ash_authentication

# SPDX-FileCopyrightText: 2026 Alembic Pty Ltd
#
# SPDX-License-Identifier: MIT

# credo:disable-for-this-file Credo.Check.Design.AliasUsage
if Code.ensure_loaded?(Igniter) do
  defmodule Mix.Tasks.AshAuthentication.AddStrategy.Webauthn do
    use Igniter.Mix.Task

    @example "mix ash_authentication.add_strategy.webauthn --rp-id example.com --rp-name \"My App\""

    @shortdoc "Adds WebAuthn/Passkey authentication to your user resource"

    @moduledoc """
    #{@shortdoc}

    Creates a credential resource and adds the WebAuthn strategy to the user
    resource. Users can sign in with hardware security keys (YubiKey),
    platform authenticators (Touch ID, Windows Hello), or passkeys.

    ## Example

    ```bash
    #{@example}
    ```

    ## Options

    * `--user`, `-u` - The user resource. Defaults to `YourApp.Accounts.User`.
    * `--identity-field`, `-i` - The field on the user resource that
      identifies the user (typically email). Defaults to `email`.
    * `--name`, `-n` - The strategy name. Defaults to `webauthn`.
    * `--rp-id` - The Relying Party ID (your domain, e.g. `example.com`).
      Required.
    * `--rp-name` - The Relying Party display name shown to the user during
      registration. Required.
    * `--origin` - The full origin URL (e.g. `https://example.com` or
      `https://localhost:4001`). Optional — defaults to `https://{rp_id}`,
      which omits the port and is wrong for non-standard dev ports.
    """

    def info(_argv, _composing_task) do
      %Igniter.Mix.Task.Info{
        group: :ash,
        example: @example,
        extra_args?: false,
        only: nil,
        positional: [],
        schema: [
          accounts: :string,
          user: :string,
          identity_field: :string,
          name: :string,
          rp_id: :string,
          rp_name: :string,
          origin: :string
        ],
        aliases: [
          a: :accounts,
          u: :user,
          i: :identity_field,
          n: :name
        ],
        defaults: [
          identity_field: "email",
          name: "webauthn"
        ],
        required: [:rp_id, :rp_name]
      }
    end

    def igniter(igniter) do
      options = parse_options(igniter)

      case Igniter.Project.Module.module_exists(igniter, options[:user]) do
        {true, igniter} ->
          igniter
          |> add_wax_dependency()
          |> add_credential_resource(options)
          |> AshAuthentication.Igniter.codegen_for_strategy(options[:name])

        {false, igniter} ->
          Igniter.add_issue(igniter, """
          User module #{inspect(options[:user])} was not found.

          Perhaps you have not yet installed ash_authentication?
          """)
      end
    end

    defp parse_options(igniter) do
      options =
        igniter.args.options
        |> Keyword.put_new_lazy(:accounts, fn ->
          Igniter.Project.Module.module_name(igniter, "Accounts")
        end)

      options
      |> Keyword.put_new_lazy(:user, fn ->
        Module.concat(options[:accounts], User)
      end)
      |> Keyword.update(:identity_field, :email, &String.to_atom/1)
      |> Keyword.update(:name, :webauthn, &String.to_atom/1)
      |> Keyword.update!(:accounts, &AshAuthentication.Igniter.maybe_parse_module/1)
      |> Keyword.update!(:user, &AshAuthentication.Igniter.maybe_parse_module/1)
    end

    defp add_wax_dependency(igniter) do
      Igniter.Project.Deps.add_dep(igniter, {:wax_, "~> 0.7"}, on_exists: :skip)
    end

    defp add_credential_resource(igniter, options) do
      credential_resource =
        options[:user]
        |> Module.split()
        |> :lists.droplast()
        |> Enum.concat([WebAuthnCredential])
        |> Module.concat()

