feat: join request backend

lib/membership/join_request.ex

@@ -0,0 +1,141 @@
+defmodule Mv.Membership.JoinRequest do
+  @moduledoc """
+  Ash resource for public join requests (onboarding flow).
+
+  Created only after email confirmation (double opt-in). Per concept §2.3.2:
+  - email (dedicated field), payload, schema_version, status, submitted_at, source
+  - approved_at, rejected_at, reviewed_by_user_id for audit (Step 2)
+  - confirmation_token_hash for idempotency (unique constraint)
+  """
+  use Ash.Resource,
+    domain: Mv.Membership,
+    data_layer: AshPostgres.DataLayer,
+    authorizers: [Ash.Policy.Authorizer]
+
+  postgres do
+    table "join_requests"
+    repo Mv.Repo
+  end
+
+  actions do
+    defaults [:read, :destroy]
+
+    create :create do
+      primary? true
+      accept [
+        :email,
+        :confirmation_token_hash,
+        :status,
+        :submitted_at,
+        :source,
+        :schema_version,
+        :payload,
+        :approved_at,
+        :rejected_at,
+        :reviewed_by_user_id
+      ]
+    end
+
+    create :confirm do
+      description "Public action: create JoinRequest after confirmation link click (actor: nil)"
+      accept [
+        :email,
+        :confirmation_token_hash,
+        :status,
+        :submitted_at,
+        :source,
+        :schema_version,
+        :payload
+      ]
+    end
+
+    update :update do
+      accept [:status, :approved_at, :rejected_at, :reviewed_by_user_id]
+      require_atomic? false
+    end
+  end
+
+  policies do
+    policy action(:confirm) do
+      description "Allow public confirmation (actor nil) for join flow"
+      authorize_if Ash.Policy.Check.Builtins.actor_absent()
+    end
+
+    policy action_type(:read) do
+      description "Allow read when actor nil (success page) or when user has permission"
+      authorize_if Ash.Policy.Check.Builtins.actor_absent()
+      authorize_if Mv.Authorization.Checks.HasPermission
+    end
+
+    policy action(:create) do
+      description "Generic create only for authorized users; public uses :confirm"
+      authorize_if Mv.Authorization.Checks.HasPermission
+    end
+
+    policy action_type([:update, :destroy]) do
+      authorize_if Mv.Authorization.Checks.HasPermission
+    end
+  end
+
+  attributes do
+    uuid_v7_primary_key :id
+
+    attribute :email, :string do
+      allow_nil? false
+      public? true
+    end
+
+    attribute :confirmation_token_hash, :string do
+      allow_nil? false
+      public? true
+    end
+
+    attribute :status, :string do
+      allow_nil? false
+      public? true
+      default "submitted"
+    end
+
+    attribute :submitted_at, :utc_datetime_usec do
+      allow_nil? false
+      public? true
+    end
+
+    attribute :source, :string do
+      allow_nil? false
+      public? true
+    end
+
+    attribute :schema_version, :integer do
+      allow_nil? false
+      public? true
+    end
+
+    attribute :payload, :map do
+      allow_nil? true
+      public? true
+      default %{}
+    end
+
+    attribute :approved_at, :utc_datetime_usec do
+      allow_nil? true
+      public? true
+    end
+
+    attribute :rejected_at, :utc_datetime_usec do
+      allow_nil? true
+      public? true
+    end
+
+    attribute :reviewed_by_user_id, :uuid do
+      allow_nil? true
+      public? true
+    end
+
+    timestamps()
+  end
+
+  identities do
+    identity :unique_confirmation_token_hash, [:confirmation_token_hash]
+  end
+end

lib/membership/membership.ex

@@ -78,6 +78,52 @@ defmodule Mv.Membership do
       define :list_member_groups, action: :read
       define :destroy_member_group, action: :destroy
     end
+
+    resource Mv.Membership.JoinRequest do
+      define :list_join_requests, action: :read
+      define :get_join_request, action: :read, get_by: [:id]
+      define :update_join_request, action: :update
+      define :destroy_join_request, action: :destroy
+    end
+  end
+
+  # Idempotent confirm: implemented in code so duplicate token returns {:ok, existing} (concept §2.3.2)
+  @doc """
+  Creates a JoinRequest after confirmation link click (public action with actor: nil).
+
+  Idempotent: if a JoinRequest with the same `confirmation_token_hash` already exists,
+  returns `{:ok, existing}` instead of creating a duplicate (per concept §2.3.2).
+  """
+  def confirm_join_request(attrs, opts \\ []) do
+    hash = attrs[:confirmation_token_hash] || attrs["confirmation_token_hash"]
+
+    if hash do
+      case get_join_request_by_confirmation_token_hash!(hash, opts) do
+        nil -> do_confirm_join_request(attrs, opts)
+        existing -> {:ok, existing}
+      end
+    else
+      do_confirm_join_request(attrs, opts)
+    end
+  end
+
+  defp do_confirm_join_request(attrs, opts) do
+    Mv.Membership.JoinRequest
+    |> Ash.Changeset.for_create(:confirm, attrs)
+    |> Ash.create(Keyword.put(opts, :domain, __MODULE__))
+  end
+
+  defp get_join_request_by_confirmation_token_hash!(hash, opts) do
+    opts = Keyword.put(opts, :domain, __MODULE__)
+
+    Mv.Membership.JoinRequest
+    |> Ash.Query.filter(confirmation_token_hash == ^hash)
+    |> Ash.read_one(opts)
+    |> case do
+      {:ok, %Mv.Membership.JoinRequest{} = existing} -> existing
+      {:ok, nil} -> nil
+      _ -> nil
+    end
   end
 
   # Singleton pattern: Get the single settings record