-module(kv).
-behaviour(gen_server).

-export([start/0, stop/0, lookup/1, store/2]).

-export([init/1, handle_call/3, handle_cast/2, terminate/2]).

start() ->
    gen_server:start_link({local,kv}, kv, arg1, []).

stop()  -> gen_server:cast(kv, stop).

init(arg1) ->
    io:format("Key-Value server starting~n"),
    {ok, dict:new()}.

store(Key, Val) ->
    gen_server:call(kv, {store, Key, Val}).

lookup(Key) ->
    gen_server:call(kv, {lookup, Key}).

handle_call({store, Key, Val}, _, Dict) ->
    Dict1 = dict:store(Key, Val, Dict),
    {reply, ack, Dict1};
handle_call({lookup, crash}, _, _) ->
    1/0;
handle_call({lookup, Key}, _, Dict) ->
    {reply, dict:find(Key, Dict), Dict}.

handle_cast(stop, Dict) -> {stop, normal, Dict}.

terminate(Reason, _) ->
    io:format("K-V server terminating~n").