%%% Copyright (c) 2014-2015, NORDUnet A/S.
%%% See LICENSE for licensing information.

%%% @doc Storage DB

-module(storagedb).
-behaviour(gen_server).
%% API
-export([start_link/0, stop/0]).
-export([add/1, fetchnewhashes/1, lastverifiednewentry/0]).
%% gen_server callbacks.
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
         code_change/3]).

-import(stacktrace, [call/2]).

init(_Args) ->
    {ok, []}.

start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

stop() ->
    call(?MODULE, stop).

lastverifiednewentry_path() ->
    {ok, Value} = application:get_env(plop, lastverifiednewentry_path),
    Value.

%%%%%%%%%%%%%%%%%%%%
%% Public API.

fetchnewhashes(Index) ->
    case index:indexsize(newentries_db) of
        0 ->
            [];
        Size ->
            index:getrange(newentries_db, Index, Size - 1)
    end.

lastverifiednewentry() ->
    case atomic:readfile(lastverifiednewentry_path()) of
        noentry ->
            {0, none};
        Contents ->
            {struct, PropList} = mochijson2:decode(Contents),
            Index = proplists:get_value(<<"index">>, PropList),
            Hash = proplists:get_value(<<"hash">>, PropList),
            {Index, mochihex:to_bin(binary_to_list(Hash))}
    end.

-spec add(binary()) -> ok.
add(LeafHash) ->
    ok = call(?MODULE, {add_nosync, LeafHash}),
    ok = index:sync(newentries_db),
    ok.

%%%%%%%%%%%%%%%%%%%%
%% gen_server callbacks.

handle_cast(_Request, State) ->
    {noreply, State}.

handle_info(_Info, State) ->
    {noreply, State}.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

terminate(_Reason, _State) ->
    io:format("~p terminating~n", [?MODULE]),
    ok.

%%%%%%%%%%%%%%%%%%%%

handle_call(stop, _From, State) ->
    {stop, normal, stopped, State};

handle_call({add_nosync, LeafHash}, _From, State) ->
    ok = index:addlast_nosync(newentries_db, LeafHash),
    {reply, ok, State}.