-- 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 plugin_dir = CFG_PLUGINDIR or "./plugins/";

local logger = require "util.logger";
local log = logger.init("modulemanager");
local config = require "core.configmanager";
local multitable_new = require "util.multitable".new;
local st = require "util.stanza";
local pluginloader = require "util.pluginloader";

local hosts = hosts;
local prosody = prosody;
local prosody_events = prosody.events;

local loadfile, pcall, xpcall = loadfile, pcall, xpcall;
local setmetatable, setfenv, getfenv = setmetatable, setfenv, getfenv;
local pairs, ipairs = pairs, ipairs;
local t_insert, t_concat = table.insert, table.concat;
local type = type;
local next = next;
local rawget = rawget;
local error = error;
local tostring, tonumber = tostring, tonumber;

local debug_traceback = debug.traceback;
local unpack, select = unpack, select;
pcall = function(f, ...)
	local n = select("#", ...);
	local params = {...};
	return xpcall(function() return f(unpack(params, 1, n)) end, function(e) return tostring(e).."\n"..debug_traceback(); end);
end

local array, set = require "util.array", require "util.set";

local autoload_modules = {"presence", "message", "iq"};
local component_inheritable_modules = {"tls", "dialback"};

-- We need this to let modules access the real global namespace
local _G = _G;

module "modulemanager"

api = {};
local api = api; -- Module API container

local modulemap = { ["*"] = {} };

local modulehelpers = setmetatable({}, { __index = _G });

local hooks = multitable_new();

local NULL = {};

-- Load modules when a host is activated
function load_modules_for_host(host)
	local component = config.get(host, "core", "component_module");
	
	local global_modules_enabled = config.get("*", "core", "modules_enabled");
	local global_modules_disabled = config.get("*", "core", "modules_disabled");
	local host_modules_enabled = config.get(host, "core", "modules_enabled");
	local host_modules_disabled = config.get(host, "core", "modules_disabled");
	
	if host_modules_enabled == global_modules_enabled then host_modules_enabled = nil; end
	if host_modules_disabled == global_modules_disabled then host_modules_disabled = nil; end
	
	local host_modules = set.new(host_modules_enabled) - set.new(host_modules_disabled);
	local global_modules = set.new(autoload_modules) + set.new(global_modules_enabled) - set.new(global_modules_disabled);
	if component then
		global_modules = set.intersection(set.new(component_inheritable_modules), global_modules);
	end
	local modules = global_modules + host_modules;
	
	if component then
		load(host, component);
	end
	for module in modules do
		load(host, module);
	end
end
prosody_events.add_handler("host-activated", load_modules_for_host);
prosody_events.add_handler("component-activated", load_modules_for_host);
--

function load(host, module_name, config)
	if not (host and module_name) then
		return nil, "insufficient-parameters";
	elseif not hosts[host] then
		return nil, "unknown-host";
	end
	
	if not modulemap[host] then
		modulemap[host] = {};
	end
	
	if modulemap[host][module_name] then
		log("warn", "%s is already loaded for %s, so not loading again", module_name, host);
		return nil, "module-already-loaded";
	elseif modulemap["*"][module_name] then
		return nil, "global-module-already-loaded";
	end
	

	local mod, err = pluginloader.load_code(module_name);
	if not mod then
		log("error", "Unable to load module '%s': %s", module_name or "nil", err or "nil");
		return nil, err;
	end

	local _log = logger.init(host..":"..module_name);
	local api_instance = setmetatable({ name = module_name, host = host, config = config,  _log = _log, log = function (self, ...) return _log(...); end }, { __index = api });

	local pluginenv = setmetatable({ module = api_instance }, { __index = _G });
	api_instance.environment = pluginenv;
	
	setfenv(mod, pluginenv);
	hosts[host].modules = modulemap[host];
	modulemap[host][module_name] = pluginenv;
	
	local success, err = pcall(mod);
	if success then
		if module_has_method(pluginenv, "load") then
			success, err = call_module_method(pluginenv, "load");
			if not success then
				log("warn", "Error loading module '%s' on '%s': %s", module_name, host, err or "nil");
			end
		end

