/**
 * 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 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");

const DENY = Object.freeze({accessStatus: 'deny'});
const WRONG_PASSWORD = Object.freeze({accessStatus: 'wrongPassword'});
const NEED_PASSWORD = Object.freeze({accessStatus: 'needPassword'});

/**
 * Determines whether the user can access a pad.
 *
 * @param padID identifies the pad the user wants to access.
 * @param sessionCookie identifies the sessions the user created via the HTTP API, if any.
 *     Note: The term "session" used here is unrelated to express-session.
 * @param token is a random token of the form t.randomstring_of_length_20 generated by the client
 *     when using the web UI (not the HTTP API). This token is only used if settings.requireSession
 *     is false and the user is accessing a public pad. If there is not an author already associated
 *     with this token then a new author object is created (including generating an author ID) and
 *     associated with this token.
 * @param password is the password the user has given to access this pad. It can be null.
 * @return {accessStatus: grant|deny|wrongPassword|needPassword, authorID: a.xxxxxx}. The caller
 *     must use the author ID returned in this object when making any changes associated with the
 *     author.
 *
 * WARNING: Tokens and session IDs MUST be kept secret, otherwise users will be able to impersonate
 * each other (which might allow them to gain privileges).
 */
exports.checkAccess = async function(padID, sessionCookie, token, password)
{
  if (!padID) {
    authLogger.debug('access denied: missing padID');
    return DENY;
  }

  // allow plugins to deny access
  const isFalse = (x) => x === false;
  if (hooks.callAll('onAccessCheck', {padID, password, token, sessionCookie}).some(isFalse)) {
    authLogger.debug('access denied: an onAccessCheck hook function returned false');
    return DENY;
  }

  // start fetching the info we may need
  const p_sessionAuthorID = sessionManager.findAuthorID(padID.split('$')[0], sessionCookie);
  const p_tokenAuthorID = authorManager.getAuthor4Token(token);
  const p_padExists = padManager.doesPadExist(padID);

  const padExists = await p_padExists;
  if (!padExists && settings.editOnly) {
    authLogger.debug('access denied: user attempted to create a pad, which is prohibited');
    return DENY;
  }

  const sessionAuthorID = await p_sessionAuthorID;
  if (settings.requireSession && !sessionAuthorID) {
    authLogger.debug('access denied: HTTP API session is required');
    return DENY;
  }

  const grant = {
    accessStatus: 'grant',
    authorID: (sessionAuthorID != null) ? sessionAuthorID : await p_tokenAuthorID,
  };

  if (!padID.includes('$')) {
    // Only group pads can be private or have passwords, so there is nothing more to check for this
    // non-group pad.
    return grant;
  }

  if (!padExists) {
    if (sessionAuthorID == null) {
      authLogger.debug('access denied: must have an HTTP API session to create a group pad');
      return DENY;
    }
    // Creating a group pad, so there is no password or public status to check.
    return grant;
  }

  const pad = await padManager.getPad(padID);

  if (!pad.getPublicStatus() && sessionAuthorID == null) {
    authLogger.debug('access denied: must have an HTTP API session to access private group pads');
    return DENY;
  }

  const passwordExempt = settings.sessionNoPassword && sesionAuthorID != null;
  const requirePassword = pad.isPasswordProtected() && !passwordExempt;
  if (requirePassword) {
    if (password == null) {
      authLogger.debug('access denied: password required');
      return NEED_PASSWORD;
    }
    if (!password || !pad.isCorrectPassword(password)) {
      authLogger.debug('access denied: wrong password');
      return WRONG_PASSWORD;
    }
  }

  return grant;
};