class AjaxNullComparisonSniff

class AjaxNullComparisonSniff implements Sniff {
    
    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        return [
            T_FUNCTION,
        ];
    }
    
    //end register()
    
    /**
     * Processes this sniff, 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();
        // Make sure it is an API function. We know this by the doc comment.
        $commentEnd = $phpcsFile->findPrevious(T_DOC_COMMENT_CLOSE_TAG, $stackPtr);
        $commentStart = $phpcsFile->findPrevious(T_DOC_COMMENT_OPEN_TAG, $commentEnd - 1);
        // If function doesn't contain any doc comments - skip it.
        if ($commentEnd === false || $commentStart === false) {
            return;
        }
        $comment = $phpcsFile->getTokensAsString($commentStart, $commentEnd - $commentStart);
        if (strpos($comment, '* @api') === false) {
            return;
        }
        // Find all the vars passed in as we are only interested in comparisons
        // to NULL for these specific variables.
        $foundVars = [];
        $open = $tokens[$stackPtr]['parenthesis_opener'];
        $close = $tokens[$stackPtr]['parenthesis_closer'];
        for ($i = $open + 1; $i < $close; $i++) {
            if ($tokens[$i]['code'] === T_VARIABLE) {
                $foundVars[$tokens[$i]['content']] = true;
            }
        }
        if (empty($foundVars) === true) {
            return;
        }
        $start = $tokens[$stackPtr]['scope_opener'];
        $end = $tokens[$stackPtr]['scope_closer'];
        for ($i = $start + 1; $i < $end; $i++) {
            if ($tokens[$i]['code'] !== T_VARIABLE || isset($foundVars[$tokens[$i]['content']]) === false) {
                continue;
            }
            $operator = $phpcsFile->findNext(T_WHITESPACE, $i + 1, null, true);
            if ($tokens[$operator]['code'] !== T_IS_IDENTICAL && $tokens[$operator]['code'] !== T_IS_NOT_IDENTICAL) {
                continue;
            }
            $nullValue = $phpcsFile->findNext(T_WHITESPACE, $operator + 1, null, true);
            if ($tokens[$nullValue]['code'] !== T_NULL) {
                continue;
            }
            $error = 'Values submitted via Ajax requests should not be compared directly to NULL; use empty() instead';
            $phpcsFile->addWarning($error, $nullValue, 'Found');
        }
        
        //end for
    }
    
    //end process()

}