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

  def change do
    # Per-resource-kind metering granularity. Daily by default; flip a
    # kind to hourly when fine-grained billing is wanted.
    create table(:metering_config, primary_key: false) do
      add :id, :binary_id, primary_key: true
      add :resource_kind, :string, null: false
      add :granularity, :string, null: false, default: "daily"
      add :retention_days, :integer, null: false, default: 400

      timestamps(type: :utc_datetime)
    end

    create unique_index(:metering_config, [:resource_kind])

    # One metered observation per (deployment, resource, period, granularity).
    # resource_kind here is the BILLING kind (droplet_hours, spaces_gb_month,
    # ...) so it joins straight to plan_items.resource_kind.
    create table(:usage_records, primary_key: false) do
      add :id, :binary_id, primary_key: true
      add :deployment_id,
        references(:cloud_deployments, type: :binary_id, on_delete: :delete_all),
        null: false
      add :resource_id, references(:cloud_resources, type: :binary_id, on_delete: :nilify_all)
      add :resource_kind, :string, null: false
      add :period_start, :utc_datetime, null: false
      add :granularity, :string, null: false, default: "daily"
      add :qty, :decimal, null: false, default: 0
      # forward-compat: tenants opting into sub-billing later can attribute
      # usage to their own end-users without a schema migration. Never
      # written in phase 3.
      add :sub_attribution, :map

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

    create unique_index(:usage_records, [:deployment_id, :resource_id, :period_start, :granularity],
             name: :usage_records_unique
           )

    create index(:usage_records, [:deployment_id, :period_start])
    create index(:usage_records, [:resource_kind])
  end
end