it responds to echo

Author: akshaykmr

.gitignore

@@ -22,3 +22,8 @@ erl_crash.dump
 # Ignore package tarball (built via "mix hex.build").
 redex-*.tar
 .elixir_ls/
+
+dump.rdb
+Makefile
+tester
+spawn_redis_server.sh

lib/command.ex

@@ -1,13 +1,16 @@
 defmodule Redex.Command do
-  @crlf "\r\n"
+  import Redex.RESPEncoder
   @invalid_command_message "Command invalid or not implemented"
 
 
-  def execute([command | _args]) do
+  def execute([command | args]) do
     case command |> String.upcase do
-      "COMMAND" -> "+OK" <> @crlf
-      "PING" -> "+PONG" <> @crlf
-      _ -> raise @invalid_command_message
+      "COMMAND" -> encode({:simple_str, "OK"})
+      "PING" -> encode({:simple_str, "PONG"})
+      "ECHO" -> encode({:simple_str, Enum.at(args, 0)})
+      _ ->
+          IO.inspect [command] ++ args
+        raise @invalid_command_message
     end
   end
 end

lib/resp_encoder.ex

@@ -0,0 +1,14 @@
+defmodule Redex.RESPEncoder do
+  @crlf "\r\n"
+
+  def encode(data) when is_list(data), do: "*#{Enum.count(data)}#{@crlf}" <> encode_array(data, "")
+  def encode({:simple_str, value}), do: "+#{value}#{@crlf}"
+  def encode({:error_str, value}), do: "-#{value}#{@crlf}"
+  def encode({:integer, value}), do: ":#{value}#{@crlf}"
+  def encode({:bulk_str, nil}), do: "$-1#{@crlf}"
+  def encode({:bulk_str, value}), do: "$#{String.length(value)}#{@crlf}#{value}#{@crlf}"
+  def encode(_), do: raise "Unable to encode response"
+
+  defp encode_array([head | tail], accumulator), do: encode_array(tail, accumulator <> encode(head))
+  defp encode_array([], accumulator), do: accumulator
+end

test/resp_encoder_test.exs

@@ -0,0 +1,9 @@
+defmodule RESPEncoderTest do
+  use ExUnit.Case
+  import Redex.RESPEncoder
+
+  test "it can encode simple string" do
+    assert encode({:simple_str, "OK"}) == "+OK\r\n"
+  end
+
+end