From 821b36f06ce1a12ef16efb57a44ba7781cbbf4fb Mon Sep 17 00:00:00 2001
From: Lain Soykaf <lain@soykaf.club>
Date: Fri, 22 Jan 2021 15:29:43 +0100
Subject: [PATCH] Groups: Add basic groups.

---
 lib/pleroma/group.ex                               | 74 ++++++++++++++++++++++
 lib/pleroma/user.ex                                |  6 ++
 .../migrations/20210113150220_create_groups.exs    | 17 +++++
 test/pleroma/group_test.exs                        | 36 +++++++++++
 4 files changed, 133 insertions(+)
 create mode 100644 lib/pleroma/group.ex
 create mode 100644 priv/repo/migrations/20210113150220_create_groups.exs
 create mode 100644 test/pleroma/group_test.exs

diff --git a/lib/pleroma/group.ex b/lib/pleroma/group.ex
new file mode 100644
index 000000000..6cc208f15
--- /dev/null
+++ b/lib/pleroma/group.ex
@@ -0,0 +1,74 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Group do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Pleroma.User
+  alias Pleroma.Repo
+  alias Pleroma.Web
+  alias Pleroma.EctoType.ActivityPub.ObjectValidators
+
+  @moduledoc """
+  Groups contain all the additional information about a group that's not stored
+  in the user table.
+
+  Concepts:
+
+  - Groups have an owner
+  - Groups have members, invited by the owner.
+  """
+
+  @type t :: %__MODULE__{}
+  @primary_key {:id, FlakeId.Ecto.CompatType, autogenerate: true}
+
+  schema "groups" do
+    belongs_to(:user, User, type: FlakeId.Ecto.CompatType)
+    belongs_to(:owner, User, type: FlakeId.Ecto.CompatType, foreign_key: :owner_id)
+
+    field(:members, {:array, ObjectValidators.ObjectID})
+    field(:name, :string)
+    field(:description, :string)
+    field(:members_collection, :string)
+
+    timestamps()
+  end
+
+  @spec create(map()) :: {:ok, t()} | {:error, Ecto.Changeset.t()}
+  def create(params) do
+    with {:ok, user} <- generate_user() do
+      %__MODULE__{user_id: user.id, members_collection: "#{user.ap_id}/members"}
+      |> changeset(params)
+      |> Repo.insert()
+    end
+  end
+
+  defp generate_ap_id(id) do
+    "#{Web.base_url()}/groups/#{id}"
+  end
+
+  defp generate_user() do
+    id = Ecto.UUID.generate()
+    ap_id = generate_ap_id(id)
+
+    %{
+      ap_id: ap_id,
+      name: id,
+      nickname: id,
+      follower_address: "#{ap_id}/followers",
+      following_address: "#{ap_id}/following",
+      local: true
+    }
+    |> User.group_changeset()
+    |> Repo.insert()
+  end
+
+  def changeset(struct, params) do
+    struct
+    |> cast(params, [:user_id, :owner_id, :name, :description, :members_collection])
+    |> validate_required([:user_id, :owner_id, :members_collection])
+  end
+end
diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index 2aeacf816..3da658950 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -407,6 +407,12 @@ defmodule Pleroma.User do
 
   defp fix_follower_address(params), do: params
 
+  def group_changeset(struct \\ %User{actor_type: "Group"}, params) do
+    struct
+    |> cast(params, [:ap_id, :nickname, :name, :follower_address, :following_address, :local])
+    |> validate_required([:ap_id, :nickname, :name, :follower_address, :following_address, :local])
+  end
+
   def remote_user_changeset(struct \\ %User{local: false}, params) do
     bio_limit = Config.get([:instance, :user_bio_length], 5000)
     name_limit = Config.get([:instance, :user_name_length], 100)
diff --git a/priv/repo/migrations/20210113150220_create_groups.exs b/priv/repo/migrations/20210113150220_create_groups.exs
new file mode 100644
index 000000000..642326d51
--- /dev/null
+++ b/priv/repo/migrations/20210113150220_create_groups.exs
@@ -0,0 +1,17 @@
+defmodule Pleroma.Repo.Migrations.CreateGroups do
+  use Ecto.Migration
+
+  def change do
+    create table(:groups, primary_key: false) do
+      add(:id, :uuid, primary_key: true)
+      add(:user_id, references(:users, type: :uuid, on_delete: :delete_all), null: false)
+      add(:owner_id, references(:users, type: :uuid, on_delete: :nilify_all))
+      add(:members, {:array, :string}, default: [])
+      add(:name, :text)
+      add(:description, :text)
+      add(:members_collection, :text)
+
+      timestamps()
+    end
+  end
+end
diff --git a/test/pleroma/group_test.exs b/test/pleroma/group_test.exs
new file mode 100644
index 000000000..f73abd237
--- /dev/null
+++ b/test/pleroma/group_test.exs
@@ -0,0 +1,36 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.GroupTest do
+  use Pleroma.DataCase, async: true
+
+  alias Pleroma.Group
+  alias Pleroma.Repo
+
+  import Pleroma.Factory
+
+  test "a user can create a group" do
+    user = insert(:user)
+    {:ok, group} = Group.create(%{owner_id: user.id, name: "cofe", description: "corndog"})
+    group = Repo.preload(group, :user)
+
+    assert group.user.actor_type == "Group"
+    assert group.owner_id == user.id
+    assert group.name == "cofe"
+    assert group.description == "corndog"
+
+    # Deleting the owner does not delete the group, just orphans it
+    Repo.delete(user)
+
+    group =
+      Repo.get(Group, group.id)
+      |> Repo.preload(:user)
+
+    assert group.owner_id == nil
+
+    # Deleting the group user deletes the group
+    Repo.delete(group.user)
+    refute Repo.get(Group, group.id)
+  end
+end