package strategy;

import model.Paper;
import org.jsoup.Jsoup;
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 ArXivStrategy extends AbstractCrawlerStrategy {
    @Override
    public String getPlatformName() {
        return "arXiv";
    }
    
    @Override
    public boolean supportsUrl(String url) {
        return url != null && url.contains("arxiv.org");
    }
    
    private String cleanPrefix(String text, String[] prefixes) {
        if (text == null) {
            return "";
        }
        String cleaned = text.trim();
        for (String prefix : prefixes) {
            if (cleaned.toLowerCase().startsWith(prefix.toLowerCase())) {
                cleaned = cleaned.substring(prefix.length()).trim();
            }
        }
        return cleaned;
    }
    
    @Override
    protected List<Paper> fetchPapers(String url, int count) throws Exception {
        List<Paper> papers = new ArrayList<>();
        System.out.println("=== 开始使用arXiv获取论文 ===");
        
        String html = Utils.sendGetRequest(url);
        if (html.isEmpty()) return papers;
        
        Document doc = Jsoup.parse(html);
        
        Elements paperElements = doc.select(".arxiv-result");
        
        if (!paperElements.isEmpty()) {
            System.out.println("检测到搜索结果页面，找到 " + paperElements.size() + " 篇论文");
            for (Element element : paperElements) {
                if (papers.size() >= count) break;
                
                try {
                    Element titleElement = element.selectFirst(".title");
                    String title = titleElement != null ? titleElement.text().trim() : "";
                    title = cleanPrefix(title, new String[]{"Title:", "Title"});
                    
                    Element linkElement = element.selectFirst(".list-title a");
                    String link = linkElement != null ? linkElement.attr("href") : "";
                    if (!link.isEmpty() && !link.startsWith("http")) {
                        link = "https://arxiv.org" + link;
                    }
                    
                    Element abstractElement = element.selectFirst(".abstract");
                    String abstractText = abstractElement != null ? abstractElement.text().trim() : "";
                    abstractText = cleanPrefix(abstractText, new String[]{"Abstract:", "Abstract"});
                    
                    Element authorsElement = element.selectFirst(".authors");
                    String authors = authorsElement != null ? authorsElement.text().trim() : "";
                    authors = cleanPrefix(authors, new String[]{"Authors:", "Author:", "Authors", "Author"});
                    
                    if (title.length() < 5 || link.isEmpty()) continue;
                    
                    papers.add(new Paper(title, authors, abstractText, link, getPlatformName()));
                } catch (Exception e) {
                    continue;
                }
            }
        } else {
            Element titleElement = doc.selectFirst("h1.title.mathjax");
            if (titleElement != null) {
                System.out.println("检测到单个论文页面");
                String title = titleElement.text().trim();
                title = cleanPrefix(title, new String[]{"Title:", "Title"});
                
                Element authorsElement = doc.selectFirst(".authors");
                String authors = authorsElement != null ? authorsElement.text().trim() : "";
                authors = cleanPrefix(authors, new String[]{"Authors:", "Author:", "Authors", "Author"});
                
                Element abstractElement = doc.selectFirst(".abstract.mathjax");
                String abstractText = abstractElement != null ? abstractElement.text().trim() : "";
                abstractText = cleanPrefix(abstractText, new String[]{"Abstract:", "Abstract"});
                
                String link = url;
                
                if (title.length() >= 5 && !link.isEmpty()) {
                    papers.add(new Paper(title, authors, abstractText, link, getPlatformName()));
                }
            } else {
                System.out.println("未找到论文元素，尝试其他选择器...");
                
                String[] selectors = {"article", ".paper", ".document", "div[role='main']"};
                for (String selector : selectors) {
                    Elements articles = doc.select(selector);
                    if (!articles.isEmpty()) {
                        for (Element article : articles) {
                            if (papers.size() >= count) break;
                            
                            String title = article.selectFirst("h1, h2, .title") != null ? 
                                article.selectFirst("h1, h2, .title").text().trim() : "";
                            title = cleanPrefix(title, new String[]{"Title:", "Title"});
                            
                            String link = article.selectFirst("a[href*='/abs/']") != null ? 
                                "https://arxiv.org" + article.selectFirst("a[href*='/abs/']").attr("href") : url;
                            
                            if (title.length() >= 5 && !link.isEmpty()) {
                                papers.add(new Paper(title, "", "", link, getPlatformName()));
                            }
                        }
                        break;
                    }
                }
            }
        }
        
        return papers;
    }
}