16007: Account for all the edges. still wip.

[arvados.git] / services / api / app / models / user.rb

# Copyright (C) The Arvados Authors. All rights reserved.
#
# SPDX-License-Identifier: AGPL-3.0

require 'can_be_an_owner'

class User < ArvadosModel
  include HasUuid
  include KindAndEtag
  include CommonApiTemplate
  include CanBeAnOwner
  extend CurrentApiClient

  serialize :prefs, Hash
  has_many :api_client_authorizations
  validates(:username,
            format: {
              with: /\A[A-Za-z][A-Za-z0-9]*\z/,
              message: "must begin with a letter and contain only alphanumerics",
            },
            uniqueness: true,
            allow_nil: true)
  validate :must_unsetup_to_deactivate
  before_update :prevent_privilege_escalation
  before_update :prevent_inactive_admin
  before_update :verify_repositories_empty, :if => Proc.new { |user|
    user.username.nil? and user.username_changed?
  }
  before_update :setup_on_activate
  before_create :check_auto_admin
  before_create :set_initial_username, :if => Proc.new { |user|
    user.username.nil? and user.email
  }
  after_create :update_permissions
  after_create :setup_on_activate
  after_create :add_system_group_permission_link
  after_create :auto_setup_new_user, :if => Proc.new { |user|
    Rails.configuration.Users.AutoSetupNewUsers and
    (user.uuid != system_user_uuid) and
    (user.uuid != anonymous_user_uuid)
  }
  after_create :send_admin_notifications
  after_update :update_permissions, :if => :owner_uuid_changed?
  after_update :send_profile_created_notification
  after_update :sync_repository_names, :if => Proc.new { |user|
    (user.uuid != system_user_uuid) and
    user.username_changed? and
    (not user.username_was.nil?)
  }


  has_many :authorized_keys, :foreign_key => :authorized_user_uuid, :primary_key => :uuid
  has_many :repositories, foreign_key: :owner_uuid, primary_key: :uuid

  default_scope { where('redirect_to_user_uuid is null') }

  api_accessible :user, extend: :common do |t|
    t.add :email
    t.add :username
    t.add :full_name
    t.add :first_name
    t.add :last_name
    t.add :identity_url
    t.add :is_active
    t.add :is_admin
    t.add :is_invited
    t.add :prefs
    t.add :writable_by
  end

  ALL_PERMISSIONS = {read: true, write: true, manage: true}

  # Map numeric permission levels (see lib/create_permission_view.sql)
  # back to read/write/manage flags.
  PERMS_FOR_VAL =
    [{},
     {read: true},
     {read: true, write: true},
     {read: true, write: true, manage: true}]

  VAL_FOR_PERM =
    {:read => 1,
     :write => 2,
     :manage => 3}


  def full_name
    "#{first_name} #{last_name}".strip
  end

  def is_invited
    !!(self.is_active ||
       Rails.configuration.Users.NewUsersAreActive ||
       self.groups_i_can(:read).select { |x| x.match(/-f+$/) }.first)
  end

  def groups_i_can(verb)
    my_groups = self.group_permissions(VAL_FOR_PERM[verb]).keys
    if verb == :read
      my_groups << anonymous_group_uuid
    end
    my_groups
  end

  def can?(actions)
    return true if is_admin
    actions.each do |action, target|
      unless target.nil?
        if target.respond_to? :uuid
          target_uuid = target.uuid
        else
          target_uuid = target
          target = ArvadosModel.find_by_uuid(target_uuid)
        end
      end
      next if target_uuid == self.uuid

      target_owner_uuid = target.owner_uuid if target.respond_to? :owner_uuid

      unless ActiveRecord::Base.connection.
        exec_query(%{
SELECT 1 FROM #{PERMISSION_VIEW}
  WHERE user_uuid = $1 and
        ((target_uuid = $2 and perm_level >= $3)
         or (target_uuid = $4 and perm_level >= $3 and traverse_owned))
},
                  # "name" arg is a query label that appears in logs:
                   "user_can_query",
                   [[nil, self.uuid],
                    [nil, target_uuid],
                    [nil, VAL_FOR_PERM[action]],
                    [nil, target_owner_uuid]]
                  ).any?
        return false
      end
    end
    true
  end

  def update_permissions

#       puts "Update permissions for #{uuid}"
#     User.printdump %{
# select * from materialized_permissions where user_uuid='#{uuid}'
# }
#     puts "---"
    User.update_permissions self.owner_uuid, self.uuid, 3

