local ipairs = ipairs;

local pairs = pairs;

local t_insert = table.insert;

local select = select;

module "events"

function new()

	local dispatchers = {};

	local handlers = {};

	local event_map = {};

	local function _rebuild_index() -- TODO optimize index rebuilding

		for event, _handlers in pairs(event_map) do

			local index = handlers[event];

			if index then

				for i=#index,1,-1 do index[i] = nil; end

			else index = {}; handlers[event] = index; end

			for handler in pairs(_handlers) do

				t_insert(index, handler);

			end

		end

	end;

	local function add_handler(event, handler)

		local map = event_map[event];

		if map then

			map[handler] = true;

		else

			map = {[handler] = true};

			event_map[event] = map;

		end

		_rebuild_index();

	end;

	local function remove_handler(event, handler)

		local map = event_map[event];

		if map then

			map[handler] = nil;

			_rebuild_index();

		end

	end;

	local function add_plugin(plugin)

		for event, handler in pairs(plugin) do

			add_handler(event, handler);

		end

	end;

	local function remove_plugin(plugin)

		for event, handler in pairs(plugin) do

			remove_handler(event, handler);

		end

	end;

	local function _create_dispatcher(event) -- FIXME duplicate code in fire_event

		local h = handlers[event];

		if not h then h = {}; handlers[event] = h; end

		local dispatcher = function(data)

			for _, handler in ipairs(h) do

			end

		end;

		dispatchers[event] = dispatcher;

		return dispatcher;

	end;

	local function get_dispatcher(event)

		return dispatchers[event] or _create_dispatcher(event);

	end;

	local function fire_event(event, data) -- FIXME duplicates dispatcher code

		local h = handlers[event];

		if h then

			for _, handler in ipairs(h) do

			end

		end

	end;

	local function get_named_arg_dispatcher(event, ...)

		local dispatcher = get_dispatcher(event);

		local keys = {...};

		local data = {};

		return function(...)

			for i, key in ipairs(keys) do data[key] = select(i, ...); end

			dispatcher(data);

		end;

	end;

	return {

		add_handler = add_handler;

		remove_handler = remove_handler;

		add_plugin = add_plugin;

		remove_plugin = remove_plugin;

		get_dispatcher = get_dispatcher;

		fire_event = fire_event;

		get_named_arg_dispatcher = get_named_arg_dispatcher;

		_dispatchers = dispatchers;

		_handlers = handlers;

		_event_map = event_map;

	};

end

return _M;