<?php

declare(strict_types=1);

/*
 * This file is part of the league/commonmark package.
 *
 * (c) Colin O'Dell <colinodell@gmail.com>
 *
 * Original code based on the CommonMark JS reference parser (https://bitly.com/commonmark-js)
 *  - (c) John MacFarlane
 *
 * Additional emphasis processing code based on commonmark-java (https://github.com/atlassian/commonmark-java)
 *  - (c) Atlassian Pty Ltd
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace League\CommonMark\Extension\CommonMark\Delimiter\Processor;

use League\CommonMark\Delimiter\DelimiterInterface;
use League\CommonMark\Delimiter\Processor\CacheableDelimiterProcessorInterface;
use League\CommonMark\Extension\CommonMark\Node\Inline\Emphasis;
use League\CommonMark\Extension\CommonMark\Node\Inline\Strong;
use League\CommonMark\Node\Inline\AbstractStringContainer;
use League\Config\ConfigurationAwareInterface;
use League\Config\ConfigurationInterface;

final class EmphasisDelimiterProcessor implements CacheableDelimiterProcessorInterface, ConfigurationAwareInterface
{
    /** @psalm-readonly */
    private string $char;

    /** @psalm-readonly-allow-private-mutation */
    private ConfigurationInterface $config;

    /**
     * @param string $char The emphasis character to use (typically '*' or '_')
     */
    public function __construct(string $char)
    {
        $this->char = $char;
    }

    public function getOpeningCharacter(): string
    {
        return $this->char;
    }

    public function getClosingCharacter(): string
    {
        return $this->char;
    }

    public function getMinLength(): int
    {
        return 1;
    }

    public function getDelimiterUse(DelimiterInterface $opener, DelimiterInterface $closer): int
    {
        // "Multiple of 3" rule for internal delimiter runs
        if (($opener->canClose() || $closer->canOpen()) && $closer->getOriginalLength() % 3 !== 0 && ($opener->getOriginalLength() + $closer->getOriginalLength()) % 3 === 0) {
            return 0;
        }

        // Calculate actual number of delimiters used from this closer
        if ($opener->getLength() >= 2 && $closer->getLength() >= 2) {
            if ($this->config->get('commonmark/enable_strong')) {
                return 2;
            }

            return 0;
        }

        if ($this->config->get('commonmark/enable_em')) {
            return 1;
        }

        return 0;
    }

    public function process(AbstractStringContainer $opener, AbstractStringContainer $closer, int $delimiterUse): void
    {
        if ($delimiterUse === 1) {
            $emphasis = new Emphasis($this->char);
        } elseif ($delimiterUse === 2) {
            $emphasis = new Strong($this->char . $this->char);
        } else {
            return;
        }

        $next = $opener->next();
        while ($next !== null && $next !== $closer) {
            $tmp = $next->next();
            $emphasis->appendChild($next);
            $next = $tmp;
        }

        $opener->insertAfter($emphasis);
    }

    public function setConfiguration(ConfigurationInterface $configuration): void
    {
        $this->config = $configuration;
    }

    public function getCacheKey(DelimiterInterface $closer): string
    {
        return \sprintf(
            '%s-%s-%d-%d',
            $this->char,
            $closer->canOpen() ? 'canOpen' : 'cannotOpen',
            $closer->getOriginalLength() % 3,
            // getDelimiterUse() only ever asks whether the closer's length is >= 2, so lengths
            // beyond that are interchangeable. Clamping keeps the key space bounded, which is
            // what makes the delimiter stack's lower-bound cache amortize.
            \min($closer->getLength(), 2),
        );
    }
}
