OTP CatStore

catstore.ex

defmodule Catstore.Server do
  use GenServer

  ## really simple API
  def new_store(cats) do
    {:ok, store} = GenServer.start_link(Catstore.Server, cats)
    store
  end

  def add(store, cat) do
    GenServer.call(store, {:push_cat, cat})
  end

  def remove(store, cat) do
    GenServer.call(store, {:remove, cat})
  end

  def list(store) do
    GenServer.call(store, :list)
  end

  def close(store, reason) do
    GenServer.cast(store, {:stop, reason})
  end


  def pr_cats(cats) do
    IO.puts "*** Your Cat Order ***"
    Enum.each(cats, fn(cat) -> IO.puts("  Name: #{cat}") end)
    IO.puts "**********************"
  end

  def init(cats) do
    IO.puts "Starting with cats: #{cats}"
    {:ok, cats}
  end

  def handle_call(:order, _pid, cats) do
    {:reply, "Your order is being processed..", cats}
  end

  def handle_call(:list, _pid, cats) do
    {:reply, pr_cats(cats), cats}
  end

  def handle_call({:push_cat, cat}, _pid, current_cats) do
    IO.puts "Adding cat #{cat}"
    {:reply, :ok, [ cat | current_cats ] }
  end

  def handle_call({:remove, cat}, _pid, current_cats) do
    case cat in current_cats do
      true ->
        {:reply, {:ok, cat}, List.delete(current_cats, cat)}
      false ->
        {:reply, :not_found, current_cats}
    end
  end


  def handle_cast({:stop, reason}, cats) do
    IO.puts "Stopping because you said: #{reason}"
    IO.puts "Ditching all cats #{cats}"
    {:stop, reason, cats}
  end

  def terminate(_reason, _state) do
    IO.puts "Terminated."
    :ok
  end
end

# To run
# {:ok, pid} = GenServer.start_link(Catstore.Server, ["Whiskers", "Tabby"])
# To Add
# GenServer.call(pid, {:push_cat, "Miss Dainty"})
# GenServer.call(pid, :list)
# To stop the madness
# GenServer.cast(pid, {:stop, "NO MOAR!"})
#
# Our public API
# store = Catstore.Server.new_store(["Friskies", "Night"])
# Catstore.Server.add(store, "Midnight")
# Catstore.Server.add(store, "Buckles")
# Catstore.Server.add(store, "Floppy")
# Catstore.Server.remove(store, "Midnight")
# Catstore.Server.list(store)
# Catstore.Server.close(store, "Closing time")