MediaWiki  master
SpecialRandomInCategory.php
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1 <?php
51  protected $extra = []; // Extra SQL statements
53  protected $category = false; // Title object of category
55  protected $maxOffset = 30; // Max amount to fudge randomness by.
57  private $maxTimestamp = null;
59  private $minTimestamp = null;
60 
61  public function __construct( $name = 'RandomInCategory' ) {
62  parent::__construct( $name );
63  }
64 
69  public function setCategory( Title $cat ) {
70  $this->category = $cat;
71  $this->maxTimestamp = null;
72  $this->minTimestamp = null;
73  }
74 
75  protected function getFormFields() {
76  $this->addHelpLink( 'Help:RandomInCategory' );
77 
78  return [
79  'category' => [
80  'type' => 'title',
81  'namespace' => NS_CATEGORY,
82  'relative' => true,
83  'label-message' => 'randomincategory-category',
84  'required' => true,
85  ]
86  ];
87  }
88 
89  public function requiresWrite() {
90  return false;
91  }
92 
93  public function requiresUnblock() {
94  return false;
95  }
96 
97  protected function getDisplayFormat() {
98  return 'ooui';
99  }
100 
101  protected function alterForm( HTMLForm $form ) {
102  $form->setSubmitTextMsg( 'randomincategory-submit' );
103  }
104 
105  protected function setParameter( $par ) {
106  // if subpage present, fake form submission
107  $this->onSubmit( [ 'category' => $par ] );
108  }
109 
110  public function onSubmit( array $data ) {
111  $cat = false;
112 
113  $categoryStr = $data['category'];
114 
115  if ( $categoryStr ) {
116  $cat = Title::newFromText( $categoryStr, NS_CATEGORY );
117  }
118 
119  if ( $cat && $cat->getNamespace() !== NS_CATEGORY ) {
120  // Someone searching for something like "Wikipedia:Foo"
121  $cat = Title::makeTitleSafe( NS_CATEGORY, $categoryStr );
122  }
123 
124  if ( $cat ) {
125  $this->setCategory( $cat );
126  }
127 
128  if ( !$this->category && $categoryStr ) {
129  $msg = $this->msg( 'randomincategory-invalidcategory',
130  wfEscapeWikiText( $categoryStr ) );
131 
132  return Status::newFatal( $msg );
133 
134  } elseif ( !$this->category ) {
135  return false; // no data sent
136  }
137 
138  $title = $this->getRandomTitle();
139 
140  if ( is_null( $title ) ) {
141  $msg = $this->msg( 'randomincategory-nopages',
142  $this->category->getText() );
143 
144  return Status::newFatal( $msg );
145  }
146 
147  $this->getOutput()->redirect( $title->getFullURL() );
148  }
149 
154  public function getRandomTitle() {
155  // Convert to float, since we do math with the random number.
156  $rand = (float)wfRandom();
157  $title = null;
158 
159  // Given that timestamps are rather unevenly distributed, we also
160  // use an offset between 0 and 30 to make any biases less noticeable.
161  $offset = mt_rand( 0, $this->maxOffset );
162 
163  if ( mt_rand( 0, 1 ) ) {
164  $up = true;
165  } else {
166  $up = false;
167  }
168 
169  $row = $this->selectRandomPageFromDB( $rand, $offset, $up );
170 
171  // Try again without the timestamp offset (wrap around the end)
172  if ( !$row ) {
173  $row = $this->selectRandomPageFromDB( false, $offset, $up );
174  }
175 
176  // Maybe the category is really small and offset too high
177  if ( !$row ) {
178  $row = $this->selectRandomPageFromDB( $rand, 0, $up );
179  }
180 
181  // Just get the first entry.
182  if ( !$row ) {
183  $row = $this->selectRandomPageFromDB( false, 0, true );
184  }
185 
186  if ( $row ) {
187  return Title::makeTitle( $row->page_namespace, $row->page_title );
188  }
189 
190  return null;
191  }
192 
204  protected function getQueryInfo( $rand, $offset, $up ) {
205  $op = $up ? '>=' : '<=';
206  $dir = $up ? 'ASC' : 'DESC';
207  if ( !$this->category instanceof Title ) {
208  throw new MWException( 'No category set' );
209  }
210  $qi = [
211  'tables' => [ 'categorylinks', 'page' ],
212  'fields' => [ 'page_title', 'page_namespace' ],
213  'conds' => array_merge( [
214  'cl_to' => $this->category->getDBkey(),
215  ], $this->extra ),
216  'options' => [
217  'ORDER BY' => 'cl_timestamp ' . $dir,
218  'LIMIT' => 1,
219  'OFFSET' => $offset
220  ],
221  'join_conds' => [
222  'page' => [ 'JOIN', 'cl_from = page_id' ]
223  ]
224  ];
225 
226  $dbr = wfGetDB( DB_REPLICA );
227  $minClTime = $this->getTimestampOffset( $rand );
228  if ( $minClTime ) {
229  $qi['conds'][] = 'cl_timestamp ' . $op . ' ' .
