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

  def change do
    # `llm_usage_recorded` events received from arcadia-llm-gateway. The
    # gateway is the LLM-pricing authority — it sends the already-priced
    # customer charge; arcadia-cloud stores it and rolls it into the
    # tenant's monthly invoice. Idempotent on gateway_request_id so a
    # gateway retry never double-bills.
    create table(:llm_usage_events, primary_key: false) do
      add :id, :binary_id, primary_key: true
      add :gateway_request_id, :string, null: false
      add :tenant_id, :string, null: false
      add :deployment_id, :string

      add :provider, :string
      add :model, :string
      add :request_kind, :string

      add :input_tokens, :integer, null: false, default: 0
      add :output_tokens, :integer, null: false, default: 0
      add :cached_input_tokens, :integer, null: false, default: 0
      add :total_tokens, :integer, null: false, default: 0

      add :upstream_cost, :decimal
      add :customer_charge, :decimal
      add :customer_charge_cents, :integer, null: false, default: 0
      add :markup_mode, :string

      add :occurred_at, :utc_datetime_usec, null: false

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

    create unique_index(:llm_usage_events, [:gateway_request_id])
    create index(:llm_usage_events, [:tenant_id, :occurred_at])
    create index(:llm_usage_events, [:deployment_id])
  end
end