###
Creates a new bucket for a user using the given parameters (if not already above the user's limit)

@param {Object} user the document of the authenticated user
@param {String} name to be used for the bucket
@param {Number} limit to be used for the bucket (in Byte)
@param {Function} callback gets two parameters - error object (if an error occured) and the new bucket document if successful.

@api public
###
Buckets::create = (user, name, limit, callback) ->
  this.list user, (err, info) =>
    return callback(err) if err

    # check the bucket name (for already taken)
    for bucket in info.buckets
      if bucket.name == name
        return callback(message: "The name \"#{name}\" is already taken.")

    # check the userlimit
    if user.limit and (info.totalSize + limit) > user.limit
      max = user.limit - info.totalSize
      return callback(message: "The desired limit of #{limit} exceeds the total limit of #{user.limit} by #{limit-max}. The maximum limit is #{max}.")

    bucket =
      name: name
      owner: user._id.toHexString()
      limit: limit
      size: 0

    this.collection.insert bucket, {safe:true}, (err, docs) ->
      return callback err if err
      return callback null, docs[0]