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%%% Copyright (c) 2014, NORDUnet A/S.
%%% See LICENSE for licensing information.
-module(db).
-behaviour(gen_server).
%% API.
-export([start_link/0, stop/0]).
-export([add/4, size/0]).
-export([get_by_index/1, get_by_indices/3, get_by_leaf_hash/1, get_by_entry_hash/1]).
%% gen_server callbacks.
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
code_change/3]).
-include_lib("stdlib/include/qlc.hrl").
-include("db.hrl").
size() ->
binary_to_integer(atomic:readfile(treesize_path())).
init(_Args) ->
{ok, []}.
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
stop() ->
gen_server:call(?MODULE, stop).
%%%%%%%%%%%%%%%%%%%%
%% Public API.
-spec add(binary(), binary(), binary(), non_neg_integer()) -> ok.
add(LeafHash, EntryHash, Data, Index) ->
gen_server:call(?MODULE, {add, {LeafHash, EntryHash, Data, Index}}).
-spec get_by_indices(integer(), integer(), {sorted, true|false}) ->
[{non_neg_integer(), binary(), binary()}].
get_by_indices(Start, End, {sorted, Sorted}) ->
gen_server:call(?MODULE, {get_by_indices, {Start, End, Sorted}}).
-spec get_by_index(binary()) -> notfound |
{non_neg_integer(), binary(), binary()}.
get_by_index(Index) ->
gen_server:call(?MODULE, {get_by_index, Index}).
-spec get_by_leaf_hash(binary()) -> notfound |
{non_neg_integer(), binary(), binary()}.
get_by_leaf_hash(LeafHash) ->
gen_server:call(?MODULE, {get_by_leaf_hash, LeafHash}).
-spec get_by_entry_hash(binary()) -> notfound |
{non_neg_integer(), binary(), binary()}.
get_by_entry_hash(EntryHash) ->
gen_server:call(?MODULE, {get_by_entry_hash, EntryHash}).
%%%%%%%%%%%%%%%%%%%%
%% 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.
%%%%%%%%%%%%%%%%%%%%
%% The meat.
% Table for Leaf hash -> Entry
entry_root_path() ->
{ok, Value} = application:get_env(plop, entry_root_path),
Value.
% Table for Leaf hash -> Entry
indexforhash_root_path() ->
{ok, Value} = application:get_env(plop, indexforhash_root_path),
Value.
% Table for Index -> Leaf hash
index_path() ->
{ok, Value} = application:get_env(plop, index_path),
Value.
% Table for Entry hash -> Leaf hash
entryhash_root_path() ->
{ok, Value} = application:get_env(plop, entryhash_root_path),
Value.
% File that stores tree size
treesize_path() ->
{ok, Value} = application:get_env(plop, treesize_path),
Value.
entry_for_leafhash(LeafHash) ->
perm:readfile(entry_root_path(), LeafHash).
index_for_leafhash(LeafHash) ->
binary_to_integer(perm:readfile(indexforhash_root_path(), LeafHash)).
leafhash_for_index(Index) ->
index:get(index_path(), Index).
leafhash_for_indices(Start, End) ->
index:getrange(index_path(), Start, End).
leafhash_for_entryhash(EntryHash) ->
perm:readfile(entryhash_root_path(), EntryHash).
get_by_indices_helper(Start, _End) when Start < 0 ->
[];
get_by_indices_helper(Start, End) ->
EndBound = min(End, size() - 1),
case Start =< EndBound of
true ->
lists:map(fun ({LeafHash, Index}) ->
{Index, LeafHash, notfetched}
end, lists:zip(leafhash_for_indices(Start, EndBound),
lists:seq(Start, EndBound)));
false ->
[]
end.
handle_call(stop, _From, State) ->
{stop, normal, stopped, State};
handle_call({add, {LeafHash, EntryHash, Data, Index}}, _From, State) ->
ok = perm:ensurefile(entry_root_path(), LeafHash, Data),
ok = perm:ensurefile(entryhash_root_path(), EntryHash, LeafHash),
ok = perm:ensurefile(indexforhash_root_path(),
LeafHash, integer_to_binary(Index)),
ok = index:add(index_path(), Index, LeafHash),
ok = atomic:replacefile(treesize_path(), integer_to_list(Index+1)),
{reply, ok, State};
handle_call({get_by_indices, {Start, End, _Sorted}}, _From, State) ->
{reply, get_by_indices_helper(Start, End), State};
handle_call({get_by_index, Index}, _From, State) ->
LeafHash = leafhash_for_index(Index),
Entry = entry_for_leafhash(LeafHash),
R = {Index, LeafHash, Entry},
{reply, R, State};
handle_call({get_by_leaf_hash, LeafHash}, _From, State) ->
Entry = entry_for_leafhash(LeafHash),
Index = index_for_leafhash(LeafHash),
R = {Index, LeafHash, Entry},
{reply, R, State};
handle_call({get_by_entry_hash, EntryHash}, _From, State) ->
R = case leafhash_for_entryhash(EntryHash) of
noentry ->
notfound;
LeafHash ->
Entry = entry_for_leafhash(LeafHash),
Index = index_for_leafhash(LeafHash),
{Index, LeafHash, Entry}
end,
{reply, R, State}.
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