neiam /gitgud

defmodule GitGud.Repo.Migrations.CreateOrganizationInvitations do
  use Ecto.Migration

  # Joining an org becomes something you accept rather than something
  # done to you. An admin creates an invitation; membership is only
  # inserted once the invitee says yes.
  #
  # Declined rows are kept rather than deleted so the same person can't
  # be re-invited into an endless loop without the admin noticing, and
  # so the org's members page can show that an invitation was answered.
  def change do
    create table(:organization_invitations) do
      add :organization_id, references(:organizations, on_delete: :delete_all), null: false
      add :invited_user_id, references(:users, on_delete: :delete_all), null: false
      add :invited_by_id, references(:users, on_delete: :nilify_all)
      add :role, :string, null: false, default: "member"
      add :state, :string, null: false, default: "pending"
      add :responded_at, :utc_datetime

      timestamps(type: :utc_datetime)
    end

    # One live invitation per person per org. Answered ones are kept,
    # so the constraint only covers pending.
    create unique_index(:organization_invitations, [:organization_id, :invited_user_id],
             where: "state = 'pending'",
             name: :organization_invitations_pending_index
           )

    # "What am I being asked to join?" — the dashboard's query.
    create index(:organization_invitations, [:invited_user_id, :state])
  end
end