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| 1 | <?php |
| 2 | |
| 3 | namespace Flow\Data\Pager; |
| 4 | |
| 5 | use Flow\Data\Index; |
| 6 | use Flow\Data\ObjectManager; |
| 7 | use Flow\Exception\InvalidInputException; |
| 8 | |
| 9 | /** |
| 10 | * Fetches paginated results from the OM provided in constructor |
| 11 | */ |
| 12 | class Pager { |
| 13 | private const VALID_DIRECTIONS = [ 'fwd', 'rev' ]; |
| 14 | private const DEFAULT_DIRECTION = 'fwd'; |
| 15 | private const DEFAULT_LIMIT = 1; |
| 16 | private const MAX_LIMIT = 500; |
| 17 | private const MAX_QUERIES = 4; |
| 18 | |
| 19 | /** |
| 20 | * @var ObjectManager |
| 21 | */ |
| 22 | protected $storage; |
| 23 | |
| 24 | /** |
| 25 | * @var Index |
| 26 | */ |
| 27 | protected $index; |
| 28 | |
| 29 | /** |
| 30 | * @var array Results sorted by the values in this array |
| 31 | */ |
| 32 | protected $sort; |
| 33 | |
| 34 | /** |
| 35 | * @var array Map of column name to column value for equality query |
| 36 | */ |
| 37 | protected $query; |
| 38 | |
| 39 | /** |
| 40 | * @var array Options effecting the result such as `sort`, `order`, and `pager-limit` |
| 41 | */ |
| 42 | protected $options; |
| 43 | |
| 44 | /** |
| 45 | * @var string |
| 46 | */ |
| 47 | protected $offsetKey; |
| 48 | |
| 49 | /** |
| 50 | * @var bool Whether this pager uses ID fields |
| 51 | */ |
| 52 | protected $useId; |
| 53 | |
| 54 | public function __construct( ObjectManager $storage, array $query, array $options ) { |
| 55 | // not sure i like this |
| 56 | $this->storage = $storage; |
| 57 | $this->query = $query; |
| 58 | $this->options = $options + [ |
| 59 | 'pager-include-offset' => null, |
| 60 | 'pager-offset' => null, |
| 61 | 'pager-limit' => self::DEFAULT_LIMIT, |
| 62 | 'pager-dir' => self::DEFAULT_DIRECTION, |
| 63 | ]; |
| 64 | |
| 65 | $this->options['pager-limit'] = intval( $this->options['pager-limit'] ); |
| 66 | if ( !( $this->options['pager-limit'] > 0 && $this->options['pager-limit'] < self::MAX_LIMIT ) ) { |
| 67 | $this->options['pager-limit'] = self::DEFAULT_LIMIT; |
| 68 | } |
| 69 | |
| 70 | if ( !in_array( $this->options['pager-dir'], self::VALID_DIRECTIONS ) ) { |
| 71 | $this->options['pager-dir'] = self::DEFAULT_DIRECTION; |
| 72 | } |
| 73 | |
| 74 | $indexOptions = [ |
| 75 | 'limit' => $this->options['pager-limit'] |
| 76 | ]; |
| 77 | if ( isset( $this->options['sort'] ) && isset( $this->options['order'] ) ) { |
| 78 | $indexOptions += [ |
| 79 | 'sort' => [ $this->options['sort'] ], |
| 80 | 'order' => $this->options['order'], |
| 81 | ]; |
| 82 | } |
| 83 | $this->sort = $storage->getIndexFor( |
| 84 | array_keys( $query ), |
| 85 | $indexOptions |
| 86 | )->getSort(); |
| 87 | |
| 88 | $useId = false; |
| 89 | foreach ( $this->sort as $val ) { |
| 90 | if ( substr( $val, -3 ) === '_id' ) { |
| 91 | $useId = true; |
| 92 | } |
| 93 | break; |
| 94 | } |
| 95 | $this->useId = $useId; |
| 96 | |
| 97 | $this->offsetKey = $useId ? 'offset-id' : 'offset'; |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * @param callable|null $filter Accepts an array of objects found in a single query |
| 102 | * as its only argument and returns an array of accepted objects. |
| 103 | * @return PagerPage |
| 104 | */ |
| 105 | public function getPage( $filter = null ) { |
| 106 | $numNeeded = $this->options['pager-limit'] + 1; |
| 107 | $storageOffsetKey = $this->useId ? 'offset-id' : 'offset-value'; |
| 108 | |
| 109 | $options = $this->options + [ |
| 110 | // We need one item of leeway to determine if there are more items |
| 111 | 'limit' => $numNeeded, |
| 112 | 'offset-dir' => $this->options['pager-dir'], |
| 113 | $storageOffsetKey => $this->options['pager-offset'], |
| 114 | 'include-offset' => $this->options['pager-include-offset'], |
| 115 | ]; |
| 116 | $offset = $this->options['pager-offset']; |
| 117 | $results = []; |
| 118 | $queries = 0; |
| 119 | |
| 120 | do { |
| 121 | if ( $queries === 2 ) { |
| 122 | // if we hit a third query ask for more items |
| 123 | $options['limit'] = min( self::MAX_LIMIT, $this->options['pager-limit'] * 5 ); |
| 124 | } |
| 125 | |
| 126 | // Retrieve results |
| 127 | $options = [ |
| 128 | $storageOffsetKey => $offset, |
