util/logger.lua

-- 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 pcall = pcall;

local config = require "core.configmanager";
local log_sources = config.get("*", "core", "log_sources");

local find = string.find;
local ipairs, pairs, setmetatable = ipairs, pairs, setmetatable;

module "logger"

local name_sinks, level_sinks = {}, {};
local name_patterns = {};

-- Weak-keyed so that loggers are collected
local modify_hooks = setmetatable({}, { __mode = "k" });

local make_logger;
local outfunction = nil;

function init(name)
	if log_sources then
		local log_this = false;
		for _, source in ipairs(log_sources) do
			if find(name, source) then 
				log_this = true;
				break;
			end
		end
		
		if not log_this then return function () end end
	end
	
	local log_debug = make_logger(name, "debug");
	local log_info = make_logger(name, "info");
	local log_warn = make_logger(name, "warn");
	local log_error = make_logger(name, "error");

	--name = nil; -- While this line is not commented, will automatically fill in file/line number info
	local namelen = #name;
	return function (level, message, ...)
			if outfunction then return outfunction(name, level, message, ...); end
			
			if level == "debug" then
				return log_debug(message, ...);
			elseif level == "info" then
				return log_info(message, ...);
			elseif level == "warn" then
				return log_warn(message, ...);
			elseif level == "error" then
				return log_error(message, ...);
			end
		end
end

function make_logger(source_name, level)
	local level_handlers = level_sinks[level];
	if not level_handlers then
		level_handlers = {};
		level_sinks[level] = level_handlers;
	end

	local source_handlers = name_sinks[source_name];
	
	-- All your premature optimisation is belong to me!
	local num_level_handlers, num_source_handlers = #level_handlers, source_handlers and #source_handlers;
	
	local logger = function (message, ...)
		if source_handlers then
			for i = 1,num_source_handlers do
				if source_handlers[i](source_name, level, message, ...) == false then
					return;
				end
			end
		end
		
		for i = 1,num_level_handlers do
			level_handlers[i](source_name, level, message, ...);
		end
	end

	-- To make sure our cached lengths stay in sync with reality
	modify_hooks[logger] = function () num_level_handlers, num_source_handlers = #level_handlers, source_handlers and #source_handlers; end; 
	
	return logger;
end

function setwriter(f)
	local old_func = outfunction;
	if not f then outfunction = nil; return true, old_func; end
	local ok, ret = pcall(f, "logger", "info", "Switched logging output successfully");
	if ok then
		outfunction = f;
		ret = old_func;
	end
	return ok, ret;
end

function add_level_sink(level, sink_function)
	if not level_sinks[level] then
		level_sinks[level] = { sink_function };
	else
		level_sinks[level][#level_sinks[level] + 1 ] = sink_function;
	end
	
	for _, modify_hook in pairs(modify_hooks) do
		modify_hook();
	end
end

function add_name_sink(name, sink_function, exclusive)
	if not name_sinks[name] then
		name_sinks[name] = { sink_function };
	else
		name_sinks[name][#name_sinks[name] + 1] = sink_function;
	end
	
	for _, modify_hook in pairs(modify_hooks) do
		modify_hook();
	end
end

function add_name_pattern_sink(name_pattern, sink_function, exclusive)
	if not name_patterns[name_pattern] then
		name_patterns[name_pattern] = { sink_function };
	else
		name_patterns[name_pattern][#name_patterns[name_pattern] + 1] = sink_function;
	end
end

_M.new = make_logger;

return _M;