#   puts "post-update"
#    User.printdump %{
# select * from materialized_permissions where user_uuid='#{uuid}'
# }
#    puts "<<<"
  end

  def self.printdump qr
    q1 = ActiveRecord::Base.connection.exec_query qr
    q1.each do |r|
      puts r
    end
  end

  def recompute_permissions
    ActiveRecord::Base.connection.execute("DELETE FROM #{PERMISSION_VIEW} where user_uuid='#{uuid}'")
    ActiveRecord::Base.connection.execute %{
INSERT INTO #{PERMISSION_VIEW}
select '#{uuid}', g.target_uuid, g.val, g.traverse_owned
from search_permission_graph('#{uuid}', 3) as g
}
  end

  def self.update_permissions perm_origin_uuid, starting_uuid, perm_level
    # Update a subset of the permission graph
    # perm_level is the inherited permission
    # perm_level is a number from 0-3
    #   can_read=1
    #   can_write=2
    #   can_manage=3
    #   call with perm_level=0 to revoke permissions
    #
    # 1. Compute set (group, permission) implied by traversing
    #    graph starting at this group
    # 2. Find links from outside the graph that point inside
    # 3. For each starting uuid, get the set of permissions from the
    #    materialized permission table
    # 3. Delete permissions from table not in our computed subset.
    # 4. Upsert each permission in our subset (user, group, val)

    ## testinging
    puts "\n__ update_permissions __"
#     puts "What's in there now for #{starting_uuid}"
#     printdump %{
# select * from materialized_permissions where user_uuid='#{starting_uuid}'
# }

    puts "search_permission_graph #{perm_origin_uuid} #{starting_uuid}, #{perm_level}"
    printdump %{
select '#{perm_origin_uuid}'::varchar as perm_origin_uuid, target_uuid, val, traverse_owned from search_permission_graph('#{starting_uuid}', #{perm_level})
}

#     puts "other_links #{perm_origin_uuid} #{starting_uuid}, #{perm_level}"
#     printdump %{
# with
# perm_from_start(perm_origin_uuid, target_uuid, val, traverse_owned) as (
#   select '#{perm_origin_uuid}'::varchar, target_uuid, val, traverse_owned
#     from search_permission_graph('#{starting_uuid}'::varchar, #{perm_level}))

#     select links.tail_uuid as perm_origin_uuid, links.head_uuid, links.name
#       from links
#       where links.link_class='permission' and
#         links.tail_uuid not in (select target_uuid from perm_from_start where traverse_owned) and
#         links.tail_uuid != '#{perm_origin_uuid}' and
#         links.head_uuid in (select target_uuid from perm_from_start)
# }

    puts "additional_perms #{perm_origin_uuid} #{starting_uuid}, #{perm_level}"
    printdump %{
with
perm_from_start(perm_origin_uuid, target_uuid, val, traverse_owned) as (
  select '#{perm_origin_uuid}'::varchar, target_uuid, val, traverse_owned
    from search_permission_graph('#{starting_uuid}'::varchar, #{perm_level})),

  edges(tail_uuid, head_uuid, val) as (
        select * from permission_graph_edges()),

  additional_perms(perm_origin_uuid, target_uuid, val, traverse_owned) as (
    select edges.tail_uuid as perm_origin_uuid, ps.target_uuid, ps.val,
           should_traverse_owned(ps.target_uuid, ps.val)
      from edges, lateral search_permission_graph(edges.head_uuid, edges.val) as ps
      where (not (edges.tail_uuid = '#{perm_origin_uuid}' and
                  edges.head_uuid = '#{starting_uuid}' and
                  edges.val = #{perm_level})) and
            edges.tail_uuid not in (select target_uuid from perm_from_start) and
            edges.head_uuid in (select target_uuid from perm_from_start)),

