Send email notifications when a participation is approved/rejected

Also handles participant status :rejected instead of deleting the
participation

Closes #164

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

priv/repo/migrations/20190929170817_rename_postgres_types.exs

@@ -0,0 +1,52 @@
+defmodule Mobilizon.Storage.Repo.Migrations.RenamePostgresTypes do
+  use Ecto.Migration
+  alias Mobilizon.Actors.{ActorVisibility, MemberRole}
+
+  alias Mobilizon.Events.{
+    CommentVisibility,
+    JoinOptions,
+    EventStatus,
+    EventVisibility,
+    ParticipantRole
+  }
+
+  alias Mobilizon.Users.UserRole
+
+  @types %{
+    "actor_visibility_type" => ActorVisibility.type(),
+    "comment_visibility_type" => CommentVisibility.type(),
+    "event_join_options_type" => JoinOptions.type(),
+    "event_status_type" => EventStatus.type(),
+    "event_visibility_type" => EventVisibility.type(),
+    "member_role_type" => MemberRole.type(),
+    "participant_role_type" => ParticipantRole.type(),
+    "user_role_type" => UserRole.type()
+  }
+
+  def up do
+    Enum.each(@types, fn {k, v} -> rename_type(k, v) end)
+  end
+
+  def down do
+    Enum.each(@types, fn {k, v} -> rename_type(v, k) end)
+  end
+
+  defp rename_type(old_type_name, new_type_name) do
+    with %Postgrex.Result{columns: ["exists"], rows: [[true]]} <-
+           Ecto.Adapters.SQL.query!(
+             Mobilizon.Storage.Repo,
+             "select exists (select 1 from pg_type where typname = '#{
+               old_type_name |> remove_schema
+             }' and typnamespace = (select oid from pg_namespace where nspname = 'public'))"
+           ) do
+      Ecto.Migration.execute(
+        "ALTER TYPE #{old_type_name |> remove_schema} RENAME TO #{new_type_name |> remove_schema}"
+      )
+    end
+  end
+
+  # We don't want the schema: public.actor_visibility => actor_visibility
+  def remove_schema(schema) when is_atom(schema), do: remove_schema(to_string(schema))
+  def remove_schema("public." <> schema), do: schema
+  def remove_schema(schema), do: schema
+end

priv/repo/migrations/20190929175229_add_rejected_to_participant_role.exs

@@ -0,0 +1,21 @@
+defmodule Mobilizon.Storage.Repo.Migrations.AddRejectedToParticipantRole do
+  use Ecto.Migration
+  alias Mobilizon.Storage.Repo
+  alias Mobilizon.Events.Participant
+  alias Mobilizon.Events.ParticipantRole
+  import Ecto.Query
+
+  @disable_ddl_transaction true
+
+  def up do
+    Ecto.Migration.execute(
+      "ALTER TYPE #{ParticipantRole.type()} ADD VALUE IF NOT EXISTS 'rejected'"
+    )
+  end
+
+  def down do
+    Participant
+    |> where(role: "rejected")
+    |> Repo.delete_all()
+  end
+end