-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local string = string;

local format = string.format;

local setmetatable = setmetatable;

local ipairs = ipairs;

local char = string.char;

local pcall = pcall;

local log = require "prosody.util.logger".init("datamanager");

local io_open = io.open;

local os_remove = os.remove;

local os_rename = os.rename;

local tonumber = tonumber;

local floor = math.floor;

local next = next;

local type = type;

local t_insert = table.insert;

local t_concat = table.concat;

local envloadfile = require"prosody.util.envload".envloadfile;

local envload = require"prosody.util.envload".envload;

local serialize = require "prosody.util.serialization".serialize;

local lfs = require "lfs";

-- Extract directory separator from package.config (an undocumented string that comes with lua)

local path_separator = assert ( package.config:match ( "^([^\n]+)" ) , "package.config not in standard form" )

local prosody = prosody;

local raw_mkdir = lfs.mkdir;

local atomic_append;

local ENOENT = 2;

pcall(function()

	local pposix = require "prosody.util.pposix";

	raw_mkdir = pposix.mkdir or raw_mkdir; -- Doesn't trample on umask

	atomic_append = pposix.atomic_append;

	ENOENT = pposix.ENOENT or ENOENT;

end);

local _ENV = nil;

-- luacheck: std none

---- utils -----

local encode, decode, store_encode;

do

	local urlcodes = setmetatable({}, { __index = function (t, k) t[k] = char(tonumber(k, 16)); return t[k]; end });

	decode = function (s)

		return s and (s:gsub("%%(%x%x)", urlcodes));

	end

	encode = function (s)

		return s and (s:gsub("%W", function (c) return format("%%%02x", c:byte()); end));

	end

	-- Special encode function for store names, which historically were unencoded.

	-- All currently known stores use a-z and underscore, so this one preserves underscores.

	store_encode = function (s)

		return s and (s:gsub("[^_%w]", function (c) return format("%%%02x", c:byte()); end));

	end

end

if not atomic_append then

	function atomic_append(f, data)

		local pos = f:seek();

		if not f:write(data) or not f:flush() then

			f:seek("set", pos);

			f:write((" "):rep(#data));

			f:flush();

			return nil, "write-failed";

		end

		return true;

	end

end

local _mkdir = {};

local function mkdir(path)

	path = path:gsub("/", path_separator); -- TODO as an optimization, do this during path creation rather than here

	if not _mkdir[path] then

		raw_mkdir(path);

		_mkdir[path] = true;

	end

	return path;

end

local data_path = (prosody and prosody.paths and prosody.paths.data) or ".";

local callbacks = {};

------- API -------------

local function set_data_path(path)

	log("debug", "Setting data path to: %s", path);

	data_path = path;

end

local function callback(username, host, datastore, data)

	for _, f in ipairs(callbacks) do

		username, host, datastore, data = f(username, host, datastore, data);

		if username == false then break; end

	end

	return username, host, datastore, data;

end

local function add_callback(func)

	if not callbacks[func] then -- Would you really want to set the same callback more than once?

		callbacks[func] = true;

		callbacks[#callbacks+1] = func;

		return true;

	end

end

local function remove_callback(func)

	if callbacks[func] then

		for i, f in ipairs(callbacks) do

			if f == func then

				callbacks[i] = nil;

				callbacks[f] = nil;

				return true;

			end

		end

	end

end

local function getpath(username, host, datastore, ext, create)

	ext = ext or "dat";

	host = (host and encode(host)) or "_global";

	username = username and encode(username);

	datastore = store_encode(datastore);

	if username then

		if create then mkdir(mkdir(mkdir(data_path).."/"..host).."/"..datastore); end

		return format("%s/%s/%s/%s.%s", data_path, host, datastore, username, ext);

	else

		if create then mkdir(mkdir(data_path).."/"..host); end

		return format("%s/%s/%s.%s", data_path, host, datastore, ext);

	end

end

local function load(username, host, datastore)

	local data, err, errno = envloadfile(getpath(username, host, datastore), {});

	if not data then

		if errno == ENOENT then

			-- No such file, ok to ignore

			return nil;

		end

		log("error", "Failed to load %s storage ('%s') for user: %s@%s", datastore, err, username or "nil", host or "nil");

		return nil, "Error reading storage";

	end

	local success, ret = pcall(data);

	if not success then

		log("error", "Unable to load %s storage ('%s') for user: %s@%s", datastore, ret, username or "nil", host or "nil");

		return nil, "Error reading storage";

	end

	return ret;

end

local function atomic_store(filename, data)

	local scratch = filename.."~";

	local f, ok, msg, errno; -- luacheck: ignore errno

	-- TODO return util.error with code=errno?