  partial_perms(perm_origin_uuid, target_uuid, val, traverse_owned) as (
      select * from perm_from_start
    union
      select * from additional_perms
  ),

  user_identity_perms(perm_origin_uuid, target_uuid, val, traverse_owned) as (
    select users.uuid as perm_origin_uuid, ps.target_uuid, ps.val, ps.traverse_owned
      from users, lateral search_permission_graph(users.uuid, 3) as ps
      where users.owner_uuid not in (select target_uuid from partial_perms where traverse_owned) and
      users.uuid in (select target_uuid from partial_perms)
  ),

  all_perms(perm_origin_uuid, target_uuid, val, traverse_owned) as (
      select * from additional_perms
    union
      select * from user_identity_perms
  )

  select * from all_perms order by perm_origin_uuid, target_uuid
}

    puts "Perms out"
    printdump %{
select * from compute_permission_subgraph('#{perm_origin_uuid}', '#{starting_uuid}', '#{perm_level}')
order by user_uuid, target_uuid
}
    ## end

    temptable_perms = "temp_perms_#{rand(2**64).to_s(10)}"
    ActiveRecord::Base.connection.exec_query %{
create temporary table #{temptable_perms} on commit drop
as select * from compute_permission_subgraph($1, $2, $3)
},
                                             'Group.search_permissions',
                                             [[nil, perm_origin_uuid],
                                              [nil, starting_uuid],
                                              [nil, perm_level]]

#     q1 = ActiveRecord::Base.connection.exec_query %{
# select * from #{temptable_perms} order by user_uuid, target_uuid
# }
#     puts "recomputed perms was #{perm_origin_uuid} #{starting_uuid}, #{perm_level}"
#     q1.each do |r|
#       puts r
#     end
#     puts "<<<<"

    ActiveRecord::Base.connection.exec_query %{
delete from materialized_permissions where
  target_uuid in (select target_uuid from #{temptable_perms}) and
  (user_uuid not in (select user_uuid from #{temptable_perms} where target_uuid=materialized_permissions.target_uuid)
   or user_uuid in (select user_uuid from #{temptable_perms} where target_uuid=materialized_permissions.target_uuid and perm_level=0))
}

    ActiveRecord::Base.connection.exec_query %{
insert into materialized_permissions (user_uuid, target_uuid, perm_level, traverse_owned)
  select user_uuid, target_uuid, val as perm_level, traverse_owned from #{temptable_perms}
on conflict (user_uuid, target_uuid) do update set perm_level=EXCLUDED.perm_level, traverse_owned=EXCLUDED.traverse_owned;
}

    # for testing only - make a copy of the table and compare it to the one generated
    # using a full permission recompute

#      puts "dump--"
#      User.printdump %{
#  select * from users
#      }
#      User.printdump %{
#  select * from groups
#      }
#      User.printdump %{
# select * from search_permission_graph('zzzzz-tpzed-000000000000000', 3)
#      }
#      puts "--"


    q1 = ActiveRecord::Base.connection.exec_query %{
select user_uuid, target_uuid, perm_level, traverse_owned from materialized_permissions
order by user_uuid, target_uuid
}

    q2 = ActiveRecord::Base.connection.exec_query %{
select users.uuid as user_uuid, g.target_uuid, g.val as perm_level, g.traverse_owned
from users, lateral search_permission_graph(users.uuid, 3) as g where g.val > 0
order by users.uuid, target_uuid
}

    if q1.count != q2.count
      puts "Didn't match incremental+: #{q1.count} != full refresh-: #{q2.count}"
    end

    if q1.count > q2.count
      q1.each_with_index do |r, i|
        if r != q2[i]
          puts "+#{r}\n-#{q2[i]}"
          raise "Didn't match"
        end
      end
    else
      q2.each_with_index do |r, i|
        if r != q1[i]
          puts "+#{q1[i]}\n-#{r}"
          raise "Didn't match"
        end
      end
    end
  end

