<?php
/**
 * PHPCSExtra, a collection of sniffs and standards for use with PHP_CodeSniffer.
 *
 * @package   PHPCSExtra
 * @copyright 2020 PHPCSExtra Contributors
 * @license   https://opensource.org/licenses/LGPL-3.0 LGPL3
 * @link      https://github.com/PHPCSStandards/PHPCSExtra
 */

namespace PHPCSExtra\Universal\Sniffs\CodeAnalysis;

use PHP_CodeSniffer\Files\File;
use PHP_CodeSniffer\Sniffs\Sniff;
use PHP_CodeSniffer\Util\Tokens;
use PHPCSUtils\Tokens\Collections;
use PHPCSUtils\Utils\GetTokensAsString;
use PHPCSUtils\Utils\Lists;

/**
 * Detects using the same variable for both the key as well as the value in a foreach assignment.
 *
 * @link https://twitter.com/exakat/status/1509103728934203397
 * @link https://3v4l.org/DdddX
 *
 * @since 1.0.0
 */
final class ForeachUniqueAssignmentSniff implements Sniff
{

    /**
     * Returns an array of tokens this test wants to listen for.
     *
     * @since 1.0.0
     *
     * @return array<int|string>
     */
    public function register()
    {
        return [\T_FOREACH];
    }

    /**
     * Processes this test, when one of its tokens is encountered.
     *
     * @since 1.0.0
     *
     * @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();

        if (isset($tokens[$stackPtr]['parenthesis_opener'], $tokens[$stackPtr]['parenthesis_closer']) === false) {
            // Parse error or live coding, not our concern.
            return;
        }

        $opener = $tokens[$stackPtr]['parenthesis_opener'];
        $closer = $tokens[$stackPtr]['parenthesis_closer'];

        $asPtr = $phpcsFile->findNext(\T_AS, ($opener + 1), $closer);
        if ($asPtr === false) {
            // Parse error or live coding, not our concern.
            return;
        }

        // Real target.
        $find = [\T_DOUBLE_ARROW];
        // Prevent matching on double arrows within a list assignment.
        $find += Collections::listTokens();

        $doubleArrowPtr = $phpcsFile->findNext($find, ($asPtr + 1), $closer);
        if ($doubleArrowPtr === false
            || $tokens[$doubleArrowPtr]['code'] !== \T_DOUBLE_ARROW
        ) {
            // No key assignment.
            return;
        }

        $isListAssignment = $phpcsFile->findNext(Tokens::$emptyTokens, ($doubleArrowPtr + 1), $closer, true);
        if ($isListAssignment === false) {
            // Parse error or live coding, not our concern.
        }

        $keyAsString      = \ltrim(GetTokensAsString::noEmpties($phpcsFile, ($asPtr + 1), ($doubleArrowPtr - 1)), '&');
        $valueAssignments = [];
        if (isset(Collections::listTokens()[$tokens[$isListAssignment]['code']]) === false) {
            // Single value assignment.
            $valueAssignments[] = GetTokensAsString::noEmpties($phpcsFile, ($doubleArrowPtr + 1), ($closer - 1));
        } else {
            // List assignment.
            $assignments = Lists::getAssignments($phpcsFile, $isListAssignment);
            foreach ($assignments as $listItem) {
                if ($listItem['assignment'] === '') {
                    // Ignore empty list assignments.
                    continue;
                }

                // Note: this doesn't take nested lists into account (yet).
                $valueAssignments[] = $listItem['assignment'];
            }
        }

        if (empty($valueAssignments)) {
            // No assignments found.
            return;
        }

        foreach ($valueAssignments as $valueAsString) {
            $valueAsString = \ltrim($valueAsString, '&');

            if ($keyAsString !== $valueAsString) {
                // Key and value not the same.
                continue;
            }

            $error  = 'The variables used for the key and the value in a foreach assignment should be unique.';
            $error .= 'Both the key and the value will currently be assigned to: "%s"';

            $fix = $phpcsFile->addFixableError($error, $doubleArrowPtr, 'NotUnique', [$valueAsString]);
            if ($fix === true) {
                $phpcsFile->fixer->beginChangeset();

                // Remove the key.
                for ($i = ($asPtr + 1); $i < ($doubleArrowPtr + 1); $i++) {
                    if ($tokens[$i]['code'] === \T_WHITESPACE
                        && isset(Tokens::$commentTokens[$tokens[($i + 1)]['code']])
                    ) {
                        // Don't remove whitespace when followed directly by a comment.
                        continue;
                    }

                    if (isset(Tokens::$commentTokens[$tokens[$i]['code']])) {
                        // Don't remove comments.
                        continue;
                    }

                    // Remove everything else.
                    $phpcsFile->fixer->replaceToken($i, '');
                }

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

            break;
        }
    }
}