%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2013. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%

-module(maps).

-export([get/3,filter/2,fold/3, map/2,
         size/1,
         without/2, with/2]).


%%% BIFs
-export([get/2, find/2, from_list/1,
         is_key/2, keys/1, merge/2,
         new/0, put/3, remove/2,
         to_list/1, update/3, values/1]).

-spec get(Key,Map) -> Value when
    Key :: term(),
    Map :: map(),
    Value :: term().

get(_,_) -> erlang:nif_error(undef).


-spec find(Key,Map) -> {ok, Value} | error when
    Key :: term(),
    Map :: map(),
    Value :: term().

find(_,_) -> erlang:nif_error(undef).


-spec from_list(List) -> Map when
    List :: [{Key,Value}],
    Key :: term(),
    Value :: term(),
    Map :: map().

from_list(_) -> erlang:nif_error(undef).


-spec is_key(Key,Map) -> boolean() when
    Key :: term(),
    Map :: map().

is_key(_,_) -> erlang:nif_error(undef).


-spec keys(Map) -> Keys when
    Map :: map(),
    Keys :: [Key],
    Key :: term().

keys(_) -> erlang:nif_error(undef).


-spec merge(Map1,Map2) -> Map3 when
    Map1 :: map(),
    Map2 :: map(),
    Map3 :: map().

merge(_,_) -> erlang:nif_error(undef).



-spec new() -> Map when
    Map :: map().

new() -> erlang:nif_error(undef).


-spec put(Key,Value,Map1) -> Map2 when
    Key :: term(),
    Value :: term(),
    Map1 :: map(),
    Map2 :: map().

put(_,_,_) -> erlang:nif_error(undef).


-spec remove(Key,Map1) -> Map2 when
    Key :: term(),
    Map1 :: map(),
    Map2 :: map().

remove(_,_) -> erlang:nif_error(undef).


-spec to_list(Map) -> [{Key,Value}] when
    Map :: map(),
    Key :: term(),
    Value :: term().

to_list(_) -> erlang:nif_error(undef).


-spec update(Key,Value,Map1) -> Map2 when
    Key :: term(),
    Value :: term(),
    Map1 :: map(),
    Map2 :: map().

update(_,_,_) -> erlang:nif_error(undef).


-spec values(Map) -> Values when
    Map :: map(),
    Values :: [Value],
    Value :: term().

values(_) -> erlang:nif_error(undef).


%%% End of BIFs

-spec get(Key, Map, Default) -> Value | Default when
        Key :: term(),
        Map :: map(),
        Value :: term(),
        Default :: term().

get(Key,Map,Default) when is_map(Map) ->
    case maps:find(Key, Map) of
        {ok, Value} ->
            Value;
        error ->
            Default
    end;
get(Key,Map,Default) ->
    erlang:error({badmap,Map},[Key,Map,Default]).


-spec filter(Pred,Map1) -> Map2 when
      Pred :: fun((Key, Value) -> boolean()),
      Key  :: term(),
      Value :: term(),
      Map1 :: map(),
      Map2 :: map().

filter(Pred,Map) when is_function(Pred,2), is_map(Map) ->
    maps:from_list([{K,V}||{K,V}<-maps:to_list(Map),Pred(K,V)]);
filter(Pred,Map) ->
    erlang:error(error_type(Map),[Pred,Map]).


-spec fold(Fun,Init,Map) -> Acc when
    Fun :: fun((K, V, AccIn) -> AccOut),
    Init :: term(),
    Acc :: term(),
    AccIn :: term(),
    AccOut :: term(),
    Map :: map(),
    K :: term(),
    V :: term().

fold(Fun,Init,Map) when is_function(Fun,3), is_map(Map) ->
    lists:foldl(fun({K,V},A) -> Fun(K,V,A) end,Init,maps:to_list(Map));
fold(Fun,Init,Map) ->
    erlang:error(error_type(Map),[Fun,Init,Map]).

-spec map(Fun,Map1) -> Map2 when
    Fun :: fun((K, V1) -> V2),
    Map1 :: map(),
    Map2 :: map(),
    K :: term(),
    V1 :: term(),
    V2 :: term().

map(Fun,Map) when is_function(Fun, 2), is_map(Map) ->
    maps:from_list([{K,Fun(K,V)}||{K,V}<-maps:to_list(Map)]);
map(Fun,Map) ->
    erlang:error(error_type(Map),[Fun,Map]).


-spec size(Map) -> non_neg_integer() when
    Map :: map().

size(Map) when is_map(Map) ->
    erlang:map_size(Map);
size(Val) ->
    erlang:error({badmap,Val},[Val]).


-spec without(Ks,Map1) -> Map2 when
    Ks :: [K],
    Map1 :: map(),
    Map2 :: map(),
    K :: term().

without(Ks,M) when is_list(Ks), is_map(M) ->
    lists:foldl(fun(K, M1) -> ?MODULE:remove(K, M1) end, M, Ks);
without(Ks,M) ->
    erlang:error(error_type(M),[Ks,M]).


-spec with(Ks, Map1) -> Map2 when
    Ks :: [K],
    Map1 :: map(),
    Map2 :: map(),
    K :: term().

with(Ks,Map1) when is_list(Ks), is_map(Map1) ->
    Fun = fun(K, List) ->
      case ?MODULE:find(K, Map1) of
          {ok, V} ->
              [{K, V} | List];
          error ->
              List
      end
    end,
    ?MODULE:from_list(lists:foldl(Fun, [], Ks));
with(Ks,M) ->
    erlang:error(error_type(M),[Ks,M]).


error_type(M) when is_map(M) -> badarg;
error_type(V) -> {badmap, V}.
