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package com.github.ibole.infrastructure.web.servlet.utils;

import com.google.common.net.HttpHeaders;

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

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;


/**
 * Http与Servlet工具类.
 */
public class Servlets {

  // -- 常用数值定义 --//
  public static final long ONE_YEAR_SECONDS = 60 * 60 * 24 * 365;


  /**
   * 设置客户端缓存过期时间 的Header.
   * @param response HttpServletResponse
   * @param expiresSeconds long
   */
  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.
   * @param response HttpServletResponse
   */
  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.
   * @param response HttpServletResponse
   * @param lastModifiedDate long
   */
  public static void setLastModifiedHeader(HttpServletResponse response, long lastModifiedDate) {
    response.setDateHeader(HttpHeaders.LAST_MODIFIED, lastModifiedDate);
  }

  /**
   * 设置Etag Header.
   * @param response HttpServletResponse
   * @param etag String
   */
  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 request HttpServletRequest
   * @param response HttpServletResponse
   * @param lastModified 内容的最后修改时间.
   * @return true if has modified, otherwise return false.
   */
  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.
   * @param request HttpServletRequest
   * @param response HttpServletResponse
   * @return true if etag is matched, otherwise return false
   */
  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.
   * @param response HttpServletResponse
   * @param fileName String
   */
  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.
   * @param request ServletRequest
   * @param prefix String
   * @return parameter map
   */
  @SuppressWarnings("rawtypes")
  public static Map getParametersStartingWith(ServletRequest request, String prefix) {
    Validate.notNull(request, "Request must not be null");
    Enumeration paramNames = request.getParameterNames();
    Map params = new TreeMap();
    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parameter name上加上prefix.
   * @param params Map
   * @param prefix String
   * @return encoded parameter string
   */
  public static String encodeParameterStringWithPrefix(Map params, String prefix) {
    StringBuilder queryStringBuilder = new StringBuilder();

    String pre = prefix;
    if (pre == null) {
      pre = "";
    }
    Iterator> it = params.entrySet().iterator();
    while (it.hasNext()) {
      Entry 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.
   * @param userName String
   * @param password String
   * @return encoded username and password
   * 
   */
  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 HttpServletRequest
   * @return true if it is a ajax 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，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 HttpServletRequest HttpServletRequest
   */
  public static HttpServletRequest getRequest() {
    try {
      return ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
    } catch (Exception e) {
      return null;
    }
  }

}