-- mod_storage_lmdb

-- Copyright (C) 2015 Kim Alvefur

--

-- This file is MIT/X11 licensed.

-- 

-- Depends on lightningdbm

-- https://github.com/shmul/lightningdbm

--

-- luacheck: globals prosody open

local lmdb = require"lightningmdb";

local lfs = require"lfs";

local path = require"util.paths";

local serialization = require"util.serialization";

local serialize = serialization.serialize;

local deserialize = serialization.deserialize;

local base_path = path.resolve_relative_path(prosody.paths.data, module.host);

lfs.mkdir(base_path);

local env = lmdb.env_create();

assert(env:set_maxdbs(module:get_option_number("lmdb_maxdbs", 20)));

local env_flags = 0;

for i, flag in ipairs(module:get_option_array("lmdb_flags", {})) do

	env_flags = env_flags + assert(lmdb["MDB_"..flag:upper()], "No such flag "..flag);

end

env:open(base_path, env_flags, tonumber("640", 8));

local keyval = {};

local keyval_mt = { __index = keyval, flags = lmdb.MDB_CREATE };

function keyval:set(user, value)

	local t = self.env:txn_begin(nil, 0);

	if type(value) == "table" and next(value) == nil then

		value = nil;

	end

	if value ~= nil then

		value = serialize(value);

	end

	local ok, err;

	if value ~= nil then

		ok, err = t:put(self.db, user, value, 0);

	else

		ok, err = t:del(self.db, user, value);

	end

	if not ok then

		t:abort();

		return nil, err;

	end

	return t:commit();

end

function keyval:get(user)

	local t = self.env:txn_begin(nil, 0);

	local data, err = t:get(self.db, user, 0);

	if not data then

		t:abort();

		return nil, err;

	end

	t:commit();

	return deserialize(data);

end

local drivers = {

	keyval = keyval_mt;

}

function open(_, store, typ)

	typ = typ or "keyval";

	local driver_mt = drivers[typ];

	if not driver_mt then

		return nil, "unsupported-store";

	end

	local t = env:txn_begin(nil, 0);

	local db = t:dbi_open(store.."_"..typ, driver_mt.flags);

	assert(t:commit());

	return setmetatable({ env = env, store = store, type = typ, db = db }, driver_mt);

end

function module.unload()

	env:sync(1);

	env:close();

end

module:provides("storage");