class JumbledIncrementerSniff

class JumbledIncrementerSniff implements Sniff {
    
    /**
     * Registers the tokens that this sniff wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        return [
            T_FOR,
        ];
    }
    
    //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();
        $token = $tokens[$stackPtr];
        // Skip for-loop without body.
        if (isset($token['scope_opener']) === false) {
            return;
        }
        // Find incrementers for outer loop.
        $outer = $this->findIncrementers($tokens, $token);
        // Skip if empty.
        if (count($outer) === 0) {
            return;
        }
        // Find nested for loops.
        $start = ++$token['scope_opener'];
        $end = --$token['scope_closer'];
        for (; $start <= $end; ++$start) {
            if ($tokens[$start]['code'] !== T_FOR) {
                continue;
            }
            $inner = $this->findIncrementers($tokens, $tokens[$start]);
            $diff = array_intersect($outer, $inner);
            if (count($diff) !== 0) {
                $error = 'Loop incrementer (%s) jumbling with inner loop';
                $data = [
                    implode(', ', $diff),
                ];
                $phpcsFile->addWarning($error, $stackPtr, 'Found', $data);
            }
        }
    }
    
    //end process()
    
    /**
     * Get all used variables in the incrementer part of a for statement.
     *
     * @param array<int, array>    $tokens Array with all code sniffer tokens.
     * @param array<string, mixed> $token  Current for loop token.
     *
     * @return string[] List of all found incrementer variables.
     */
    protected function findIncrementers(array $tokens, array $token) {
        // Skip invalid statement.
        if (isset($token['parenthesis_opener'], $token['parenthesis_closer']) === false) {
            return [];
        }
        $start = ++$token['parenthesis_opener'];
        $end = --$token['parenthesis_closer'];
        $incrementers = [];
        $semicolons = 0;
        for ($next = $start; $next <= $end; ++$next) {
            $code = $tokens[$next]['code'];
            if ($code === T_SEMICOLON) {
                ++$semicolons;
            }
            else {
                if ($semicolons === 2 && $code === T_VARIABLE) {
                    $incrementers[] = $tokens[$next]['content'];
                }
            }
        }
        return $incrementers;
    }
    
    //end findIncrementers()

}