| 129 | ] + $options; |
| 130 | $found = $this->storage->find( $this->query, $options ); |
| 131 | |
| 132 | if ( !$found ) { |
| 133 | // nothing found |
| 134 | break; |
| 135 | } |
| 136 | $filtered = $filter ? $filter( $found ) : $found; |
| 137 | if ( $this->options['pager-dir'] === 'rev' ) { |
| 138 | // Paging A-Z with pager-offset F, pager-dir rev, pager-limit 2 gives |
| 139 | // DE on first query, BC on second, and A on third. The output |
| 140 | // needs to be ABCDE |
| 141 | $results = array_merge( $filtered, $results ); |
| 142 | } else { |
| 143 | $results = array_merge( $results, $filtered ); |
| 144 | } |
| 145 | |
| 146 | if ( count( $found ) !== $options['limit'] ) { |
| 147 | // last page |
| 148 | break; |
| 149 | } |
| 150 | |
| 151 | // setup offset for next query |
| 152 | if ( $this->options['pager-dir'] === 'rev' ) { |
| 153 | $last = reset( $found ); |
| 154 | } else { |
| 155 | $last = end( $found ); |
| 156 | } |
| 157 | $offset = $this->storage->serializeOffset( $last, $this->sort ); |
| 158 | |
| 159 | } while ( count( $results ) < $numNeeded && ++$queries < self::MAX_QUERIES ); |
| 160 | |
| 161 | if ( $queries >= self::MAX_QUERIES ) { |
| 162 | $count = count( $results ); |
| 163 | $limit = $this->options['pager-limit']; |
| 164 | wfDebugLog( |
| 165 | 'Flow', |
| 166 | __METHOD__ . "Reached maximum of $queries queries with $count results of $limit " . |
| 167 | "requested with query of " . json_encode( $this->query ) . ' and options ' . |
| 168 | json_encode( $options ) |
| 169 | ); |
| 170 | } |
| 171 | |
| 172 | if ( $results ) { |
| 173 | return $this->processPage( $results ); |
| 174 | } else { |
| 175 | return new PagerPage( [], [], $this ); |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | /** |
| 180 | * @param array $results |
| 181 | * @return PagerPage |
| 182 | * @throws InvalidInputException |
| 183 | */ |
| 184 | protected function processPage( array $results ) { |
| 185 | $pagingLinks = []; |
| 186 | |
| 187 | // Retrieve paging links |
| 188 | if ( $this->options['pager-dir'] === 'fwd' ) { |
| 189 | if ( count( $results ) > $this->options['pager-limit'] ) { |
| 190 | // We got extra, another page exists |
| 191 | $results = array_slice( $results, 0, $this->options['pager-limit'] ); |
| 192 | $pagingLinks['fwd'] = $this->makePagingLink( |
| 193 | 'fwd', |
| 194 | end( $results ), |
| 195 | $this->options['pager-limit'] |
| 196 | ); |
| 197 | } |
| 198 | |
| 199 | if ( $this->options['pager-offset'] !== null ) { |
| 200 | $pagingLinks['rev'] = $this->makePagingLink( |
| 201 | 'rev', |
| 202 | reset( $results ), |
| 203 | $this->options['pager-limit'] |
| 204 | ); |
| 205 | } |
| 206 | } elseif ( $this->options['pager-dir'] === 'rev' ) { |
| 207 | if ( count( $results ) > $this->options['pager-limit'] ) { |
| 208 | // We got extra, another page exists |
| 209 | $results = array_slice( $results, -$this->options['pager-limit'] ); |
| 210 | $pagingLinks['rev'] = $this->makePagingLink( |
| 211 | 'rev', |
| 212 | reset( $results ), |
| 213 | $this->options['pager-limit'] |
| 214 | ); |
| 215 | } |
| 216 | |
| 217 | if ( $this->options['pager-offset'] !== null ) { |
| 218 | $pagingLinks['fwd'] = $this->makePagingLink( |
| 219 | 'fwd', |
| 220 | end( $results ), |
| 221 | $this->options['pager-limit'] |
| 222 | ); |
| 223 | } |
| 224 | } else { |
| 225 | throw new InvalidInputException( "Unrecognised direction " . $this->options['pager-dir'], 'invalid-input' ); |
| 226 | } |
| 227 | |
| 228 | return new PagerPage( $results, $pagingLinks, $this ); |
| 229 | } |
| 230 | |
| 231 | /** |
| 232 | * @param string $direction |
| 233 | * @param object $object |
| 234 | * @param int $pageLimit |
| 235 | * @return array |
| 236 | */ |
| 237 | protected function makePagingLink( $direction, $object, $pageLimit ) { |
| 238 | $return = [ |
| 239 | 'offset-dir' => $direction, |
| 240 | 'limit' => $pageLimit, |
| 241 | $this->offsetKey => $this->storage->serializeOffset( $object, $this->sort ), |
| 242 | ]; |
| 243 | if ( isset( $this->options['sortby'] ) ) { |
| 244 | $return['sortby'] = $this->options['sortby']; |
| 245 | } |
| 246 | return $return; |
| 247 | } |
| 248 | } |