230  $dbr->addQuotes( $dbr->timestamp( $minClTime ) );
231  }
232 
233  return $qi;
234  }
235 
241  protected function getTimestampOffset( $rand ) {
242  if ( $rand === false ) {
243  return false;
244  }
245  if ( !$this->minTimestamp || !$this->maxTimestamp ) {
246  try {
247  list( $this->minTimestamp, $this->maxTimestamp ) = $this->getMinAndMaxForCat( $this->category );
248  } catch ( Exception $e ) {
249  // Possibly no entries in category.
250  return false;
251  }
252  }
253 
254  $ts = ( $this->maxTimestamp - $this->minTimestamp ) * $rand + $this->minTimestamp;
255 
256  return intval( $ts );
257  }
258 
266  protected function getMinAndMaxForCat( Title $category ) {
267  $dbr = wfGetDB( DB_REPLICA );
268  $res = $dbr->selectRow(
269  'categorylinks',
270  [
271  'low' => 'MIN( cl_timestamp )',
272  'high' => 'MAX( cl_timestamp )'
273  ],
274  [
275  'cl_to' => $this->category->getDBkey(),
276  ],
277  __METHOD__,
278  [
279  'LIMIT' => 1
280  ]
281  );
282  if ( !$res ) {
283  throw new MWException( 'No entries in category' );
284  }
285 
286  return [ wfTimestamp( TS_UNIX, $res->low ), wfTimestamp( TS_UNIX, $res->high ) ];
287  }
288 
296  private function selectRandomPageFromDB( $rand, $offset, $up, $fname = __METHOD__ ) {
297  $dbr = wfGetDB( DB_REPLICA );
298 
299  $query = $this->getQueryInfo( $rand, $offset, $up );
300  $res = $dbr->select(
301  $query['tables'],
302  $query['fields'],
303  $query['conds'],
304  $fname,
305  $query['options'],
306  $query['join_conds']
307  );
308 
309  return $res->fetchObject();
310  }
311 
312  protected function getGroupName() {
313  return 'redirects';
314  }
315 }
static newFatal( $message,... $parameters)
Factory function for fatal errors.
Definition: StatusValue.php:69
wfEscapeWikiText( $text)
Escapes the given text so that it may be output using addWikiText() without any linking, formatting, etc.
setCategory(Title $cat)
Set which category to use.
wfGetDB( $db, $groups=[], $wiki=false)
Get a Database object.
addHelpLink( $to, $overrideBaseUrl=false)
Adds help link with an icon via page indicators.
getOutput()
Get the OutputPage being used for this instance.
Special page which uses an HTMLForm to handle processing.
wfTimestamp( $outputtype=TS_UNIX, $ts=0)
Get a timestamp string in one of various formats.
msg( $key,... $params)
Wrapper around wfMessage that sets the current context.
getMinAndMaxForCat(Title $category)
Get the lowest and highest timestamp for a category.
getQueryInfo( $rand, $offset, $up)
const NS_CATEGORY
Definition: Defines.php:74
__construct( $name='RandomInCategory')
Special page to direct the user to a random page.
static makeTitleSafe( $ns, $title, $fragment='', $interwiki='')
Create a new Title from a namespace index and a DB key.
Definition: Title.php:612
static makeTitle( $ns, $title, $fragment='', $interwiki='')
Create a new Title from a namespace index and a DB key.
Definition: Title.php:586
string null $par
The sub-page of the special page.
wfRandom()
Get a random decimal value in the domain of [0, 1), in a way not likely to give duplicate values for ...
getRandomTitle()
Choose a random title.
setSubmitTextMsg( $msg)
Set the text for the submit button to a message.
Definition: HTMLForm.php:1392
selectRandomPageFromDB( $rand, $offset, $up, $fname=__METHOD__)
const DB_REPLICA
Definition: defines.php:25
static newFromText( $text, $defaultNamespace=NS_MAIN)
Create a new Title from text, such as what one would find in a link.
Definition: Title.php:319