-module(ow_util).

-export([
    run_checks/1,
    run_bchecks/1,
    any_in_list/2,
    pipeline/2,
    remove_dups/1
]).

-export([
    mapfind/3,
    mapstore/4,
    maplistsort/2,
    maplistsort/3
]).

-export([
    take_random/1,
    take_random/2,
    weighted_random/1
]).

-spec run_bchecks(list()) -> ok | any().
run_bchecks([]) ->
    ok;
run_bchecks([H | T]) when is_function(H, 0) ->
    case H() of
        true -> run_bchecks(T);
        _ -> false
    end.

-spec run_checks(list()) -> ok | any().
run_checks([]) ->
    ok;
run_checks([H | T]) when is_function(H, 0) ->
    case H() of
        ok -> run_checks(T);
        Error -> Error
    end.

% poor man's pipe
-spec pipeline(any(), list()) -> any().
pipeline(Input, Funs) ->
    lists:foldl(fun(F, State) -> F(State) end, Input, Funs).

-spec any_in_list(list(), list()) -> list().
any_in_list(L1, L2) ->
    % Checks to see if any item in L1 is present in L2
    [X || X <- L1, lists:member(X, L2) == true].

% Remove duplicates from a list
% https://stackoverflow.com/questions/13673161/remove-duplicate-elements-from-a-list-in-erlang
-spec remove_dups(list()) -> list().
remove_dups([]) -> [];
remove_dups([H | T]) -> [H | [X || X <- remove_dups(T), X /= H]].

% some map* functions equivalent to the list functions that operate over tuples
% shamelessly stolen from
% https://github.com/biokoda/bkdcore/blob/master/src/butil.erl
-spec mapfind(term(), term(), list()) -> term() | false.
mapfind(K, V, [H | L]) ->
    case maps:get(K, H) of
        V ->
            H;
        _ ->
            mapfind(K, V, L)
    end;
mapfind(_, _, []) ->
    false.

-spec mapstore(term(), term(), list(), map()) -> [map()].
mapstore(Key, Val, [H | L], Map) ->
    case maps:get(Key, H) of
        Val ->
            [Map | L];
        _ ->
            [H | mapstore(Key, Val, L, Map)]
    end;
mapstore(_, _, [], Map) ->
    [Map].

-spec maplistsort(term(), list()) -> list().
maplistsort(Key, L) ->
    maplistsort(Key, L, asc).
maplistsort(Key, L, asc) ->
    Asc = fun(A, B) -> maps:get(Key, A) =< maps:get(Key, B) end,
    lists:sort(Asc, L);
maplistsort(Key, L, desc) ->
    Desc = fun(A, B) -> maps:get(Key, A) >= maps:get(Key, B) end,
    lists:sort(Desc, L).

%%-----------------------------------------------------------------------------
%% @doc This function will take a list of items and return a random element
%%      Alternatively an integer number of items may be specified
%% @end
%%-----------------------------------------------------------------------------
-spec take_random(list()) -> list().
take_random(List) ->
    take_random(List, 1).

-spec take_random(list(), pos_integer()) -> list().
take_random(List, N) when N > length(List) ->
    take_random(List, length(List));
take_random(List, N) ->
    take_random(List, N, []).

take_random(_List, N, Acc) when length(Acc) == N ->
    Acc;
take_random(List, N, Acc) when length(Acc) < N ->
    Index = rand:uniform(length(List)),
    Item = lists:nth(Index, List),
    NewList = lists:delete(Item, List),
    take_random(NewList, N, [Item | Acc]).

-spec weighted_random([{term(), integer()}]) -> [term()].
weighted_random([]) ->
    [];
weighted_random([Head | Tail]) ->
    [expand_list(Head) | weighted_random(Tail)].

expand_list({Item, Number}) ->
    [Item || _ <- lists:seq(1, Number)].