<?php
/**
 * A simple sniff for detecting a BOM definition that may corrupt application work.
 *
 * @author    Piotr Karas <office@mediaself.pl>
 * @author    Greg Sherwood <gsherwood@squiz.net>
 * @copyright 2010-2014 mediaSELF Sp. z o.o.
 * @copyright 2023 PHPCSStandards and contributors
 * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/HEAD/licence.txt BSD Licence
 */

namespace PHP_CodeSniffer\Standards\Generic\Sniffs\Files;

use PHP_CodeSniffer\Files\File;
use PHP_CodeSniffer\Sniffs\Sniff;

class ByteOrderMarkSniff implements Sniff
{

    /**
     * List of supported BOM definitions.
     *
     * Use encoding names as keys and hex BOM representations as values.
     *
     * @var array<string, string>
     */
    protected const BOM_DEFINITIONS = [
        'UTF-8'       => 'efbbbf',
        'UTF-16 (BE)' => 'feff',
        'UTF-16 (LE)' => 'fffe',
    ];

    /**
     * List of supported BOM definitions.
     *
     * @var array<string, string>
     *
     * @deprecated 4.0.0 Use the ByteOrderMarkSniff::BOM_DEFINITIONS constant instead.
     */
    protected $bomDefinitions = self::BOM_DEFINITIONS;


    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @return array<int|string>
     */
    public function register()
    {
        return [T_INLINE_HTML];
    }


    /**
     * 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
     */
    public function process(File $phpcsFile, int $stackPtr)
    {
        // The BOM will be the very first token in the file.
        if ($stackPtr !== 0) {
            return $phpcsFile->numTokens;
        }

        $tokens = $phpcsFile->getTokens();

        foreach (static::BOM_DEFINITIONS as $bomName => $expectedBomHex) {
            $bomByteLength = (strlen($expectedBomHex) / 2);
            $htmlBomHex    = bin2hex(substr($tokens[$stackPtr]['content'], 0, $bomByteLength));
            if ($htmlBomHex === $expectedBomHex) {
                $errorData = [$bomName];
                $error     = 'File contains %s byte order mark, which may corrupt your application';
                $phpcsFile->addError($error, $stackPtr, 'Found', $errorData);
                $phpcsFile->recordMetric($stackPtr, 'Using byte order mark', 'yes');
                return $phpcsFile->numTokens;
            }
        }

        $phpcsFile->recordMetric($stackPtr, 'Using byte order mark', 'no');

        return $phpcsFile->numTokens;
    }
}
