/**
 * Copyright (c) 2005-2012 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 */
package com.ejweb.core.web;

import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.StringTokenizer;
import java.util.TreeMap;

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

import org.apache.commons.lang3.Validate;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import com.google.common.net.HttpHeaders;
import com.ejweb.conf.GConstants;
import com.ejweb.core.utils.Encodes;
import com.ejweb.core.utils.StringUtils;
import com.ejweb.modules.sys.security.SystemAuthorizingRealm.Principal;
import com.ejweb.modules.sys.utils.UserUtils;

/**
 * Http与Servlet工具类.
 * @author calvin/thinkgem
 * @version 2014-8-19
 */
public class Servlets {

    // -- 常用数值定义 --//
    public static final long ONE_YEAR_SECONDS = 60 * 60 * 24 * 365;
    
    // 静态文件后缀
    private final static String[] staticFiles = StringUtils.split(GConstants.getValue("web.staticFile"), ",");
    
    // 动态映射URL后缀
    private final static String urlSuffix = GConstants.getUrlSuffix();

    /**
     * 设置客户端缓存过期时间 的Header.
     */
    public static void setExpiresHeader(HttpServletResponse response, long expiresSeconds) {
        // Http 1.0 header, set a fix expires date.
        response.setDateHeader(HttpHeaders.EXPIRES, System.currentTimeMillis() + expiresSeconds * 1000);
        // Http 1.1 header, set a time after now.
        response.setHeader(HttpHeaders.CACHE_CONTROL, "private, max-age=" + expiresSeconds);
    }

    /**
     * 设置禁止客户端缓存的Header.
     */
    public static void setNoCacheHeader(HttpServletResponse response) {
        // Http 1.0 header
        response.setDateHeader(HttpHeaders.EXPIRES, 1L);
        response.addHeader(HttpHeaders.PRAGMA, "no-cache");
        // Http 1.1 header
        response.setHeader(HttpHeaders.CACHE_CONTROL, "no-cache, no-store, max-age=0");
    }

    /**
     * 设置LastModified Header.
     */
    public static void setLastModifiedHeader(HttpServletResponse response, long lastModifiedDate) {
        response.setDateHeader(HttpHeaders.LAST_MODIFIED, lastModifiedDate);
    }

    /**
     * 设置Etag Header.
     */
    public static void setEtag(HttpServletResponse response, String etag) {
        response.setHeader(HttpHeaders.ETAG, etag);
    }

    /**
     * 根据浏览器If-Modified-Since Header, 计算文件是否已被修改.
     * 
     * 如果无修改, checkIfModify返回false ,设置304 not modify status.
     * 
     * @param lastModified 内容的最后修改时间.
     */
    public static boolean checkIfModifiedSince(HttpServletRequest request, HttpServletResponse response,
            long lastModified) {
        long ifModifiedSince = request.getDateHeader(HttpHeaders.IF_MODIFIED_SINCE);
        if ((ifModifiedSince != -1) && (lastModified < ifModifiedSince + 1000)) {
            response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            return false;
        }
        return true;
    }

    /**
     * 根据浏览器 If-None-Match Header, 计算Etag是否已无效.
     * 
     * 如果Etag有效, checkIfNoneMatch返回false, 设置304 not modify status.
     * 
     * @param etag 内容的ETag.
     */
    public static boolean checkIfNoneMatchEtag(HttpServletRequest request, HttpServletResponse response, String etag) {
        String headerValue = request.getHeader(HttpHeaders.IF_NONE_MATCH);
        if (headerValue != null) {
            boolean conditionSatisfied = false;
            if (!"*".equals(headerValue)) {
                StringTokenizer commaTokenizer = new StringTokenizer(headerValue, ",");

                while (!conditionSatisfied && commaTokenizer.hasMoreTokens()) {
                    String currentToken = commaTokenizer.nextToken();
                    if (currentToken.trim().equals(etag)) {
                        conditionSatisfied = true;
                    }
                }
            } else {
                conditionSatisfied = true;
            }

            if (conditionSatisfied) {
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                response.setHeader(HttpHeaders.ETAG, etag);
                return false;
            }
        }
        return true;
    }