  # Return a hash of {user_uuid: group_perms}
  def self.all_group_permissions
    all_perms = {}
    ActiveRecord::Base.connection.
      exec_query("SELECT user_uuid, target_uuid, perm_level
                  FROM #{PERMISSION_VIEW}
                  WHERE traverse_owned",
                  # "name" arg is a query label that appears in logs:
                 "all_group_permissions").
      rows.each do |user_uuid, group_uuid, max_p_val|
      all_perms[user_uuid] ||= {}
      all_perms[user_uuid][group_uuid] = PERMS_FOR_VAL[max_p_val.to_i]
    end
    all_perms
  end

  # Return a hash of {group_uuid: perm_hash} where perm_hash[:read]
  # and perm_hash[:write] are true if this user can read and write
  # objects owned by group_uuid.
  def group_permissions(level=1)
    group_perms = {}
    ActiveRecord::Base.connection.
      exec_query(%{
SELECT target_uuid, perm_level
  FROM #{PERMISSION_VIEW}
  WHERE user_uuid = $1 and perm_level >= $2
},
                  # "name" arg is a query label that appears in logs:
                  "group_permissions_for_user",
                  # "binds" arg is an array of [col_id, value] for '$1' vars:
                  [[nil, uuid],
                   [nil, level]]).
      rows.each do |group_uuid, max_p_val|
      group_perms[group_uuid] = PERMS_FOR_VAL[max_p_val.to_i]
    end
    group_perms
  end

  # create links
  def setup(repo_name: nil, vm_uuid: nil)
    repo_perm = create_user_repo_link repo_name
    vm_login_perm = create_vm_login_permission_link(vm_uuid, username) if vm_uuid
    group_perm = create_user_group_link

    return [repo_perm, vm_login_perm, group_perm, self].compact
  end

  # delete user signatures, login, repo, and vm perms, and mark as inactive
  def unsetup
    # delete oid_login_perms for this user
    #
    # note: these permission links are obsolete, they have no effect
    # on anything and they are not created for new users.
    Link.where(tail_uuid: self.email,
                     link_class: 'permission',
                     name: 'can_login').destroy_all

    # delete repo_perms for this user
    Link.where(tail_uuid: self.uuid,
                     link_class: 'permission',
                     name: 'can_manage').destroy_all

    # delete vm_login_perms for this user
    Link.where(tail_uuid: self.uuid,
                     link_class: 'permission',
                     name: 'can_login').destroy_all

    # delete "All users" group read permissions for this user
    group = Group.where(name: 'All users').select do |g|
      g[:uuid].match(/-f+$/)
    end.first
    Link.where(tail_uuid: self.uuid,
                     head_uuid: group[:uuid],
                     link_class: 'permission',
                     name: 'can_read').destroy_all

    # delete any signatures by this user
    Link.where(link_class: 'signature',
                     tail_uuid: self.uuid).destroy_all

    # delete user preferences (including profile)
    self.prefs = {}

    # mark the user as inactive
    self.is_active = false
    self.save!
  end

  def must_unsetup_to_deactivate
    if self.is_active_changed? &&
       self.is_active_was == true &&
       !self.is_active

      group = Group.where(name: 'All users').select do |g|
        g[:uuid].match(/-f+$/)
      end.first

