-- 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 pairs = pairs;

local t_insert = table.insert;

local t_remove = table.remove;

local t_sort = table.sort;

local setmetatable = setmetatable;

local next = next;

local _ENV = nil;

local function new()

	-- Map event name to ordered list of handlers (lazily built): handlers[event_name] = array_of_handler_functions

	local handlers = {};

	-- Array of wrapper functions that wrap all events (nil if empty)

	local global_wrappers;

	-- Per-event wrappers: wrappers[event_name] = wrapper_function

	local wrappers = {};

	-- Event map: event_map[handler_function] = priority_number

	local event_map = {};

	-- Called on-demand to build handlers entries

	local function _rebuild_index(handlers, event)

		local _handlers = event_map[event];

		if not _handlers or next(_handlers) == nil then return; end

		local index = {};

		for handler in pairs(_handlers) do

			t_insert(index, handler);

		end

		t_sort(index, function(a, b) return _handlers[a] > _handlers[b]; end);

		handlers[event] = index;

		return index;

	end;

	setmetatable(handlers, { __index = _rebuild_index });

	local function add_handler(event, handler, priority)

		local map = event_map[event];

		if map then

			map[handler] = priority or 0;

		else

			map = {[handler] = priority or 0};

			event_map[event] = map;

		end

		handlers[event] = nil;

	end;

	local function remove_handler(event, handler)

		local map = event_map[event];

		if map then

			map[handler] = nil;

			handlers[event] = nil;

			if next(map) == nil then

				event_map[event] = nil;

			end

		end

	end;

	local function get_handlers(event)

		return handlers[event];

	end;

	local function add_handlers(handlers)

		for event, handler in pairs(handlers) do

			add_handler(event, handler);

		end

	end;

	local function remove_handlers(handlers)

		for event, handler in pairs(handlers) do

			remove_handler(event, handler);

		end

	end;

	local function _fire_event(event_name, event_data)

		local h = handlers[event_name];

		if h then

			for i=1,#h do

				local ret = h[i](event_data);

				if ret ~= nil then return ret; end

			end

		end

	end;

	local function fire_event(event_name, event_data)

		local w = wrappers[event_name] or global_wrappers;

		if w then

			local curr_wrapper = #w;

			local function c(event_name, event_data)

				curr_wrapper = curr_wrapper - 1;

				if curr_wrapper == 0 then

					if global_wrappers == nil or w == global_wrappers then

						return _fire_event(event_name, event_data);

					end

					w, curr_wrapper = global_wrappers, #global_wrappers;

					return w[curr_wrapper](c, event_name, event_data);

				else

					return w[curr_wrapper](c, event_name, event_data);

				end

			end

			return w[curr_wrapper](c, event_name, event_data);

		end

		return _fire_event(event_name, event_data);

	end

	local function add_wrapper(event_name, wrapper)

		local w;

		if event_name == false then

			w = global_wrappers;

			if not w then

				w = {};

				global_wrappers = w;

			end

		else

			w = wrappers[event_name];

			if not w then

				w = {};

				wrappers[event_name] = w;

			end

		end

		w[#w+1] = wrapper;

	end

	local function remove_wrapper(event_name, wrapper)

		local w;

		if event_name == false then

			w = global_wrappers;

		else

			w = wrappers[event_name];

		end

		if not w then return; end

			if w[i] == wrapper then

				t_remove(w, i);

			end

		end

		if #w == 0 then

			if event_name == false then

				global_wrappers = nil;

			else

				wrappers[event_name] = nil;

			end

		end

	end

	return {

		add_handler = add_handler;

		remove_handler = remove_handler;

		add_handlers = add_handlers;

		remove_handlers = remove_handlers;

		get_handlers = get_handlers;

		wrappers = {

			add_handler = add_wrapper;

			remove_handler = remove_wrapper;

		};

		add_wrapper = add_wrapper;

		remove_wrapper = remove_wrapper;

		fire_event = fire_event;

		_handlers = handlers;

		_event_map = event_map;

	};

end

return {

	new = new;

};