<?php

define('WIKIPEDIA_SUBJECT_TFA', 0); // Today's featured article
define('WIKIPEDIA_SUBJECT_DYK', 1); // Did you know...

class WikipediaBridge extends BridgeAbstract
{
    const MAINTAINER = 'logmanoriginal';
    const NAME = 'Wikipedia bridge for many languages';
    const URI = 'https://www.wikipedia.org/';
    const DESCRIPTION = 'Returns articles for a language of your choice';

    const PARAMETERS = [ [
        'language' => [
            'name' => 'Language',
            'type' => 'list',
            'title' => 'Select your language',
            'exampleValue' => 'English',
            'values' => [
                'English' => 'en',
                'Русский' => 'ru',
                'Dutch' => 'nl',
                'Esperanto' => 'eo',
                'French' => 'fr',
                'German' => 'de',
            ]
        ],
        'subject' => [
            'name' => 'Subject',
            'type' => 'list',
            'title' => 'What subject are you interested in?',
            'exampleValue' => 'Today\'s featured article',
            'values' => [
                'Today\'s featured article' => 'tfa',
                'Did you know…' => 'dyk'
            ]
        ],
        'fullarticle' => [
            'name' => 'Load full article',
            'type' => 'checkbox',
            'title' => 'Activate to always load the full article'
        ]
    ]];

    public function getURI()
    {
        if (!is_null($this->getInput('language'))) {
            return 'https://'
            . strtolower($this->getInput('language'))
            . '.wikipedia.org';
        }

        return parent::getURI();
    }

    public function getName()
    {
        switch ($this->getInput('subject')) {
            case 'tfa':
                $subject = WIKIPEDIA_SUBJECT_TFA;
                break;
            case 'dyk':
                $subject = WIKIPEDIA_SUBJECT_DYK;
                break;
            default:
                return parent::getName();
        }

        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $name = 'Today\'s featured article from '
                . strtolower($this->getInput('language'))
                . '.wikipedia.org';
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $name = 'Did you know? - articles from '
                . strtolower($this->getInput('language'))
                . '.wikipedia.org';
                break;
            default:
                $name = 'Articles from '
                . strtolower($this->getInput('language'))
                . '.wikipedia.org';
                break;
        }
        return $name;
    }

    public function collectData()
    {
        switch ($this->getInput('subject')) {
            case 'tfa':
                $subject = WIKIPEDIA_SUBJECT_TFA;
                break;
            case 'dyk':
                $subject = WIKIPEDIA_SUBJECT_DYK;
                break;
            default:
                $subject = WIKIPEDIA_SUBJECT_TFA;
                break;
        }

        $fullArticle = $this->getInput('fullarticle');

        // This will automatically send us to the correct main page in any language (try it!)
        $html = getSimpleHTMLDOM($this->getURI() . '/wiki');

        if (!$html) {
            returnServerError('Could not load site: ' . $this->getURI() . '!');
        }

        /*
        * Now read content depending on the language (make sure to create one function per language!)
        * We build the function name automatically, just make sure you create a private function ending
        * with your desired language code, where the language code is upper case! (en -> getContentsEN).
        */
        $function = 'getContents' . ucfirst(strtolower($this->getInput('language')));

        if (!method_exists($this, $function)) {
            returnServerError('A function to get the contents for your language is missing (\'' . $function . '\')!');
        }

        /*
        * The method takes care of creating all items.
        */
        $this->$function($html, $subject, $fullArticle);
    }

    /**
    * Replaces all relative URIs with absolute ones
    * @param $element A simplehtmldom element
    * @return The $element->innertext with all URIs replaced
    */
    private function replaceUriInHtmlElement($element)
    {
        return str_replace('href="/', 'href="' . $this->getURI() . '/', $element->innertext);
    }

    /*
    * Adds a new item to $items using a generic operation (should work for most
    * (all?) wikis) $anchorText can be specified if the wiki in question doesn't
    * use '...' (like Dutch, French and Italian) $anchorFallbackIndex can be
    * used to specify a different fallback link than the first
    * (e.g., -1 for the last)
    */
    private function addTodaysFeaturedArticleGeneric(
        $element,
        $fullArticle,
        $anchorText = '...',
        $anchorFallbackIndex = 0
    ) {
        // Clean the bottom of the featured article
        if ($element->find('ul', -1)) {
            $element->find('ul', -1)->outertext = '';
        } elseif ($element->find('div', -1)) {
            $element->find('div', -1)->outertext = '';
        }

