%%%----------------------------------------------------------------------
%%% File    : bxe_util.erl
%%% Author  : Zachary Dean <contact@zadean.com>
%%% Purpose : Utility stuff for the BaseX client
%%% Created : 22 Mar 2017 by Zachary Dean <contact@zadean.com>
%%%----------------------------------------------------------------------

-module(bxe_util).

%% ====================================================================
%% API functions
%% ====================================================================
-export([
    utf8_to_base64/1,
    base64_to_utf8/1,
    utf8_to_hex/1,
    hex_to_utf8/1,
    nvl/2
]).

utf8_to_base64(Data) when is_binary(Data) ->
    base64:encode(Data);
utf8_to_base64(Data) when is_list(Data) ->
    base64:encode_to_string(Data).

base64_to_utf8(Base64) when is_binary(Base64) ->
    base64:decode(Base64);
base64_to_utf8(Base64) when is_list(Base64) ->
    base64:decode_to_string(Base64).

utf8_to_hex(String) when is_binary(String) ->
    HexList = utf8_to_hex_l(String),
    list_to_binary(HexList);
utf8_to_hex(String) when is_list(String) ->
    Bin = list_to_binary(String),
    HexList = utf8_to_hex_l(Bin),
    BinHex = list_to_binary(HexList),
    binary_to_list(BinHex).

hex_to_utf8(Hex) when is_binary(Hex) ->
    Str = hex_to_utf8_l(Hex),
    list_to_binary(Str);
hex_to_utf8(Hex) when is_list(Hex) ->
    Bin = list_to_binary(Hex),
    StrList = hex_to_utf8_l(Bin),
    BinStr = list_to_binary(StrList),
    binary_to_list(BinStr).

%% ==========================================================
%%                Internal functions
%% ==========================================================

utf8_to_hex_l(<<H, T/binary>>) ->
    [integer_to_list(H, 16) | utf8_to_hex_l(T)];
utf8_to_hex_l(<<>>) ->
    [].

hex_to_utf8_l(<<H:2/bytes, T/binary>>) ->
    [binary_to_integer(H, 16) | hex_to_utf8_l(T)];
hex_to_utf8_l(<<>>) ->
    [].

nvl([], Val2) -> Val2;
nvl(Val1, _Val2) -> Val1.