package strategy;

import model.CrawlResult;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import exception.ParseException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Random;
import java.util.ArrayList;
import java.util.List;

public abstract class AbstractCrawlStrategy implements CrawlStrategy {
    protected static final Logger logger = LoggerFactory.getLogger(AbstractCrawlStrategy.class);

    private static final Random random = new Random();

    protected static final String[] USER_AGENTS = {
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36 Edg/119.0.0.0",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Safari/605.1.15",
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36",
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0"
    };

    protected int baseDelay = 1000;
    protected int maxDelay = 2000;

    public Document fetchDocument(String url) throws IOException {
        int maxRetries = 3;
        logger.debug("开始获取页面: {}", url);

        for (int retry = 0; retry < maxRetries; retry++) {
            try {
                String userAgent = USER_AGENTS[random.nextInt(USER_AGENTS.length)];
                int delay = baseDelay + random.nextInt(maxDelay - baseDelay);
                logger.debug("随机延迟: {}ms", delay);
                Thread.sleep(delay);

                Document doc = Jsoup.connect(url)
                        .timeout(20000)
                        .userAgent(userAgent)
                        .header("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8")
                        .header("Accept-Language", "zh-CN,zh;q=0.9,en;q=0.8")
                        .header("Accept-Encoding", "gzip, deflate, br")
                        .header("Connection", "keep-alive")
                        .header("Sec-Fetch-Dest", "document")
                        .header("Sec-Fetch-Mode", "navigate")
                        .header("Sec-Fetch-Site", "none")
                        .header("Sec-Fetch-User", "?1")
                        .header("Upgrade-Insecure-Requests", "1")
                        .header("Cache-Control", "max-age=0")
                        .header("Referer", getReferer(url))
                        .followRedirects(true)
                        .get();

                logger.debug("页面获取成功: {} (尝试 {}/{})", url, retry + 1, maxRetries);
                return doc;
            } catch (java.net.ConnectException e) {
                logger.error("【断网异常】网络连接失败 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                if (retry == maxRetries - 1) {
                    throw new IOException("【网络连接失败】无法连接到服务器，请检查网络连接状态: " + url, e);
                }
            } catch (java.net.UnknownHostException e) {
                logger.error("【断网异常】无法解析域名 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                throw new IOException("【网络连接失败】无法解析域名，请检查网络连接或DNS设置: " + url, e);
            } catch (java.net.SocketTimeoutException e) {
                logger.error("【网络超时】请求超时 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                if (retry == maxRetries - 1) {
                    throw new IOException("【网络超时】连接超时，请检查网络稳定性: " + url, e);
                }
            } catch (java.net.NoRouteToHostException e) {
                logger.error("【断网异常】无法到达目标主机 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                throw new IOException("【网络连接失败】无法到达目标主机，请检查网络连接: " + url, e);
            } catch (java.net.SocketException e) {
                logger.error("【断网异常】Socket异常 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                throw new IOException("【网络连接失败】Socket异常，请检查网络连接: " + url, e);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                logger.warn("页面获取过程被中断");
                throw new IOException("获取被中断: " + url, e);
            } catch (IOException e) {
                logger.error("获取页面失败 (尝试 {}/{}): {}", retry + 1, maxRetries, e.getMessage());
                if (retry == maxRetries - 1) {
                    throw e;
                }
            }

            if (retry < maxRetries - 1) {
                try {
                    int retryDelay = baseDelay * (int) Math.pow(2, retry) + random.nextInt(500);
                    logger.debug("重试前等待: {}ms", retryDelay);
                    Thread.sleep(retryDelay);
                } catch (InterruptedException ie) {
                    Thread.currentThread().interrupt();
                    logger.warn("重试等待被中断");
                    throw new IOException("重试等待被中断", ie);
                }
            }
        }

        throw new IOException("【网络连接失败】多次尝试后仍无法获取页面: " + url);
    }

    protected String getReferer(String url) {
        if (url.contains("douban")) {
            return "https://movie.douban.com/";
        } else if (url.contains("dangdang")) {
            return "http://www.dangdang.com/";
        } else if (url.contains("weather")) {
            return "http://www.weather.com.cn/";
        } else if (url.contains("12306")) {
            return "https://www.12306.cn/";
        }
        return "";
    }

    public CrawlResult parseItem(Element element) throws ParseException {
        throw new ParseException("parseItem method must be implemented by subclass");
    }

    protected double parsePrice(String priceText) {
        if (priceText == null || priceText.isEmpty()) {
            return 0;
        }
        String cleaned = priceText.replaceAll("[^0-9.]", "");
        try {
            return Double.parseDouble(cleaned);
        } catch (NumberFormatException e) {
            logger.warn("价格解析失败: '{}' -> {}", priceText, cleaned);
            return 0;
        }
    }

    protected double parseDiscount(double price, double originalPrice) {
        if (originalPrice <= 0) {
            return 10.0;
        }
        double discount = (price / originalPrice) * 10;
        return Math.round(discount * 10) / 10.0;
    }

    protected List<String> extractTextList(Elements elements) {
        List<String> result = new ArrayList<>();
        if (elements != null) {
            for (Element el : elements) {
                String text = el.text().trim();
                if (!text.isEmpty()) {
                    result.add(text);
                }
            }
        }
        return result;
    }

    protected String cleanText(String text) {
        if (text == null) return "";
        return text.replaceAll("\\s+", " ").trim();
    }

    @Override
    public int getPageSize() {
        return 20;
    }
}