logger.gd

# Copyright (c) 2016 KOBUGE Games
# Distributed under the terms of the MIT license.
# https://github.com/KOBUGE-Games/godot-logger/blob/master/LICENSE.md
#
# Upstream repo: https://github.com/KOBUGE-Games/godot-logger

extends Node  # Needed to work as a singleton

##================##
## Inner classes  ##
##================##


class ExternalSink:
	# Queue modes
	enum QUEUE_MODES {
		NONE = 0,
		ALL = 1,
		SMART = 2,
	}

	var name
	var queue_mode
	var buffer = PackedStringArray()
	var buffer_idx = 0

	func _init(_name, _queue_mode = QUEUE_MODES.NONE) -> void:
		name = _name
		queue_mode = _queue_mode

	func flush_buffer():
		"""Flush the buffer, i.e. write its contents to the target external sink."""
		print("[ERROR] [logger] Using method which has to be overriden in your custom sink")

	func write(output, level):
		"""Write the string at the end of the sink (append mode), following
		the queue mode."""
		print("[ERROR] [logger] Using method which has to be overriden in your custom sink")

	func set_queue_mode(new_mode):
		queue_mode = new_mode

	func get_queue_mode():
		return queue_mode

	func get_name():
		return name

	func get_config():
		return {
			"queue_mode": get_queue_mode(),
		}


class Logfile:
	extends ExternalSink
	# TODO: Godot doesn't support docstrings for inner classes, GoDoIt (GH-1320)
	# """Class for log files that can be shared between various modules."""
	const FILE_BUFFER_SIZE = 30
	var path = ""

	func _init(_path, _queue_mode = QUEUE_MODES.NONE):
		super(_path, _queue_mode)
		if validate_path(_path):
			path = _path
		buffer.resize(FILE_BUFFER_SIZE)

	func get_path():
		return path

	func get_write_mode():
		if not FileAccess.file_exists(path):
			return FileAccess.WRITE  # create
		else:
			return FileAccess.READ_WRITE  # append

	func validate_path(path):
		"""Validate the path given as argument, making it possible to write to
		the designated file or folder. Returns whether the path is valid."""
		if not (path.is_absolute_path() or path.is_rel_path()):
			print("[ERROR] [logger] The given path '%s' is not valid." % path)
			return false
		var base_dir = path.get_base_dir()
		var dir = DirAccess.open(base_dir)
		if not dir:
			var err = DirAccess.get_open_error()
			if err:
				print("[ERROR] [logger] Could not create the '%s' directory; exited with error %d." % [base_dir, err])
				return false
			else:
				# TODO: Move directory creation to the function that will actually *write*
				dir.make_dir_recursive(base_dir)
				var err2 = DirAccess.get_open_error()
				if err2:
					print("[ERROR] [logger] Could not create the '%s' directory; exited with error %d." % [base_dir, err2])
					return false

				print("[INFO] [logger] Successfully created the '%s' directory." % base_dir)
		return true

	func flush_buffer():
		"""Flush the buffer, i.e. write its contents to the target file."""
		if buffer_idx == 0:
			return  # Nothing to write
		var temp_file = _open_file(path)
		if temp_file:
			temp_file.seek_end()
			for i in range(buffer_idx):
				temp_file.store_line(buffer[i])
			temp_file.close()
			buffer_idx = 0  # We don't clear the memory, we'll just overwrite it

	func write(output, level):
		"""Write the string at the end of the file (append mode), following
		the queue mode."""
		var queue_action = queue_mode
		if queue_action == QUEUE_MODES.SMART:
			if level >= WARN:  # Don't queue warnings and errors
				queue_action = QUEUE_MODES.NONE
				flush_buffer()
			else:  # Queue the log, not important enough for "smart"
				queue_action = QUEUE_MODES.ALL

		if queue_action == QUEUE_MODES.NONE:
			var temp_file = _open_file(path)
			if temp_file == null:
				return
			else:
				temp_file.seek_end()
				temp_file.store_line(output)
				temp_file.close()

		if queue_action == QUEUE_MODES.ALL:
			buffer[buffer_idx] = output
			buffer_idx += 1
			if buffer_idx >= FILE_BUFFER_SIZE:
				flush_buffer()

	func get_config():
		return {
			"path": get_path(),
			"queue_mode": get_queue_mode(),
		}

	func _open_file(path):
		var result = FileAccess.open(path, get_write_mode())

		if result == null:
			var err = FileAccess.get_open_error()
			print("[ERROR] [logger] Could not open the '%s' log file; exited with error %d." % [path, err])
			return null
		else:
			return result


class Module:
	# """Class for customizable logging modules."""
	var name = ""
	var output_level = 0
	var output_strategies = []
	var external_sink = null

