/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.hadoop.chukwa.hicc;
  
  
  import java.io.*;
  import java.util.*;
  import javax.servlet.*;
  import javax.servlet.http.*;
  import java.sql.*;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.chukwa.util.XssFilter;
  import org.json.*;
  import org.apache.hadoop.chukwa.util.ExceptionUtil;
  
  public class Workspace extends HttpServlet {
    public static final long serialVersionUID = 101L;
    private static final Log log = LogFactory.getLog(Workspace.class);
    private String path = System.getenv("CHUKWA_DATA_DIR");
    transient private JSONObject hash = new JSONObject();
    transient private XssFilter xf;
  
    @Override  
    protected void doTrace(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED); 
    }
  
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException {
      xf = new XssFilter(request);
      response.setContentType("text/plain");
      String method = xf.getParameter("method");
      if (method.equals("get_views_list")) {
        getViewsList(request, response);
      }
      if (method.equals("get_view")) {
        getView(request, response);
      }
      if (method.equals("save_view")) {
        saveView(request, response);
      }
      if (method.equals("change_view_info")) {
        changeViewInfo(request, response);
      }
      if (method.equals("get_widget_list")) {
        getWidgetList(request, response);
      }
      if (method.equals("clone_view")) {
        cloneView(request, response);
      }
      if (method.equals("delete_view")) {
        deleteView(request, response);
      }
    }
  
    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException {
      doGet(request, response);
    }
  
    static public String getContents(File aFile) {
      // ...checks on aFile are elided
      StringBuffer contents = new StringBuffer();
  
      try {
        // use buffering, reading one line at a time
        // FileReader always assumes default encoding is OK!
        BufferedReader input = new BufferedReader(new FileReader(aFile));
        try {
          String line = null; // not declared within while loop
          /*
           * readLine is a bit quirky : it returns the content of a line MINUS the
           * newline. it returns null only for the END of the stream. it returns
           * an empty String if two newlines appear in a row.
           */
          while ((line = input.readLine()) != null) {
            contents.append(line);
            contents.append(System.getProperty("line.separator"));
          }
        } finally {
          input.close();
        }
     } catch (IOException ex) {
       ex.printStackTrace();
     }
 
     return contents.toString();
   }
 
   public void setContents(String fName, String buffer) {
     try {
       FileWriter fstream = new FileWriter(fName);
       BufferedWriter out = new BufferedWriter(fstream);
       out.write(buffer);
       out.close();
     } catch (Exception e) {
       System.err.println("Error: " + e.getMessage());
     }
   }
 
   public void cloneView(HttpServletRequest request, HttpServletResponse response)
       throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     String name = xf.getParameter("name");
     String template = xf.getParameter("clone_name");
     File aFile = new File(path + "/views/" + template);
     String config = getContents(aFile);
     int i = 0;
     boolean check = true;
     while (check) {
       String tmpName = name;
       if (i > 0) {
         tmpName = name + i;
       }
       File checkFile = new File(path + "/views/" + tmpName + ".view");
       check = checkFile.exists();
       if (!check) {
         name = tmpName;
       }
       i = i + 1;
     }
     setContents(path + "/views/" + name + ".view", config);
     File deleteCache = new File(path + "/views/workspace_view_list.cache");
     if(!deleteCache.delete()) {
       log.warn("Can not delete "+path + "/views/workspace_view_list.cache");
     }
     genViewCache(path + "/views");
     aFile = new File(path + "/views/workspace_view_list.cache");
     String viewsCache = getContents(aFile);
     out.println(viewsCache);
   }
 
   public void deleteView(HttpServletRequest request,
       HttpServletResponse response) throws IOException, ServletException {
     String name = xf.getParameter("name");
     File aFile = new File(path + "/views/" + name + ".view");
     if(!aFile.delete()) {
       log.warn("Can not delete " + path + "/views/" + name + ".view");
     }
     File deleteCache = new File(path + "/views/workspace_view_list.cache");
     if(!deleteCache.delete()) {
       log.warn("Can not delete "+path + "/views/workspace_view_list.cache");
     }
     genViewCache(path + "/views");
   }
 
   public void getViewsList(HttpServletRequest request,
       HttpServletResponse response) throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     genViewCache(path + "/views");
     File aFile = new File(path + "/views/workspace_view_list.cache");
     String viewsCache = getContents(aFile);
     out.println(viewsCache);
   }
 
   public void getView(HttpServletRequest request, HttpServletResponse response)
       throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     String id = xf.getParameter("id");
     genViewCache(path + "/views");
     File aFile = new File(path + "/views/" + id + ".view");
     String view = getContents(aFile);
     out.println(view);
   }
 
   public void changeViewInfo(HttpServletRequest request,
       HttpServletResponse response) throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     String id = xf.getParameter("name");
     String config = request.getParameter("config");
     try {
       JSONObject jt = new JSONObject(config);
       File aFile = new File(path + "/views/" + id + ".view");
       String original = getContents(aFile);
       JSONObject updateObject = new JSONObject(original);
       updateObject.put("description", jt.get("description"));
       setContents(path + "/views/" + id + ".view", updateObject.toString());
       if (!rename(id, jt.get("description").toString())) {
         throw new Exception("Rename view file failed");
       }
       File deleteCache = new File(path + "/views/workspace_view_list.cache");
       if(!deleteCache.delete()) {
         log.warn("Can not delete "+path + "/views/workspace_view_list.cache");
       }
       genViewCache(path + "/views");
       out.println("Workspace is stored successfully.");
     } catch (Exception e) {
       out.println("Workspace store failed.");
     }
   }
 