		-- Use modified host, if the module set one
		if api_instance.host == "*" and host ~= "*" then
			modulemap[host][module_name] = nil;
			modulemap["*"][module_name] = pluginenv;
			api_instance:set_global();
		end
	else
		log("error", "Error initializing module '%s' on '%s': %s", module_name, host, err or "nil");
	end
	if success then
		(hosts[api_instance.host] or prosody).events.fire_event("module-loaded", { module = module_name, host = host });
		return true;
	else -- load failed, unloading
		unload(api_instance.host, module_name);
		return nil, err;
	end
end

function get_module(host, name)
	return modulemap[host] and modulemap[host][name];
end

function is_loaded(host, name)
	return modulemap[host] and modulemap[host][name] and true;
end

function unload(host, name, ...)
	local mod = get_module(host, name);
	if not mod then return nil, "module-not-loaded"; end
	
	if module_has_method(mod, "unload") then
		local ok, err = call_module_method(mod, "unload");
		if (not ok) and err then
			log("warn", "Non-fatal error unloading module '%s' on '%s': %s", name, host, err);
		end
	end
	-- unhook event handlers hooked by module:hook
	for event, handlers in pairs(hooks:get(host, name) or NULL) do
		for handler in pairs(handlers or NULL) do
			(hosts[host] or prosody).events.remove_handler(event, handler);
		end
	end
	hooks:remove(host, name);
	if mod.module.items then -- remove items
		for key,t in pairs(mod.module.items) do
			for i = #t,1,-1 do
				local value = t[i];
				t[i] = nil;
				hosts[host].events.fire_event("item-removed/"..key, {source = self, item = value});
			end
		end
	end
	modulemap[host][name] = nil;
	(hosts[host] or prosody).events.fire_event("module-unloaded", { module = name, host = host });
	return true;
end

function reload(host, name, ...)
	local mod = get_module(host, name);
	if not mod then return nil, "module-not-loaded"; end

	local _mod, err = pluginloader.load_code(name); -- checking for syntax errors
	if not _mod then
		log("error", "Unable to load module '%s': %s", name or "nil", err or "nil");
		return nil, err;
	end

	local saved;

	if module_has_method(mod, "save") then
		local ok, ret, err = call_module_method(mod, "save");
		if ok then
			saved = ret;
		else
			log("warn", "Error saving module '%s:%s' state: %s", host, module, ret);
			if not config.get(host, "core", "force_module_reload") then
				log("warn", "Aborting reload due to error, set force_module_reload to ignore this");
				return nil, "save-state-failed";
			else
				log("warn", "Continuing with reload (using the force)");
			end
		end
	end

	unload(host, name, ...);
	local ok, err = load(host, name, ...);
	if ok then
		mod = get_module(host, name);
		if module_has_method(mod, "restore") then
			local ok, err = call_module_method(mod, "restore", saved or {})
			if (not ok) and err then
				log("warn", "Error restoring module '%s' from '%s': %s", name, host, err);
			end
		end
		return true;
	end
	return ok, err;
end

function module_has_method(module, method)
	return type(module.module[method]) == "function";
end

function call_module_method(module, method, ...)
	if module_has_method(module, method) then
		local f = module.module[method];
		return pcall(f, ...);
	else
		return false, "no-such-method";
	end
end

----- API functions exposed to modules -----------
-- Must all be in api.*

-- Returns the name of the current module
function api:get_name()
	return self.name;
end

-- Returns the host that the current module is serving
function api:get_host()
	return self.host;
end

function api:get_host_type()
	return hosts[self.host].type;
end

function api:set_global()
	self.host = "*";
	-- Update the logger
	local _log = logger.init("mod_"..self.name);
	self.log = function (self, ...) return _log(...); end;
	self._log = _log;
end

function api:add_feature(xmlns)
	self:add_item("feature", xmlns);
end
function api:add_identity(category, type, name)
	self:add_item("identity", {category = category, type = type, name = name});
end

function api:fire_event(...)
	return (hosts[self.host] or prosody).events.fire_event(...);
end

