local tonumber = tonumber;

local assert = assert;

local httpstream = {};

function httpstream.new(success_cb, error_cb, parser_type, options_cb)

	local client = true;

	if not parser_type or parser_type == "server" then client = false; else assert(parser_type == "client", "Invalid parser type"); end

	local buf = "";

	local chunked;

	local state = nil;

	local packet;

	local len;

	local have_body;

	local error;

	return {

		feed = function(self, data)

			if error then return nil, "parse has failed"; end

			if not data then -- EOF

				if state and client and not len then -- reading client body until EOF

					packet.body = buf;

					success_cb(packet);

				elseif buf ~= "" then -- unexpected EOF

					error = true; return error_cb();

				end

				return;

			end

			buf = buf..data;

			while #buf > 0 do

				if state == nil then -- read request

					local index = buf:find("\r\n\r\n", nil, true);

					if not index then return; end -- not enough data

					local method, path, httpversion, status_code, reason_phrase;

					local first_line;

					local headers = {};

					for line in buf:sub(1,index+1):gmatch("([^\r\n]+)\r\n") do -- parse request

						if first_line then

							local key, val = line:match("^([^%s:]+): *(.*)$");

							if not key then error = true; return error_cb("invalid-header-line"); end -- TODO handle multi-line and invalid headers

							key = key:lower();

							headers[key] = headers[key] and headers[key]..","..val or val;

						else

							first_line = line;

							if client then

								httpversion, status_code, reason_phrase = line:match("^HTTP/(1%.[01]) (%d%d%d) (.*)$");

								if not status_code then error = true; return error_cb("invalid-status-line"); end

								have_body = not

									 ( (options_cb and options_cb().method == "HEAD")

									or (status_code == 204 or status_code == 304 or status_code == 301)

									or (status_code >= 100 and status_code < 200) );

								chunked = have_body and headers["transfer-encoding"] == "chunked";

							else

								method, path, httpversion = line:match("^(%w+) (%S+) HTTP/(1%.[01])$");

								if not method then error = true; return error_cb("invalid-status-line"); end

							end

						end

					end

					len = tonumber(headers["content-length"]); -- TODO check for invalid len

					if client then

						-- FIXME handle '100 Continue' response (by skipping it)

						if not have_body then len = 0; end

						packet = {

							code = status_code;

							httpversion = httpversion;

							headers = headers;

							body = have_body and "" or nil;

							-- COMPAT the properties below are deprecated

							responseversion = httpversion;

							responseheaders = headers;

						};

					else

						len = len or 0;

						packet = {

							method = method;

							path = path;

							httpversion = httpversion;

							headers = headers;

							body = nil;

						};

					end

					buf = buf:sub(index + 4);

					state = true;

				end

				if state then -- read body

					if client then

						if chunked then

							local index = buf:find("\r\n", nil, true);

							if not index then return; end -- not enough data

							local chunk_size = buf:match("^%x+");

							if not chunk_size then error = true; return error_cb("invalid-chunk-size"); end

							chunk_size = tonumber(chunk_size, 16);

							index = index + 2;

							if chunk_size == 0 then

								state = nil; success_cb(packet);

							elseif #buf - index + 1 >= chunk_size then -- we have a chunk

								packet.body = packet.body..buf:sub(index, index + chunk_size - 1);

								buf = buf:sub(index + chunk_size);

							end

							error("trailers"); -- FIXME MUST read trailers

						elseif len and #buf >= len then

							packet.body, buf = buf:sub(1, len), buf:sub(len + 1);

							state = nil; success_cb(packet);

						end

					elseif #buf >= len then

						packet.body, buf = buf:sub(1, len), buf:sub(len + 1);

						state = nil; success_cb(packet);

					end

				end

			end

		end;

	};

end

return httpstream;