-- 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_rep = string.rep;

local type = type;

local tostring = tostring;

local t_insert = table.insert;

local t_concat = table.concat;

local pairs = pairs;

local next = next;

local pcall = pcall;

local debug_traceback = debug.traceback;

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

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

local _ENV = nil;

local indent = function(i)

	return string_rep("\t", i);

end

local function basicSerialize (o)

	if type(o) == "number" or type(o) == "boolean" then

		-- no need to check for NaN, as that's not a valid table index

		if o == 1/0 then return "(1/0)";

		elseif o == -1/0 then return "(-1/0)";

		else return tostring(o); end

	else -- assume it is a string -- FIXME make sure it's a string. throw an error otherwise.

		return (("%q"):format(tostring(o)):gsub("\\\n", "\\n"));

	end

end

local function _simplesave(o, ind, t, func)

	if type(o) == "number" then

		if o ~= o then func(t, "(0/0)");

		elseif o == 1/0 then func(t, "(1/0)");

		elseif o == -1/0 then func(t, "(-1/0)");

		else func(t, tostring(o)); end

	elseif type(o) == "string" then

		func(t, (("%q"):format(o):gsub("\\\n", "\\n")));

	elseif type(o) == "table" then

		if next(o) ~= nil then

			func(t, "{\n");

			for k,v in pairs(o) do

				func(t, indent(ind));

				func(t, "[");

				func(t, basicSerialize(k));

				func(t, "] = ");

				if ind == 0 then

					_simplesave(v, 0, t, func);

				else

					_simplesave(v, ind+1, t, func);

				end

				func(t, ";\n");

			end

			func(t, indent(ind-1));

			func(t, "}");

		else

			func(t, "{}");

		end

	elseif type(o) == "boolean" then

		func(t, (o and "true" or "false"));

	else

		log("error", "cannot serialize a %s: %s", type(o), debug_traceback())

		func(t, "nil");

	end

end

local function append(t, o)

	_simplesave(o, 1, t, t.write or t_insert);

	return t;

end

local function serialize(o)

	return t_concat(append({}, o));

end

local function deserialize(str)

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

	str = "return "..str;

	local f, err = envload(str, "@data", {});

	if not f then return nil, err; end

	local success, ret = pcall(f);

	if not success then return nil, ret; end

	return ret;

end

return {

	append = append;

	serialize = serialize;

	deserialize = deserialize;

};