function api:hook(event, handler, priority)
	hooks:set(self.host, self.name, event, handler, true);
	(hosts[self.host] or prosody).events.add_handler(event, handler, priority);
end

function api:hook_stanza(xmlns, name, handler, priority)
	if not handler and type(name) == "function" then
		-- If only 2 options then they specified no xmlns
		xmlns, name, handler, priority = nil, xmlns, name, handler;
	elseif not (handler and name) then
		self:log("warn", "Error: Insufficient parameters to module:hook_stanza()");
		return;
	end
	return api.hook(self, "stanza/"..(xmlns and (xmlns..":") or "")..name, function (data) return handler(data.origin, data.stanza, data); end, priority);
end

function api:require(lib)
	local f, n = pluginloader.load_code(self.name, lib..".lib.lua");
	if not f then
		f, n = pluginloader.load_code(lib, lib..".lib.lua");
	end
	if not f then error("Failed to load plugin library '"..lib.."', error: "..n); end -- FIXME better error message
	setfenv(f, self.environment);
	return f();
end

function api:get_option(name, default_value)
	local value = config.get(self.host, self.name, name);
	if value == nil then
		value = config.get(self.host, "core", name);
		if value == nil then
			value = default_value;
		end
	end
	return value;
end

function api:get_option_string(name, default_value)
	local value = self:get_option(name, default_value);
	if type(value) == "table" then
		if #value > 1 then
			self:log("error", "Config option '%s' does not take a list, using just the first item", name);
		end
		value = value[1];
	end
	if value == nil then
		return nil;
	end
	return tostring(value);
end

function api:get_option_number(name, ...)
	local value = self:get_option(name, ...);
	if type(value) == "table" then
		if #value > 1 then
			self:log("error", "Config option '%s' does not take a list, using just the first item", name);
		end
		value = value[1];
	end
	local ret = tonumber(value);
	if value ~= nil and ret == nil then
		self:log("error", "Config option '%s' not understood, expecting a number", name);
	end
	return ret;
end

function api:get_option_boolean(name, ...)
	local value = self:get_option(name, ...);
	if type(value) == "table" then
		if #value > 1 then
			self:log("error", "Config option '%s' does not take a list, using just the first item", name);
		end
		value = value[1];
	end
	if value == nil then
		return nil;
	end
	local ret = value == true or value == "true" or value == 1 or nil;
	if ret == nil then
		ret = (value == false or value == "false" or value == 0);
		if ret then
			ret = false;
		else
			ret = nil;
		end
	end
	if ret == nil then
		self:log("error", "Config option '%s' not understood, expecting true/false", name);
	end
	return ret;
end

function api:get_option_array(name, ...)
	local value = self:get_option(name, ...);

	if value == nil then
		return nil;
	end
	
	if type(value) ~= "table" then
		return array{ value }; -- Assume any non-list is a single-item list
	end
	
	return array():append(value); -- Clone
end

function api:get_option_set(name, ...)
	local value = self:get_option_array(name, ...);
	
	if value == nil then
		return nil;
	end
	
	return set.new(value);
end

local t_remove = _G.table.remove;
local module_items = multitable_new();
function api:add_item(key, value)
	self.items = self.items or {};
	self.items[key] = self.items[key] or {};
	t_insert(self.items[key], value);
	self:fire_event("item-added/"..key, {source = self, item = value});
end
function api:remove_item(key, value)
	local t = self.items and self.items[key] or NULL;
	for i = #t,1,-1 do
		if t[i] == value then
			t_remove(self.items[key], i);
			self:fire_event("item-removed/"..key, {source = self, item = value});
			return value;
		end
	end
end

function api:get_host_items(key)
	local result = {};
	for mod_name, module in pairs(modulemap[self.host]) do
		module = module.module;
		if module.items then
			for _, item in ipairs(module.items[key] or NULL) do
				t_insert(result, item);
			end
		end
	end
	for mod_name, module in pairs(modulemap["*"]) do
		module = module.module;
		if module.items then
			for _, item in ipairs(module.items[key] or NULL) do
				t_insert(result, item);
			end
		end
	end
	return result;
end

return _M;