pipe_operator_answer.ex

# Use this code and data to answer the questions.

defmodule Millenium.Falcon do
  def rebel?(c = %{rebel: true}) do
    c.type != :droid
  end

  def rebel?(_), do: false

  def fill_ship(characters) do
    characters
    |> Enum.map(&(&1.name))
    |> Enum.join(",")
  end
end

characters = [
  %{name: "Han",        type: :human,   rebel: true,    weight: 185},
  %{name: "Jabba",      type: :hutt,    rebel: false,   weight: 2200},
  %{name: "Chewie",     type: :wookie,  rebel: true,    weight: 350},
  %{name: "r2d2",       type: :droid,   rebel: true,    weight: 250},
  %{name: "Luke",       type: :human,   rebel: true,    weight: 140},
  %{name: "Boba Fett",  type: :human,   rebel: false,   weight: 175},
]

# Question 1 - Create a list of all the rebel scum

characters
|> Enum.filter(&Millenium.Falcon.rebel?/1)
|> IO.inspect

# Question 2 - Fill the Millenium Falcon with all the rebels

characters
|> Enum.filter(&Millenium.Falcon.rebel?/1)
|> Millenium.Falcon.fill_ship
|> IO.puts

# Question 3 - How much do all the humans weigh?

characters
|> Enum.filter(fn(c) -> Map.get(c, :type) == :human end)
|> Enum.reduce(0, fn(h, acc) -> h.weight + acc end)
|> IO.puts

# Question 4 (BONUS) - If the Millenium Falcon can hold 1000 pounds, what is the optimal set of characters?

characters
|> Enum.sort(fn(c1,c2) -> c1.weight < c2.weight end)
|> Enum.flat_map_reduce(0, fn(c,acc) -> if c.weight + acc < 1000, do: {[c], c.weight + acc}, else: {:halt, acc} end)
|> elem(0)
|> IO.inspect