<?php

namespace Erusev\Parsedown\Components\Inlines;

use Erusev\Parsedown\Components\BacktrackingInline;
use Erusev\Parsedown\Components\Inline;
use Erusev\Parsedown\Html\Renderables\Element;
use Erusev\Parsedown\Html\Renderables\Text;
use Erusev\Parsedown\Parsing\Excerpt;
use Erusev\Parsedown\State;

final class Url implements BacktrackingInline
{
    use WidthTrait;

    private const URI = 'https?+:[^\s[:cntrl:]<>]*';
    private const NO_TRAILING_PUNCT = '(?<![?!.,:*_~])';

    /** @var string */
    private $url;

    /** @var int */
    private $position;

    /**
     * @param string $url
     * @param int $position
     */
    private function __construct($url, $position)
    {
        $this->url = $url;
        $this->width = \strlen($url);
        $this->position = $position;
    }

    /**
     * @param Excerpt $Excerpt
     * @param State $State
     * @return static|null
     */
    public static function build(Excerpt $Excerpt, State $State)
    {
        // this needs some work to follow spec
        if (
            \preg_match(
                '/'.self::URI.self::NO_TRAILING_PUNCT.'/iu',
                $Excerpt->context(),
                $matches,
                \PREG_OFFSET_CAPTURE
            )
        ) {
            /** @var array{0: array{string, int}} $matches */
            $url = $matches[0][0];
            $position = \intval($matches[0][1]);

            if (\preg_match('/[)]++$/', $url, $matches)) {
                $trailingParens = \strlen($matches[0]);

                $openingParens = \substr_count($url, '(');
                $closingParens = \substr_count($url, ')');

                if ($closingParens > $openingParens) {
                    $url = \substr($url, 0, -\min($trailingParens, $closingParens - $openingParens));
                }
            }

            return new self($url, $position);
        }

        return null;
    }

    /**
     * Return an integer to declare that the inline should be treated as if it
     * started from that position in the excerpt given to static::build.
     * Return null to use the excerpt offset value.
     * @return int|null
     * */
    public function modifyStartPositionTo()
    {
        return $this->position;
    }

    /** @return string */
    public function url()
    {
        return $this->url;
    }

    /**
     * @return Element
     */
    public function stateRenderable()
    {
        return new Element('a', ['href' => $this->url()], [new Text($this->url())]);
    }

    /**
     * @return Text
     */
    public function bestPlaintext()
    {
        return new Text($this->url());
    }
}