	func _init(_name, _output_level, _output_strategies, _external_sink):
		name = _name
		set_output_level(_output_level)

		if typeof(_output_strategies) == TYPE_INT:  # Only one strategy, use it for all
			for i in range(0, LEVELS.size()):
				output_strategies.append(_output_strategies)
		else:
			for strategy in _output_strategies:  # Need to force deep copy
				output_strategies.append(strategy)

		set_external_sink(_external_sink)

	func get_name():
		return name

	func set_output_level(level):
		"""Set the custom minimal level for the output of the module.
		All levels greater or equal to the given once will be output based
		on their respective strategies, while levels lower than the given one
		will be discarded."""
		if not level in range(0, LEVELS.size()):
			print("[ERROR] [%s] The level must be comprised between 0 and %d." % [PLUGIN_NAME, LEVELS.size() - 1])
			return
		output_level = level

	func get_output_level():
		return output_level

	func set_common_output_strategy(output_strategy_mask):
		"""Set the common output strategy mask for all levels of the module."""
		if not output_strategy_mask in range(0, MAX_STRATEGY + 1):
			print("[ERROR] [%s] The output strategy mask must be comprised between 0 and %d." % [PLUGIN_NAME, MAX_STRATEGY])
			return
		for i in range(0, LEVELS.size()):
			output_strategies[i] = output_strategy_mask

	func set_output_strategy(output_strategy_mask, level = -1):
		"""Set the output strategy for the given level or (by default) all
		levels of the module."""
		if not output_strategy_mask in range(0, MAX_STRATEGY + 1):
			print("[ERROR] [%s] The output strategy mask must be comprised between 0 and %d." % [PLUGIN_NAME, MAX_STRATEGY])
			return
		if level == -1:  # Set for all levels
			for i in range(0, LEVELS.size()):
				output_strategies[i] = output_strategy_mask
		else:
			if not level in range(0, LEVELS.size()):
				print("[ERROR] [%s] The level must be comprised between 0 and %d." % [PLUGIN_NAME, LEVELS.size() - 1])
				return
			output_strategies[level] = output_strategy_mask

	func get_output_strategy(level = -1):
		if level == -1:
			return output_strategies
		else:
			return output_strategies[level]

	func set_external_sink(new_external_sink):
		"""Set the external sink instance for the module."""
		external_sink = new_external_sink

	func get_external_sink():
		return external_sink

	func get_config():
		return {
			"name": get_name(),
			"output_level": get_output_level(),
			"output_strategies": get_output_strategy(),
			"external_sink": get_external_sink().get_config(),
		}


##=============##
##  Constants  ##
##=============##

const PLUGIN_NAME = "logger"

# Logging levels - the array and the integers should be matching
const LEVELS = ["VERBOSE", "DEBUG", "INFO", "WARN", "ERROR"]
const VERBOSE = 0
const DEBUG = 1
const INFO = 2
const WARN = 3
const ERROR = 4

# Output strategies
const STRATEGY_MUTE = 0
const STRATEGY_PRINT = 1
const STRATEGY_EXTERNAL_SINK = 2
const STRATEGY_PRINT_AND_EXTERNAL_SINK = STRATEGY_PRINT | STRATEGY_EXTERNAL_SINK
const STRATEGY_MEMORY = 4
const MAX_STRATEGY = STRATEGY_MEMORY * 2 - 1

# Output format identifiers
const FORMAT_IDS = {
	"level": "{LVL}",
	"module": "{MOD}",
	"message": "{MSG}",
	"time": "{TIME}",
	"error_message": "{ERR_MSG}",
}

