
 349                 }
 350             }
 351
 352             if ($found) {
 353                 $filtered[$link['linkdate']] = $link;
 354             }
 355         }
 356         krsort($filtered);
 357         return $filtered;
 358     }
 359
 360     /**
 361      * Returns the list of links associated with a given list of tags
 362      *
 363      * You can specify one or more tags, separated by space or a comma, e.g.
 364      *  print_r($mydb->filterTags('linux programming'));
 365      */
 366     public function filterTags($tags, $casesensitive=false)
 367     {
 368         // Same as above, we use UTF-8 conversion to handle various graphemes (i.e. cyrillic, or greek)
 369         // FIXME: is $casesensitive ever true?
 370         $t = str_replace(
 371             ',', ' ',
 372             ($casesensitive ? $tags : mb_convert_case($tags, MB_CASE_LOWER, 'UTF-8'))
 373         );
 374
 375         $searchtags = explode(' ', $t);
 376         $filtered = array();
 377
 378         foreach ($this->_links as $l) {
 379             $linktags = explode(
 380                 ' ',
 381                 ($casesensitive ? $l['tags']:mb_convert_case($l['tags'], MB_CASE_LOWER, 'UTF-8'))
 382             );
 383
 384             if (count(array_intersect($linktags, $searchtags)) == count($searchtags)) {
 385                 $filtered[$l['linkdate']] = $l;
 386             }
 387         }
 388         krsort($filtered);
 389         return $filtered;
 390     }
 391
 392
 393     /**
 394      * Returns the list of articles for a given day, chronologically sorted
 395      *
 396      * Day must be in the form 'YYYYMMDD' (e.g. '20120125'), e.g.
 397      *  print_r($mydb->filterDay('20120125'));
 398      */
 399     public function filterDay($day)
 400     {
 401         if (! checkDateFormat('Ymd', $day)) {
 402             throw new Exception('Invalid date format');
 403         }
 404
 405         $filtered = array();
 406         foreach ($this->_links as $l) {
 407             if (startsWith($l['linkdate'], $day)) {
 408                 $filtered[$l['linkdate']] = $l;
 409             }
 410         }
 411         ksort($filtered);
 412         return $filtered;
 413     }
 414
 415     /**
 416      * Returns the article corresponding to a smallHash
 417      */
 418     public function filterSmallHash($smallHash)
 419     {
 420         $filtered = array();
 421         foreach ($this->_links as $l) {
 422             if ($smallHash == smallHash($l['linkdate'])) {
 423                 // Yes, this is ugly and slow
 424                 $filtered[$l['linkdate']] = $l;
 425                 return $filtered;
 426             }
 427         }
 428         return $filtered;
 429     }
 430
 431     /**
 432      * Returns the list of all tags
 433      * Output: associative array key=tags, value=0
 434      */
 435     public function allTags()
 436     {
 437         $tags = array();
 438         foreach ($this->_links as $link) {
 439             foreach (explode(' ', $link['tags']) as $tag) {
 440                 if (!empty($tag)) {
 441                     $tags[$tag] = (empty($tags[$tag]) ? 1 : $tags[$tag] + 1);
 442                 }
 443             }
 444         }
 445         // Sort tags by usage (most used tag first)
 446         arsort($tags);
 447         return $tags;
 448     }
 449
 450     /**
 451      * Returns the list of days containing articles (oldest first)
 452      * Output: An array containing days (in format YYYYMMDD).
 453      */
 454     public function days()
 455     {
 456         $linkDays = array();
 457         foreach (array_keys($this->_links) as $day) {
 458             $linkDays[substr($day, 0, 8)] = 0;
 459         }
 460         $linkDays = array_keys($linkDays);
 461         sort($linkDays);
 462         return $linkDays;
 463     }
 464 }