iot_cloud/apps/iot/src/iot_util.erl

%%%-------------------------------------------------------------------
%%% @author licheng5
%%% @copyright (C) 2020, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 11. 12月 2020 上午10:57
%%%-------------------------------------------------------------------
-module(iot_util).
-author("licheng5").

%% API
-export([timestamp/0, number_format/2, current_time/0, timestamp_of_seconds/0, float_to_binary/2, int_format/2, file_uri/1]).
-export([step/3, chunks/2, rand_bytes/1, uuid/0, md5/1, parse_mapper/1]).
-export([json_data/1, json_error/2, is_json/1]).
-export([queue_limited_in/3, assert_call/2, assert/2]).

-spec is_json(Json :: term()) -> boolean().
is_json(Json) when is_binary(Json) ->
    case catch jiffy:decode(Json, [return_maps]) of
        Result when is_list(Result) orelse is_map(Result) ->
            true;
        _ ->
            false
    end;
is_json(_Json) ->
    false.

%% 时间，精确到毫秒
timestamp() ->
    {Mega, Seconds, Micro} = os:timestamp(),
    (Mega * 1000000 + Seconds) * 1000 + Micro div 1000.

current_time() ->
    {Mega, Seconds, _Micro} = os:timestamp(),
    Mega * 1000000 + Seconds.

timestamp_of_seconds() ->
    {Mega, Seconds, _Micro} = os:timestamp(),
    Mega * 1000000 + Seconds.

number_format(Num, _Decimals) when is_integer(Num) ->
    Num;
number_format(Float, Decimals) when is_float(Float) ->
    list_to_float(float_to_list(Float, [{decimals, Decimals}, compact])).

int_format(Num, Len) when is_integer(Num), Len > 0 ->
    S = integer_to_list(Num),
    case length(S) > Len of
        true ->
            list_to_integer(lists:sublist(S, 1, Len));
        false ->
            Num
    end.

step(Start, End, Step) when is_integer(Start), is_integer(End), is_integer(Step), Start < End, Step > 0 ->
    step(Start, End, Step, []).
step(Start, End, Step, Acc) when Start < End ->
    step(Start + Step, End, Step, [{Start, min(Start + Step, End)} | Acc]);
step(_, _, _, Acc) ->
    lists:reverse(Acc).

%% 将数据分组
-spec chunks(list(), integer()) -> [list()].
chunks(List, Size) when is_list(List), is_integer(Size), Size > 0, length(List) =< Size ->
    [List];
chunks(List, Size) when is_list(List), is_integer(Size), Size > 0 ->
    chunks0(List, Size, Size, [], []).
chunks0([], _, _, [], AccTarget) ->
    lists:reverse(AccTarget);
chunks0([], _, _, Target, AccTarget) ->
    lists:reverse([lists:reverse(Target) | AccTarget]);
chunks0(List, Size, 0, Target, AccTarget) ->
    chunks0(List, Size, Size, [], [lists:reverse(Target) | AccTarget]);
chunks0([Hd | Tail], Size, Num, Target, AccTarget) ->
    chunks0(Tail, Size, Num - 1, [Hd | Target], AccTarget).

json_data(Data) ->
    jiffy:encode(#{
        <<"result">> => Data
    }, [force_utf8]).

json_error(ErrCode, ErrMessage) when is_integer(ErrCode), is_binary(ErrMessage) ->
    jiffy:encode(#{
        <<"error">> => #{
            <<"code">> => ErrCode,
            <<"message">> => ErrMessage
        }
    }, [force_utf8]).

uuid() ->
    rand_bytes(16).

-spec rand_bytes(Size :: integer()) -> string().
rand_bytes(Size) when is_integer(Size), Size > 0 ->
    Size1 = erlang:ceil(Size / 2),
    Bytes = crypto:strong_rand_bytes(Size1),
    S = lists:flatten([integer_to_list(E, 16) || <<E:4>> <= Bytes]),
    lists:sublist(string:to_lower(S), 1, Size).

queue_limited_in(Item, Q, Num) when is_integer(Num) ->
    case queue:len(Q) >= Num of
        true ->
            Q1 = queue:drop(Q),
            queue:in(Item, Q1);
        false ->
            queue:in(Item, Q)
    end.

assert_call(true, Fun) ->
    Fun();
assert_call(false, _) ->
    ok.

-spec md5(Str :: binary()) -> binary().
md5(Str) when is_binary(Str) ->
    list_to_binary(lists:flatten([hex(X) || <<X:4>> <= erlang:md5(Str)])).

hex(N) when N < 10 ->
    $0 + N;
hex(N) ->
    $a + (N - 10).

%% 转换映射器
-spec parse_mapper(Mapper :: binary() | string()) -> error | {ok, F :: fun((binary(), any()) -> any())}.
parse_mapper(Mapper) when is_binary(Mapper) ->
    parse_mapper(binary_to_list(Mapper));
parse_mapper(Mapper) when is_list(Mapper) ->
    {ok, Tokens, _} = erl_scan:string(Mapper),
    {ok, ExprList} = erl_parse:parse_exprs(Tokens),
    {value, F, _} = erl_eval:exprs(ExprList, []),
    case is_function(F, 2) orelse is_function(F, 3) of
        true ->
            {ok, F};
        false ->
            error
    end.

-spec float_to_binary(Num :: number(), integer()) -> binary().
float_to_binary(V, _) when is_integer(V) ->
    integer_to_binary(V);
float_to_binary(V, Decimals) when is_float(V), is_integer(Decimals) ->
    S = float_to_list(V, [{decimals, Decimals}, compact]),
    list_to_binary(S).

assert(true, _) ->
    ok;
assert(false, F) when is_function(F) ->
    F();
assert(false, Msg) ->
    throw(Msg).


-spec file_uri(Filename :: binary()) -> error | {ok, FileUri :: binary()}.
file_uri(Filename) when is_binary(Filename) ->
    case binary:split(Filename, <<"-">>, [global]) of
        [Year, Month, Day | _] ->
            {ok, <<"https://lgsiot.njau.edu.cn/upload/", Year/binary, $/, Month/binary, $/, Day/binary, $/, Filename/binary>>};
        _ ->
            error
    end.