    /**
     * 设置让浏览器弹出下载对话框的Header.
     * 
     * @param fileName 下载后的文件名.
     */
    public static void setFileDownloadHeader(HttpServletResponse response, String fileName) {
        try {
            // 中文文件名支持
            String encodedfileName = new String(fileName.getBytes(), "ISO8859-1");
            response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + encodedfileName + "\"");
        } catch (UnsupportedEncodingException e) {
            e.getMessage();
        }
    }

    /**
     * 取得带相同前缀的Request Parameters, copy from spring WebUtils.
     * 
     * 返回的结果的Parameter名已去除前缀.
     */
    @SuppressWarnings("rawtypes")
    public static Map<String, Object> getParametersStartingWith(ServletRequest request, String prefix) {
        Validate.notNull(request, "Request must not be null");
        Enumeration paramNames = request.getParameterNames();
        Map<String, Object> params = new TreeMap<String, Object>();
        String pre = prefix;
        if (pre == null) {
            pre = "";
        }
        while (paramNames != null && paramNames.hasMoreElements()) {
            String paramName = (String) paramNames.nextElement();
            if ("".equals(pre) || paramName.startsWith(pre)) {
                String unprefixed = paramName.substring(pre.length());
                String[] values = request.getParameterValues(paramName);
                if (values == null || values.length == 0) {
                    values = new String[]{};
                    // Do nothing, no values found at all.
                } else if (values.length > 1) {
                    params.put(unprefixed, values);
                } else {
                    params.put(unprefixed, values[0]);
                }
            }
        }
        return params;
    }

    /**
     * 组合Parameters生成Query String的Parameter部分,并在paramter name上加上prefix.
     * 
     */
    public static String encodeParameterStringWithPrefix(Map<String, Object> params, String prefix) {
        StringBuilder queryStringBuilder = new StringBuilder();

        String pre = prefix;
        if (pre == null) {
            pre = "";
        }
        Iterator<Entry<String, Object>> it = params.entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, Object> entry = it.next();
            queryStringBuilder.append(pre).append(entry.getKey()).append("=").append(entry.getValue());
            if (it.hasNext()) {
                queryStringBuilder.append("&");
            }
        }
        return queryStringBuilder.toString();
    }

    /**
     * 客户端对Http Basic验证的 Header进行编码.
     */
    public static String encodeHttpBasic(String userName, String password) {
        String encode = userName + ":" + password;
        return "Basic " + Encodes.encodeBase64(encode.getBytes());
    }
    
    /**
     * 是否是Ajax异步请求
     * @param request
     */
    public static boolean isAjaxRequest(HttpServletRequest request){
        
        String accept = request.getHeader("accept");
        String xRequestedWith = request.getHeader("X-Requested-With");
        Principal principal = UserUtils.getPrincipal();

        // 如果是异步请求或是手机端，则直接返回信息
        return ((accept != null && accept.indexOf("application/json") != -1 
            || (xRequestedWith != null && xRequestedWith.indexOf("XMLHttpRequest") != -1)
            || (principal != null && principal.isMobileLogin())));
    }
    
    /**
     * 获取当前请求对象
     * @return
     */
    public static HttpServletRequest getRequest(){
        try{
            return ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
        }catch(Exception e){
            return null;
        }
    }

    /**
     * 判断访问URI是否是静态文件请求
     * @throws Exception 
     */
    public static boolean isStaticFile(String uri){
        if (staticFiles == null){
            try {
                throw new Exception("检测到“app.properties”中没有配置“web.staticFile”属性。配置示例：\n#静态文件后缀\n"
                    +"web.staticFile=.css,.js,.png,.jpg,.gif,.jpeg,.bmp,.ico,.swf,.psd,.htc,.crx,.xpi,.exe,.ipa,.apk");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
//        if ((StringUtils.startsWith(uri, "/static/") || StringUtils.endsWithAny(uri, sfs)) 
//                && !StringUtils.endsWithAny(uri, ".jsp") && !StringUtils.endsWithAny(uri, ".java")){
//            return true;
//        }
        if (StringUtils.endsWithAny(uri, staticFiles) && !StringUtils.endsWithAny(uri, urlSuffix)
                && !StringUtils.endsWithAny(uri, ".jsp") && !StringUtils.endsWithAny(uri, ".java")){
            return true;
        }
        return false;
    }
}
