package com.dsideal.gw.Handler;

import com.dsideal.gw.Bean.RetBean;
import com.dsideal.gw.GwApplication;
import com.dsideal.gw.Util.JwtUtil;
import com.dsideal.gw.Config.GatewayConfig;
import com.jfinal.handler.Handler;
import com.jfinal.kit.StrKit;
import com.jfinal.upload.MultipartRequest;
import com.jfinal.upload.UploadFile;
import com.jfinal.plugin.activerecord.Record;
import io.jsonwebtoken.Claims;
import okhttp3.*;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.*;
import java.util.concurrent.TimeUnit;

public class RouterHandler extends Handler {
    private static final Logger logger = LoggerFactory.getLogger(RouterHandler.class);

    // 常量定义
    private static final class Constants {
        static final String CONTENT_TYPE_JSON = "application/json";
        static final String CONTENT_TYPE_MULTIPART = "multipart/form-data";
        static final String HEADER_AUTHORIZATION = "Authorization";
        static final String HEADER_COOKIE = "Cookie";
        static final String HEADER_ACCEPT = "Accept";
        static final String HEADER_CONTENT_TYPE = "Content-Type";
    }

    // 静态资源扩展名
    private static final Set<String> STATIC_EXTENSIONS = new HashSet<>(Arrays.asList(
            "html", "js", "css", "png", "jpg", "jpeg", "gif", "ico", "svg",
            "woff", "woff2", "ttf", "eot", "map", "json", "xml", "txt"
    ));

    // OkHttp客户端配置
    private static final OkHttpClient OK_HTTP_CLIENT = new OkHttpClient.Builder()
            .connectTimeout(GatewayConfig.CONNECT_TIMEOUT, TimeUnit.MILLISECONDS)
            .readTimeout(GatewayConfig.READ_TIMEOUT, TimeUnit.MILLISECONDS)
            .writeTimeout(GatewayConfig.WRITE_TIMEOUT, TimeUnit.MILLISECONDS)
            .connectionPool(new ConnectionPool(GatewayConfig.MAX_CONNECTIONS,
                    GatewayConfig.KEEP_ALIVE_DURATION,
                    TimeUnit.SECONDS))
            .build();

    @Override
    public void handle(String target, HttpServletRequest req, HttpServletResponse res, boolean[] isHandled) {
        try {
            // 处理OPTIONS请求
            if (req.getMethod().equals("OPTIONS")) {
                handleOptionsRequest(res, isHandled);
                return;
            }

            String servletPath = req.getServletPath();
            String queryString = req.getQueryString();

            // 处理静态资源
            if (isStaticResource(servletPath)) {
                next.handle(target, req, res, isHandled);
                return;
            }

            // 处理内部调用
            if (isInternalCall(servletPath, res, isHandled)) {
                return;
            }

            // 处理认证
            if (!isAuthenticated(req, res, isHandled)) {
                return;
            }

            // 获取转发URL
            String forwardUrl = getForwardUrl(servletPath);
            if (forwardUrl == null) {
                handleError(res, isHandled, "无效的请求路径", null);
                return;
            }

            // 记录请求日志
            logRequest(req, forwardUrl);

            // 根据请求方法处理
            switch (req.getMethod()) {
                case "GET":
                    handleGetRequest(req, res, isHandled, forwardUrl, queryString);
                    break;
                case "POST":
                    if (isMultipartRequest(req)) {
                        handleFileUpload(req, res, isHandled, forwardUrl);
                    } else {
                        handlePostRequest(req, res, isHandled, forwardUrl, queryString);
                    }
                    break;
                default:
                    handleError(res, isHandled, "不支持的请求方法: " + req.getMethod(), null);
            }
        } catch (Exception e) {
            logger.error("请求处理异常", e);
            handleError(res, isHandled, "系统异常", e);
        }
    }

    // 处理OPTIONS请求
    private void handleOptionsRequest(HttpServletResponse res, boolean[] isHandled) {
        addCorsHeaders(res);
        res.setStatus(HttpServletResponse.SC_OK);
        isHandled[0] = true;
    }

    // 添加CORS头信息
    private void addCorsHeaders(HttpServletResponse res) {
        // 设置允许的源
        for (String origin : GatewayConfig.ALLOWED_ORIGINS) {
            if ("*".equals(origin)) {
                res.setHeader("Access-Control-Allow-Origin", "*");
                break;
            }
        }

        // 设置允许的方法
        res.setHeader("Access-Control-Allow-Methods", String.join(",", GatewayConfig.ALLOWED_METHODS));

        // 设置允许的头信息
        res.setHeader("Access-Control-Allow-Headers", String.join(",", GatewayConfig.ALLOWED_HEADERS));

        // 设置是否允许发送Cookie
        res.setHeader("Access-Control-Allow-Credentials", String.valueOf(GatewayConfig.ALLOW_CREDENTIALS));

