<?php

declare(strict_types=1);

/*
 * This file is part of PHP CS Fixer.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

namespace PhpCsFixer\Fixer\Whitespace;

use PhpCsFixer\AbstractFixer;
use PhpCsFixer\Fixer\WhitespacesAwareFixerInterface;
use PhpCsFixer\FixerDefinition\CodeSample;
use PhpCsFixer\FixerDefinition\FixerDefinition;
use PhpCsFixer\FixerDefinition\FixerDefinitionInterface;
use PhpCsFixer\Preg;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Dariusz Rumiński <dariusz.ruminski@gmail.com>
 */
final class NoWhitespaceInBlankLineFixer extends AbstractFixer implements WhitespacesAwareFixerInterface
{
    public function getDefinition(): FixerDefinitionInterface
    {
        return new FixerDefinition(
            'Remove trailing whitespace at the end of blank lines.',
            [new CodeSample("<?php\n   \n\$a = 1;\n")]
        );
    }

    /**
     * {@inheritdoc}
     *
     * Must run after AssignNullCoalescingToCoalesceEqualFixer, CombineConsecutiveIssetsFixer, CombineConsecutiveUnsetsFixer, FunctionToConstantFixer, NoEmptyCommentFixer, NoEmptyStatementFixer, NoUselessElseFixer, NoUselessReturnFixer, YieldFromArrayToYieldsFixer.
     */
    public function getPriority(): int
    {
        return -99;
    }

    public function isCandidate(Tokens $tokens): bool
    {
        return true;
    }

    protected function applyFix(\SplFileInfo $file, Tokens $tokens): void
    {
        // skip first as it cannot be a white space token
        for ($i = 1, $count = \count($tokens); $i < $count; ++$i) {
            if ($tokens[$i]->isWhitespace()) {
                $this->fixWhitespaceToken($tokens, $i);
            }
        }
    }

    private function fixWhitespaceToken(Tokens $tokens, int $index): void
    {
        $content = $tokens[$index]->getContent();
        $lines = Preg::split("/(\r\n|\n)/", $content);
        $lineCount = \count($lines);

        if (
            // fix T_WHITESPACES with at least 3 lines (eg `\n   \n`)
            $lineCount > 2
            // and T_WHITESPACES with at least 2 lines at the end of file or after open tag with linebreak
            || ($lineCount > 0 && (!isset($tokens[$index + 1]) || $tokens[$index - 1]->isGivenKind(T_OPEN_TAG)))
        ) {
            $lMax = isset($tokens[$index + 1]) ? $lineCount - 1 : $lineCount;

            $lStart = 1;
            if ($tokens[$index - 1]->isGivenKind(T_OPEN_TAG) && "\n" === substr($tokens[$index - 1]->getContent(), -1)) {
                $lStart = 0;
            }

            for ($l = $lStart; $l < $lMax; ++$l) {
                $lines[$l] = Preg::replace('/^\h+$/', '', $lines[$l]);
            }
            $content = implode($this->whitespacesConfig->getLineEnding(), $lines);
            $tokens->ensureWhitespaceAtIndex($index, 0, $content);
        }
    }
}
