package com.smtaiserver.smtaiserver.session;

import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

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

import org.springframework.session.web.http.CookieHttpSessionIdResolver;
import org.springframework.session.web.http.DefaultCookieSerializer;
import org.springframework.session.web.http.HttpSessionIdResolver;

import com.smtservlet.util.SMTStatic;

import org.springframework.session.web.http.CookieSerializer.CookieValue;

public class HSWaterNetSessionResolver implements HttpSessionIdResolver {

	private static final String WRITTEN_SESSION_ID_ATTR = CookieHttpSessionIdResolver.class.getName()
			.concat(".WRITTEN_SESSION_ID_ATTR");

	private Pattern _patQueryStringToken = Pattern.compile("\\b?sessionid=([^&]+)");
	private boolean _useHeader = false;
	private boolean _useCookie = false;
	private String headerName = "x-auth-token";
	private String urlParamName = "websessionid";
	private DefaultCookieSerializer cookieSerializer = null;
	
	public HSWaterNetSessionResolver(String sessionName, boolean useHeader, boolean useCookie)
	{
		if(!useHeader && !useCookie)
			throw new RuntimeException("can't set use head and use cookie all false");
		_useHeader = useHeader;
		_useCookie = useCookie;
		headerName = sessionName;
		
		if(_useCookie)
		{
			cookieSerializer = new DefaultCookieSerializer();
			cookieSerializer.setCookieName(sessionName);
		}
	}

	@Override
	public List<String> resolveSessionIds(HttpServletRequest request) 
	{
		String requestURI = request.getRequestURI();
		
		if(!"/login".equals(requestURI))
		{
			// 如果存在url,则使用
			String urlParam = request.getQueryString();
			if(!SMTStatic.isNullOrEmpty(urlParam))
			{
				Matcher m = _patQueryStringToken.matcher(urlParam);
				if(m.find())
				{
					String sessionKey = m.group(1);
					return Collections.singletonList(sessionKey);
				}
			}
			
			// 如果存在头信息，则使用
			if(_useHeader)
			{
				String urlValue = request.getParameter(urlParamName);
				if(!SMTStatic.isNullOrEmpty(urlValue))
					return Collections.singletonList(urlValue);
				
				String headerValue = request.getHeader(this.headerName);
				if(!SMTStatic.isNullOrEmpty(headerValue))
					return Collections.singletonList(headerValue);
				
				if(!_useCookie)
					return  Collections.emptyList();
			}
			
			// 如果不存在则使用cookie
			return this.cookieSerializer.readCookieValues(request);
		}
		else
		{
			return  Collections.emptyList();
		}
	}

	@Override
	public void setSessionId(HttpServletRequest request, HttpServletResponse response, String sessionId) 
	{
		// 设置头的session id
		if(_useHeader)
		{
			response.setHeader(this.headerName, sessionId);
		}
		
		// 设置cookie的session id 
		if(_useCookie)
		{
			if (sessionId.equals(request.getAttribute(WRITTEN_SESSION_ID_ATTR))) {
				return;
			}
			request.setAttribute(WRITTEN_SESSION_ID_ATTR, sessionId);
			this.cookieSerializer.writeCookieValue(new CookieValue(request, response, sessionId));
		}
	}

	@Override
	public void expireSession(HttpServletRequest request, HttpServletResponse response) 
	{
		// 清空头session
		if(_useHeader)
		{
			response.setHeader(this.headerName, "");
		}
		
		// 清空cookie
		if(_useCookie)
		{
			this.cookieSerializer.writeCookieValue(new CookieValue(request, response, ""));
		}
	}
}