harness_ff_erlang_server_sdk

%% @doc
%% Funcctions to pull feature and target configuration from server via the API.
%% @end

-module(cfclient_retrieve).

-export([retrieve_flags/1, retrieve_segments/1]).

-type flag() :: cfapi_feature_config:cfapi_feature_config().
-type segment() :: cfapi_segment:cfapi_segment().
-type config() :: map().

-include_lib("kernel/include/logger.hrl").

% @doc Retrieve all features from Feature Flags API.
-spec retrieve_flags(config()) -> {ok, [flag()]} | {error, Reason :: term()}.
retrieve_flags(Config) ->
  #{auth_token := AuthToken, project := Project, config_url := ConfigUrl} = Config,
  #{environment := Env, clusterIdentifier := Cluster} = Project,
  Opts =
    #{
      cfg
      =>
      #{
        auth => #{'BearerAuth' => <<"Bearer ", AuthToken/binary>>},
        host => ConfigUrl,
        hackney_opts => [{timeout, 1}]
      },
      params => #{cluster => Cluster}
    },
  % Maximum number of retries
  RetryLimit = 5,
  % Initial delay between retries in milliseconds
  RetryDelay = 1000,
  retrieve_with_retry(
    fun cfapi_client_api:get_feature_config/3,
    [ctx:new(), Env, Opts],
    RetryLimit,
    RetryDelay,
    flags
  ).


% @doc Retrieve all segments from Feature Flags API.
-spec retrieve_segments(config()) -> {ok, [segment()]} | {error, Reason :: term()}.
retrieve_segments(Config) ->
  #{auth_token := AuthToken, project := Project, config_url := ConfigUrl} = Config,
  #{environment := Env, clusterIdentifier := Cluster} = Project,
  RetryLimit = 5,
  RetryDelay = 1000,
  Opts =
    #{
      cfg
      =>
      #{
        auth => #{'BearerAuth' => <<"Bearer ", AuthToken/binary>>},
        host => ConfigUrl,
        hackney_opts => [{timeout, 20000}]
      },
      params => #{cluster => Cluster}
    },
  retrieve_with_retry(
    fun cfapi_client_api:get_all_segments/3,
    [ctx:new(), Env, Opts],
    RetryLimit,
    RetryDelay,
    segments
  ).


% Recursive function for retrying the request
retrieve_with_retry(Func, Args, RetryLimit, RetryDelay, Endpoint) ->
  case apply(Func, Args) of
    {ok, Values, _} -> {ok, Values};
    % Retry on certain status codes
    {error, Reason, Response} ->
      case cfclient_config:is_retry_code(Response) of
        true when RetryLimit > 0 ->
          timer:sleep(RetryDelay),
          NewRetryLimit = RetryLimit - 1,
          NewRetryDelay = RetryDelay * 2,
          ?LOG_WARNING(
            "Error retrieving ~p: ~p, retrying with ~p: attempts left",
            [Endpoint, Reason, NewRetryLimit]
          ),
          retrieve_with_retry(Func, Args, NewRetryLimit, NewRetryDelay, Endpoint);

        _ -> {error, Reason}
      end;

    % Retry on request errors
    {error, Reason} when RetryLimit > 0 ->
      timer:sleep(RetryDelay),
      NewRetryLimit = RetryLimit - 1,
      % Exponential backoff
      NewRetryDelay = RetryDelay * 2,
      ?LOG_WARNING(
        "Error retrieving ~p: ~p, retrying with: ~p attempts left",
        [Endpoint, Reason, NewRetryLimit]
      ),
      retrieve_with_retry(Func, Args, NewRetryLimit, NewRetryDelay, Endpoint);

    {error, Reason} when RetryLimit == 0 -> {error, Reason}
  end.