   public void saveView(HttpServletRequest request, HttpServletResponse response)
       throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     String id = xf.getParameter("name");
     String config = request.getParameter("config");
     setContents(path + "/views/" + id + ".view", config);
     out.println("Workspace is stored successfully.");
   }
 
   public void getWidgetList(HttpServletRequest request,
       HttpServletResponse response) throws IOException, ServletException {
     PrintWriter out = response.getWriter();
     genWidgetCache(path + "/descriptors");
     File aFile = new File(path + "/descriptors/workspace_plugin.cache");
     String viewsCache = getContents(aFile);
     out.println(viewsCache);
   }
 
   private void genViewCache(String source) {
     File cacheFile = new File(source + "/workspace_view_list.cache");
     if (!cacheFile.exists()) {
       File dir = new File(source);
       File[] filesWanted = dir.listFiles(new FilenameFilter() {
         public boolean accept(File dir, String name) {
           return name.endsWith(".view");
         }
       });
       JSONObject[] cacheGroup = new JSONObject[filesWanted.length];
       for (int i = 0; i < filesWanted.length; i++) {
         String buffer = getContents(filesWanted[i]);
         try {
           JSONObject jt = new JSONObject(buffer);
           String fn = filesWanted[i].getName();
           jt.put("key", fn.substring(0, (fn.length() - 5)));
           cacheGroup[i] = jt;
         } catch (Exception e) {
           log.debug(ExceptionUtil.getStackTrace(e));
         }
       }
       String viewList = convertObjectsToViewList(cacheGroup);
       setContents(source + "/workspace_view_list.cache", viewList);
     }
   }
 
   public String convertObjectsToViewList(JSONObject[] objArray) {
     JSONArray jsonArr = new JSONArray();
     JSONObject permission = new JSONObject();
     JSONObject user = new JSONObject();
     try {
       permission.put("read", 1);
       permission.put("modify", 1);
       user.put("all", permission);
     } catch (Exception e) {
       System.err.println("JSON Exception: " + e.getMessage());
     }
     for (int i = 0; i < objArray.length; i++) {
       try {
         JSONObject jsonObj = new JSONObject();
         jsonObj.put("key", objArray[i].get("key"));
         jsonObj.put("description", objArray[i].get("description"));
         jsonObj.put("owner", "");
         jsonObj.put("permission", user);
         jsonArr.put(jsonObj);
       } catch (Exception e) {
         System.err.println("JSON Exception: " + e.getMessage());
       }
     }
     return jsonArr.toString();
   }
 
   private void genWidgetCache(String source) {
     File cacheFile = new File(source + "/workspace_plugin.cache");
     File cacheDir = new File(source);
     if (!cacheFile.exists()
         || cacheFile.lastModified() < cacheDir.lastModified()) {
       File dir = new File(source);
       File[] filesWanted = dir.listFiles(new FilenameFilter() {
         public boolean accept(File dir, String name) {
           return name.endsWith(".descriptor");
         }
       });
       JSONObject[] cacheGroup = new JSONObject[filesWanted.length];
       for (int i = 0; i < filesWanted.length; i++) {
         String buffer = getContents(filesWanted[i]);
         try {
           JSONObject jt = new JSONObject(buffer);
           cacheGroup[i] = jt;
         } catch (Exception e) {
           log.debug(ExceptionUtil.getStackTrace(e));
         }
       }
       String widgetList = convertObjectsToWidgetList(cacheGroup);
       setContents(source + "/workspace_plugin.cache", widgetList);
     }
   }
 
   public String convertObjectsToWidgetList(JSONObject[] objArray) {
     JSONObject jsonObj = new JSONObject();
     JSONArray jsonArr = new JSONArray();
     for (int i = 0; i < objArray.length; i++) {
       jsonArr.put(objArray[i]);
     }
     try {
       jsonObj.put("detail", jsonArr);
     } catch (Exception e) {
       System.err.println("JSON Exception: " + e.getMessage());
     }
     for (int i = 0; i < objArray.length; i++) {
       try {
         String[] categoriesArray = objArray[i].get("categories").toString()
             .split(",");
         hash = addToHash(hash, categoriesArray, objArray[i]);
       } catch (JSONException e) {
         System.err.println("JSON Exception: " + e.getMessage());
       }
     }
     try {
       jsonObj.put("children", hash);
     } catch (Exception e) {
       System.err.println("JSON Exception: " + e.getMessage());
     }
     return jsonObj.toString();
   }
 
   public JSONObject addToHash(JSONObject hash, String[] categoriesArray,
       JSONObject obj) {
     JSONObject subHash = hash;
     for (int i = 0; i < categoriesArray.length; i++) {
       String id = categoriesArray[i];
       if (i >= categoriesArray.length - 1) {
         try {
           subHash.put("leaf:" + obj.get("title"), obj.get("id"));
         } catch (Exception e) {
           System.err.println("JSON Exception: " + e.getMessage());
         }
       } else {
         try {
           subHash = subHash.getJSONObject("node:" + id);
         } catch (JSONException e) {
           try {
             JSONObject tmpHash = new JSONObject();
             subHash.put("node:" + id, tmpHash);
             subHash = tmpHash;
           } catch (JSONException ex) {
             log.debug(ExceptionUtil.getStackTrace(e));
           }
         }
       }
     }
     return hash;
   }
 
   private boolean rename(String id, String desc) {
     try {
       File view = new File(path + "/views/" + id + ".view");
       File newFile = new File(path + File.separator + "views" + File.separator
           + desc + ".view");
       if(!view.renameTo(newFile)) {
         log.warn("Can not rename " + path + "/views/" + id + ".view to " + 
             path + File.separator + "views" + File.separator + desc + ".view");
       }
     } catch (Exception e) {
       return false;
     }
     return true;
   }
 
 }