sure/app/controllers/oidc_accounts_controller.rb

class OidcAccountsController < ApplicationController
  skip_authentication only: [ :link, :create_link, :new_user, :create_user ]
  layout "auth"

  def link
    # Check if there's pending OIDC auth in session
    @pending_auth = session[:pending_oidc_auth]

    if @pending_auth.nil?
      redirect_to new_session_path, alert: t(".no_pending_oidc")
      return
    end

    @email = @pending_auth["email"]
    @user_exists = User.exists?(email: @email) if @email.present?

    # Check for a pending invitation for this email
    @pending_invitation = Invitation.pending.find_by(email: @email) if @email.present?

    # Determine whether we should offer JIT account creation for this
    # pending auth, based on JIT mode and allowed domains.
    @allow_account_creation = @pending_invitation.present? || (!AuthConfig.jit_link_only? && AuthConfig.allowed_oidc_domain?(@email))
  end

  def create_link
    @pending_auth = session[:pending_oidc_auth]

    if @pending_auth.nil?
      redirect_to new_session_path, alert: t(".no_pending_oidc")
      return
    end

    # Verify user's password to confirm identity
    user = User.authenticate_by(email: params[:email], password: params[:password])

    if user
      # Create the OIDC identity link
      oidc_identity = OidcIdentity.create_from_omniauth(
        build_auth_hash(@pending_auth),
        user
      )

      # Log account linking
      SsoAuditLog.log_link!(
        user: user,
        provider: @pending_auth["provider"],
        request: request
      )

      # Clear pending auth from session
      session.delete(:pending_oidc_auth)

      if user.otp_required?
        session[:mfa_user_id] = user.id
        redirect_to verify_mfa_path
      else
        @session = create_session_for(user)
        notice = if accept_pending_invitation_for(user)
          t("invitations.accept_choice.joined_household")
        else
          t("sessions.openid_connect.account_linked", provider: @pending_auth["provider"])
        end
        redirect_to root_path, notice: notice
      end
    else
      @email = params[:email]
      @user_exists = User.exists?(email: @email) if @email.present?
      flash.now[:alert] = "Invalid email or password"
      render :link, status: :unprocessable_entity
    end
  end

  def new_user
    # Check if there's pending OIDC auth in session
    @pending_auth = session[:pending_oidc_auth]

    if @pending_auth.nil?
      redirect_to new_session_path, alert: t(".no_pending_oidc")
      return
    end

    # Pre-fill user details from OIDC provider
    @user = User.new(
      email: @pending_auth["email"],
      first_name: @pending_auth["first_name"],
      last_name: @pending_auth["last_name"]
    )
  end

  def create_user
    @pending_auth = session[:pending_oidc_auth]

    if @pending_auth.nil?
      redirect_to new_session_path, alert: t(".no_pending_oidc")
      return
    end

    email = @pending_auth["email"]

    # Check for a pending invitation for this email
    invitation = Invitation.pending.find_by(email: email)

    # Respect global JIT configuration: in link_only mode or when the email
    # domain is not allowed, block JIT account creation—unless there's a
    # pending invitation for this user.
    unless invitation.present? || (!AuthConfig.jit_link_only? && AuthConfig.allowed_oidc_domain?(email))
      redirect_to new_session_path, alert: t(".account_creation_disabled")
      return
    end

    # Create SSO-only user without local password.
    # Security: JIT users should NOT have password_digest set to prevent
    # chained authentication attacks where SSO users gain local login access
    # via password reset.
    # Allow user to edit first_name and last_name from the form, but email comes from OIDC
    user_params = params.fetch(:user, {}).permit(:first_name, :last_name)
    @user = User.new(
      email: email,
      first_name: user_params[:first_name].presence || @pending_auth["first_name"],
      last_name: user_params[:last_name].presence || @pending_auth["last_name"],
      skip_password_validation: true
    )

    if invitation.present?
      # Accept the pending invitation: join the existing family
      @user.family_id = invitation.family_id
      @user.role = invitation.role
    else
      # Create new family for this user
      @user.family = Family.new

      # Use provider-configured default role, or fall back to admin for family creators
      # First user of an instance always becomes super_admin regardless of provider config
      provider_config = Rails.configuration.x.auth.sso_providers&.find { |p| p[:name] == @pending_auth["provider"] }
      provider_default_role = provider_config&.dig(:settings, :default_role)
      @user.role = User.role_for_new_family_creator(fallback_role: provider_default_role || :admin)
    end

    identity = nil
    account_created = false

    begin
      account_created = ActiveRecord::Base.transaction do
        unless @user.save
          raise ActiveRecord::Rollback
        end

        # Mark invitation as accepted if one was used
        invitation&.update!(accepted_at: Time.current)

        # Joining an existing family via invitation must honor the family's
        # default sharing policy, matching Invitation#accept_for. Without this a
        # JIT SSO invitee lands in the family but sees none of its accounts.
        @user.family.auto_share_existing_accounts_with(@user) if invitation.present?

        # Create the OIDC (or other SSO) identity
        identity = OidcIdentity.create_from_omniauth(
          build_auth_hash(@pending_auth),
          @user
        )

        true
      end
    rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique => e
      # Expected persistence failures (e.g. a duplicate identity) roll the whole
      # onboarding back and re-render the form. Unexpected errors propagate so
      # they surface instead of being hidden as a form validation message.
      @user.errors.add(:base, e.message)
    end

    if account_created
      # Only log JIT account creation if identity was successfully created
      if identity&.persisted?
        SsoAuditLog.log_jit_account_created!(
          user: @user,
          provider: @pending_auth["provider"],
          request: request
        )
      end

      # Clear pending auth from session
      session.delete(:pending_oidc_auth)

      @session = create_session_for(@user)
      notice = if invitation.present?
        t("invitations.accept_choice.joined_household")
      elsif accept_pending_invitation_for(@user)
        t("invitations.accept_choice.joined_household")
      else
        t(".account_created")
      end
      redirect_to root_path, notice: notice
    else
      render :new_user, status: :unprocessable_entity
    end
  end

  private

    # Convert pending auth hash to OmniAuth-like structure
    def build_auth_hash(pending_auth)
      OpenStruct.new(
        provider: pending_auth["provider"],
        uid: pending_auth["uid"],
        info: OpenStruct.new(pending_auth.slice("email", "name", "first_name", "last_name"))
      )
    end
end