Split Command validations (#7)

* move mix and escript examples module to an external dir

* add supported types config

* accumulate commands attr

* improve cmd parsing and create exceptions

config/config.exs

@@ -0,0 +1,3 @@
+import Config
+
+config :nexus, supported_types: ~w(string atom integer float)a

lib/nexus.ex

@@ -36,7 +36,7 @@ defmodule Nexus do
 
   defmacro __using__(_opts) do
     quote do
-      @commands %{}
+      Module.register_attribute(__MODULE__, :commands, accumulate: true)
 
       import Nexus, only: [defcommand: 2]
       require Nexus
@@ -57,12 +57,7 @@ defmodule Nexus do
   @spec defcommand(atom, keyword) :: Macro.t()
   defmacro defcommand(cmd, opts) do
     quote do
-      command =
-        unquote(opts)
-        |> Keyword.put(:module, __MODULE__)
-        |> Nexus.Command.parse!()
-
-      @commands Map.put(@commands, unquote(cmd), command)
+      @commands Nexus.__make_command__!(__MODULE__, unquote(cmd), unquote(opts))
     end
   end
 
@@ -120,7 +115,7 @@ defmodule Nexus do
       def __commands__, do: @commands
 
       def run([name | args]) do
-        cmd = Enum.find(@commands, fn {cmd, _spec} -> to_string(cmd) == name end)
+        cmd = Enum.find(@commands, fn cmd -> to_string(cmd.name) == name end)
         Nexus.CommandDispatcher.dispatch!(cmd, args)
       end
 
@@ -142,12 +137,11 @@ defmodule Nexus do
 
     banner =
       if function_exported?(cli_module, :banner, 0) do
-        "#{cli_module.banner()}"
+        "#{cli_module.banner()}\n\n"
       end
 
     """
-    #{banner}\n
-
+    #{banner}
     COMMANDS:\n
     #{Enum.map_join(cmds, "\n", &"  #{elem(&1, 0)} - ")}
     """
@@ -168,4 +162,12 @@ defmodule Nexus do
   def parse_to(:float, value) do
     String.to_float(value)
   end
+
+  def __make_command__!(module, cmd_name, opts) do
+    opts
+    |> Keyword.put(:name, cmd_name)
+    |> Keyword.put(:module, module)
+    |> Keyword.put_new(:required?, false)
+    |> Nexus.Command.parse!()
+  end
 end

lib/nexus/command.ex

@@ -4,37 +4,19 @@ defmodule Nexus.Command do
   implements some basic validations.
   """
 
-  require Logger
+  import Nexus.Command.Validation
 
-  @type t :: %Nexus.Command{module: atom, type: String.t(), required?: boolean}
+  @type t :: %Nexus.Command{module: atom, type: String.t(), required?: boolean, name: atom}
 
-  @enforce_keys ~w(module type)a
-  defstruct module: nil, required?: true, type: nil
+  @enforce_keys ~w(module type name)a
+  defstruct module: nil, required?: true, type: nil, name: nil
 
-  @spec parse!(keyword | map) :: Nexus.Command.t()
+  @spec parse!(keyword) :: Nexus.Command.t()
   def parse!(attrs) do
     attrs
-    |> maybe_convert_to_map()
-    |> validate_field(:type)
+    |> Map.new()
+    |> validate_type()
+    |> validate_name()
     |> then(&struct(__MODULE__, &1))
   end
-
-  defp maybe_convert_to_map(kw) when is_list(kw) do
-    Map.new(kw)
-  end
-
-  defp maybe_convert_to_map(map), do: map
-
-  defp validate_field(%{type: type} = attrs, :type) do
-    unless valid_type?(type) do
-      raise "Invalid command type"
-    end
-
-    attrs
-  end
-
-  defp validate_field(_, _), do: raise("Invalid command param")
-
-  defp valid_type?(:string), do: true
-  defp valid_type?(_), do: false
 end

lib/nexus/command/missing_type.ex

@@ -0,0 +1,3 @@
+defmodule Nexus.Command.MissingType do
+  defexception message: "Command type is missing"
+end

lib/nexus/command/not_supported_type.ex

@@ -0,0 +1,8 @@
+defmodule Nexus.Command.NotSupportedType do
+  defexception [:message]
+
+  @impl true
+  def exception(type) do
+    %__MODULE__{message: "Command type not supported yet: #{inspect(type)}"}
+  end
+end

lib/nexus/command/validation.ex

@@ -0,0 +1,30 @@
+defmodule Nexus.Command.Validation do
+  @moduledoc """
+  Defines validations for a `Nexus.Command` struct
+  """
+
+  alias Nexus.Command.MissingType
+  alias Nexus.Command.NotSupportedType
+
+  @supported_types Application.compile_env!(:nexus, :supported_types)
+
+  @spec validate_type(map) :: map
+  def validate_type(%{type: type} = attrs) do
+    if type in @supported_types do
+      attrs
+    else
+      raise NotSupportedType, type
+    end
+  end
+
+  def validate_type(_), do: raise(MissingType)
+
+  @spec validate_name(map) :: map
+  def validate_name(%{name: name} = attrs) do
+    if is_atom(name) do
+      attrs
+    else
+      raise ArgumentError, "Command name must be an atom"
+    end
+  end
+end