-- 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 format = string.format;
local setmetatable = setmetatable;
local ipairs = ipairs;
local char = string.char;
local pcall = pcall;
local log = require "util.logger".init("datamanager");
local io_open = io.open;
local os_remove = os.remove;
local os_rename = os.rename;
local tonumber = tonumber;
local next = next;
local t_insert = table.insert;
local t_concat = table.concat;
local envloadfile = require"util.envload".envloadfile;
local serialize = require "util.serialization".serialize;
local path_separator = assert ( package.config:match ( "^([^\n]+)" ) , "package.config not in standard form" ) -- Extract directory seperator from package.config (an undocumented string that comes with lua)
local lfs = require "lfs";
local prosody = prosody;

local raw_mkdir = lfs.mkdir;
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
	f:seek("set", offset);
	return true;
end;
pcall(function()
	local pposix = require "util.pposix";
	raw_mkdir = pposix.mkdir or raw_mkdir; -- Doesn't trample on umask
	fallocate = pposix.fallocate or fallocate;
end);

module "datamanager"

---- utils -----
local encode, decode;
do
	local urlcodes = setmetatable({}, { __index = function (t, k) t[k] = char(tonumber("0x"..k)); return t[k]; end });

	decode = function (s)
		return s and (s:gsub("+", " "):gsub("%%([a-fA-F0-9][a-fA-F0-9])", urlcodes));
	end

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

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
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
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

function getpath(username, host, datastore, ext, create)
	ext = ext or "dat";
	host = (host and encode(host)) or "_global";
	username = username and encode(username);
	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);
	elseif host then
		if create then mkdir(mkdir(data_path).."/"..host); end
		return format("%s/%s/%s.%s", data_path, host, datastore, ext);
	else
		if create then mkdir(data_path); end
		return format("%s/%s.%s", data_path, datastore, ext);
	end
end

function load(username, host, datastore)
	local data, ret = envloadfile(getpath(username, host, datastore), {});
	if not data then
		local mode = lfs.attributes(getpath(username, host, datastore), "mode");
		if not mode then
			log("debug", "Assuming empty %s storage ('%s') for user: %s@%s", datastore, ret, username or "nil", host or "nil");
			return nil;
		else -- file exists, but can't be read
			-- TODO more detailed error checking and logging?
			log("error", "Failed to load %s storage ('%s') for user: %s@%s", datastore, ret, username or "nil", host or "nil");
			return nil, "Error reading storage";
		end
	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;
	repeat
		f, msg = io_open(scratch, "w");
		if not f then break end

		ok, msg = f:write(data);
		if not ok then break end

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

		return os_rename(scratch, filename);
	until false;

	-- Cleanup
	if f then f:close(); end
	os_remove(scratch);
	return nil, msg;
end

if 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

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 ok, msg = atomic_store(getpath(username, host, datastore, nil, true), 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 nil, "Error saving to storage";
	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 non-exisitng files
	return true;
end

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
	local f, msg = io_open(getpath(username, host, datastore, "list", true), "r+");
	if not f then
		f, msg = io_open(getpath(username, host, datastore, "list", true), "w");
	end
	if not f then
		log("error", "Unable to write to %s storage ('%s') for user: %s@%s", datastore, msg, username or "nil", host or "nil");
		return;
	end
	local data = "item(" ..  serialize(data) .. ");\n";
	local pos = f:seek("end");
	local ok, msg = fallocate(f, pos, #data);
	f:seek("set", pos);
	if ok then
		f:write(data);
	else
		log("error", "Unable to write to %s storage ('%s') for user: %s@%s", datastore, msg, username or "nil", host or "nil");
		return ok, msg;
	end
	f:close();
	return true;
end

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 _, item in ipairs(data) do
		d[#d+1] = "item(" .. serialize(item) .. ");\n";
	end
	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 non-exisitng files
	return true;
end

function list_load(username, host, datastore)
	local items = {};
	local data, ret = envloadfile(getpath(username, host, datastore, "list"), {item = function(i) t_insert(items, i); end});
	if not data then
		local mode = lfs.attributes(getpath(username, host, datastore, "list"), "mode");
		if not mode then
			log("debug", "Assuming empty %s storage ('%s') for user: %s@%s", datastore, ret, username or "nil", host or "nil");
			return nil;
		else -- file exists, but can't be read
			-- TODO more detailed error checking and logging?
			log("error", "Failed to load %s storage ('%s') for user: %s@%s", datastore, ret, username or "nil", host or "nil");
			return nil, "Error reading storage";
		end
	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 items;
end

function list_stores(username, host)
	if not host then
		return nil, "bad argument #2 to 'list_stores' (string expected, got nothing)";
	end
	local list = {};
	local host_dir = format("%s/%s/", data_path, encode(host));
	for node in lfs.dir(host_dir) do
		if not node:match"^%." then -- dots should be encoded, this is probably . or ..
			local store = decode(node);
			local path = host_dir..node;
			if username == true then
				if lfs.attributes(path, "mode") == "directory" then
					list[#list+1] = store;
				end
			elseif username then
				if lfs.attributes(getpath(username, host, store), "mode")
					or lfs.attributes(getpath(username, host, store, "list"), "mode") then
					list[#list+1] = store;
				end
			elseif lfs.attributes(path, "mode") == "file" then
				list[#list+1] = store:gsub("%.[dalist]+$","");
			end
		end
	end
	return list;
end

local function do_remove(path)
	local ok, err = os_remove(path);
	if not ok and lfs.attributes(path, "mode") then
		return ok, err;
	end
	return true
end

function purge(username, host)
	local host_dir = format("%s/%s/", data_path, encode(host));
	local deleted = 0;
	local errs = {};
	for file in lfs.dir(host_dir) do
		if lfs.attributes(host_dir..file, "mode") == "directory" then
			local store = decode(file);
			local ok, err = do_remove(getpath(username, host, store));
			if not ok then errs[#errs+1] = err; end

			local ok, err = do_remove(getpath(username, host, store, "list"));
			if not ok then errs[#errs+1] = err; end
		end
	end
	return #errs == 0, t_concat(errs, ", ");
end

return _M;