-module(zipper_default).

-export([list/1, bin_tree/1, map_tree/2]).

-type bin_tree_node(T) :: nil | {T, bin_tree_node(T), bin_tree_node(T)}.

-export_type([bin_tree_node/1]).

%% @doc Generates a zipper for lists.
-spec list(list()) -> zipper:zipper(list()).
list(Root) ->
    IsBranchFun = fun is_list/1,
    ChildrenFun = fun(List) -> List end,
    MakeNodeFun = fun(_Node, Children) -> Children end,
    zipper:new(IsBranchFun, ChildrenFun, MakeNodeFun, Root).

%% @doc Generates a zipper for binary trees.
-spec bin_tree(bin_tree_node(T)) -> zipper:zipper(bin_tree_node(T)).
bin_tree(Root) ->
    IsBranchFun = fun(Node) -> is_tuple(Node) andalso tuple_size(Node) == 3 end,
    ChildrenFun = fun({_, Left, Right}) -> [Left, Right] end,
    MakeNodeFun = fun(Node, [Left, Right]) -> {Node, Left, Right} end,
    zipper:new(IsBranchFun, ChildrenFun, MakeNodeFun, Root).

%% @doc Generates a zipper for maps.
-spec map_tree(M, CK) -> zipper:zipper(M)
    when M :: #{K => _},
         CK :: K.
map_tree(Root, ChildrenKey) ->
    IsBranchFun =
        fun(M) ->
           is_map(M) andalso maps:is_key(ChildrenKey, M) andalso maps:get(ChildrenKey, M) /= []
        end,
    ChildrenFun = fun(Node) -> maps:get(ChildrenKey, Node) end,
    MakeNodeFun = fun(Node, Children) -> maps:put(ChildrenKey, Children, Node) end,
    zipper:new(IsBranchFun, ChildrenFun, MakeNodeFun, Root).