local dm = require "core.storagemanager".olddm;

local hmac_sha256 = require"util.hashes".hmac_sha256;

local st = require"util.stanza";

local dt = require"util.datetime";

local new_stream = require "util.xmppstream".new;

local empty = {};

local function fallocate(f, offset, len)

	-- This assumes that current position == offset

	local fake_data = (" "):rep(len);

	local ok, msg = f:write(fake_data);

	if not ok then

		return ok, msg;

	end

end;

pcall(function()

	local pposix = require "util.pposix";

	fallocate = pposix.fallocate or fallocate;

end);

local archive = {};

local archive_mt = { __index = archive };

function archive:append(username, _, when, with, data)

	if getmetatable(data) ~= st.stanza_mt then

		return nil, "unsupported-datatype";

	end

	username = username or "@";

	data = tostring(data) .. "\n";

	local day = dt.date(when);

	local filename = dm.getpath(username.."@"..day, module.host, self.store, "xml", true);

	local ok, err;

	local f = io.open(filename, "r+");

	if not f then

		f, err = io.open(filename, "w");

		if not f then return nil, err; end

		ok, err = dm.list_append(username, module.host, self.store, day);

		if not ok then return nil, err; end

	end

	local offset = f and f:seek("end");

	ok, err = fallocate(f, offset, #data);

	if not ok then return nil, err; end

	f:seek("set", offset);

	ok, err = f:write(data);

	if not ok then return nil, err; end

	ok, err = f:close();

	if not ok then return nil, err; end

	local id = day .. "-" .. hmac_sha256(username.."@"..day.."+"..offset, data, true):sub(-16);

	ok, err = dm.list_append(username.."@"..day, module.host, self.store, { id = id, when = when, with = with, offset = offset, length = #data });

	if not ok then return nil, err; end

	return id;

end

function archive:find(username, query)

	username = username or "@";

	query = query or empty;

	local result;

	local function cb(_, stanza)

		if result then

			module:log("warn", "Multiple items in chunk");

		end

		result = stanza;

	end

	local stream_sess = { notopen = true };

	local stream = new_stream(stream_sess, { handlestanza = cb, stream_ns = "jabber:client"});

	local dates = dm.list_load(username, module.host, self.store) or empty;

	stream:feed(st.stanza("stream", { xmlns = "jabber:client" }):top_tag());

	local function reset_stream()

		stream:reset();

		stream_sess.notopen = true;

		stream:feed(st.stanza("stream", { xmlns = "jabber:client" }):top_tag());

		stream_sess.notopen = nil;

	end

	reset_stream();

	local limit = query.limit;

	local start_day, step, last_day = 1, 1, #dates;

	local count = 0;

	local rev = query.reverse;

	local in_range = not (query.after or query.before);

	if query.after or query.start then

		local d = query.after and query.after:sub(1, 10) or dt.date(query.start);

		for i = 1, #dates do

			if dates[i] == d then

				start_day = i; break;

			end

		end

	end

	if query.before or query["end"] then

		local d = query.before and query.before:sub(1, 10) or dt.date(query["end"]);

		for i = #dates, 1, -1 do

			if dates[i] == d then

				last_day = i; break;

			end

		end

	end

	if rev then

		start_day, step, last_day = last_day, -step, start_day;

	end

	local items, xmlfile;

	local first_item, last_item;

	return function ()

		if limit and count >= limit then xmlfile:close() return; end

		local filename;

		for d = start_day, last_day, step do

			if d ~= start_day or not items then

				module:log("debug", "Loading items from %s", dates[d]);

				start_day = d;

				items = dm.list_load(username .. "@" .. dates[d], module.host, self.store) or empty;

				if not rev then

					first_item, last_item = 1, #items;

				else

					first_item, last_item = #items, 1;

				end

				local ferr;

				filename = dm.getpath(username .. "@" .. dates[d], module.host, self.store, "xml");

				xmlfile, ferr = io.open(filename);

				if not xmlfile then

					module:log("error", "Error: %s", ferr);

					return;

				end

			end

			for i = first_item, last_item, step do

				local item = items[i];

				if not item then

					module:log("warn", "data[%q][%d] is nil", dates[d], i);

					break;

				end

				if xmlfile and in_range

				and (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

					count = count + 1;

					first_item = i + step;

					xmlfile:seek("set", item.offset);

					local data = xmlfile:read(item.length);

					local ok, err = stream:feed(data);

					if not ok then

						module:log("warn", "Parse error in %s at %d+%d: %s", filename, item.offset, item.length, err);

						reset_stream();

					end

					if result then

						local stanza = result;

						result = nil;

						return item.id, stanza, item.when, item.with;

					end

				end

				if (rev and item.id == query.after) or

					(not rev and item.id == query.before) then

					in_range = false;

					limit = count;

				end

				if (rev and item.id == query.before) or

					(not rev and item.id == query.after) then

					in_range = true;

				end

			end

		end

		if xmlfile then

			xmlfile:close();

			xmlfile = nil;

		end

	end

end

function archive:delete(username, query)

	username = username or "@";

	query = query or empty;

	if query.with or query.start or query.after then

		return nil, "not-implemented"; -- Only trimming the oldest messages

	end

	local before = query.before or query["end"] or "9999-12-31";

	if type(before) == "number" then before = dt.date(before); else before = before:sub(1, 10); end

	local dates = dm.list_load(username, module.host, self.store) or empty;

	local remaining_dates = {};

	for d = 1, #dates do

		if dates[d] >= before then

			table.insert(remaining_dates, dates[d]);

		end

	end

	table.sort(remaining_dates);

	local ok, err = dm.list_store(username, module.host, self.store, remaining_dates);

	if not ok then return ok, err; end

	for d = 1, #dates do

		if dates[d] < before then

			os.remove(dm.getpath(username .. "@" .. dates[d], module.host, self.store, "list"));

			os.remove(dm.getpath(username .. "@" .. dates[d], module.host, self.store, "xml"));

		end

	end

	return true;

end

local provider = {};

function provider:open(store, typ)

	if typ ~= "archive" then return nil, "unsupported-store"; end

	return setmetatable({ store = store }, archive_mt);

end

module:provides("storage", provider);