local t_insert, t_remove, t_concat = table.insert, table.remove, table.concat;

local parser_new = require "net.http.parser".new;

local events = require "util.events".new();

local addserver = require "net.server".addserver;

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

local os_date = os.date;

local pairs = pairs;

local s_upper = string.upper;

local setmetatable = setmetatable;

local xpcall = xpcall;

local traceback = debug.traceback;

local tostring = tostring;

local cache = require "util.cache";

local codes = require "net.http.codes";

local blocksize = 2^16;

local _M = {};

local sessions = {};

local incomplete = {};

local listener = {};

local hosts = {};

local default_host;

local options = {};

local function is_wildcard_event(event)

	return event:sub(-2, -1) == "/*";

end

local function is_wildcard_match(wildcard_event, event)

	return wildcard_event:sub(1, -2) == event:sub(1, #wildcard_event-1);

end

local _handlers = events._handlers;

local recent_wildcard_events = cache.new(10000, function (key, value) -- luacheck: ignore 212/value

	rawset(_handlers, key, nil);

end);

local event_map = events._event_map;

setmetatable(events._handlers, {

	-- Called when firing an event that doesn't exist (but may match a wildcard handler)

	__index = function (handlers, curr_event)

		if is_wildcard_event(curr_event) then return; end -- Wildcard events cannot be fired

		-- Find all handlers that could match this event, sort them

		-- and then put the array into handlers[curr_event] (and return it)

		local matching_handlers_set = {};

		local handlers_array = {};

		for event, handlers_set in pairs(event_map) do

			if event == curr_event or

			is_wildcard_event(event) and is_wildcard_match(event, curr_event) then

				for handler, priority in pairs(handlers_set) do

					matching_handlers_set[handler] = { (select(2, event:gsub("/", "%1"))), is_wildcard_event(event) and 0 or 1, priority };

					table.insert(handlers_array, handler);

				end

			end

		end

		if #handlers_array > 0 then

			table.sort(handlers_array, function(b, a)

				local a_score, b_score = matching_handlers_set[a], matching_handlers_set[b];

				for i = 1, #a_score do

					if a_score[i] ~= b_score[i] then -- If equal, compare next score value

						return a_score[i] < b_score[i];

					end

				end

				return false;

			end);

		else

			handlers_array = false;

		end

		rawset(handlers, curr_event, handlers_array);

		if not event_map[curr_event] then -- Only wildcard handlers match, if any

			recent_wildcard_events:set(curr_event, true);

		end

		return handlers_array;

	end;

	__newindex = function (handlers, curr_event, handlers_array)

		if handlers_array == nil

		and is_wildcard_event(curr_event) then

			-- Invalidate the indexes of all matching events

			for event in pairs(handlers) do

				if is_wildcard_match(curr_event, event) then

					handlers[event] = nil;

				end

			end

		end

		rawset(handlers, curr_event, handlers_array);

	end;

});

local handle_request;

local _1, _2, _3;

local function _handle_request() return handle_request(_1, _2, _3); end

local last_err;

local function _traceback_handler(err) last_err = err; log("error", "Traceback[httpserver]: %s", traceback(tostring(err), 2)); end

events.add_handler("http-error", function (error)

	return "Error processing request: "..codes[error.code]..". Check your error log for more information.";

end, -1);

function listener.onconnect(conn)

	local secure = conn:ssl() and true or nil;

	local pending = {};

	local waiting = false;

	local function process_next()

		if waiting then return; end -- log("debug", "can't process_next, waiting");

		waiting = true;

		while sessions[conn] and #pending > 0 do

			local request = t_remove(pending);

			--log("debug", "process_next: %s", request.path);

			--handle_request(conn, request, process_next);

			_1, _2, _3 = conn, request, process_next;

			if not xpcall(_handle_request, _traceback_handler) then

				conn:write("HTTP/1.0 500 Internal Server Error\r\n\r\n"..events.fire_event("http-error", { code = 500, private_message = last_err }));

				conn:close();

			end

		end

		--log("debug", "ready for more");

		waiting = false;

	end

	local function success_cb(request)

		--log("debug", "success_cb: %s", request.path);

		if waiting then

			log("error", "http connection handler is not reentrant: %s", request.path);

			assert(false, "http connection handler is not reentrant");

		end

		request.secure = secure;

		t_insert(pending, request);

		process_next();

	end

	local function error_cb(err)

		log("debug", "error_cb: %s", err or "<nil>");

		-- FIXME don't close immediately, wait until we process current stuff

		-- FIXME if err, send off a bad-request response

		sessions[conn] = nil;

		conn:close();

	end

	local function options_cb()

		return options;

	end

	sessions[conn] = parser_new(success_cb, error_cb, "server", options_cb);

end

function listener.ondisconnect(conn)

	local open_response = conn._http_open_response;

	if open_response and open_response.on_destroy then

		open_response.finished = true;

		open_response:on_destroy();

	end

	incomplete[conn] = nil;

	sessions[conn] = nil;

end

function listener.ondetach(conn)

	sessions[conn] = nil;

	incomplete[conn] = nil;

end

function listener.onincoming(conn, data)

	sessions[conn]:feed(data);

end

function listener.ondrain(conn)

	local response = incomplete[conn];

	if response and response._send_more then

		response._send_more();

	end

end

local headerfix = setmetatable({}, {

	__index = function(t, k)

		local v = "\r\n"..k:gsub("_", "-"):gsub("%f[%w].", s_upper)..": ";

		t[k] = v;

		return v;

	end

});

function _M.hijack_response(response, listener) -- luacheck: ignore

	error("TODO");

end

function handle_request(conn, request, finish_cb)