        // The title and URI of the article can be found in an anchor containing
        // the string '...' in most wikis ('full article ...')
        $target = $element->find('p a', $anchorFallbackIndex);
        foreach ($element->find('//a') as $anchor) {
            if (strpos($anchor->innertext, $anchorText) !== false) {
                $target = $anchor;
                break;
            }
        }

        $item = [];
        $item['uri'] = $this->getURI() . $target->href;
        $item['title'] = $target->title;

        if (!$fullArticle) {
            $item['content'] = strip_tags($this->replaceUriInHtmlElement($element), '<a><p><br><img>');
        } else {
            $item['content'] = $this->loadFullArticle($item['uri']);
        }

        $this->items[] = $item;
    }

    /*
    * Adds a new item to $items using a generic operation (should work for most (all?) wikis)
    */
    private function addDidYouKnowGeneric($element, $fullArticle)
    {
        foreach ($element->find('ul', 0)->find('li') as $entry) {
            $item = [];

            // We can only use the first anchor, there is no way of finding the 'correct' one if there are multiple
            $item['uri'] = $this->getURI() . $entry->find('a', 0)->href;
            $item['title'] = strip_tags($entry->innertext);

            if (!$fullArticle) {
                $item['content'] = $this->replaceUriInHtmlElement($entry);
            } else {
                $item['content'] = $this->loadFullArticle($item['uri']);
            }

            $this->items[] = $item;
        }
    }

    /**
    * Loads the full article from a given URI
    */
    private function loadFullArticle($uri)
    {
        $content_html = getSimpleHTMLDOMCached($uri);

        if (!$content_html) {
            returnServerError('Could not load site: ' . $uri . '!');
        }

        $content = $content_html->find('#mw-content-text', 0);

        if (!$content) {
            returnServerError('Could not find content in page: ' . $uri . '!');
        }

        // Let's remove a couple of things from the article
        $table = $content->find('#toc', 0); // Table of contents
        if (!$table === false) {
            $table->outertext = '';
        }

        foreach ($content->find('ol.references') as $reference) { // References
            $reference->outertext = '';
        }

        return str_replace('href="/', 'href="' . $this->getURI() . '/', $content->innertext);
    }

    /**
    * Implementation for de.wikipedia.org
    */
    private function getContentsDe($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('div[id=artikel] div.hauptseite-box-content', 0);
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle);
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('div[id=wissenswertes]', 0);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }

    /**
    * Implementation for fr.wikipedia.org
    */
    private function getContentsFr($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('div[class=accueil_2017_cadre]', 0);
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle, 'Lire la suite');
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('div[class=accueil_2017_cadre]', 2);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }

    /**
    * Implementation for en.wikipedia.org
    */
    private function getContentsEn($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('div[id=mp-tfa]', 0);
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle, -1);
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('div[id=mp-dyk]', 0);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }

    /**
    * Implementation for ru.wikipedia.org
    */
    private function getContentsRu($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('div[id=main-tfa]', 0);
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle, -1);
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('div[id=main-dyk]', 0);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }

    /**
    * Implementation for eo.wikipedia.org
    */
    private function getContentsEo($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('div[id=mf-artikolo-de-la-monato]', 0);
                $element->find('div', -2)->outertext = '';
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle);
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('div.hp', 1)->find('table', 4)->find('td', -1);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }

    /**
    * Implementation for nl.wikipedia.org
    */
    private function getContentsNl($html, $subject, $fullArticle)
    {
        switch ($subject) {
            case WIKIPEDIA_SUBJECT_TFA:
                $element = $html->find('td[id=segment-Uitgelicht] div', 0);
                $element->find('p', 1)->outertext = '';
                $this->addTodaysFeaturedArticleGeneric($element, $fullArticle, 'Lees verder');
                break;
            case WIKIPEDIA_SUBJECT_DYK:
                $element = $html->find('td[id=segment-Wist_je_dat] div', 0);
                $this->addDidYouKnowGeneric($element, $fullArticle);
                break;
            default:
                break;
        }
    }
}