	f, msg, errno = io_open(scratch, "w");

	if not f then

		return nil, msg;

	end

	ok, msg = f:write(data);

	if not ok then

		f:close();

		os_remove(scratch);

		return nil, msg;

	end

	ok, msg = f:close();

	if not ok then

		os_remove(scratch);

		return nil, msg;

	end

	return os_rename(scratch, filename);

end

if prosody and prosody.platform ~= "posix" then

	-- os.rename does not overwrite existing files on Windows

	-- TODO We could use Transactional NTFS on Vista and above

	function atomic_store(filename, data)

		local f, err = io_open(filename, "w");

		if not f then return f, err; end

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

		if not ok then f:close(); return ok, msg; end

		return f:close();

	end

end

local function store(username, host, datastore, data)

	if not data then

		data = {};

	end

	username, host, datastore, data = callback(username, host, datastore, data);

	if username == false then

		return true; -- Don't save this data at all

	end

	-- save the datastore

	local d = "return " .. serialize(data) .. ";\n";

	local mkdir_cache_cleared;

	repeat

		local ok, msg = atomic_store(getpath(username, host, datastore, nil, true), d);

		if not ok then

			if not mkdir_cache_cleared then -- We may need to recreate a removed directory

				_mkdir = {};

				mkdir_cache_cleared = true;

			else

				log("error", "Unable to write to %s storage ('%s') for user: %s@%s", datastore, msg, username or "nil", host or "nil");

				return nil, "Error saving to storage";

			end

		end

		if next(data) == nil then -- try to delete empty datastore

			log("debug", "Removing empty %s datastore for user %s@%s", datastore, username or "nil", host or "nil");

			os_remove(getpath(username, host, datastore));

		end

		-- we write data even when we are deleting because lua doesn't have a

		-- platform independent way of checking for nonexisting files

	until ok;

	return true;

end

-- Append a blob of data to a file

local function append(username, host, datastore, ext, data)

	if type(data) ~= "string" then return; end

	local filename = getpath(username, host, datastore, ext, true);

	local f = io_open(filename, "r+");

	if not f then

		return atomic_store(filename, data);

		-- File did probably not exist, let's create it

	end

	local pos = f:seek("end");

	local ok, msg = atomic_append(f, data);

	if not ok then

		f:close();

		return ok, msg, "write";

	end

	ok, msg = f:close();

	if not ok then

		return ok, msg, "close";

	end

	return true, pos;

end

local index_fmt, index_item_size, index_magic;

if string.packsize then

	index_fmt = "T"; -- offset to the end of the item, length can be derived from two index items

	index_item_size = string.packsize(index_fmt);

	index_magic = string.pack(index_fmt, 7767639 + 1); -- Magic string: T9 for "prosody", version number

end

local function list_append(username, host, datastore, data)

	if not data then return; end

	if callback(username, host, datastore) == false then return true; end

	-- save the datastore

	data = "item(" ..  serialize(data) .. ");\n";

	local ok, msg, where = append(username, host, datastore, "list", data);

	if not ok then

		log("error", "Unable to write to %s storage ('%s' in %s) for user: %s@%s",

			datastore, msg, where, username or "nil", host or "nil");

		return ok, msg;

	end

	if string.packsize then

		local offset = type(msg) == "number" and msg or 0;

		local index_entry = string.pack(index_fmt, offset + #data);

		if offset == 0 then

			index_entry = index_magic .. index_entry;

		end

		local ok, off = append(username, host, datastore, "lidx", index_entry);

		off = off or 0;

		-- If this was the first item, then both the data and index offsets should

		-- be zero, otherwise there's some kind of mismatch and we should drop the

		-- index and recreate it from scratch

		-- TODO Actually rebuild the index in this case?

		if not ok or (off == 0 and offset ~= 0) or (off ~= 0 and offset == 0) then

			os_remove(getpath(username, host, datastore, "lidx"));

		end

	end

	return true;

end

local function list_store(username, host, datastore, data)

	if not data then

		data = {};

	end

	if callback(username, host, datastore) == false then return true; end

	-- save the datastore

	local d = {};

	for i, item in ipairs(data) do

		d[i] = "item(" .. serialize(item) .. ");\n";

	end

	os_remove(getpath(username, host, datastore, "lidx"));

	local ok, msg = atomic_store(getpath(username, host, datastore, "list", true), t_concat(d));

	if not ok then

		log("error", "Unable to write to %s storage ('%s') for user: %s@%s", datastore, msg, username or "nil", host or "nil");

		return;

	end

	if next(data) == nil then -- try to delete empty datastore

		log("debug", "Removing empty %s datastore for user %s@%s", datastore, username or "nil", host or "nil");

		os_remove(getpath(username, host, datastore, "list"));

	end

	-- we write data even when we are deleting because lua doesn't have a

	-- platform independent way of checking for nonexisting files

	return true;

end

local function build_list_index(username, host, datastore, items)

	log("debug", "Building index for (%s@%s/%s)", username, host, datastore);

	local filename = getpath(username, host, datastore, "list");

	local fh, err, errno = io_open(filename);

	if not fh then

		return fh, err, errno;

	end

	local prev_pos = 0; -- position before reading

	if items and items[1] then

		local last_item = items[#items];

		last_item_start = fh:seek("set", last_item.start + last_item.length);

	else

		items = {};

	end

	for line in fh:lines() do

		if line:sub(1, 4) == "item" then

				t_insert(items, { start = last_item_start; length = prev_pos - last_item_start });

			end

			last_item_start = prev_pos

		end

		-- seek position is at the start of the next line within each loop iteration

		-- so we need to collect the "current" position at the end of the previous

		prev_pos = fh:seek()

	end

	if prev_pos ~= 0 then

		t_insert(items, { start = last_item_start; length = prev_pos - last_item_start });

	end

	return items;

end

local function store_list_index(username, host, datastore, index)

	local data = { index_magic };

	for i, v in ipairs(index) do

		data[i + 1] = string.pack(index_fmt, v.start + v.length);

	end