doc_by_place in Erlang

scratch.erl

% Benchmarking code for REPL nicked and modified to remove module param from here:
%  https://erlangcentral.org/wiki/index.php/Measuring_Function_Execution_Time
% Params: FnName, Params, Rounds, eg:
%  TC(DeepGet, [DeepGet, [<<"userCtx">>, <<"name">>], Req], 100000).
% TC = fun(TC_F, TC_A, TC_N) when TC_N > 0 -> TC_L = tl([begin {TC_T, _Result} = timer:tc(TC_F, TC_A), TC_T end || _ <- lists:seq(1, TC_N)]), TC_Min = lists:min(TC_L), TC_Max = lists:max(TC_L), TC_Med = lists:nth(round((TC_N - 1) / 2), lists:sort(TC_L)), TC_Avg = round(lists:foldl(fun(TC_X, TC_Sum) -> TC_X + TC_Sum end, 0, TC_L) / (TC_N - 1)), io:format("Range: ~b - ~b mics~nMedian: ~b mics ~nAverage: ~b mics~n", [TC_Min, TC_Max, TC_Med, TC_Avg]), TC_Med end.

% Made "cmd+v futon-ready" with the following disgusting display of black magic
% cat scratch.erl | sed 's/%.*//' | sed 's/"/\\"/'g | sed -e ':a' -e 'N' -e '$!ba' -e 's/\n/ /g' | pbcopy
fun ({Doc}, {Req}) ->
  SafeGetValue = fun(Key, PropListMaybe, Default) ->
    if
      is_tuple(PropListMaybe) andalso size(PropListMaybe) == 1 ->
        % Some are wrapped in a tuple for some arbitrary reason
        % {[{...}]} instead of [{...}]
        proplists:get_value(Key, element(1, PropListMaybe), Default);
      is_list(PropListMaybe) ->
        proplists:get_value(Key, PropListMaybe, Default);
      true ->
        Default
    end
  end,

  DeepGet = fun(DeepGet, KeyList, PropList) ->
    if
      length(KeyList) > 1 andalso PropList == [] ->
        undefined;
      length(KeyList) == 1 ->
        SafeGetValue(hd(KeyList), PropList, undefined);
      true ->
        DeepGet(DeepGet, tl(KeyList), SafeGetValue(hd(KeyList), PropList, []))
    end
  end,

  FindPlace = fun(FindPlace, Place, QueryId) ->
    if
      Place == undefined ->
        false;
      true ->
        case SafeGetValue(<<"_id">>, Place, undefined) =:= QueryId of
          true -> true;
          false -> FindPlace(FindPlace, SafeGetValue(<<"parent">>, Place, undefined), QueryId)
        end
    end
  end,

  Ok = fun(Place) ->
    QueryId = DeepGet(DeepGet, [<<"query">>, <<"id">>], Req),
    case QueryId =:= undefined of
      true -> true; % Admin
      false ->
        case Place =:= undefined of
          true -> DeepGet(DeepGet, [<<"query">>, <<"unassigned">>], Req) =:= <<"true">>;
          false -> FindPlace(FindPlace, Place, QueryId)
        end
    end
  end,

  CouchUser = list_to_binary([
      <<"org.couchdb.user:">>,
      DeepGet(DeepGet, [<<"userCtx">>, <<"name">>], Req)]),

  case proplists:get_value(<<"_id">>, Doc) of
    <<"design/medic">> -> false;     % Never replicate the ddoc as it's too big.
                                     % Changes are tracked in the watchDesignDoc function of the DB service.
    <<"resources">> -> true;
    CouchUser -> true;
    _ -> case proplists:get_value(<<"type">>, Doc) of
          <<"data_record">> ->
            case proplists:get_value(<<"kujua_message">>, Doc) =:= <<"true">> of
              true ->
                % Outgoing message
                Ok(
                  proplists:get_value(<<"contact">>,
                    hd(proplists:get_value(<<"messages">>,
                      hd(proplists:get_value(<<"tasks">>, Doc, [])), []))));
              false ->
                % Incoming message
                Ok(proplists:get_value(<<"contact">>, Doc))
            end;
          <<"form">> -> true;
          <<"clinic">> -> Ok(Doc);
          <<"district_hospital">> -> Ok(Doc);
          <<"health_centre">> -> Ok(Doc);
          <<"person">> -> Ok(Doc);
          _ -> false
        end
  end
end.