        // 设置预检请求的缓存时间
        res.setHeader("Access-Control-Max-Age", String.valueOf(GatewayConfig.MAX_AGE));
    }

    // 处理GET请求
    private void handleGetRequest(HttpServletRequest req, HttpServletResponse res,
                                  boolean[] isHandled, String forwardUrl, String queryString) {
        try {
            Request request = buildGetRequest(req, forwardUrl, queryString);
            executeRequest(request, res);
            isHandled[0] = true;
        } catch (Exception e) {
            handleError(res, isHandled, "GET请求处理失败", e);
        }
    }

    // 处理POST请求
    private void handlePostRequest(HttpServletRequest req, HttpServletResponse res,
                                   boolean[] isHandled, String forwardUrl, String queryString) {
        try {
            Request request = buildPostRequest(req, forwardUrl, queryString);
            executeRequest(request, res);
            isHandled[0] = true;
        } catch (Exception e) {
            handleError(res, isHandled, "POST请求处理失败", e);
        }
    }

    // 处理文件上传
    private void handleFileUpload(HttpServletRequest req, HttpServletResponse res,
                                  boolean[] isHandled, String forwardUrl) {
        try {
            MultipartRequest mp = new MultipartRequest(req);
            List<UploadFile> files = mp.getFiles();

            if (files.isEmpty()) {
                handleError(res, isHandled, "没有上传文件", null);
                return;
            }

            Request request = buildFileUploadRequest(files.getFirst(), forwardUrl);
            executeRequest(request, res);
            isHandled[0] = true;
        } catch (Exception e) {
            handleError(res, isHandled, "文件上传失败", e);
        }
    }

    // 构建GET请求
    private Request buildGetRequest(HttpServletRequest req, String forwardUrl, String queryString) {
        Request.Builder builder = new Request.Builder()
                .url(buildUrl(forwardUrl, queryString));
        addCommonHeaders(req, builder);
        return builder.build();
    }

    // 构建POST请求
    private Request buildPostRequest(HttpServletRequest req, String forwardUrl, String queryString) {
        Request.Builder builder = new Request.Builder()
                .url(buildUrl(forwardUrl, queryString));
        addCommonHeaders(req, builder);
        return builder.post(createRequestBody(req)).build();
    }

    // 构建文件上传请求
    private Request buildFileUploadRequest(UploadFile uploadFile, String forwardUrl) {
        MediaType mediaType = MediaType.parse(Constants.CONTENT_TYPE_MULTIPART);
        RequestBody requestBody = RequestBody.create(uploadFile.getFile(), mediaType);

        MultipartBody body = new MultipartBody.Builder()
                .setType(MultipartBody.FORM)
                .addFormDataPart("file", uploadFile.getFileName(), requestBody)
                .build();

        return new Request.Builder()
                .url(forwardUrl)
                .post(body)
                .build();
    }

    // 添加通用头信息
    private void addCommonHeaders(HttpServletRequest req, Request.Builder builder) {
        // 处理Authorization头
        String authHeader = req.getHeader(Constants.HEADER_AUTHORIZATION);
        if (!StrKit.isBlank(authHeader)) {
            builder.addHeader(Constants.HEADER_AUTHORIZATION, authHeader);
            builder.addHeader(Constants.HEADER_ACCEPT, "application/json;odata=verbose");
        }

        // 处理Cookie
        String cookie = req.getHeader(Constants.HEADER_COOKIE);
        if (!StrKit.isBlank(cookie)) {
            builder.addHeader(Constants.HEADER_COOKIE, cookie);
        }

        // 添加其他重要头信息
        addImportantHeaders(req, builder);
    }

    // 添加重要头信息
    private void addImportantHeaders(HttpServletRequest req, Request.Builder builder) {
        String[] importantHeaders = {
                Constants.HEADER_ACCEPT,
                Constants.HEADER_CONTENT_TYPE,
                "User-Agent",
                "Referer",
                "Origin",
                "Host"
        };

        for (String header : importantHeaders) {
            String value = req.getHeader(header);
            if (!StrKit.isBlank(value)) {
                builder.addHeader(header, value);
            }
        }
    }

    // 创建请求体
    private RequestBody createRequestBody(HttpServletRequest req) {
        FormBody.Builder formBodyBuilder = new FormBody.Builder();
        Enumeration<String> parameterNames = req.getParameterNames();
        while (parameterNames.hasMoreElements()) {
            String paramName = parameterNames.nextElement();
            String paramValue = req.getParameter(paramName);
            formBodyBuilder.add(paramName, paramValue);
        }
        return formBodyBuilder.build();
    }

