package strategy;

import model.Paper;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import utils.Utils;
import java.util.ArrayList;
import java.util.List;

public class CNKIStrategy extends AbstractCrawlerStrategy {
    @Override
    public String getPlatformName() {
        return "中国知网 (CNKI)";
    }
    
    @Override
    public boolean supportsUrl(String url) {
        return url != null && (url.contains("cnki.net") || url.contains("cnki.cn"));
    }
    
    @Override
    protected List<Paper> fetchPapers(String url, int count) throws Exception {
        List<Paper> papers = new ArrayList<>();
        System.out.println("=== 开始使用中国知网获取论文 ===");
        
        String html = Utils.sendGetRequest(url);
        if (html.isEmpty()) return papers;
        
        Document doc = Utils.parseHtml(html);
        
        String[] selectors = {".list-item", ".article-item", ".result-item", "tr[class*='item']", "div[class*='result']", "li[class*='result']"};
        
        Elements paperElements = null;
        for (String selector : selectors) {
            paperElements = doc.select(selector);
            if (paperElements.size() > 0) {
                break;
            }
        }
        
        if (paperElements != null && paperElements.size() > 0) {
            int collected = 0;
            for (Element element : paperElements) {
                if (collected >= count) break;
                
                try {
                    Element titleElement = element.select("a").first();
                    if (titleElement == null) continue;
                    
                    String title = titleElement.text();
                    String paperUrl = titleElement.attr("href");
                    
                    if (title.length() < 10 || paperUrl.isEmpty()) continue;
                    
                    if (!paperUrl.startsWith("http")) {
                        paperUrl = "https://kns.cnki.net" + paperUrl;
                    }
                    
                    String authors = "";
                    Elements authorElements = element.select(".author");
                    if (!authorElements.isEmpty()) {
                        authors = authorElements.first().text();
                    }
                    
                    String abstractText = "";
                    Elements abstractElements = element.select(".abstract");
                    if (!abstractElements.isEmpty()) {
                        abstractText = abstractElements.first().text();
                    }
                    
                    papers.add(new Paper(title, authors, abstractText, paperUrl, getPlatformName()));
                    collected++;
                } catch (Exception e) {
                    continue;
                }
            }
        }
        
        return papers;
    }
}