defmodule Keyring do

use GenServer

require Logger


@moduledoc "A Simple Keyring to store your api keys."


@registry_name :keyring_registry
@name __MODULE__

defstruct keys: [ ]


def start_link(id) do

  name = via_tuple(id)

  GenServer.start_link(__MODULE__, [id], name: name)
end

defp via_tuple(id) do

  {:via, Registry, {@registry_name, id}}
end

@doc """
Add a key/value pair.
## Examples
    iex> Keyring.add("google", %{key: 'google_location_api', value: 'value'})
    "[keys]"
"""
def add(id, data) do

  GenServer.call(via_tuple(id), { :add, data } )
end

@doc """
Pop the top key/value pair.
## Examples
    iex> Keyring.pop("google")
    "%{key: 'google_location_api', value: 'value'}"
"""
def pop(id, data) do

  GenServer.call(via_tuple(id), { :pop, data } )
end

@doc """
Update key/value pair.
## Examples
    iex> Keyring.update("google", %{key: 'google_location_api', value: 'value'})
    "[keys]"
"""
def update(id, data) do

  GenServer.call(via_tuple(id), { :update, data } )
end

@doc """
Delete the key/value pair.
## Examples
    iex> Keyring.delete("google", %{key: 'google_location_api', value: 'value'})
    "[keys]"
"""
def delete(id, data) do

  GenServer.call(via_tuple(id), { :delete, data } )
end

@doc """
Show all key/value pairs.
## Examples
    iex> Keyring.show("google")
    "[keys]"
"""
def show(id, data) do

  GenServer.call(via_tuple(id), { :show } )
end

def handle_call({ :add, data }, _from, %__MODULE__{ keys: keys } = state) do

  updated_data = keys ++ [data]

  updated_state = %__MODULE__{state |  keys: updated_data }

  {:reply, state, updated_state}
end

def handle_call({ :pop, data }, _from, %__MODULE__{ keys: keys } = state) do

  [h|t] = data

  updated_data = t

  updated_state = %__MODULE__{ state |  keys: updated_data }

  { :reply, h, updated_state }
end

def handle_call({ :update, data }, _from, %__MODULE__{ keys: keys } = state) do

  new_data = Enum.map(keys, fn(x) ->
                                case x.key == data.key do
                                true -> %{ key: x.key, data: data.data }
                                false -> x
                                 end
                              end)

  updated_state = %__MODULE__{state |  keys: new_data }

  { :reply, updated_state, updated_state }
end

def handle_call({ :delete, data }, _from, %__MODULE__{ keys: keys } = state) do

  new_data = Enum.filter(keys, fn(x) -> x.key == data.key end)

  updated_state = %__MODULE__{state |  keys: new_data }

  { :reply, updated_state, updated_state }
end

def handle_call({ :show }, _from, %__MODULE__{ keys: keys } = state) do

  { :reply, keys, state }
end


end