# An second example of using pipes in Elixir.
#
# The major difference here is the use of named functions
# inside a module and replacing most of the Enum functions
# with recursion
#
# author gtowell
# Created: July 19, 2022


defmodule UpTest do
  @doc """
  a function to capitalize the first letter of a string
  This takes a stirng as an arguement and returns a string
  with the firstletter capitalized
  """
  def up_first (str) do
    String.upcase(String.slice(str, 0..0)) <> String.slice(str, 1..-1)
  end

  @doc """
  Replace the Enum with my own recursion.   Usually this is
  unnecessary and silly; better to use Enum.reduce.   But
  as an example, OK.
  """
  # if the list is empty
  def cap_list ([]) do
    []
  end
  # if the list of not empty
  def cap_list([head | rest]) do
    [up_first(head) | cap_list(rest)]
  end

  @doc """
  Joint together the strings in the given list separating
  them with the string given in the insert param
  """
  # Handle the case where the list is empty
  def mjoin([], _insert) do
    ""
  end
  # Handle the case where the list has exactly one item
  # Jusr ensures that the resulting string does not have a
  # trailing insert
  def mjoin([h], _insert) do
    h
  end
  # Handle the general case
  def mjoin([head | rest], insert) do
   head <> insert <> mjoin(rest, insert)
  end
end


defmodule Main do
  def main do
    # example
    IO.puts UpTest.up_first("this")
    # examples
    IO.inspect UpTest.cap_list(["a", "test"])
    IO.inspect UpTest.cap_list(~w[aaa bbb ccc ddd])
    IO.inspect UpTest.cap_list(String.split("this is a test"))

    IO.puts UpTest.mjoin(~w[aaa bbb ccc ddd], "<>")

    IO.inspect String.split("this is a test")
            |> UpTest.cap_list
            |> UpTest.mjoin(" ")

    # Putting everything together without using pipes
    #IO.inspect Enum.join(cap_list.(String.split("this is a test")), "_")

  end
end


Main.main