<?php
/**
 * Prefer the use of nowdoc over heredoc.
 *
 * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
 * @copyright 2024 PHPCSStandards and contributors
 * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/HEAD/licence.txt BSD Licence
 */

namespace PHP_CodeSniffer\Standards\Generic\Sniffs\Strings;

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

class UnnecessaryHeredocSniff implements Sniff
{

    /**
     * Escape chars which are supported in heredocs, but not in nowdocs.
     *
     * @var array<string>
     */
    private const ESCAPE_CHARS = [
        // Octal sequences.
        '\0',
        '\1',
        '\2',
        '\3',
        '\4',
        '\5',
        '\6',
        '\7',

        // Various whitespace and the escape char.
        '\n',
        '\r',
        '\t',
        '\v',
        '\e',
        '\f',

        // Hex and unicode sequences.
        '\x',
        '\u',
    ];


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


    /**
     * 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, int $stackPtr)
    {
        $tokens = $phpcsFile->getTokens();

        if (isset($tokens[$stackPtr]['scope_closer']) === false) {
            // Just to be safe. Shouldn't be possible as in that case, the opener shouldn't be tokenized
            // to T_START_HEREDOC by PHP.
            return; // @codeCoverageIgnore
        }

        $closer = $tokens[$stackPtr]['scope_closer'];
        $body   = '';

        // Collect all the tokens within the heredoc body.
        for ($i = ($stackPtr + 1); $i < $closer; $i++) {
            $body .= $tokens[$i]['content'];
        }

        $tokenizedBody = token_get_all(sprintf("<?php <<<EOD\n%s\nEOD;\n?>", $body));
        foreach ($tokenizedBody as $ptr => $bodyToken) {
            if (is_array($bodyToken) === false) {
                continue;
            }

            if ($bodyToken[0] === T_DOLLAR_OPEN_CURLY_BRACES
                || $bodyToken[0] === T_VARIABLE
            ) {
                // Contains interpolation or expression.
                $phpcsFile->recordMetric($stackPtr, 'Heredoc contains interpolation or expression', 'yes');
                return;
            }

            if ($bodyToken[0] === T_CURLY_OPEN
                && is_array($tokenizedBody[($ptr + 1)]) === false
                && $tokenizedBody[($ptr + 1)] === '$'
            ) {
                // Contains interpolation or expression.
                $phpcsFile->recordMetric($stackPtr, 'Heredoc contains interpolation or expression', 'yes');
                return;
            }
        }

        $phpcsFile->recordMetric($stackPtr, 'Heredoc contains interpolation or expression', 'no');

        // Check for escape sequences which aren't supported in nowdocs.
        foreach (self::ESCAPE_CHARS as $testChar) {
            if (strpos($body, $testChar) !== false) {
                return;
            }
        }

        $warning = 'Detected heredoc without interpolation or expressions. Use nowdoc syntax instead';

        $fix = $phpcsFile->addFixableWarning($warning, $stackPtr, 'Found');
        if ($fix === true) {
            $phpcsFile->fixer->beginChangeset();

            $identifier  = trim(ltrim($tokens[$stackPtr]['content'], '<'));
            $replaceWith = "'" . trim($identifier, '"') . "'";
            $replacement = str_replace($identifier, $replaceWith, $tokens[$stackPtr]['content']);
            $phpcsFile->fixer->replaceToken($stackPtr, $replacement);

            for ($i = ($stackPtr + 1); $i < $closer; $i++) {
                $content = $tokens[$i]['content'];
                $content = str_replace(['\\$', '\\\\'], ['$', '\\'], $content);
                if ($tokens[$i]['content'] !== $content) {
                    $phpcsFile->fixer->replaceToken($i, $content);
                }
            }

            $phpcsFile->fixer->endChangeset();
        }
    }
}
