class User < ArvadosModel
  include AssignUuid
  include KindAndEtag
  include CommonApiTemplate
  serialize :prefs, Hash
  has_many :api_client_authorizations
  before_update :prevent_privilege_escalation
  before_update :prevent_inactive_admin
  before_create :check_auto_admin
  after_create :add_system_group_permission_link
  after_create AdminNotifier

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

  api_accessible :user, extend: :common do |t|
    t.add :email
    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
  end

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

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

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

  def groups_i_can(verb)
    self.group_permissions.select { |uuid, mask| mask[verb] }.keys
  end

  def can?(actions)
    return true if is_admin
    actions.each do |action, target|
      target_uuid = target
      if target.respond_to? :uuid
        target_uuid = target.uuid
      end
      next if target_uuid == self.uuid
      next if (group_permissions[target_uuid] and
               group_permissions[target_uuid][action])
      if target.respond_to? :owner_uuid
        next if target.owner_uuid == self.uuid
        next if (group_permissions[target.owner_uuid] and
                 group_permissions[target.owner_uuid][action])
      end
      return false
    end
    true
  end

  def self.invalidate_permissions_cache
    Rails.cache.delete_matched(/^groups_for_user_/)
  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
    Rails.cache.fetch "groups_for_user_#{self.uuid}" do
      permissions_from = {}
      todo = {self.uuid => true}
      done = {}
      while !todo.empty?
        lookup_uuids = todo.keys
        lookup_uuids.each do |uuid| done[uuid] = true end
        todo = {}
        newgroups = []
        Group.where('owner_uuid in (?)', lookup_uuids).each do |group|
          newgroups << [group.owner_uuid, group.uuid, 'can_manage']
        end
        Link.where('tail_uuid in (?) and link_class = ? and (head_uuid like ? or head_uuid like ?)',
                   lookup_uuids,
                   'permission',
                   Group.uuid_like_pattern,
                   User.uuid_like_pattern).each do |link|
          newgroups << [link.tail_uuid, link.head_uuid, link.name]
        end
        newgroups.each do |tail_uuid, head_uuid, perm_name|
          unless done.has_key? head_uuid
            todo[head_uuid] = true
          end
          link_permissions = {}
          case perm_name
          when 'can_read'
            link_permissions = {read:true}
          when 'can_write'
            link_permissions = {read:true,write:true}
          when 'can_manage'
            link_permissions = ALL_PERMISSIONS
          end
          permissions_from[tail_uuid] ||= {}
          permissions_from[tail_uuid][head_uuid] ||= {}
          link_permissions.each do |k,v|
            permissions_from[tail_uuid][head_uuid][k] ||= v
          end
        end
      end
      search_permissions(self.uuid, permissions_from)
    end
  end

  def self.setup(user, openid_prefix, repo_name=nil, vm_uuid=nil)
    return user.setup_repo_vm_links(repo_name, vm_uuid, openid_prefix)
  end

  # create links
  def setup_repo_vm_links(repo_name, vm_uuid, openid_prefix)
    oid_login_perm = create_oid_login_perm openid_prefix
    repo_perm = create_user_repo_link repo_name
    vm_login_perm = create_vm_login_permission_link vm_uuid, repo_name
    group_perm = create_user_group_link

    return [oid_login_perm, 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
    oid_login_perms = Link.where(tail_uuid: self.email,
                                 link_class: 'permission',
                                 name: 'can_login')
    oid_login_perms.each do |perm|
      Link.delete perm
    end

    # delete repo_perms for this user
    repo_perms = Link.where(tail_uuid: self.uuid,
                            link_class: 'permission',
                            name: 'can_write')
    repo_perms.each do |perm|
      Link.delete perm
    end

    # delete vm_login_perms for this user
    vm_login_perms = Link.where(tail_uuid: self.uuid,
                                link_class: 'permission',
                                name: 'can_login')
    vm_login_perms.each do |perm|
      Link.delete perm
    end

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

    # delete any signatures by this user
    signed_uuids = Link.where(link_class: 'signature',
                              tail_uuid: self.uuid)
    signed_uuids.each do |sign|
      Link.delete sign
    end