      # When a user is set up, they are added to the "All users"
      # group.  A user that is part of the "All users" group is
      # allowed to self-activate.
      #
      # It doesn't make sense to deactivate a user (set is_active =
      # false) without first removing them from the "All users" group,
      # because they would be able to immediately reactivate
      # themselves.
      #
      # The 'unsetup' method removes the user from the "All users"
      # group (and also sets is_active = false) so send a message
      # explaining the correct way to deactivate a user.
      #
      if Link.where(tail_uuid: self.uuid,
                    head_uuid: group[:uuid],
                    link_class: 'permission',
                    name: 'can_read').any?
        errors.add :is_active, "cannot be set to false directly, use the 'Deactivate' button on Workbench, or the 'unsetup' API call"
      end
    end
  end

  def set_initial_username(requested: false)
    if !requested.is_a?(String) || requested.empty?
      email_parts = email.partition("@")
      local_parts = email_parts.first.partition("+")
      if email_parts.any?(&:empty?)
        return
      elsif not local_parts.first.empty?
        requested = local_parts.first
      else
        requested = email_parts.first
      end
    end
    requested.sub!(/^[^A-Za-z]+/, "")
    requested.gsub!(/[^A-Za-z0-9]/, "")
    unless requested.empty?
      self.username = find_usable_username_from(requested)
    end
  end

  def update_uuid(new_uuid:)
    if !current_user.andand.is_admin
      raise PermissionDeniedError
    end
    if uuid == system_user_uuid || uuid == anonymous_user_uuid
      raise "update_uuid cannot update system accounts"
    end
    if self.class != self.class.resource_class_for_uuid(new_uuid)
      raise "invalid new_uuid #{new_uuid.inspect}"
    end
    transaction(requires_new: true) do
      reload
      old_uuid = self.uuid
      self.uuid = new_uuid
      save!(validate: false)
      change_all_uuid_refs(old_uuid: old_uuid, new_uuid: new_uuid)
    end
  end

  # Move this user's (i.e., self's) owned items to new_owner_uuid and
  # new_user_uuid (for things normally owned directly by the user).
  #
  # If redirect_auth is true, also reassign auth tokens and ssh keys,
  # and redirect this account to redirect_to_user_uuid, i.e., when a
  # caller authenticates to this account in the future, the account
  # redirect_to_user_uuid account will be used instead.
  #
  # current_user must have admin privileges, i.e., the caller is
  # responsible for checking permission to do this.
  def merge(new_owner_uuid:, new_user_uuid:, redirect_to_new_user:)
    raise PermissionDeniedError if !current_user.andand.is_admin
    raise "Missing new_owner_uuid" if !new_owner_uuid
    raise "Missing new_user_uuid" if !new_user_uuid
    transaction(requires_new: true) do
      reload
      raise "cannot merge an already merged user" if self.redirect_to_user_uuid

      new_user = User.where(uuid: new_user_uuid).first
      raise "user does not exist" if !new_user
      raise "cannot merge to an already merged user" if new_user.redirect_to_user_uuid

      # If 'self' is a remote user, don't transfer authorizations
      # (i.e. ability to access the account) to the new user, because
      # that gives the remote site the ability to access the 'new'
      # user account that takes over the 'self' account.
      #
      # If 'self' is a local user, it is okay to transfer
      # authorizations, even if the 'new' user is a remote account,
      # because the remote site does not gain the ability to access an
      # account it could not before.

      if redirect_to_new_user and self.uuid[0..4] == Rails.configuration.ClusterID
        # Existing API tokens and ssh keys are updated to authenticate
        # to the new user.
        ApiClientAuthorization.
          where(user_id: id).
          update_all(user_id: new_user.id)

        user_updates = [
          [AuthorizedKey, :owner_uuid],
          [AuthorizedKey, :authorized_user_uuid],
          [Link, :owner_uuid],
          [Link, :tail_uuid],
          [Link, :head_uuid],
        ]
      else
        # Destroy API tokens and ssh keys associated with the old
        # user.
        ApiClientAuthorization.where(user_id: id).destroy_all
        AuthorizedKey.where(owner_uuid: uuid).destroy_all
        AuthorizedKey.where(authorized_user_uuid: uuid).destroy_all
        user_updates = [
          [Link, :owner_uuid],
          [Link, :tail_uuid]
        ]
      end

      # References to the old user UUID in the context of a user ID
      # (rather than a "home project" in the project hierarchy) are
      # updated to point to the new user.
      user_updates.each do |klass, column|
        klass.where(column => uuid).update_all(column => new_user.uuid)
      end

