defmodule DaProductApp.Repo.Migrations.CreateMerchantAdjustments do
  use Ecto.Migration

  @moduledoc """
  Single and bulk debit/credit adjustments applied at merchant (MID) level.

  Applied to Settlement MIS before payout generation. Supports:
    - Chargeback recovery
    - MDR adjustments
    - Credit / Debit adjustments (per MPR terms)
    - Other fees as per MPR

  Can be entered via:
    1. Manual single-entry form on Finance Team interface
    2. Bulk CSV upload (format to be defined with Finance team)

  Status lifecycle: pending → applied (linked to a settlement_mis) | cancelled
  """

  def change do
    create table(:merchant_adjustments) do
      add :merchant_mid, :string, size: 25, null: false
      add :merchant_name, :string, size: 200,
          comment: "Denormalized at creation time"
      add :adjustment_date, :date, null: false
      add :debit_credit, :string, size: 6, null: false,
          comment: "DEBIT | CREDIT"
      add :amount, :decimal, precision: 12, scale: 2, null: false
      add :currency, :string, size: 5, default: "AED"
      add :adjustment_type, :string, size: 50, null: false,
          comment: "chargeback_recovery | mdr_adjustment | credit_adjustment | debit_adjustment | transaction_fee | other_fee"
      add :description, :text,
          comment: "Memo / reason entered by Finance team"

      # Linking to MIS when applied
      add :settlement_mis_id, :bigint,
          comment: "FK settlement_mis.id — NULL until applied to a MIS"
      add :status, :string, size: 20, null: false, default: "pending",
          comment: "pending | applied | cancelled"
      add :applied_at, :naive_datetime
      add :cancelled_at, :naive_datetime
      add :cancel_reason, :text

      # Audit
      add :created_by, :bigint, null: false,
          comment: "users.id of Finance team member"
      add :updated_by, :bigint

      add :inserted_at, :naive_datetime, null: false
      add :updated_at, :naive_datetime, null: false
    end

    create index(:merchant_adjustments, [:merchant_mid])
    create index(:merchant_adjustments, [:adjustment_date])
    create index(:merchant_adjustments, [:status])
    create index(:merchant_adjustments, [:settlement_mis_id])
    create index(:merchant_adjustments, [:adjustment_type])
  end
end