defmodule ExOvh.Ovh.Cache do
@moduledoc ~s"""
Caches the ovh api time diff
"""
use GenServer
alias ExOvh.Ovh.Defaults
############################
# Public
###########################
@doc "Starts a genserver to keep state on the config and time diff"
def start_link({client, config, opts}) do
LoggingUtils.log_mod_func_line(__ENV__, :debug)
GenServer.start_link(__MODULE__, {client, config, opts}, [name: gen_server_name(client)])
end
@doc "Retrieves the ovh api time diff from the cache"
def get_time_diff(client) do
GenServer.call(gen_server_name(client), :get_diff)
end
@doc "Retrieves the ovh config map"
def get_config(client) do
GenServer.call(gen_server_name(client), :get_config)
end
############################
# Genserver Callbacks
###########################
def init({client, config, opts}) do
LoggingUtils.log_mod_func_line(__ENV__, :debug)
LoggingUtils.log_return({client, config, opts}, :warn)
diff = calculate_diff(config)
{:ok, {config, diff}}
end
def handle_call(:get_diff, _from, {config, diff}) do
LoggingUtils.log_mod_func_line(__ENV__, :debug)
{:reply, diff, {config, diff}}
end
def handle_call(:get_config, _from, {config, diff}) do
LoggingUtils.log_mod_func_line(__ENV__, :debug)
{:reply, config, {config, diff}}
end
def handle_cast({:set_diff, new_diff}, {config, diff}) do
LoggingUtils.log_mod_func_line(__ENV__, :debug)
{:noreply, {config, new_diff}}
end
def terminate(:shutdown, state) do
LoggingUtils.log_mod_func_line(__ENV__, :warn)
LoggingUtils.log_return("gen_server #{__MODULE__} shutting down", :warn)
:ok
end
############################
# Private
###########################
defp gen_server_name(client), do: String.to_atom(Atom.to_string(client) <> Atom.to_string(__MODULE__))
defp endpoint(config), do: Defaults.endpoints()[config[:endpoint]]
defp api_version(config), do: config[:api_version]
defp api_time_request(config) do
time_uri = endpoint(config) <> api_version(config) <> "/auth/time"
options = [ headers: ["Content-Type": "application/json; charset=utf-8"], timeout: 10_000 ]
api_time = HTTPotion.request(:get, time_uri, options) |> Map.get(:body) |> Poison.decode!()
end
defp calculate_diff(config) do
api_time = api_time_request(config)
os_t = :os.system_time(:seconds)
os_t - api_time
end
#Caches the ovh api time diff
defp set_time_diff(client) do
config = get_config(client)
set_time_diff(client, config)
end
defp set_time_diff(client, config) when is_map(config) do
diff = calculate_diff(config)
GenServer.cast(gen_server_name(client), {:set_diff, diff})
end
end
