Complex classes like SystemParamsService often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use SystemParamsService, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 20 | class SystemParamsService  | 
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| 21 | { | 
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| 22 | const ARRAY_KEYS_SEPARATOR = '.';  | 
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| 23 | const PARAM_IS_NOT_SET = 'CONFIG_VALUE_IS_NOT_SET';  | 
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| 24 | const CACHE_KEY = 'YII_SYSTEM_PARAM';  | 
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| 25 | |||
| 26 | /**  | 
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| 27 | * Cache duration  | 
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| 28 | *  | 
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| 29 | * @var int  | 
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| 30 | */  | 
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| 31 | public $cacheDuration = 0;  | 
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| 32 | |||
| 33 | /**  | 
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| 34 | * Params array  | 
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| 35 | *  | 
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| 36 | * @var array  | 
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| 37 | */  | 
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| 38 | private $params = [];  | 
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| 39 | |||
| 40 | /**  | 
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| 41 | * Get system param  | 
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| 42 | *  | 
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| 43 | * @param string $param  | 
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| 44 | *  | 
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| 45 | * @return mixed  | 
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| 46 | */  | 
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| 47 | public function getParam(string $param)  | 
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| 55 | |||
| 56 | /**  | 
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| 57 | * Prepare params  | 
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| 58 | *  | 
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| 59 | * @return bool  | 
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| 60 | */  | 
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| 61 | protected function prepareParams()  | 
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| 82 | |||
| 83 | /**  | 
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| 84 | * Load params from db.  | 
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| 85 | *  | 
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| 86 | * @return bool  | 
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| 87 | */  | 
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| 88 | protected function loadParamsFromCache()  | 
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| 98 | |||
| 99 | /**  | 
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| 100 | * Load params from db.  | 
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| 101 | *  | 
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| 102 | * @return bolean  | 
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| 103 | */  | 
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| 104 | protected function loadParamsFromDb()  | 
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| 119 | |||
| 120 | /**  | 
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| 121 | * Merge params  | 
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| 122 | *  | 
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| 123 | * @param $params  | 
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| 124 | * @param bool $autoUpdate  | 
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| 125 | *  | 
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| 126 | * @return bool  | 
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| 127 | */  | 
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| 128 | public function mergeParams(array $params, bool $autoUpdate = false)  | 
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| 191 | |||
| 192 | /**  | 
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| 193 | * Flush system params cache  | 
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| 194 | */  | 
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| 195 | public static function flushCache()  | 
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| 201 | |||
| 202 | /**  | 
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| 203 | * Generate array of keys recursively in string.  | 
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| 204 | *  | 
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| 205 | * @param $dataArray  | 
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| 206 | *  | 
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| 207 | * @return array  | 
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| 208 | *  | 
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| 209 | * @author Virchenko Maksim <[email protected]>  | 
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| 210 | */  | 
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| 211 | protected function getArrayKeysRecursivelyInString(array $dataArray): array  | 
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| 227 | |||
| 228 | /**  | 
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| 229 | * Return param value or false if param not exist.  | 
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| 230 | *  | 
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| 231 | * @param $pk  | 
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| 232 | * @param $array  | 
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| 233 | *  | 
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| 234 | * @return bool  | 
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| 235 | *  | 
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| 236 | * @author Chaykovskiy Roman  | 
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| 237 | */  | 
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| 238 | protected function getParamValueByKey($pk, $array)  | 
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| 251 | |||
| 252 | /**  | 
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| 253 | * Generate multidimensional array for pk with value.  | 
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| 254 | *  | 
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| 255 | * @param $pk can be string like 'a|b...|n'  | 
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| 256 | * @param $value  | 
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| 257 | *  | 
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| 258 | * @return array  | 
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| 259 | *  | 
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| 260 | * @author Chaykovskiy Roman  | 
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| 261 | */  | 
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| 262 | protected function generateArrayForParamValue($pk, $value)  | 
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| 281 | }  | 
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| 282 | 
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..