local format, rep = string.format, string.rep;

local pcall = pcall;

local debug = debug;

local tostring, setmetatable, rawset, pairs, ipairs, type = 

	tostring, setmetatable, rawset, pairs, ipairs, type;

local io_open, io_write = io.open, io.write;

local math_max, rep = math.max, string.rep;

local os_date, os_getenv = os.date, os.getenv;

local getstyle, getstring = require "util.termcolours".getstyle, require "util.termcolours".getstring;

local config = require "core.configmanager";

local eventmanager = require "core.eventmanager";

local logger = require "util.logger";

_G.log = logger.init("general");

module "loggingmanager"

-- The log config used if none specified in the config file

local default_logging = { { to = "console" } };

local default_timestamp = "%b %d %T";

-- The actual config loggingmanager is using

local logging_config = config.get("*", "core", "log") or default_logging;

local apply_sink_rules;

local log_sink_types = setmetatable({}, { __newindex = function (t, k, v) rawset(t, k, v); apply_sink_rules(k); end; });

local get_levels;

local logging_levels = { "debug", "info", "warn", "error", "critical" }

-- Put a rule into action. Requires that the sink type has already been registered.

-- This function is called automatically when a new sink type is added [see apply_sink_rules()]

local function add_rule(sink_config)

	local sink_maker = log_sink_types[sink_config.to];

	if sink_maker then

		if sink_config.levels and not sink_config.source then

			-- Create sink

			local sink = sink_maker(sink_config);

			-- Set sink for all chosen levels

			for level in pairs(get_levels(sink_config.levels)) do

				logger.add_level_sink(level, sink);

			end

		elseif sink_config.source and not sink_config.levels then

			logger.add_name_sink(sink_config.source, sink_maker(sink_config));

		elseif sink_config.source and sink_config.levels then

			local levels = get_levels(sink_config.levels);

			local sink = sink_maker(sink_config);

			logger.add_name_sink(sink_config.source,

				function (name, level, ...)

					if levels[level] then

						return sink(name, level, ...);

					end

				end);

		else

			-- All sources

			-- Create sink

			local sink = sink_maker(sink_config);

			-- Set sink for all levels

			for _, level in pairs(logging_levels) do

				logger.add_level_sink(level, sink);

			end

		end

	else

		-- No such sink type

	end

end

-- Search for all rules using a particular sink type, and apply

-- them. Called automatically when a new sink type is added to

-- the log_sink_types table.

function apply_sink_rules(sink_type)

	if type(logging_config) == "table" then

		for _, sink_config in pairs(logging_config) do

			if sink_config.to == sink_type then

				add_rule(sink_config);

			end

		end

	elseif type(logging_config) == "string" and (not logging_config:match("^%*")) and sink_type == "file" then

		-- User specified simply a filename, and the "file" sink type 

		-- was just added

		for _, sink_config in pairs(default_file_logging) do

			sink_config.filename = logging_config;

			add_rule(sink_config);

			sink_config.filename = nil;

		end

	elseif type(logging_config) == "string" and logging_config:match("^%*(.+)") == sink_type then

		-- Log all levels (debug+) to this sink

		add_rule({ levels = { min = "debug" }, to = sink_type });

	end

end

--- Helper function to get a set of levels given a "criteria" table

function get_levels(criteria, set)

	set = set or {};

	if type(criteria) == "string" then

		set[criteria] = true;

		return set;

	end

	local min, max = criteria.min, criteria.max;

	if min or max then

		local in_range;

		for _, level in ipairs(logging_levels) do

			if min == level then

				set[level] = true;

				in_range = true;

			elseif max == level then

				set[level] = true;

				return set;

			elseif in_range then

				set[level] = true;

			end	

		end

	end

	for _, level in ipairs(criteria) do

		set[level] = true;

	end

	return set;

end

--- Definition of built-in logging sinks ---

-- Null sink, must enter log_sink_types *first*

function log_sink_types.nowhere()

	return function () return false; end;

end

-- Column width for "source" (used by stdout and console)

local sourcewidth = 20;

function log_sink_types.stdout()

	local timestamps = config.timestamps;

	if timestamps == true then

		timestamps = default_timestamp; -- Default format

	end

	return function (name, level, message, ...)

		sourcewidth = math_max(#name+2, sourcewidth);

		local namelen = #name;

		if timestamps then

			io_write(os_date(timestamps), " ");

		end

		if ... then 

			io_write(name, rep(" ", sourcewidth-namelen), level, "\t", format(message, ...), "\n");

		else

			io_write(name, rep(" ", sourcewidth-namelen), level, "\t", message, "\n");

		end

	end	

end

do

	local do_pretty_printing = not os_getenv("WINDIR");

	local logstyles = {};

	if do_pretty_printing then

		logstyles["info"] = getstyle("bold");

		logstyles["warn"] = getstyle("bold", "yellow");

		logstyles["error"] = getstyle("bold", "red");

	end

	function log_sink_types.console(config)

		-- Really if we don't want pretty colours then just use plain stdout

		if not do_pretty_printing then

			return log_sink_types.stdout(config);

		end

		local timestamps = config.timestamps;

		if timestamps == true then

			timestamps = default_timestamp; -- Default format

		end

		return function (name, level, message, ...)

			sourcewidth = math_max(#name+2, sourcewidth);

			local namelen = #name;

			if timestamps then

				io_write(os_date(timestamps), " ");

			end

			if ... then 

				io_write(name, rep(" ", sourcewidth-namelen), getstring(logstyles[level], level), "\t", format(message, ...), "\n");

			else

				io_write(name, rep(" ", sourcewidth-namelen), getstring(logstyles[level], level), "\t", message, "\n");

			end

		end

	end

end

local empty_function = function () end;

function log_sink_types.file(config)

	local log = config.filename;

	local logfile = io_open(log, "a+");

	if not logfile then

		return empty_function;

	end

	local write, flush = logfile.write, logfile.flush;

	eventmanager.add_event_hook("reopen-log-files", function ()

			if logfile then

				logfile:close();

			end

			logfile = io_open(log, "a+");

			if not logfile then

				write, flush = empty_function, empty_function;

			else

				write, flush = logfile.write, logfile.flush;

			end

		end);

	local timestamps = config.timestamps;

	if timestamps == true then

		timestamps = default_timestamp; -- Default format

	end

	return function (name, level, message, ...)

		if timestamps then

			write(logfile, os_date(timestamps), " ");

		end

		if ... then 

			write(logfile, name, "\t", level, "\t", format(message, ...), "\n");

		else

			write(logfile, name, "\t" , level, "\t", message, "\n");

		end

		flush(logfile);

	end;

end

function register_sink_type(name, sink_maker)

	local old_sink_maker = log_sink_types[name];

	log_sink_types[name] = sink_maker;

	return old_sink_maker;

end

return _M;