bencoding

%%%-------------------------------------------------------------------
%%% @author Ralf Thomas Pietsch <ratopi@abwesend.de>
%%% @copyright (C) 2018, Ralf Thomas Pietsch
%%% @doc
%%%
%%% @end
%%% Created : 27. Okt 2018 05:42
%%%-------------------------------------------------------------------
-module(bt_utils).
-author("Ralf Thomas Pietsch <ratopi@abwesend.de>").

%% API
-export([mapa/2, sha1/1, url_encode/1, gen_uid/0]).

mapa([], Value) ->
	Value;

mapa([H | T], Map) ->
	mapa(T, maps:get(H, Map)).


sha1(<<Bin/binary>>) ->
	crypto:hash(sha, Bin).

url_encode(<<Bin/binary>>) ->
	url_encode(Bin, []).


url_encode(<<>>, List) ->
	list_to_binary(lists:reverse(List));

url_encode(<<V, Bin/binary>>, List) ->
	url_encode(Bin, [to_hex(V rem 16), to_hex(V div 16), $% | List]).



to_hex(V) when V =< 9 ->
	V + $0;
to_hex(V) ->
	V + $A - 10.

gen_uid() ->
	list_to_binary(
		[
			rand:uniform(256)
			|| _ <- lists:seq(0, 19)
		]
	).