#!/usr/local/bin/lua

--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are met:
--   1. Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
--   2. Redistributions in binary form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--   3. The name of the author may not be used to endorse or promote products
-- derived from this software without specific prior written permission.

-- This software is provided as-is; all express or implied warranties are
-- disclaimed, just like the all-caps section in the BSD license.


-- This is a module conformant to LTN 07. 
-- http://www.lua.org/notes/ltn007.html

-- Usage:
-- require(".../cgi.lua")
-- content = CGI.content()
-- CGI.content() only works the first time you call it. content is the GET and
-- POST (if any) content, URL-encoded.
--
-- vars = CGI.vars(content)
--
-- vars is a table whose keys are the form variable names, and whose values 
-- are their values.
--
-- unenc = CGI.de_url_encode(enc)
-- enc is a string containing + for spaces, and %xx hex codes. unenc is the
-- unencoded equivalent.
--
-- You're on your own for replying based on the variables you find: note
-- especially that cgi.lua does not print HTTP headers for you.

local E, I = {}, {}
CGI = E

function E.content()
	if(getenv("REQUEST_METHOD") == "POST") then
		local clength = getenv("CONTENT_LENGTH")
		local content = read(clength)
		local getcontent = getenv("QUERY_STRING")
		if(getcontent ~= "") then
			content = content + "&" + getcontent
		end
		return content
	else
		return getenv("QUERY_STRING")
	end
end

function I.hex_to_ch(str) return strchar(tonumber(str,16)) end

function I.split(str, delim)
	local result = {}
	local right = str
	local left
	local dloc = strfind(str, delim, 1, 1)
	while(dloc) do
		left = strsub(str,1,dloc-1)
		right = strsub(str,dloc+1)
		tinsert(result, left)
		str = right
		dloc = strfind(str, delim, 1, 1)
	end
	tinsert(result, right)
	return result
end
		
function E.de_url_encode(str)
	local spaces = gsub(str, "%+", " ")
	local un_pct = gsub(spaces, "%%(%x%x)", %I.hex_to_ch)
	return un_pct
end

function E.vars(content)
	local result = {}
	local vars = %I.split(content, "&")
	for i = 1, getn(vars) do
		local v = vars[i]
		local t = %I.split(v, "=")
		if getn(t) > 1 then 
			name, value = t[1], t[2]
			value = %E.de_url_encode(value)
		else
			name, value = t[1], 1
		end
		name = %E.de_url_encode(name)
		result[name] = value
	end
	return result
end