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

  protected

  def permission_to_update
    # users must be able to update themselves (even if they are
    # inactive) in order to create sessions
    self == current_user or super
  end

  def permission_to_create
    current_user.andand.is_admin or
      (self == current_user and
       self.is_active == Rails.configuration.new_users_are_active)
  end

  def check_auto_admin
    if User.where("uuid not like '%-000000000000000'").where(:is_admin => true).count == 0 and Rails.configuration.auto_admin_user
      if current_user.email == Rails.configuration.auto_admin_user
        self.is_admin = true
        self.is_active = true
      end
    end
  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_admin_was} to #{self.is_admin} 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_oid_login_perm (openid_prefix)
    login_perm_props = { "identity_url_prefix" => openid_prefix}

    # Check oid_login_perm
    oid_login_perms = Link.where(tail_uuid: self.email,
                                   link_class: 'permission',
                                   name: 'can_login').where("head_uuid = ?", self.uuid)

    if !oid_login_perms.any?
      # create openid login permission
      oid_login_perm = Link.create(link_class: 'permission',
                                   name: 'can_login',
                                   tail_uuid: self.email,
                                   head_uuid: self.uuid,
                                   properties: login_perm_props
                                  )
      logger.info { "openid login permission: " + oid_login_perm[:uuid] }
    else
      oid_login_perm = oid_login_perms.first
    end

    return oid_login_perm
  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

    # Check for an existing repository with the same name we're about to use.
    repo = Repository.where(name: repo_name).first

    if repo
      logger.warn "Repository exists for #{repo_name}: #{repo[:uuid]}."

      # Look for existing repository access for this repo
      repo_perms = Link.where(tail_uuid: self.uuid,
                              head_uuid: repo[:uuid],
                              link_class: 'permission',
                              name: 'can_write')
      if repo_perms.any?
        logger.warn "User already has repository access " +
            repo_perms.collect { |p| p[:uuid] }.inspect
        return repo_perms.first
      end
    end

    # create repo, if does not already exist
    repo ||= Repository.create(name: repo_name)
    logger.info { "repo uuid: " + repo[:uuid] }

    repo_perm = Link.create(tail_uuid: self.uuid,
                            head_uuid: repo[:uuid],
                            link_class: 'permission',
                            name: 'can_write')
    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)
    begin

      # vm uuid is optional
      if vm_uuid
        vm = VirtualMachine.where(uuid: vm_uuid).first

        if not vm
          logger.warn "Could not find virtual machine for #{vm_uuid.inspect}"
          raise "No vm found for #{vm_uuid}"
        end
      else
        return
      end

      logger.info { "vm uuid: " + vm[:uuid] }

      login_perms = Link.where(tail_uuid: self.uuid,
                              head_uuid: vm[:uuid],
                              link_class: 'permission',
                              name: 'can_login')

      perm_exists = false
      login_perms.each do |perm|
        if perm.properties[:username] == repo_name
          perm_exists = true
          break
        end
      end

      if !perm_exists
        login_perm = Link.create(tail_uuid: self.uuid,
                                 head_uuid: vm[:uuid],
                                 link_class: 'permission',
                                 name: 'can_login',
                                 properties: {username: repo_name})
        logger.info { "login permission: " + login_perm[:uuid] }
      else
        login_perm = login_perms.first
      end

      return login_perm
    end
  end

  # add the user to the 'All users' group
  def create_user_group_link
    # Look up the "All users" group (we expect uuid *-*-fffffffffffffff).
    group = Group.where(name: 'All users').select do |g|
      g[:uuid].match /-f+$/
    end.first

    if not group
      logger.warn "No 'All users' group with uuid '*-*-fffffffffffffff'."
      raise "No 'All users' group with uuid '*-*-fffffffffffffff' is found"
    else
      logger.info { "\"All users\" group uuid: " + group[:uuid] }

      group_perms = Link.where(tail_uuid: self.uuid,
                              head_uuid: group[:uuid],
                              link_class: 'permission',
                              name: 'can_read')

      if !group_perms.any?
        group_perm = Link.create(tail_uuid: self.uuid,
                                 head_uuid: group[:uuid],
                                 link_class: 'permission',
                                 name: 'can_read')
        logger.info { "group permission: " + group_perm[:uuid] }
      else
        group_perm = group_perms.first
      end

      return group_perm
    end
  end

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