defmodule Contexto do
  @moduledoc """
  Abstracts away common schema functions, such as list, get, create, update, delete, etc.
  Assumes that the schema module has a `changeset` function.

  Usage:
    defmodule MyContext do
      use ContextBase, repo: MyApp.Repo, schema: MyApp.MySchema
    end

  Options:
    - :repo: the repo module to use
    - :schema: the schema module to use
  """
  defmacro __using__(opts) do
    repo = Module.concat([opts |> Keyword.get(:repo) |> Macro.to_string()])
    schema = Module.concat([opts |> Keyword.get(:schema) |> Macro.to_string()])

    quote do
      def list do
        unquote(repo).all(unquote(schema))
      end

      def get(id) do
        unquote(repo).get(unquote(schema), id)
      end

      def get!(id) do
        unquote(repo).get!(unquote(schema), id)
      end

      def create(attrs) do
        %unquote(schema){}
        |> unquote(schema).changeset(attrs)
        |> unquote(repo).insert()
      end

      def update(%unquote(schema){} = record, attrs) do
        record
        |> unquote(schema).changeset(attrs)
        |> unquote(repo).update()
      end

      def update!(%unquote(schema){} = record, attrs) do
        record
        |> unquote(schema).changeset(attrs)
        |> unquote(repo).update!()
      end

      def delete(record) do
        unquote(repo).delete(record)
      end

      def preload(record, associations) do
        unquote(repo).preload(record, associations)
      end
    end
  end
end