defmodule Argos.Validation do
  @moduledoc """
  Módulo de validación de inputs para Argos.

  Proporciona funciones de validación exhaustivas para prevenir errores
  y mejorar la seguridad del sistema.
  """

  @max_process_name_length 255
  @process_name_pattern ~r/^[a-zA-Z0-9_.-]+$/

  @doc """
  Valida un nombre de proceso.

  ## Validaciones

  - Debe ser un string no vacío
  - Longitud máxima: 255 caracteres
  - Solo caracteres alfanuméricos, puntos, guiones y guiones bajos

  ## Ejemplos

      iex> Argos.Validation.validate_process_name("my_process")
      :ok

      iex> Argos.Validation.validate_process_name("")
      {:error, "Process name cannot be empty"}

      iex> Argos.Validation.validate_process_name("invalid@name")
      {:error, "Process name contains invalid characters"}
  """
  @spec validate_process_name(String.t()) :: :ok | {:error, String.t()}
  def validate_process_name(name) when is_binary(name) do
    cond do
      String.length(name) == 0 ->
        {:error, "Process name cannot be empty"}

      String.length(name) > @max_process_name_length ->
        {:error, "Process name too long (max #{@max_process_name_length} characters)"}

      not String.match?(name, @process_name_pattern) ->
        {:error, "Process name contains invalid characters"}

      true ->
        :ok
    end
  end

  def validate_process_name(_invalid) do
    {:error, "Process name must be a string"}
  end

  @doc """
  Valida un comando a ejecutar.

  ## Validaciones

  - No puede ser nil
  - Si es string, no puede estar vacío
  - Si es lista, debe tener al menos un elemento

  ## Ejemplos

      iex> Argos.Validation.validate_command("echo test")
      :ok

      iex> Argos.Validation.validate_command("")
      {:error, "Command cannot be empty"}

      iex> Argos.Validation.validate_command(["echo", "test"])
      :ok
  """
  @spec validate_command(String.t() | [String.t()] | term()) :: :ok | {:error, String.t()}
  def validate_command(command) when is_binary(command) do
    if String.trim(command) == "" do
      {:error, "Command cannot be empty"}
    else
      :ok
    end
  end

  def validate_command(command) when is_list(command) do
    if Enum.empty?(command) do
      {:error, "Command list cannot be empty"}
    else
      :ok
    end
  end

  def validate_command(nil) do
    {:error, "Command cannot be nil"}
  end

  def validate_command(_invalid) do
    {:error, "Command must be a string or a list of strings"}
  end

  @doc """
  Valida una especificación de worker.

  ## Validaciones

  - `id` no puede ser nil
  - `tasks` debe ser una lista no vacía

  ## Ejemplos

      iex> Argos.Validation.validate_worker_spec(%{id: :w1, tasks: [fn -> :ok end]})
      :ok

      iex> Argos.Validation.validate_worker_spec(%{id: nil, tasks: [fn -> :ok end]})
      {:error, "Worker id cannot be nil"}

      iex> Argos.Validation.validate_worker_spec(%{id: :w1, tasks: []})
      {:error, "Worker tasks cannot be empty"}
  """
  @spec validate_worker_spec(map()) :: :ok | {:error, String.t()}
  def validate_worker_spec(%{id: id, tasks: tasks}) when is_list(tasks) do
    cond do
      id == nil ->
        {:error, "Worker id cannot be nil"}

      Enum.empty?(tasks) ->
        {:error, "Worker tasks cannot be empty"}

      true ->
        :ok
    end
  end

  def validate_worker_spec(_invalid) do
    {:error, "Worker spec must be a map with :id and :tasks keys"}
  end

  @doc """
  Escapa un nombre de proceso para prevenir injection en comandos shell.

  ## Ejemplos

      iex> Argos.Validation.escape_process_name("my_process")
      "my_process"

      iex> Argos.Validation.escape_process_name("process'name")
      "process'\\''name"
  """
  @spec escape_process_name(String.t()) :: String.t()
  def escape_process_name(name) when is_binary(name) do
    String.replace(name, "'", "'\\''")
  end

  @doc """
  Valida un path de archivo o directorio.

  ## Validaciones

  - Debe ser un string no vacío
  - No puede contener caracteres peligrosos

  ## Ejemplos

      iex> Argos.Validation.validate_path("/path/to/file")
      :ok

      iex> Argos.Validation.validate_path("")
      {:error, "Path cannot be empty"}
  """
  @spec validate_path(String.t()) :: :ok | {:error, String.t()}
  def validate_path(path) when is_binary(path) do
    if String.trim(path) == "" do
      {:error, "Path cannot be empty"}
    else
      :ok
    end
  end

  def validate_path(_invalid) do
    {:error, "Path must be a string"}
  end
end