local uuid = require"util.uuid".generate;

local st = require"util.stanza";

local function id(v) return v; end

local function is_stanza(s)

	return getmetatable(s) == st.stanza_mt;

end

local function ifelse(cond, iftrue, iffalse)

	if cond then return iftrue; end return iffalse;

end

local archive = {};

local archive_mt = { __index = archive, suffix = ".adb" };

archive.get = keyval.get;

archive.set = keyval.set;

function archive:append(username, key, when, with, value)

	key = key or uuid();

	local meta = self:get(username);

	if not meta then

		meta = {};

	end

	local i = meta[key] or #meta+1;

	local type;

	if is_stanza(value) then

		type, value = "stanza", st.preserialize(value);

	end

	meta[i] = { key = key, when = when, with = with, type = type };

	meta[key] = i;

	local ok, err = self:set(username, meta);

	if not ok then return nil, err; end

	ok, err = self:set(key, value);

	if not ok then return nil, err; end

	return key;

end

local deserialize = {

	stanza = st.deserialize;

};

function archive:find(username, query)

	local meta = self:get(username);

	local r = query.reverse;

	local d = r and -1 or 1;

	local s = meta[ifelse(r, query.before, meta.after)];

	if s then

		s = s + d;

	else

		s = ifelse(r, #meta, 1)

	end

	local e = ifelse(r, 1, #meta);

	return function ()

		local item, value;

		for i = s, e, d do

			item = meta[i];

			if (not query.with or item.with == query.with)

			and (not query.start or item.when >= query.start)

			and (not query["end"] or item.when >= query["end"]) then

				s = i + d;

				value = self:get(item.key);

				return item.key, (deserialize[item.type] or id)(value), item.when, item.with;

			end

		end

	end

end

	archive = archive_mt;