From e0330fdec0eca781912fbb8b3a948a57eefe1d80 Mon Sep 17 00:00:00 2001
From: Rob Watson <rob@mixlr.com>
Date: Sat, 7 Apr 2018 10:07:31 +0200
Subject: [PATCH] Add basic CLI

---
 lib/amazon_history/cli.ex        | 50 ++++++++++++++++++++++++++++++++
 test/amazon_history/cli_test.exs | 31 ++++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 lib/amazon_history/cli.ex
 create mode 100644 test/amazon_history/cli_test.exs

diff --git a/lib/amazon_history/cli.ex b/lib/amazon_history/cli.ex
new file mode 100644
index 0000000..e7e7c2d
--- /dev/null
+++ b/lib/amazon_history/cli.ex
@@ -0,0 +1,50 @@
+defmodule AmazonHistory.CLI do
+  @moduledoc """
+  Handle the command-line parsing for the amazon_history tool
+  """
+
+  def run(argv) do
+    argv
+    |> parse_args
+    |> process
+  end
+
+  def process(username: username, password: password) do
+    IO.puts("Will continue with username: #{username}, password: #{password}")
+  end
+
+  def process(_) do
+    IO.puts("Usage: --username <username> --password <password>")
+  end
+
+  @doc """
+  Options:
+  -u/--username: Amazon username
+  -p/--password: Amazon password
+  """
+  def parse_args(argv) do
+    OptionParser.parse(
+      argv,
+      switches: [
+        help: :boolean,
+        username: :string,
+        password: :string
+      ],
+      aliases: [
+        h: :help,
+        u: :username,
+        p: :password
+      ]
+    )
+    |> elem(0)
+    |> args_to_internal_representation
+  end
+
+  defp args_to_internal_representation(username: username, password: password) do
+    [username: username, password: password]
+  end
+
+  defp args_to_internal_representation(_) do
+    :help
+  end
+end
diff --git a/test/amazon_history/cli_test.exs b/test/amazon_history/cli_test.exs
new file mode 100644
index 0000000..a5737ec
--- /dev/null
+++ b/test/amazon_history/cli_test.exs
@@ -0,0 +1,31 @@
+defmodule CliTest do
+  use ExUnit.Case
+
+  describe "parse_args/1" do
+    import AmazonHistory.CLI, only: [parse_args: 1]
+
+    test ":help returned by passing -h and --help options" do
+      assert parse_args(["-h"]) == :help
+      assert parse_args(["--help"]) == :help
+    end
+
+    test ":help returned by passing only a username" do
+      assert parse_args(["-u", "rob"]) == :help
+      assert parse_args(["--username", "rob"]) == :help
+    end
+
+    test ":help returned by passing only a password" do
+      assert parse_args(["-p", "hackme"]) == :help
+      assert parse_args(["--password", "hackme"]) == :help
+    end
+
+    test "arguments returned by passing valid parameters" do
+      assert parse_args(["-u", "rob", "-p", "hackme"]) == [username: "rob", password: "hackme"]
+
+      assert parse_args(["--username", "rob", "--password", "hackme"]) == [
+               username: "rob",
+               password: "hackme"
+             ]
+    end
+  end
+end