#-- encoding: UTF-8

#-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2020 the OpenProject GmbH
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License version 3.
#
# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
# Copyright (C) 2006-2017 Jean-Philippe Lang
# Copyright (C) 2010-2013 the ChiliProject Team
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# See docs/COPYRIGHT.rdoc for more details.
#++

module Authentication
  class OmniauthService
    include Contracted

    attr_accessor :auth_hash,
                  :strategy,
                  :controller,
                  :contract,
                  :user_attributes,
                  :identity_url,
                  :user

    delegate :session, to: :controller

    def initialize(strategy:, auth_hash:, controller:)
      self.strategy = strategy
      self.auth_hash = auth_hash
      self.controller = controller
      self.contract = ::Authentication::OmniauthAuthHashContract.new(auth_hash)
    end

    def call(additional_user_params = nil)
      Rails.logger.debug { "Returning from omniauth with hash #{auth_hash&.to_hash.inspect} Valid? #{auth_hash&.valid?}" }

      unless contract.validate
        result = ServiceResult.new(success: false, errors: contract.errors)
        Rails.logger.warn { "Failed to process omniauth response for #{auth_uid}: #{result.message}" }

        return result
      end

      # Create or update the user from omniauth
      # and assign non-nil parameters from the registration form - if any
      assignable_params = (additional_user_params || {}).reject { |_, v| v.nil? }
      update_user_from_omniauth!(assignable_params)

      # If we have a new or invited user, we still need to register them
      activation_call = activate_user!

      # The user should be logged in now
      tap_service_result activation_call
    end

    private

    ##
    # After login flow
    def tap_service_result(call)
      if call.success? && user.active?
        OpenProject::OmniAuth::Authorization.after_login! user, auth_hash, self
      end

      call
    end

    ##
    # After validating the omniauth hash
    # and the authorization is successful,
    #
    # login the user by locating or creating it
    def update_user_from_omniauth!(additional_user_params)
      # Find or create the user from the auth hash
      self.user_attributes = build_omniauth_hash_to_user_attributes.merge(additional_user_params)
      self.identity_url = user_attributes[:identity_url]
      self.user = lookup_or_initialize_user

      # Assign or update the user with the omniauth attributes
      update_attributes
    end

    ##
    # Try to find or create the user
    # in the following order:
    #
    # 1. Look for an active invitation token
    # 2. Look for an existing user for the current identity_url
    # 3. Look for an existing user that we can remap (IF remapping is allowed)
    # 4. Try to register a new user and activate according to settings
    def lookup_or_initialize_user
      find_invited_user ||
        find_existing_user ||
        remap_existing_user ||
        initialize_new_user
    end

    ##
    # Return an invited user, if there is a token
    def find_invited_user
      return unless session.include?(:invitation_token)

      tok = Token::Invitation.find_by value: session[:invitation_token]
      return unless tok

      tok.user.tap do |user|
        user.identity_url = user_attributes[:identity_url]
        tok.destroy
        session.delete :invitation_token
      end
    end

    ##
    # Find an existing user by the identity url
    def find_existing_user
      User.find_by(identity_url: identity_url)
    end

    ##
    # Allow to map existing users with an Omniauth source if the login
    # already exists, and no existing auth source or omniauth provider is
    # linked
    def remap_existing_user
      return unless Setting.oauth_allow_remapping_of_existing_users?

      User.find_by_login(user_attributes[:login])
    end

    ##
    # Create the new user and try to activate it
    # according to settings and system limits
    def initialize_new_user
      User.new(identity_url: user_attributes[:identity_url])
    end

    ##
    # Update or assign the user attributes
    def update_attributes
      if user.new_record? || user.invited?
        user.assign_attributes user_attributes
        user.register unless user.invited?
      else
        # Update the user, but never change the admin flag
        user.update user_attributes.except(:admin)
      end
    end

    def activate_user!
      if user.new_record? || user.invited?
        ::Users::RegisterUserService
          .new(user)
          .call
      else
        ServiceResult.new(success: true, result: user)
      end
    end

    ##
    # Maps the omniauth attribute hash
    # to our internal user attributes
    def build_omniauth_hash_to_user_attributes
      info = auth_hash[:info]

      attribute_map = {
        login: info[:email],
        mail: info[:email],
        firstname: info[:first_name] || info[:name],
        lastname: info[:last_name],
        identity_url: identity_url_from_omniauth
      }

      # Allow strategies to override mapping
      if strategy.respond_to?(:omniauth_hash_to_user_attributes)
        attribute_map.merge!(strategy.omniauth_hash_to_user_attributes(auth_hash))
      end

      # Remove any nil values to avoid
      # overriding existing attributes
      attribute_map.compact!

      Rails.logger.debug { "Mapped auth_hash user attributes #{attribute_map.inspect}" }
      attribute_map
    end

    ##
    # Allow strategies to map a value for uid instead
    # of always taking the global UID.
    # For SAML, the global UID may change with every session
    # (in case of transient nameIds)
    def identity_url_from_omniauth
      identifier = auth_hash[:info][:uid] || auth_hash[:uid]
      "#{auth_hash[:provider]}:#{identifier}"
    end

    ##
    # Try to provide some context of the auth_hash in case of errors
    def auth_uid
      hash = (auth_hash || {})
      hash.dig(:info, :uid) || hash.dig(:uid) || 'unknown'
    end
  end
end