      # Need to update repository names to new username
      if username
        old_repo_name_re = /^#{Regexp.escape(username)}\//
        Repository.where(:owner_uuid => uuid).each do |repo|
          repo.owner_uuid = new_user.uuid
          repo_name_sub = "#{new_user.username}/"
          name = repo.name.sub(old_repo_name_re, repo_name_sub)
          while (conflict = Repository.where(:name => name).first) != nil
            repo_name_sub += "migrated"
            name = repo.name.sub(old_repo_name_re, repo_name_sub)
          end
          repo.name = name
          repo.save!
        end
      end

      # References to the merged user's "home project" are updated to
      # point to new_owner_uuid.
      ActiveRecord::Base.descendants.reject(&:abstract_class?).each do |klass|
        next if [ApiClientAuthorization,
                 AuthorizedKey,
                 Link,
                 Log,
                 Repository].include?(klass)
        next if !klass.columns.collect(&:name).include?('owner_uuid')
        klass.where(owner_uuid: uuid).update_all(owner_uuid: new_owner_uuid)
      end

      if redirect_to_new_user
        update_attributes!(redirect_to_user_uuid: new_user.uuid, username: nil)
      end
      self.recompute_permissions
      new_user.recompute_permissions
    end
  end

  def redirects_to
    user = self
    redirects = 0
    while (uuid = user.redirect_to_user_uuid)
      break if uuid.empty?
      nextuser = User.unscoped.find_by_uuid(uuid)
      if !nextuser
        raise Exception.new("user uuid #{user.uuid} redirects to nonexistent uuid '#{uuid}'")
      end
      user = nextuser
      redirects += 1
      if redirects > 15
        raise "Starting from #{self.uuid} redirect_to_user_uuid exceeded maximum number of redirects"
      end
    end
    user
  end

  def self.register info
    # login info expected fields, all can be optional but at minimum
    # must supply either 'identity_url' or 'email'
    #
    #   email
    #   first_name
    #   last_name
    #   username
    #   alternate_emails
    #   identity_url

    primary_user = nil

    # local database
    identity_url = info['identity_url']

    if identity_url && identity_url.length > 0
      # Only local users can create sessions, hence uuid_like_pattern
      # here.
      user = User.unscoped.where('identity_url = ? and uuid like ?',
                                 identity_url,
                                 User.uuid_like_pattern).first
      primary_user = user.redirects_to if user
    end

    if !primary_user
      # identity url is unset or didn't find matching record.
      emails = [info['email']] + (info['alternate_emails'] || [])
      emails.select! {|em| !em.nil? && !em.empty?}

      User.unscoped.where('email in (?) and uuid like ?',
                          emails,
                          User.uuid_like_pattern).each do |user|
        if !primary_user
          primary_user = user.redirects_to
        elsif primary_user.uuid != user.redirects_to.uuid
          raise "Ambiguous email address, directs to both #{primary_user.uuid} and #{user.redirects_to.uuid}"
        end
      end
    end

    if !primary_user
      # New user registration
      primary_user = User.new(:owner_uuid => system_user_uuid,
                              :is_admin => false,
                              :is_active => Rails.configuration.Users.NewUsersAreActive)

      primary_user.set_initial_username(requested: info['username']) if info['username'] && !info['username'].blank?
      primary_user.identity_url = info['identity_url'] if identity_url
    end

    primary_user.email = info['email'] if info['email']
    primary_user.first_name = info['first_name'] if info['first_name']
    primary_user.last_name = info['last_name'] if info['last_name']

    if (!primary_user.email or primary_user.email.empty?) and (!primary_user.identity_url or primary_user.identity_url.empty?)
      raise "Must have supply at least one of 'email' or 'identity_url' to User.register"
    end

    act_as_system_user do
      primary_user.save!
    end

    primary_user
  end

  protected

  def change_all_uuid_refs(old_uuid:, new_uuid:)
    ActiveRecord::Base.descendants.reject(&:abstract_class?).each do |klass|
      klass.columns.each do |col|
        if col.name.end_with?('_uuid')
          column = col.name.to_sym
          klass.where(column => old_uuid).update_all(column => new_uuid)
        end
      end
    end
  end

