package com.example.crawler;

import com.example.exception.CrawlerException;
import com.example.exception.ParseException;
import com.example.model.News;
import com.example.util.FileUtil;
import com.example.util.HttpUtil;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class NewsCrawler implements Crawler<News> {

    private List<News> newsList = new ArrayList<>();

    @Override
    public void crawl() throws CrawlerException {
        newsList.clear();
        String url = "https://news.sina.com.cn/";

        System.out.println("正在爬取新浪新闻...");

        try {
            String html = HttpUtil.getHtmlContent(url);
            extractNews(html);
        } catch (Exception e) {
            throw new CrawlerException("爬取新闻失败", e);
        }

        System.out.println("新闻爬取完成，共获取 " + newsList.size() + " 条新闻");
    }

    private void extractNews(String html) throws CrawlerException {
        try {
            Document doc = Jsoup.parse(html);
            Elements items = doc.select("a[href*=sina.com.cn]");

            Set<String> seenTitles = new HashSet<>();

            for (Element item : items) {
                String title = item.text().trim();
                String link = item.attr("href");

                if (title.length() > 5 && title.length() < 100 && !seenTitles.contains(title)) {
                    News news = new News();
                    news.setTitle(title);
                    news.setLink(link);

                    newsList.add(news);
                    seenTitles.add(title);
                }

                if (newsList.size() >= 50) {
                    break;
                }
            }
        } catch (Exception e) {
            throw new ParseException("解析新闻数据失败", e);
        }
    }

    @Override
    public void saveToFile() throws CrawlerException {
        List<String> headers = List.of("新闻标题", "链接");
        List<List<String>> data = new ArrayList<>();

        for (News news : newsList) {
            List<String> row = new ArrayList<>();
            row.add(news.getTitle());
            row.add(news.getLink());
            data.add(row);
        }

        FileUtil.writeCsv("news.csv", headers, data);
    }

    @Override
    public int getCount() {
        return newsList.size();
    }
}