TgChannelParser

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;

import java.io.IOException;
import java.net.URL;
import java.time.Duration;
import java.util.Optional;

/**
 * A class that gets the image from a telegram channel post
 *
 * @author t.me/Chase_22
 * @author t.me/MouamleH
 * @version 0.0.1
 */
public class TgChannelParser {

    private static int READ_TIMEOUT = (int) Duration.ofSeconds(5).toMillis();
    private Document html;

    /**
     * @param url the post url
     * @throws IOException throws an exception if the url was not found
     *                     or the timeout was reached
     */
    public TgChannelParser(String url) throws IOException {
        html = Jsoup.parse(new URL(url + "?embed=1"), READ_TIMEOUT);
    }

    /**
     * @return an Optional containing the image url if the post contains an image
     */
    public Optional<String> getImageUrl() {
        Element element = html.selectFirst(".tgme_widget_message_photo_wrap");

        if (element == null) {
            element = html.selectFirst(".link_preview_image");
        }

        if (element != null) {
            String style = element.attr("style");
            String imageUrl = style.substring(style.indexOf("'") + 1, style.lastIndexOf("'"));
            return Optional.of(imageUrl);
        }

        return Optional.empty();
    }

    /**
     * @return true if the post is present, false otherwise
     */
    public boolean isPresent() {
        return !html.toString().contains("Post not found");
    }

    /**
     * @return true if the post contains an image, false otherwise
     */
    public boolean containsImage() {
        return getImageUrl().isPresent();
    }

}