customer-service/lib/customer_service/aggregates/customer.ex

defmodule CustomerService.Aggregates.Customer do
  defstruct [
    :id,
    :first_name,
    :last_name,
    :birth_date,
    :gender,
    :email,
    :phone,
    :address,
    :document_id
  ]

  alias __MODULE__
  alias Commanded.Aggregates.Aggregate
  alias CustomerService.Commands
  alias CustomerService.Events

  @behaviour Aggregate
  @impl Aggregate
  def execute(%Customer{id: nil}, %Commands.CreateCustomer{} = cmd) do
    %Events.CustomerCreated{
      id: cmd.id,
      first_name: cmd.first_name,
      last_name: cmd.last_name,
      birth_date: cmd.birth_date,
      gender: cmd.gender,
      email: cmd.email,
      phone: cmd.phone,
      document_id: cmd.document_id,
      address: cmd.address
    }
  end

  @impl Aggregate
  def execute(%Customer{id: _id}, %Commands.UpdateCustomer{} = cmd) do
    %Events.CustomerUpdated{
      id: cmd.id,
      first_name: cmd.first_name,
      last_name: cmd.last_name,
      birth_date: cmd.birth_date,
      gender: cmd.gender,
      email: cmd.email,
      phone: cmd.phone,
      document_id: cmd.document_id,
      address: cmd.address
    }
  end

  @impl Aggregate
  def apply(%Customer{} = c, %Events.CustomerCreated{} = e) do
    %__MODULE__{
      c
      | id: e.id,
        first_name: e.first_name,
        last_name: e.last_name,
        birth_date: e.birth_date,
        gender: e.gender,
        email: e.email,
        phone: e.phone,
        address: e.address,
        document_id: e.document_id
    }
  end

  @impl Aggregate
  def apply(%Customer{} = c, %Events.CustomerUpdated{} = e) do
    %__MODULE__{
      c
      | first_name: e.first_name || c.first_name,
        last_name: e.last_name || c.last_name,
        birth_date: e.birth_date || c.birth_date,
        gender: e.gender || c.gender,
        email: e.email || c.email,
        phone: e.phone || c.phone,
        address: e.address || c.address,
        document_id: e.document_id || c.document_id
    }
  end
end