  def ensure_ownership_path_leads_to_user
    true
  end

  def permission_to_update
    if username_changed? || redirect_to_user_uuid_changed? || email_changed?
      current_user.andand.is_admin
    else
      # users must be able to update themselves (even if they are
      # inactive) in order to create sessions
      self == current_user or super
    end
  end

  def permission_to_create
    current_user.andand.is_admin or
      (self == current_user &&
       self.redirect_to_user_uuid.nil? &&
       self.is_active == Rails.configuration.Users.NewUsersAreActive)
  end

  def check_auto_admin
    return if self.uuid.end_with?('anonymouspublic')
    if (User.where("email = ?",self.email).where(:is_admin => true).count == 0 and
        !Rails.configuration.Users.AutoAdminUserWithEmail.empty? and self.email == Rails.configuration.Users["AutoAdminUserWithEmail"]) or
       (User.where("uuid not like '%-000000000000000'").where(:is_admin => true).count == 0 and
        Rails.configuration.Users.AutoAdminFirstUser)
      self.is_admin = true
      self.is_active = true
    end
  end

  def find_usable_username_from(basename)
    # If "basename" is a usable username, return that.
    # Otherwise, find a unique username "basenameN", where N is the
    # smallest integer greater than 1, and return that.
    # Return nil if a unique username can't be found after reasonable
    # searching.
    quoted_name = self.class.connection.quote_string(basename)
    next_username = basename
    next_suffix = 1
    while Rails.configuration.Users.AutoSetupUsernameBlacklist[next_username]
      next_suffix += 1
      next_username = "%s%i" % [basename, next_suffix]
    end
    0.upto(6).each do |suffix_len|
      pattern = "%s%s" % [quoted_name, "_" * suffix_len]
      self.class.unscoped.
          where("username like '#{pattern}'").
          select(:username).
          order('username asc').
          each do |other_user|
        if other_user.username > next_username
          break
        elsif other_user.username == next_username
          next_suffix += 1
          next_username = "%s%i" % [basename, next_suffix]
        end
      end
      return next_username if (next_username.size <= pattern.size)
    end
    nil
  end

  def prevent_privilege_escalation
    if current_user.andand.is_admin
      return true
    end
    if self.is_active_changed?
      if self.is_active != self.is_active_was
        logger.warn "User #{current_user.uuid} tried to change is_active from #{self.is_active_was} to #{self.is_active} for #{self.uuid}"
        self.is_active = self.is_active_was
      end
    end
    if self.is_admin_changed?
      if self.is_admin != self.is_admin_was
        logger.warn "User #{current_user.uuid} tried to change is_admin from #{self.is_admin_was} to #{self.is_admin} for #{self.uuid}"
        self.is_admin = self.is_admin_was
      end
    end
    true
  end

  def prevent_inactive_admin
    if self.is_admin and not self.is_active
      # There is no known use case for the strange set of permissions
      # that would result from this change. It's safest to assume it's
      # a mistake and disallow it outright.
      raise "Admin users cannot be inactive"
    end
    true
  end

  def search_permissions(start, graph, merged={}, upstream_mask=nil, upstream_path={})
    nextpaths = graph[start]
    return merged if !nextpaths
    return merged if upstream_path.has_key? start
    upstream_path[start] = true
    upstream_mask ||= ALL_PERMISSIONS
    nextpaths.each do |head, mask|
      merged[head] ||= {}
      mask.each do |k,v|
        merged[head][k] ||= v if upstream_mask[k]
      end
      search_permissions(head, graph, merged, upstream_mask.select { |k,v| v && merged[head][k] }, upstream_path)
    end
    upstream_path.delete start
    merged
  end

  def create_user_repo_link(repo_name)
    # repo_name is optional
    if not repo_name
      logger.warn ("Repository name not given for #{self.uuid}.")
      return
    end

    repo = Repository.where(owner_uuid: uuid, name: repo_name).first_or_create!
    logger.info { "repo uuid: " + repo[:uuid] }
    repo_perm = Link.where(tail_uuid: uuid, head_uuid: repo.uuid,
                           link_class: "permission",
                           name: "can_manage").first_or_create!
    logger.info { "repo permission: " + repo_perm[:uuid] }
    return repo_perm
  end