      {exists?, igniter} = Igniter.Project.Module.module_exists(igniter, credential_resource)

      if exists? do
        Igniter.add_issue(
          igniter,
          "WebAuthn credential resource already exists: #{inspect(credential_resource)}."
        )
      else
        igniter
        |> generate_credential_resource(credential_resource, options)
        |> add_user_attributes_and_relationship(credential_resource, options)
        |> add_strategy_to_user(credential_resource, options)
      end
    end

    defp generate_credential_resource(igniter, credential_resource, options) do
      extensions = data_layer_extension()

      igniter
      |> Igniter.compose_task("ash.gen.resource", [
        inspect(credential_resource),
        "--uuid-primary-key",
        "id",
        "--default-actions",
        "read,destroy",
        "--attribute",
        "credential_id:binary:required",
        "--attribute",
        "sign_count:integer",
        "--attribute",
        "label:string",
        "--attribute",
        "last_used_at:utc_datetime_usec",
        "--relationship",
        "belongs_to:user:#{inspect(options[:user])}:required",
        "--extend",
        extensions
      ])
      |> Ash.Resource.Igniter.add_new_attribute(credential_resource, :public_key, """
      attribute :public_key, AshAuthentication.Strategy.WebAuthn.CoseKey do
        allow_nil? false
        public? true
      end
      """)
      |> Ash.Resource.Igniter.add_new_action(credential_resource, :create, """
      create :create do
        primary? true
        accept [:credential_id, :public_key, :sign_count, :label, :user_id]
      end
      """)
      |> Ash.Resource.Igniter.add_new_action(credential_resource, :update, """
      update :update do
        primary? true
        accept [:sign_count, :label, :last_used_at]
      end
      """)
      |> add_credential_resource_authorizer(credential_resource)
      |> Ash.Resource.Igniter.add_new_identity(credential_resource, :unique_credential_id, """
      identity :unique_credential_id, [:credential_id]
      """)
    end

    defp add_credential_resource_authorizer(igniter, credential_resource) do
      Igniter.Project.Module.find_and_update_module!(
        igniter,
        credential_resource,
        &ensure_authorizer_bypass/1
      )
    end

    defp ensure_authorizer_bypass(zipper) do
      with {:ok, do_zipper} <- Igniter.Code.Common.move_to_do_block(zipper),
           :error <-
             Igniter.Code.Function.move_to_function_call_in_current_scope(
               do_zipper,
               :policies,
               1
             ) do
        {:ok,
         Igniter.Code.Common.add_code(do_zipper, """
         policies do
           bypass AshAuthentication.Checks.AshAuthenticationInteraction do
             authorize_if always()
           end
         end
         """)}
      else
        {:ok, _} -> {:ok, zipper}
        :error -> {:ok, zipper}
      end
    end

    defp add_user_attributes_and_relationship(igniter, credential_resource, options) do
      identity_field = options[:identity_field]

      igniter
      |> Ash.Resource.Igniter.add_new_attribute(options[:user], identity_field, """
      attribute #{inspect(identity_field)}, :ci_string do
        allow_nil? false
        public? true
      end
      """)
      |> AshAuthentication.Igniter.ensure_identity(options[:user], identity_field)
      |> Ash.Resource.Igniter.add_new_relationship(
        options[:user],
        :webauthn_credentials,
        """
        has_many :webauthn_credentials, #{inspect(credential_resource)}
        """
      )
    end

    defp add_strategy_to_user(igniter, credential_resource, options) do
      AshAuthentication.Igniter.add_new_strategy(
        igniter,
        options[:user],
        options[:name],
        options[:name],
        strategy_block(credential_resource, options)
      )
    end

    defp strategy_block(credential_resource, options) do
      origin_line =
        case options[:origin] do
          nil -> ""
          origin -> "  origin #{inspect(origin)}\n"
        end

      """
      webauthn #{inspect(options[:name])} do
        credential_resource #{inspect(credential_resource)}
        rp_id #{inspect(options[:rp_id])}
        rp_name #{inspect(options[:rp_name])}
      #{origin_line}  identity_field #{inspect(options[:identity_field])}
      end
      """
    end

    defp data_layer_extension do
      cond do
        Code.ensure_loaded?(AshPostgres.DataLayer) -> "postgres"
        Code.ensure_loaded?(AshSqlite.DataLayer) -> "sqlite"
        true -> ""
      end
    end
  end
else
  defmodule Mix.Tasks.AshAuthentication.AddStrategy.Webauthn do
    @shortdoc "Adds WebAuthn/Passkey authentication to your user resource"

    @moduledoc @shortdoc

    use Mix.Task

    def run(_argv) do
      Mix.shell().error("""
      The task 'ash_authentication.add_strategy.webauthn' requires igniter to be run.

      Please install igniter and try again.

      For more information, see: https://hexdocs.pm/igniter
      """)

      exit({:shutdown, 1})
    end
  end
end