class FileEncodingSniff

class FileEncodingSniff implements Sniff {
    
    /**
     * List of encodings that files may be encoded with.
     *
     * Any other detected encodings will throw a warning.
     *
     * @var array<string>
     */
    public $allowedEncodings = [
        'UTF-8',
    ];
    
    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register() {
        return [
            T_INLINE_HTML,
            T_OPEN_TAG,
        ];
    }
    
    //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 int|void
     */
    public function process(File $phpcsFile, $stackPtr) {
        // Not all PHP installs have the multi byte extension - nothing we can do.
        if (function_exists('mb_check_encoding') === false) {
            return $phpcsFile->numTokens;
        }
        $fileContent = $phpcsFile->getTokensAsString(0, $phpcsFile->numTokens);
        $validEncodingFound = false;
        foreach ($this->allowedEncodings as $encoding) {
            if (mb_check_encoding($fileContent, $encoding) === true) {
                $validEncodingFound = true;
            }
        }
        if ($validEncodingFound === false) {
            $warning = 'File encoding is invalid, expected %s';
            $data = [
                implode(' or ', $this->allowedEncodings),
            ];
            $phpcsFile->addWarning($warning, $stackPtr, 'InvalidEncoding', $data);
        }
        return $phpcsFile->numTokens;
    }
    
    //end process()

}