Base command module for CQRS pattern implementation in Raxol.

Commands represent write operations in the system and encapsulate the intent to perform an action. All commands should be immutable and contain all the data necessary to perform the operation.

Command Design Principles

1. Intention Revealing: Command names should express business intent
2. Immutable: Commands should be immutable once created
3. Self-Contained: Commands should contain all necessary data
4. Validated: Commands should validate their data upon creation
5. Traceable: Commands should include metadata for auditing

Usage

defmodule MyApp.Commands.CreateUserCommand do
  use Raxol.Architecture.CQRS.Command

  defstruct [:user_id, :name, :email, :created_by, :metadata]

  @type t :: %__MODULE__{
    user_id: String.t(),
    name: String.t(),
    email: String.t(),
    created_by: String.t(),
    metadata: map()
  }

  def new(attrs) do
    %__MODULE__{
      user_id: attrs[:user_id] || UUID.uuid4(),
      name: attrs[:name],
      email: attrs[:email],
      created_by: attrs[:created_by],
      metadata: build_metadata(attrs)
    }
    |> validate()
  end

  defp validate(%__MODULE__{} = command) do
    with :ok <- validate_required(command, [:name, :email, :created_by]),
         :ok <- validate_email(command.email) do
      {:ok, command}
    else
      {:error, reason} -> {:error, reason}
    end
  end
end