/**
 * Controls the security of pad access
 */

/*
 * 2011 Peter 'Pita' Martischka (Primary Technology Ltd)
 *
 * Licensed 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.
 */

var ERR = require("async-stacktrace");
var async = require("async");
var authorManager = require("./AuthorManager");
var hooks = require("ep_etherpad-lite/static/js/pluginfw/hooks.js");
var padManager = require("./PadManager");
var sessionManager = require("./SessionManager");
var settings = require("../utils/Settings");
var log4js = require('log4js');
var authLogger = log4js.getLogger("auth");

/**
 * This function controlls the access to a pad, it checks if the user can access a pad.
 * @param padID the pad the user wants to access
 * @param sessionCookie the session the user has (set via api)
 * @param token the token of the author (randomly generated at client side, used for public pads)
 * @param password the password the user has given to access this pad, can be null
 * @param callback will be called with (err, {accessStatus: grant|deny|wrongPassword|needPassword, authorID: a.xxxxxx})
 */
exports.checkAccess = function(padID, sessionCookie, token, password, callback)
{
  var statusObject;

  if (!padID) {
    callback(null, {accessStatus: "deny"});
    return;
  }

  // allow plugins to deny access
  var deniedByHook = hooks.callAll("onAccessCheck", {'padID': padID, 'password': password, 'token': token, 'sessionCookie': sessionCookie}).indexOf(false) > -1;
  if (deniedByHook) {
    callback(null, {accessStatus: "deny"});
    return;
  }

  if (settings.requireSession) {
    // a valid session is required (api-only mode)
    if (!sessionCookie) {
      // without sessionCookie, access is denied
      callback(null, {accessStatus: "deny"});

      return;
    }
  } else {
    // a session is not required, so we'll check if it's a public pad
    if (padID.indexOf("$") == -1) {
      // it's not a group pad, means we can grant access

      // get author for this token
      authorManager.getAuthor4Token(token, function(err, author) {
        if (ERR(err, callback)) return;

        // assume user has access
        statusObject = { accessStatus: "grant", authorID: author };

        if (settings.editOnly) {
          // user can't create pads

          // check if pad exists
          padManager.doesPadExists(padID, function(err, exists) {
            if (ERR(err, callback)) return;

            if (!exists) {
              // pad doesn't exist - user can't have access
              statusObject.accessStatus = "deny";
            }

            // grant or deny access, with author of token
            callback(null, statusObject);
          });

          return;
        }

        // user may create new pads - no need to check anything
        // grant access, with author of token
        callback(null, statusObject);
      });

      // don't continue
      return;
    }
  }

  var groupID = padID.split("$")[0];
  var padExists = false;
  var validSession = false;
  var sessionAuthor;
  var tokenAuthor;
  var isPublic;
  var isPasswordProtected;
  var passwordStatus = password == null ? "notGiven" : "wrong"; // notGiven, correct, wrong

  async.series([
    // get basic informations from the database
    function(callback) {
      async.parallel([
        // does pad exist
        function(callback) {
          padManager.doesPadExists(padID, function(err, exists) {
            if (ERR(err, callback)) return;

            padExists = exists;
            callback();
          });
        },

        // get information about all sessions contained in this cookie
        function(callback) {
          if (!sessionCookie) {
            callback();
            return;
          }

          var sessionIDs = sessionCookie.split(',');

          async.forEach(sessionIDs, function(sessionID, callback) {
            sessionManager.getSessionInfo(sessionID, function(err, sessionInfo) {
              // skip session if it doesn't exist
              if (err && err.message == "sessionID does not exist") {
                authLogger.debug("Auth failed: unknown session");
                callback();

                return;
              }

              if (ERR(err, callback)) return;

              var now = Math.floor(Date.now()/1000);

