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<?php

    namespace Inteve\FeedGenerator\Feeds\PostFeed;

    use Inteve\FeedGenerator\Feed;
    use Inteve\FeedGenerator\IOutput;
    use Inteve\FeedGenerator\InvalidItemException;
    use Nette\Utils\Json;


    class PostFeed extends Feed
    {
        /**
         * @return string
         */
        public function getContentType()
        {
            return 'application/json';
        }


        /**
         * @return void
         * @throws InvalidItemException
         */
        public function generate(IOutput $output)
        {
            $output->open();
            $output->output('[');
            $skipSeparator = TRUE;
            $timezone = new \DateTimezone('UTC');

            foreach ($this->items as $item) {
                if (!($item instanceof PostFeedItem)) {
                    throw new InvalidItemException('Feed item must be instance of PostFeedItem.');
                }

                if ($skipSeparator) {
                    $skipSeparator = FALSE;

                } else {
                    $output->output(',');
                }

                $output->output("\n");
                $date = clone $item->getDate();
                $date->setTimezone($timezone);

                $data = array(
                    'id' => $item->getId(),
                    'title' => $item->getTitle(),
                    'date' => $date->format('Y-m-d H:i:s'),
                    'text' => $item->getText(),
                    'url' => $item->getUrl(),
                    'image' => $item->getImage(),
                );

                if ($data['text'] === NULL) {
                    unset($data['text']);
                }

                if ($data['url'] === NULL) {
                    unset($data['url']);
                }

                if ($data['image'] === NULL) {
                    unset($data['image']);
                }

                $output->output(Json::encode($data));
            }

            $output->output("\n]\n");
            $output->close();
        }
    }