	--log("debug", "handler: %s", request.path);

	local headers = {};

	for k,v in pairs(request.headers) do headers[k:gsub("-", "_")] = v; end

	request.headers = headers;

	request.conn = conn;

	local date_header = os_date('!%a, %d %b %Y %H:%M:%S GMT'); -- FIXME use

	local conn_header = request.headers.connection;

	conn_header = conn_header and ","..conn_header:gsub("[ \t]", ""):lower().."," or ""

	local httpversion = request.httpversion

	local persistent = conn_header:find(",keep-alive,", 1, true)

		or (httpversion == "1.1" and not conn_header:find(",close,", 1, true));

	local response_conn_header;

	if persistent then

		response_conn_header = "Keep-Alive";

	else

		response_conn_header = httpversion == "1.1" and "close" or nil

	end

	local response = {

		request = request;

		status_code = 200;

		headers = { date = date_header, connection = response_conn_header };

		persistent = persistent;

		conn = conn;

		send = _M.send_response;

		send_file = _M.send_file;

		done = _M.finish_response;

		finish_cb = finish_cb;

	};

	conn._http_open_response = response;

	local host = (request.headers.host or ""):match("[^:]+");

	-- Some sanity checking

	local err_code, err;

	if not request.path then

		err_code, err = 400, "Invalid path";

	elseif not hosts[host] then

		if hosts[default_host] then

			host = default_host;

		elseif host then

			err_code, err = 404, "Unknown host: "..host;

		else

			err_code, err = 400, "Missing or invalid 'Host' header";

		end

	end

	if err then

		response.status_code = err_code;

		response:send(events.fire_event("http-error", { code = err_code, message = err, response = response }));

		return;

	end

	local payload = { request = request, response = response };

	log("debug", "Firing event: %s", event);

	local result = events.fire_event(event, payload);

	if result ~= nil then

		if result ~= true then

			local body;

			local result_type = type(result);

			if result_type == "number" then

				response.status_code = result;

				if result >= 400 then

					payload.code = result;

					body = events.fire_event("http-error", payload);

				end

			elseif result_type == "string" then

				body = result;

			elseif result_type == "table" then

				for k, v in pairs(result) do

					if k ~= "headers" then

						response[k] = v;

					else

						for header_name, header_value in pairs(v) do

							response.headers[header_name] = header_value;

						end

					end

				end

			end

			response:send(body);

		end

		return;

	end

	-- if handler not called, return 404

	response.status_code = 404;

	payload.code = 404;

	response:send(events.fire_event("http-error", payload));

end

local function prepare_header(response)

	local status_line = "HTTP/"..response.request.httpversion.." "..(response.status or codes[response.status_code]);

	local headers = response.headers;

	local output = { status_line };

	for k,v in pairs(headers) do

		t_insert(output, headerfix[k]..v);

	end

	t_insert(output, "\r\n\r\n");

	return output;

end

_M.prepare_header = prepare_header;

function _M.send_response(response, body)

	if response.finished then return; end

	body = body or response.body or "";

	response.headers.content_length = #body;

	local output = prepare_header(response);

	t_insert(output, body);

	response.conn:write(t_concat(output));

	response:done();

end

function _M.send_file(response, f)

	if response.finished then return; end

	local chunked = not response.headers.content_length;

	if chunked then response.headers.transfer_encoding = "chunked"; end

	incomplete[response.conn] = response;

	response._send_more = function ()

		if response.finished then

			incomplete[response.conn] = nil;

			return;

		end

		local chunk = f:read(blocksize);

		if chunk then

			if chunked then

				chunk = ("%x\r\n%s\r\n"):format(#chunk, chunk);

			end

			-- io.write("."); io.flush();

			response.conn:write(chunk);

		else

			if chunked then

				response.conn:write("0\r\n\r\n");

			end

			-- io.write("\n");

			if f.close then f:close(); end

			incomplete[response.conn] = nil;

			return response:done();

		end

	end

	response.conn:write(t_concat(prepare_header(response)));

	return true;

end

function _M.finish_response(response)

	if response.finished then return; end

	response.finished = true;

	response.conn._http_open_response = nil;

	if response.on_destroy then

		response:on_destroy();

		response.on_destroy = nil;

	end

	if response.persistent then

		response:finish_cb();

	else

		response.conn:close();

	end

end

function _M.add_handler(event, handler, priority)

	events.add_handler(event, handler, priority);

end

function _M.remove_handler(event, handler)

	events.remove_handler(event, handler);

end

function _M.listen_on(port, interface, ssl)

	return addserver(interface or "*", port, listener, "*a", ssl);

end

function _M.add_host(host)

	hosts[host] = true;

end

function _M.remove_host(host)

	hosts[host] = nil;

end

function _M.set_default_host(host)

	default_host = host;

end

function _M.fire_event(event, ...)

	return events.fire_event(event, ...);

end

function _M.set_option(name, value)

	options[name] = value;

end

_M.listener = listener;

_M.codes = codes;

_M._events = events;

return _M;