package com.yaozhitech.spring5.filter;


import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Date;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.authc.AuthenticatingFilter;
import org.apache.shiro.web.util.WebUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMethod;

import com.yaozhitech.spring5.dto.UserDto;
import com.yaozhitech.spring5.jwt.JWTToken;
import com.yaozhitech.spring5.service.UserService;
import com.yaozhitech.spring5.utils.JwtUtils;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class JwtAuthFilter extends AuthenticatingFilter {
	
	@Value("${jwt.header}")
    private String tokenHeader;

    @Value("${jwt.tokenHead}")
    private String tokenHead;

    private static final int tokenRefreshInterval = 300;
    private UserService userService;

    public JwtAuthFilter(UserService userService){
        this.userService = userService;
        this.setLoginUrl("/login");
    }

    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = WebUtils.toHttp(request);
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) //对于OPTION请求做拦截，不做token校验
            return false;

        return super.preHandle(request, response);
    }

    @Override
    protected void postHandle(ServletRequest request, ServletResponse response){
        this.fillCorsHeader(WebUtils.toHttp(request), WebUtils.toHttp(response));
        request.setAttribute("jwtShiroFilter.FILTERED", true);
    }

    /**
          * 父类会在请求进入拦截器后调用该方法，返回true则继续，返回false则会调用onAccessDenied()。这里在不通过时，还调用了isPermissive()方法，
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        if(this.isLoginRequest(request, response))
            return true;

        Boolean afterFiltered = (Boolean)(request.getAttribute("jwtShiroFilter.FILTERED"));
        if(afterFiltered != null && afterFiltered)
        	return true;
        
        boolean allowed = false;
        try {
            allowed = executeLogin(request, response);
        } catch(IllegalStateException e){ //not found any token
            log.error("Not found any token", e);
        }catch (Exception e) {
            log.error("Error occurs when login", e);
        }
        return allowed;// || super.isPermissive(mappedValue);
    }

    /**
          * 这里重写了父类的方法，使用我们自己定义的Token类，提交给shiro。这个方法返回null的话会直接抛出异常，进入isAccessAllowed（）的异常处理逻辑。
     */
    @Override
    protected AuthenticationToken createToken(ServletRequest servletRequest, ServletResponse servletResponse) {
        String jwtToken = getAuthzHeader(servletRequest);
        if(!StringUtils.isEmpty(jwtToken)&&!JwtUtils.isTokenExpired(jwtToken))
            return new JWTToken(jwtToken);

        return null;
    }

    @Override
    protected boolean onAccessDenied(ServletRequest servletRequest, ServletResponse servletResponse) throws Exception {
        
    	HttpServletRequest httpServletRequest = WebUtils.toHttp(servletRequest);
        HttpServletResponse httpResponse = WebUtils.toHttp(servletResponse);
        // 返回401
        httpResponse.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        httpResponse.getOutputStream().println("401 UNAUTHORIZED");
        // 设置响应码为401或者直接输出消息
        String url = httpServletRequest.getRequestURI();
        log.error("onAccessDenied url：{}", url);

    	return false;
    }

    /**
          *  如果Shiro Login认证成功，会进入该方法，等同于用户名密码登录成功，我们这里还判断了是否要刷新Token
     */
    @Override
    protected boolean onLoginSuccess(AuthenticationToken token, Subject subject, ServletRequest request, ServletResponse response) throws Exception {
        HttpServletResponse httpResponse = WebUtils.toHttp(response);
        String newToken = null;
        if(token instanceof JWTToken){
            JWTToken jwtToken = (JWTToken)token;
            UserDto user = (UserDto) subject.getPrincipal();
            boolean shouldRefresh = shouldTokenRefresh(JwtUtils.getIssuedAt(jwtToken.getToken()));
            if(shouldRefresh) {
                newToken = userService.generateJwtToken(user.getUsername());
            }
        }
        if(!StringUtils.isEmpty(newToken))
            httpResponse.setHeader("x-auth-token", newToken);

        return true;
    }

    @Override
    protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e, ServletRequest request, ServletResponse response) {
        log.error("Validate token fail, token:{}, error:{}", token.toString(), e.getMessage());
        return false;
    }

    protected String getAuthzHeader(ServletRequest request) {
        HttpServletRequest httpRequest = WebUtils.toHttp(request);
        String header = httpRequest.getHeader("x-auth-token");
        if (StringUtils.startsWithIgnoreCase(header, "Bearer ")) {
			return StringUtils.replace(header, "Bearer ", "");
		}
        return header;
    }

    protected boolean shouldTokenRefresh(Date issueAt){
        LocalDateTime issueTime = LocalDateTime.ofInstant(issueAt.toInstant(), ZoneId.systemDefault());
        return LocalDateTime.now().minusSeconds(tokenRefreshInterval).isAfter(issueTime);
    }

    protected void fillCorsHeader(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse){
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,HEAD");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
    }
}