Auth Setup

Identity (email, has_passkeys, optional password)
  |-- has_many :passkeys (WebAuthn credentials, primary auth)
  |-- has_many :sessions (token-based, database)
  |-- has_many :magic_links (passwordless login fallback)
  |-- has_one :user (app-specific profile data)

ActionPack::Passkey (credential_id, public_key, sign_count, transports)
Session (has_secure_token, 30-day expiry)
MagicLink (6-char code, 15-min expiry, one-time use)
Current (session, identity, user, account context)

Rails.application.routes.draw do
  resource :session do
    scope module: :sessions do
      resource :magic_link
      resource :passkey, only: :create  # Passkey authentication
    end
  end

  # Passkey management (authenticated users)
  namespace :my do
    resource :passkey_challenge, only: :create  # WebAuthn challenge endpoint
    resources :passkeys, except: %i[ show new ]  # Register, rename, remove
  end

  resource :signup, only: [:new, :create]  # Optional
  root "boards#index"
end

class SessionsController < ApplicationController
  include ActionPack::Passkey::Request

  allow_unauthenticated_access only: [:new, :create]
  rate_limit to: 10, within: 3.minutes, only: :create

  def new
    @authentication_options = passkey_authentication_options  # For passkey sign-in
  end

  def create
    if identity = Identity.find_by(email_address: params[:email_address])
      identity.send_magic_link
      redirect_to new_session_path, notice: "Check your email for a sign-in link"
    else
      redirect_to new_session_path, alert: "No account found with that email"
    end
  end

  def destroy
    terminate_session
    redirect_to root_path
  end
end

class Sessions::PasskeysController < ApplicationController
  include ActionPack::Passkey::Request

  allow_unauthenticated_access
  rate_limit to: 10, within: 3.minutes, only: :create

  def create
    if credential = ActionPack::Passkey.authenticate(passkey_authentication_params)
      start_new_session_for credential.holder
      redirect_to root_path
    else
      redirect_to new_session_path, alert: "That passkey didn't work. Try again."
    end
  end
end

class My::PasskeysController < ApplicationController
  include ActionPack::Passkey::Request

  before_action :set_passkey, only: %i[ edit update destroy ]

  def index
    @passkeys = Current.identity.passkeys.order(name: :asc, created_at: :desc)
    @registration_options = passkey_registration_options(holder: Current.identity)
  end

  def create
    passkey = Current.identity.passkeys.register(passkey_registration_params)
    redirect_to edit_my_passkey_path(passkey, created: true)
  end

  def edit; end

  def update
    @passkey.update!(params.expect(passkey: [ :name ]))
    redirect_to my_passkeys_path
  end

  def destroy
    @passkey.destroy!
    redirect_to my_passkeys_path
  end

  private
    def set_passkey
      @passkey = Current.identity.passkeys.find(params[:id])
    end
end

# WebAuthn challenge endpoint (inherits from framework controller)
class My::PasskeyChallengesController < ActionPack::Passkey::ChallengesController
  include Authentication
  allow_unauthenticated_access
end

class Sessions::MagicLinksController < ApplicationController
  allow_unauthenticated_access

  def show
    if magic_link = MagicLink.authenticate(params[:code])
      start_new_session_for(magic_link.identity)
      redirect_to session.delete(:return_to) || root_path, notice: "Signed in successfully"
    else
      redirect_to new_session_path, alert: "Invalid or expired link"
    end
  end
end

class Current < ActiveSupport::CurrentAttributes
  attribute :session, :identity, :user, :account
  attribute :user_agent, :ip_address

  def account=(account)
    super
    Time.zone = account&.timezone
  end

  resets { Time.zone = "UTC" }
end

class MagicLinkMailer < ApplicationMailer
  def sign_in_instructions(magic_link)
    @magic_link = magic_link
    @identity = magic_link.identity
    @url = session_magic_link_url(code: magic_link.code)
    mail to: @identity.email_address, subject: "Sign in to #{app_name}"
  end
end

class SessionCleanupJob < ApplicationJob
  def perform
    Session.where("created_at < ?", 30.days.ago).delete_all
    MagicLink.where("expires_at < ?", 1.day.ago).delete_all
  end
end

# config/recurring.yml
# production:
#   cleanup_old_sessions:
#     command: "SessionCleanupJob.perform_later"
#     schedule: every day at 3am

class Signup
  include ActiveModel::Model

  attr_accessor :email_address, :full_name, :password

  validates :email_address, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }
  validates :full_name, presence: true

  def save
    return false unless valid?

    ActiveRecord::Base.transaction do
      @identity = Identity.create!(email_address: email_address, password: password)
      @identity.create_user!(full_name: full_name)
      @identity.send_magic_link(purpose: "verify_email")
    end
    true
  rescue ActiveRecord::RecordInvalid
    false
  end

  def identity = @identity
end