ecto_context

defmodule EctoContext.Validate do
  @moduledoc """
  Validation helpers used by the EEx templates in `priv/templates/ecto_context/`.

  These functions are called at runtime from code generated by `EctoContext`.
  They guard against invalid options and unknown associations before
  queries hit the database.
  """

  @doc """
  Validates that `assoc_atom` is a known association or `_id` field on `module`.

  Raises `ArgumentError` if neither a `belongs_to` association nor a
  corresponding `_id` field exists on the schema.
  """
  @spec validate_assoc!(module(), atom()) :: :ok
  def validate_assoc!(module, assoc_atom) do
    has_association = not is_nil(module.__schema__(:association, assoc_atom))
    has_field = :"#{assoc_atom}_id" in module.__schema__(:fields)

    unless has_association or has_field do
      raise ArgumentError, """
      Invalid association. :#{assoc_atom} on #{module} does not exist.
      Expected a belongs_to association or a :#{assoc_atom}_id field.
      """
    end
  end

  @doc """
  Validates that all keys in `opts` are in the `valid_keys` list.

  Raises `ArgumentError` listing the unsupported keys if any are found.
  """
  @spec validate_opts!(keyword(), [atom()]) :: :ok
  def validate_opts!(opts, valid_keys) do
    invalid_keys = Keyword.keys(opts) -- valid_keys

    if Enum.any?(invalid_keys) do
      raise ArgumentError, """
      Unsupported option(s) found: #{Enum.map_join(invalid_keys, ", ", &":#{&1}")}.
      Supported options are: #{Enum.map_join(valid_keys, ", ", &":#{&1}")}
      """
    end

    :ok
  end
end