              // is it for this group?
              if (sessionInfo.groupID != groupID) {
                authLogger.debug("Auth failed: wrong group");
                callback();

                return;
              }

              // is validUntil still ok?
              if (sessionInfo.validUntil <= now) {
                authLogger.debug("Auth failed: validUntil");
                callback();

                return;
              }

              // There is a valid session
              validSession = true;
              sessionAuthor = sessionInfo.authorID;

              callback();
            });
          }, callback);
        },

        // get author for token
        function(callback) {
          // get author for this token
          authorManager.getAuthor4Token(token, function(err, author) {
            if (ERR(err, callback)) return;

            tokenAuthor = author;
            callback();
          });
        }
      ], callback);
    },

    // get more informations of this pad, if avaiable
    function(callback) {
      // skip this if the pad doesn't exist
      if (padExists == false) {
        callback();

        return;
      }

      padManager.getPad(padID, function(err, pad) {
        if (ERR(err, callback)) return;

        // is it a public pad?
        isPublic = pad.getPublicStatus();

        // is it password protected?
        isPasswordProtected = pad.isPasswordProtected();

        // is password correct?
        if (isPasswordProtected && password && pad.isCorrectPassword(password)) {
          passwordStatus = "correct";
        }

        callback();
      });
    },

    function(callback) {
      if (validSession && padExists) {
        // - a valid session for this group is avaible AND pad exists
        if (!isPasswordProtected) {
          // - the pad is not password protected

          // --> grant access
          statusObject = { accessStatus: "grant", authorID: sessionAuthor };
        } else if (settings.sessionNoPassword) {
          // - the setting to bypass password validation is set

          // --> grant access
          statusObject = { accessStatus: "grant", authorID: sessionAuthor };
        } else if (isPasswordProtected && passwordStatus == "correct") {
          // - the pad is password protected and password is correct

          // --> grant access
          statusObject = { accessStatus: "grant", authorID: sessionAuthor };
        } else if (isPasswordProtected && passwordStatus == "wrong") {
          // - the pad is password protected but wrong password given

          // --> deny access, ask for new password and tell them that the password is wrong
          statusObject = { accessStatus: "wrongPassword" };
        } else if (isPasswordProtected && passwordStatus == "notGiven") {
          // - the pad is password protected but no password given

          // --> ask for password
          statusObject = { accessStatus: "needPassword" };
        } else {
          throw new Error("Ops, something wrong happend");
        }
      } else if (validSession && !padExists) {
        // - a valid session for this group avaible but pad doesn't exist

        // --> grant access
        statusObject = {accessStatus: "grant", authorID: sessionAuthor};

        if (settings.editOnly) {
          // --> deny access if user isn't allowed to create the pad
          authLogger.debug("Auth failed: valid session & pad does not exist");
          statusObject.accessStatus = "deny";
        }
      } else if (!validSession && padExists) {
        // there is no valid session avaiable AND pad exists

        // -- it's public and not password protected
        if (isPublic && !isPasswordProtected) {
          // --> grant access, with author of token
          statusObject = {accessStatus: "grant", authorID: tokenAuthor};
        } else if (isPublic && isPasswordProtected && passwordStatus == "correct") {
          // - it's public and password protected and password is correct

          // --> grant access, with author of token
          statusObject = {accessStatus: "grant", authorID: tokenAuthor};
        } else if (isPublic && isPasswordProtected && passwordStatus == "wrong") {
          // - it's public and the pad is password protected but wrong password given

          // --> deny access, ask for new password and tell them that the password is wrong
          statusObject = {accessStatus: "wrongPassword"};
        } else if (isPublic && isPasswordProtected && passwordStatus == "notGiven") {
          // - it's public and the pad is password protected but no password given

          // --> ask for password
          statusObject = {accessStatus: "needPassword"};
        } else if (!isPublic) {
          // - it's not public

          authLogger.debug("Auth failed: invalid session & pad is not public");
          // --> deny access
          statusObject = {accessStatus: "deny"};
        } else {
          throw new Error("Ops, something wrong happend");
        }
      } else {
        // there is no valid session avaiable AND pad doesn't exist
        authLogger.debug("Auth failed: invalid session & pad does not exist");
        // --> deny access
        statusObject = {accessStatus: "deny"};
      }

      callback();
    }
  ],
  function(err) {
    if (ERR(err, callback)) return;

    callback(null, statusObject);
  });
};