class LowercasePHPFunctionsSniff

class LowercasePHPFunctionsSniff implements Sniff {
    
    /**
     * String -> int hash map of all php built in function names
     *
     * @var array
     */
    private $builtInFunctions;
    
    /**
     * Construct the LowercasePHPFunctionSniff
     */
    public function __construct() {
        $allFunctions = get_defined_functions();
        $this->builtInFunctions = array_flip($allFunctions['internal']);
    }
    
    //end __construct()
    
    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        return [
            T_STRING,
        ];
    }
    
    //end register()
    
    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
     * @param int                         $stackPtr  The position of the current token in
     *                                               the stack passed in $tokens.
     *
     * @return void
     */
    public function process(File $phpcsFile, $stackPtr) {
        $tokens = $phpcsFile->getTokens();
        $content = $tokens[$stackPtr]['content'];
        $contentLc = strtolower($content);
        if ($content === $contentLc) {
            return;
        }
        // Make sure it is an inbuilt PHP function.
        // PHP_CodeSniffer can possibly include user defined functions
        // through the use of vendor/autoload.php.
        if (isset($this->builtInFunctions[$contentLc]) === false) {
            return;
        }
        // Make sure this is a function call or a use statement.
        if (empty($tokens[$stackPtr]['nested_attributes']) === false) {
            // Class instantiation in attribute, not function call.
            return;
        }
        $next = $phpcsFile->findNext(Tokens::$emptyTokens, $stackPtr + 1, null, true);
        if ($next === false) {
            // Not a function call.
            return;
        }
        $ignore = Tokens::$emptyTokens;
        $ignore[] = T_BITWISE_AND;
        $prev = $phpcsFile->findPrevious($ignore, $stackPtr - 1, null, true);
        $prevPrev = $phpcsFile->findPrevious(Tokens::$emptyTokens, $prev - 1, null, true);
        if ($tokens[$next]['code'] !== T_OPEN_PARENTHESIS) {
            // Is this a use statement importing a PHP native function ?
            if ($tokens[$next]['code'] !== T_NS_SEPARATOR && $tokens[$prev]['code'] === T_STRING && $tokens[$prev]['content'] === 'function' && $prevPrev !== false && $tokens[$prevPrev]['code'] === T_USE) {
                $error = 'Use statements for PHP native functions must be lowercase; expected "%s" but found "%s"';
                $data = [
                    $contentLc,
                    $content,
                ];
                $fix = $phpcsFile->addFixableError($error, $stackPtr, 'UseStatementUppercase', $data);
                if ($fix === true) {
                    $phpcsFile->fixer
                        ->replaceToken($stackPtr, $contentLc);
                }
            }
            // No open parenthesis; not a "use function" statement nor a function call.
            return;
        }
        
        //end if
        if ($tokens[$prev]['code'] === T_FUNCTION) {
            // Function declaration, not a function call.
            return;
        }
        if ($tokens[$prev]['code'] === T_NS_SEPARATOR) {
            if ($prevPrev !== false && ($tokens[$prevPrev]['code'] === T_STRING || $tokens[$prevPrev]['code'] === T_NAMESPACE || $tokens[$prevPrev]['code'] === T_NEW)) {
                // Namespaced class/function, not an inbuilt function.
                // Could potentially give false negatives for non-namespaced files
                // when namespace\functionName() is encountered.
                return;
            }
        }
        if ($tokens[$prev]['code'] === T_NEW) {
            // Object creation, not an inbuilt function.
            return;
        }
        if ($tokens[$prev]['code'] === T_OBJECT_OPERATOR || $tokens[$prev]['code'] === T_NULLSAFE_OBJECT_OPERATOR) {
            // Not an inbuilt function.
            return;
        }
        if ($tokens[$prev]['code'] === T_DOUBLE_COLON) {
            // Not an inbuilt function.
            return;
        }
        $error = 'Calls to PHP native functions must be lowercase; expected "%s" but found "%s"';
        $data = [
            $contentLc,
            $content,
        ];
        $fix = $phpcsFile->addFixableError($error, $stackPtr, 'CallUppercase', $data);
        if ($fix === true) {
            $phpcsFile->fixer
                ->replaceToken($stackPtr, $contentLc);
        }
    }
    
    //end process()

}