  # create login permission for the given vm_uuid, if it does not already exist
  def create_vm_login_permission_link(vm_uuid, repo_name)
    # vm uuid is optional
    return if vm_uuid == ""

    vm = VirtualMachine.where(uuid: vm_uuid).first
    if !vm
      logger.warn "Could not find virtual machine for #{vm_uuid.inspect}"
      raise "No vm found for #{vm_uuid}"
    end

    logger.info { "vm uuid: " + vm[:uuid] }
    login_attrs = {
      tail_uuid: uuid, head_uuid: vm.uuid,
      link_class: "permission", name: "can_login",
    }

    login_perm = Link.
      where(login_attrs).
      select { |link| link.properties["username"] == repo_name }.
      first

    login_perm ||= Link.
      create(login_attrs.merge(properties: {"username" => repo_name}))

    logger.info { "login permission: " + login_perm[:uuid] }
    login_perm
  end

  # add the user to the 'All users' group
  def create_user_group_link
    #puts "In create_user_group_link"
    return (Link.where(tail_uuid: self.uuid,
                       head_uuid: all_users_group[:uuid],
                       link_class: 'permission',
                       name: 'can_read').first or
            Link.create(tail_uuid: self.uuid,
                        head_uuid: all_users_group[:uuid],
                        link_class: 'permission',
                        name: 'can_read'))
  end

  # Give the special "System group" permission to manage this user and
  # all of this user's stuff.
  def add_system_group_permission_link
    return true if uuid == system_user_uuid
    act_as_system_user do
      Link.create(link_class: 'permission',
                  name: 'can_manage',
                  tail_uuid: system_group_uuid,
                  head_uuid: self.uuid)
    end
  end

  # Send admin notifications
  def send_admin_notifications
    AdminNotifier.new_user(self).deliver_now
    if not self.is_active then
      AdminNotifier.new_inactive_user(self).deliver_now
    end
  end

  # Automatically setup if is_active flag turns on
  def setup_on_activate
    return if [system_user_uuid, anonymous_user_uuid].include?(self.uuid)
    if is_active && (new_record? || is_active_changed?)
      setup
    end
  end

  # Automatically setup new user during creation
  def auto_setup_new_user
    setup
    if username
      create_vm_login_permission_link(Rails.configuration.Users.AutoSetupNewUsersWithVmUUID,
                                      username)
      repo_name = "#{username}/#{username}"
      if Rails.configuration.Users.AutoSetupNewUsersWithRepository and
          Repository.where(name: repo_name).first.nil?
        repo = Repository.create!(name: repo_name, owner_uuid: uuid)
        Link.create!(tail_uuid: uuid, head_uuid: repo.uuid,
                     link_class: "permission", name: "can_manage")
      end
    end
  end

  # Send notification if the user saved profile for the first time
  def send_profile_created_notification
    if self.prefs_changed?
      if self.prefs_was.andand.empty? || !self.prefs_was.andand['profile']
        profile_notification_address = Rails.configuration.Users.UserProfileNotificationAddress
        ProfileNotifier.profile_created(self, profile_notification_address).deliver_now if profile_notification_address and !profile_notification_address.empty?
      end
    end
  end

  def verify_repositories_empty
    unless repositories.first.nil?
      errors.add(:username, "can't be unset when the user owns repositories")
      throw(:abort)
    end
  end

  def sync_repository_names
    old_name_re = /^#{Regexp.escape(username_was)}\//
    name_sub = "#{username}/"
    repositories.find_each do |repo|
      repo.name = repo.name.sub(old_name_re, name_sub)
      repo.save!
    end
  end
end