/**
 * The Group Manager provides functions to manage groups in the database
 */

/*
 * 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 customError = require("../utils/customError");
var randomString = require('ep_etherpad-lite/static/js/pad_utils').randomString;
var db = require("./DB").db;
var async = require("async");
var padManager = require("./PadManager");
var sessionManager = require("./SessionManager");
const thenify = require("thenify").withCallback;

exports.listAllGroups = thenify(function(callback) {
  db.get("groups", function (err, groups) {
    if (ERR(err, callback)) return;

    if (groups == null) {
      // there are no groups
      callback(null, {groupIDs: []});

      return;
    }

    var groupIDs = [];
    for (var groupID in groups) {
      groupIDs.push(groupID);
    }
    callback(null, {groupIDs: groupIDs});
  });
});

exports.deleteGroup = thenify(function(groupID, callback)
{
  var group;

  async.series([
    // ensure group exists
    function (callback) {
      // try to get the group entry
      db.get("group:" + groupID, function (err, _group) {
        if (ERR(err, callback)) return;

        if (_group == null) {
          // group does not exist
          callback(new customError("groupID does not exist", "apierror"));
          return;
        }

        // group exists, everything is fine
        group = _group;
        callback();
      });
    },

    // iterate through all pads of this group and delete them
    function(callback) {
      // collect all padIDs in an array, that allows us to use async.forEach
      var padIDs = [];
      for(var i in group.pads) {
        padIDs.push(i);
      }

      // loop through all pads and delete them
      async.forEach(padIDs, function(padID, callback) {
        padManager.getPad(padID, function(err, pad) {
          if (ERR(err, callback)) return;

          pad.remove(callback);
        });
      }, callback);
    },

    // iterate through group2sessions and delete all sessions
    function(callback)
    {
      // try to get the group entry
      db.get("group2sessions:" + groupID, function (err, group2sessions) {
        if (ERR(err, callback)) return;

        // skip if there is no group2sessions entry
        if (group2sessions == null) { callback(); return }

        // collect all sessions in an array, that allows us to use async.forEach
        var sessions = [];
        for (var i in group2sessions.sessionsIDs) {
          sessions.push(i);
        }

        // loop through all sessions and delete them
        async.forEach(sessions, function(session, callback) {
          sessionManager.deleteSession(session, callback);
        }, callback);
      });
    },

    // remove group and group2sessions entry
    function(callback) {
      db.remove("group2sessions:" + groupID);
      db.remove("group:" + groupID);
      callback();
    },

    // unlist the group
    function(callback) {
      exports.listAllGroups(function(err, groups) {
        if (ERR(err, callback)) return;
        groups = groups? groups.groupIDs : [];

        let index = groups.indexOf(groupID);

        if (index === -1) {
          // it's not listed
          callback();

          return;
        }

        // remove from the list
        groups.splice(index, 1);

        // store empty group list
        if (groups.length == 0) {
          db.set("groups", {});
          callback();
          return;
        }

        // regenerate group list
        var newGroups = {};
        async.forEach(groups, function(group, cb) {
          newGroups[group] = 1;
          cb();
        },
        function() {
          db.set("groups", newGroups);
          callback();
        });
      });
    }
  ],
  function(err) {
    if (ERR(err, callback)) return;
    callback();
  });
});

exports.doesGroupExist = thenify(function(groupID, callback)
{
  // try to get the group entry
  db.get("group:" + groupID, function (err, group) {
    if (ERR(err, callback)) return;
    callback(null, group != null);
  });
});

exports.createGroup = thenify(function(callback)
{
  // search for non existing groupID
  var groupID = "g." + randomString(16);

  // create the group
  db.set("group:" + groupID, {pads: {}});

  // list the group
  exports.listAllGroups(function(err, groups) {
    if (ERR(err, callback)) return;

    groups = groups? groups.groupIDs : [];
    groups.push(groupID);

    // regenerate group list
    var newGroups = {};
    async.forEach(groups, function(group, cb) {
      newGroups[group] = 1;
      cb();
    },
    function() {
      db.set("groups", newGroups);
      callback(null, {groupID: groupID});
    });
  });
});

exports.createGroupIfNotExistsFor = thenify(function(groupMapper, callback)
{
  // ensure mapper is optional
  if (typeof groupMapper !== "string") {
    callback(new customError("groupMapper is not a string", "apierror"));
    return;
  }

  // try to get a group for this mapper
  db.get("mapper2group:" + groupMapper, function(err, groupID) {
    function createGroupForMapper(cb) {
      exports.createGroup(function(err, responseObj) {
        if (ERR(err, cb)) return;

        // create the mapper entry for this group
        db.set("mapper2group:" + groupMapper, responseObj.groupID);

        cb(null, responseObj);
      });
    }

    if (ERR(err, callback)) return;

    if (groupID) {
      // there is a group for this mapper
      exports.doesGroupExist(groupID, function(err, exists) {
        if (ERR(err, callback)) return;

        if (exists) return callback(null, {groupID: groupID});

        // hah, the returned group doesn't exist, let's create one
        createGroupForMapper(callback)
      });

      return;
    }

    // there is no group for this mapper, let's create a group
    createGroupForMapper(callback)
  });
});

exports.createGroupPad = thenify(function(groupID, padName, text, callback)
{
  // create the padID
  var padID = groupID + "$" + padName;

  async.series([
    // ensure group exists
    function (callback) {
      exports.doesGroupExist(groupID, function(err, exists) {
        if (ERR(err, callback)) return;

        if (!exists) {
          // group does not exist
          callback(new customError("groupID does not exist", "apierror"));
          return;
        }

        // group exists, everything is fine
        callback();
      });
    },

    // ensure pad doesn't exist already
    function (callback) {
      padManager.doesPadExists(padID, function(err, exists) {
        if (ERR(err, callback)) return;

        if (exists == true) {
          // pad exists already
          callback(new customError("padName does already exist", "apierror"));
          return;
        }

        // pad does not exist, everything is fine
        callback();
      });
    },

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

        callback();
      });
    },

    // create an entry in the group for this pad
    function (callback) {
      db.setSub("group:" + groupID, ["pads", padID], 1);
      callback();
    }
  ],
  function(err) {
    if (ERR(err, callback)) return;

    callback(null, {padID: padID});
  });
});

exports.listPads = thenify(function(groupID, callback)
{
  exports.doesGroupExist(groupID, function(err, exists) {
    if (ERR(err, callback)) return;

    // ensure the group exists
    if (!exists) {
      callback(new customError("groupID does not exist", "apierror"));
      return;
    }

    // group exists, let's get the pads
    db.getSub("group:" + groupID, ["pads"], function(err, result) {
      if (ERR(err, callback)) return;

      var pads = [];
      for ( var padId in result ) {
        pads.push(padId);
      }
      callback(null, {padIDs: pads});
    });
  });
});