Main4.ex

defmodule Main4 do

    @spec main :: {:ok, BookShop.Order.t} | {:error, term}
    def main do
        BookShop.test_data |> handle_create_order
    end


    @spec handle_create_order(map) :: {:ok, BookShop.Order.t} | {:error, term}
    def handle_create_order data0 do
        Pipeline.bind data0, [
            &BookShop.validate_incoming_data/1,
            &validate_cat/1,
            &validate_address/1,
            &validate_books/1,
            &create_order/1
        ]
    end


    @spec validate_cat(map) :: {:ok, map} | {:error, term}
    def validate_cat %{"cat" => cat0} = state do
        case BookShop.validate_cat cat0 do
            {:ok, cat} -> {:ok, (Map.put state, :cat, cat)}
            error -> error
        end
    end


    @spec validate_address(map) :: {:ok, map} | {:error, term}
    def validate_address %{"address" => address0} = state do
        case BookShop.validate_address address0 do
            {:ok, address} -> {:ok, (Map.put state, :address, address)}
            error -> error
        end
    end


    @spec validate_books(map) :: {:ok, map} | {:error, term}
    def validate_books %{"books" => books0} = state do
        books1 = Enum.map books0,
                          fn %{"title" => title, "author" => author} ->
                              BookShop.get_book title, author
                          end
        case Pipeline.sequence books1 do
            {:ok, books2} -> {:ok, (Map.put state, :books, books2)}
            error -> error
        end
    end


    @spec create_order(map) :: {:ok, BookShop.Order.t}
    def create_order %{:cat => cat, :address => address, :books => books} do
        order = BookShop.create_order cat, address, books
        {:ok, order}
    end

end