defmodule ArcadiaCloud.Repo.Migrations.CreateDrift do
  use Ecto.Migration

  def change do
    # One row per drifted field of a provisioned resource. The operator
    # resolves each: "accept" (desired-state := actual) or "revert"
    # (schedule a saga to put actual back to desired).
    create table(:cloud_drift, primary_key: false) do
      add :id, :binary_id, primary_key: true
      add :resource_id, references(:cloud_resources, type: :binary_id, on_delete: :delete_all),
        null: false
      add :provisioned_id,
        references(:cloud_provisioned, type: :binary_id, on_delete: :delete_all),
        null: false
      add :field, :string, null: false
      add :expected, :map
      add :actual, :map
      add :status, :string, null: false, default: "open"
      add :detected_at, :utc_datetime, null: false
      add :resolved_at, :utc_datetime
      add :resolved_by, :string

      timestamps(type: :utc_datetime)
    end

    # At most one OPEN drift per (resource, field); resolved ones are history.
    create unique_index(:cloud_drift, [:resource_id, :field],
             where: "status = 'open'",
             name: :cloud_drift_open_unique
           )

    create index(:cloud_drift, [:status])
    create index(:cloud_drift, [:provisioned_id])
  end
end