<?php
/*
Copyright (c) 2006, Maurice Svay
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of Maurice Svay nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/**
 * Planet, main app class
 */
class Planet
{
    /** @var PlanetConfig */
    public $config;

    /** @var PlanetItem[] */
    public $items;

    /** @var PlanetFeed[] */
    public $people;

    /** @var PlanetError[] */
    public $errors;

    /**
     * Planet constructor.
     *
     * @param PlanetConfig $config
     */
    public function __construct($config=null)
    {
        $this->config = $config === null ? new PlanetConfig() : $config;

        $this->items  = [];
        $this->people = [];
        $this->errors = [];
    }

    /**
     * Compare the supplied password with the known one.
     *
     * This functions uses a type-safe and timing-safe comparison, in order to
     * improve the security of the authentication.
     *
     * Read more about this sort of attacks (used for the < PHP 5.6.0 implementation):
     *  - https://security.stackexchange.com/questions/83660/simple-string-comparisons-not-secure-against-timing-attacks
     *  - https://github.com/laravel/framework/blob/a1dc78820d2dbf207dbdf0f7075f17f7021c4ee8/src/Illuminate/Support/Str.php#L289
     *  - https://github.com/symfony/security-core/blob/master/Util/StringUtils.php#L39
     *
     * @param  string $known
     * @param  string $supplied
     * @return bool
     */
    public static function authenticateUser($known = '', $supplied = '')
    {
        // The hash_equals function was introduced in PHP 5.6.0. If it's not
        // existing in the current context (PHP version too old), and to ensure
        // compatibility with those old interpreters, we'll have to provide
        // an PHP implementation of this function.
        if (function_exists('hash_equals')) {
            return hash_equals($known, $supplied);
        }

        // Some implementation references can be found on the function comment.
        $knownLen = mb_strlen($known);
        if ($knownLen !== mb_strlen($supplied)) {
            return false;
        }

        // Ensure that all the characters are the same, and continue until the
        // end of the string even if an difference was found.
        for ($i = 0, $comparison = 0; $i < $knownLen; $i++) {
            $comparison |= ord($known[$i]) ^ ord($supplied[$i]);
        }

        return ($comparison === 0);
    }

    /**
     * Getters
     */
    public function getItems()
    {
        $this->items = $this->_filterItemsByCategory(
            $this->items,
            $this->config->getCategories());

        return $this->items;
    }

    public function getPeople()
    {
        return $this->people;
    }

    /**
     * Adds a feed to the planet.
     *
     * @param PlanetFeed $feed
     */
    public function addPerson(&$feed)
    {
        $this->people[] = $feed;
    }

    /**
     * Load people from an OPML.
     *
     * @param  string  $file File to load the OPML from.
     * @return integer Number of people loaded.
     */
    public function loadOpml($file)
    {
        if (!is_file($file)) {
            $this->errors[] = new PlanetError(3, $file.' is missing.');
            return 0;
        }

        $opml = OpmlManager::load($file);
        $opml_people = $opml->getPeople();
        foreach ($opml_people as $opml_person){
            $person = new PlanetFeed(
                $opml_person['name'],
                $opml_person['feed'],
                $opml_person['website'],
                $opml_person['isDown']
            );
            $this->addPerson($person);
        }
        return count($opml_people);
    }

    /**
     * Load feeds
     */
    public function loadFeeds()
    {
        foreach ($this->people as $feed) {
            //Is down it's filled by cron.php, $Planet->download(1.0) proccess
            if (!$feed->isDown) {
                $feed->set_timeout(-1);
                $feed->init();
                $this->items = array_merge($this->items, $feed->get_items());
            }

        }
        $this->sort();
    }

    /**
     * Fetch feeds and see if new data is present.
     *
     * @param float $max_load Percentage of feeds to load
     */
    public function download($max_load=0.1)
    {
        $max_load_feeds = ceil(count($this->people) * $max_load);
        $opml = OpmlManager::load(__DIR__.'/../../custom/people.opml');

        foreach ($this->people as $feed) {
            //Avoid mass loading with variable cache duration
            $feed->set_cache_duration($this->config->getCacheTimeout());

            //Load only a few feeds, force other to fetch from the cache
            if (0 > $max_load_feeds--) {
                $feed->set_timeout(-1);
                $this->errors[] = new PlanetError(1, 'Forced from cache : '.$feed->getFeed());
            }

            // Bypass remote's SSL/TLS certificate if the user explicitly
            // asked for it in the configuration.
            if ($this->config->checkcerts === false) {
                $feed->set_curl_options([
                    CURLOPT_SSL_VERIFYHOST => false,
                    CURLOPT_SSL_VERIFYPEER => false
                ]);
            }

            $feed->init();
            $isDown = '';

            // http://simplepie.org/wiki/reference/simplepie/merge_items ?
            if (($feed->data) && ($feed->get_item_quantity() > 0)){
                $items = $feed->get_items();
                $this->items = array_merge($this->items, $items);
            } else {
                $this->errors[] = new PlanetError(1, 'No items or down : ' . $feed->getFeed());
                $isDown = '1';
            }

            foreach ($opml->entries as $key => $entrie) {
                if ($feed->getFeed() === $entrie['feed']) {
                    $opml->entries[$key]['isDown'] = $isDown;
                }
            }
        }

        OpmlManager::save($opml, __DIR__.'/../../custom/people.opml');
    }

    public function sort()
    {
        usort($this->items, array('PlanetItem','compare'));
    }

    /**
     * Filter out items that do not match at least one
     * of the defined categories.
     *
     * If there's no category, return all items.
     *
     * @param array  $items to filter
     * @param string $categories to filter against; may be a single word
     * or a comma-separated list of words.
     *
     * @return array resulting list of items
    */
    public function _filterItemsByCategory($items, $categories = null)
    {
        $categories = trim($categories);

        if (empty($categories))
            return $items;

        $categories         = array_map('trim', explode(',', strtolower($categories)));
        $cb_category_filter =
            function ($item) use ($categories)
            {
                if (!is_array($item_categories = $item->get_categories()))
                    return false;

                $item_categories = array_map(
                    function ($i) { return strtolower($i->get_label()); },
                    $item_categories
                );

                return array_intersect($categories, $item_categories);
            };

        return array_values(array_filter($items, $cb_category_filter));
    }
}