neiam /gitgud

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

  def change do
    # Labels can now be owned by an organization instead of a single
    # repository. Org labels are visible across every repo the org
    # owns unless that repo opts out (see `repository_label_opt_outs`).
    alter table(:labels) do
      add :organization_id, references(:organizations, on_delete: :delete_all)
    end

    # Repository_id was NOT NULL — relax it now that org-scoped rows
    # exist. Enforce one-or-the-other via a CHECK so we don't end up
    # with orphan rows.
    execute(
      "ALTER TABLE labels ALTER COLUMN repository_id DROP NOT NULL",
      "ALTER TABLE labels ALTER COLUMN repository_id SET NOT NULL"
    )

    create constraint(:labels, :labels_scope_xor,
             check:
               "(repository_id IS NOT NULL AND organization_id IS NULL) OR " <>
                 "(repository_id IS NULL AND organization_id IS NOT NULL)"
           )

    create index(:labels, [:organization_id])

    create unique_index(:labels, [:organization_id, :name],
             where: "organization_id IS NOT NULL",
             name: :labels_organization_id_name_index
           )

    # Per-repo opt-outs from org labels. Presence of a row means this
    # repo hides that org label from its inherited set.
    create table(:repository_label_opt_outs) do
      add :repository_id, references(:repositories, on_delete: :delete_all), null: false
      add :label_id, references(:labels, on_delete: :delete_all), null: false

      timestamps(type: :utc_datetime, updated_at: false)
    end

    create unique_index(:repository_label_opt_outs, [:repository_id, :label_id])
    create index(:repository_label_opt_outs, [:label_id])
  end
end