    // 执行请求
    private void executeRequest(Request request, HttpServletResponse res) throws IOException {
        Response response = OK_HTTP_CLIENT.newCall(request).execute();
        if (response.isSuccessful()) {
            ResponseBody body = response.body();
            if (body != null) {
                String contentType = response.header(Constants.HEADER_CONTENT_TYPE);
                if (contentType != null && contentType.startsWith("image/")) {
                    handleImageResponse(res, body, contentType);
                } else {
                    handleTextResponse(res, body);
                }
            } else {
                renderJson(res, new RetBean(RetBean.ERROR, "响应体为空").toString());
            }
        } else {
            renderJson(res, new RetBean(RetBean.ERROR, "请求失败！").toString());
        }
    }

    // 处理图片响应
    private void handleImageResponse(HttpServletResponse res, ResponseBody body, String contentType) throws IOException {
        res.setContentType(contentType);
        res.setHeader("Cache-Control", "no-store");
        res.setHeader("Pragma", "no-cache");
        res.setDateHeader("Expires", 0);

        try (InputStream inputStream = body.byteStream()) {
            IOUtils.copy(inputStream, res.getOutputStream());
        }
    }

    // 处理文本响应
    private void handleTextResponse(HttpServletResponse res, ResponseBody body) throws IOException {
        String responseBody = body.string();
        renderJson(res, responseBody);
    }

    // 渲染JSON响应
    private void renderJson(HttpServletResponse res, String body) {
        // 添加CORS头信息
        addCorsHeaders(res);

        res.setHeader("Cache-Control", "no-cache");
        res.setCharacterEncoding("UTF-8");
        res.setContentType(Constants.CONTENT_TYPE_JSON);
        try {
            res.getWriter().println(body);
            res.getWriter().flush();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    // 处理错误
    private void handleError(HttpServletResponse res, boolean[] isHandled, String message, Exception e) {
        String errorMessage = e != null ? message + ": " + e.getMessage() : message;
        renderJson(res, new RetBean(RetBean.ERROR, errorMessage).toString());
        isHandled[0] = true;
    }

    // 检查认证
    private boolean isAuthenticated(HttpServletRequest req, HttpServletResponse res, boolean[] isHandled) {
        String servletPath = req.getServletPath();
        if (GwApplication.whiteSet.contains(servletPath)) {
            return true;
        }

        // 检查Session
        Record rPerson = JwtUtil.getPersonInfo(req);
        if (isValidPersonInfo(rPerson)) {
            return true;
        }

        // 检查JWT
        String jwtToken = req.getHeader(Constants.HEADER_AUTHORIZATION);
        if (!StrKit.isBlank(jwtToken)) {
            Claims claims = JwtUtil.getClaims(jwtToken);
            if (claims != null) {
                return true;
            }
        }

        handleError(res, isHandled, "登录已过期，请重新登录！", null);
        return false;
    }

    // 验证人员信息
    private boolean isValidPersonInfo(Record rPerson) {
        return rPerson != null &&
                !StrKit.isBlank(rPerson.getStr("bureau_id")) &&
                !StrKit.isBlank(rPerson.getStr("identity_id")) &&
                !StrKit.isBlank(rPerson.getStr("person_id"));
    }

    // 获取转发URL
    private String getForwardUrl(String servletPath) {
        int xie1 = servletPath.indexOf('/');
        int xie2 = servletPath.indexOf('/', xie1 + 1);
        if (xie1 == -1 || xie2 == -1) {
            return null;
        }

        String prefix = servletPath.substring(xie1 + 1, xie2);
        String action = servletPath.substring(xie2 + 1);

        if (!GwApplication.routeList.containsKey(prefix)) {
            return null;
        }

        return GwApplication.routeList.get(prefix) + "/" + prefix + "/" + action;
    }

    // 检查是否为静态资源
    private boolean isStaticResource(String servletPath) {
        if (servletPath.equals("/")) {
            return true;
        }
        int lastDotIndex = servletPath.lastIndexOf('.');
        if (lastDotIndex == -1) {
            return false;
        }
        String extension = servletPath.substring(lastDotIndex + 1).toLowerCase();
        return STATIC_EXTENSIONS.contains(extension);
    }

    // 检查是否为内部调用
    private boolean isInternalCall(String servletPath, HttpServletResponse res, boolean[] isHandled) {
        if (servletPath.endsWith("/internal/")) {
            handleError(res, isHandled, "微服务间内部接口调用，是不需要走网关的！", null);
            return true;
        }
        return false;
    }

    // 检查是否为multipart请求
    private boolean isMultipartRequest(HttpServletRequest req) {
        String contentType = req.getContentType();
        return contentType != null && contentType.startsWith(Constants.CONTENT_TYPE_MULTIPART);
    }

    // 构建URL
    private String buildUrl(String baseUrl, String queryString) {
        return queryString != null ? baseUrl + "?" + queryString : baseUrl;
    }

    // 记录请求日志
    private void logRequest(HttpServletRequest req, String forwardUrl) {
        logger.info("Request: {} {} -> {}", req.getMethod(), req.getRequestURI(), forwardUrl);
    }
}