# Maps Error code to strings.
# This might eventually be supported out of the box in Godot,
# so we'll be able to drop this.
const ERROR_MESSAGES = {
	OK: "OK.",
	FAILED: "Generic error.",
	ERR_UNAVAILABLE: "Unavailable error.",
	ERR_UNCONFIGURED: "Unconfigured error.",
	ERR_UNAUTHORIZED: "Unauthorized error.",
	ERR_PARAMETER_RANGE_ERROR: "Parameter range error.",
	ERR_OUT_OF_MEMORY: "Out of memory (OOM) error.",
	ERR_FILE_NOT_FOUND: "File: Not found error.",
	ERR_FILE_BAD_DRIVE: "File: Bad drive error.",
	ERR_FILE_BAD_PATH: "File: Bad path error.",
	ERR_FILE_NO_PERMISSION: "File: No permission error.",
	ERR_FILE_ALREADY_IN_USE: "File: Already in use error.",
	ERR_FILE_CANT_OPEN: "File: Can't open error.",
	ERR_FILE_CANT_WRITE: "File: Can't write error.",
	ERR_FILE_CANT_READ: "File: Can't read error.",
	ERR_FILE_UNRECOGNIZED: "File: Unrecognized error.",
	ERR_FILE_CORRUPT: "File: Corrupt error.",
	ERR_FILE_MISSING_DEPENDENCIES: "File: Missing dependencies error.",
	ERR_FILE_EOF: "File: End of file (EOF) error.",
	ERR_CANT_OPEN: "Can't open error.",
	ERR_CANT_CREATE: "Can't create error.",
	ERR_QUERY_FAILED: "Query failed error.",
	ERR_ALREADY_IN_USE: "Already in use error.",
	ERR_LOCKED: "Locked error.",
	ERR_TIMEOUT: "Timeout error.",
	ERR_CANT_CONNECT: "Can't connect error.",
	ERR_CANT_RESOLVE: "Can't resolve error.",
	ERR_CONNECTION_ERROR: "Connection error.",
	ERR_CANT_ACQUIRE_RESOURCE: "Can't acquire resource error.",
	ERR_CANT_FORK: "Can't fork process error.",
	ERR_INVALID_DATA: "Invalid data error.",
	ERR_INVALID_PARAMETER: "Invalid parameter error.",
	ERR_ALREADY_EXISTS: "Already exists error.",
	ERR_DOES_NOT_EXIST: "Does not exist error.",
	ERR_DATABASE_CANT_READ: "Database: Read error.",
	ERR_DATABASE_CANT_WRITE: "Database: Write error.",
	ERR_COMPILATION_FAILED: "Compilation failed error.",
	ERR_METHOD_NOT_FOUND: "Method not found error.",
	ERR_LINK_FAILED: "Linking failed error.",
	ERR_SCRIPT_FAILED: "Script failed error.",
	ERR_CYCLIC_LINK: "Cycling link (import cycle) error.",
	ERR_INVALID_DECLARATION: "Invalid declaration error.",
	ERR_DUPLICATE_SYMBOL: "Duplicate symbol error.",
	ERR_PARSE_ERROR: "Parse error.",
	ERR_BUSY: "Busy error.",
	ERR_SKIP: "Skip error.",
	ERR_HELP: "Help error.",
	ERR_BUG: "Bug error.",
	ERR_PRINTER_ON_FIRE: "Printer on fire error.",
}

##=============##
##  Variables  ##
##=============##

# Configuration
var default_output_level = INFO
# TODO: Find (or implement in Godot) a more clever way to achieve that

var default_output_strategies = [STRATEGY_PRINT, STRATEGY_PRINT, STRATEGY_PRINT, STRATEGY_PRINT, STRATEGY_PRINT]
var default_logfile_path = "user://%s.log" % ProjectSettings.get_setting("application/config/name")  # TODO @File
var default_configfile_path = "user://%s.cfg" % PLUGIN_NAME

# e.g. "[INFO] [main] The young alpaca started growing a goatie."
var output_format = "[{TIME}] [{LVL}] [{MOD}]{ERR_MSG} {MSG}"
# Example with all supported placeholders: "YYYY.MM.DD hh.mm.ss.SSS"
# would output e.g.: "2020.10.09 12:10:47.034".
var time_format = "hh:mm:ss"

# Holds the name of the debug module for easy usage across all logging functions.
var default_module_name = "main"

# Specific to STRATEGY_MEMORY
var max_memory_size = 30
var memory_buffer = []
var memory_idx = 0
var memory_first_loop = true
var memory_cache = []
var invalid_memory_cache = false

# Holds default and custom modules and external sinks defined by the user
# Default modules are initialized in _init via add_module
var external_sinks = {}
var modules = {}

##=============##
##  Functions  ##
##=============##


func put(level, message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with the given logging level."""
	var module_ref = get_module(module)
	var output_strategy = module_ref.get_output_strategy(level)
	if output_strategy == STRATEGY_MUTE or module_ref.get_output_level() > level:
		return  # Out of scope

	var output = format(output_format, level, module, message, error_code)

	if output_strategy & STRATEGY_PRINT:
		print(output)

	if output_strategy & STRATEGY_EXTERNAL_SINK:
		module_ref.get_external_sink().write(output, level)

	if output_strategy & STRATEGY_MEMORY:
		memory_buffer[memory_idx] = output
		memory_idx += 1
		invalid_memory_cache = true
		if memory_idx >= max_memory_size:
			memory_idx = 0
			memory_first_loop = false


# Helper functions for each level
# -------------------------------


func verbose(message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with level VERBOSE."""
	put(VERBOSE, message, module, error_code)


func debug(message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with level DEBUG."""
	put(DEBUG, message, module, error_code)


func info(message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with level INFO."""
	put(INFO, message, module, error_code)


func warn(message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with level WARN."""
	put(WARN, message, module, error_code)


func error(message, module = default_module_name, error_code = -1):
	"""Log a message in the given module with level ERROR."""
	put(ERROR, message, module, error_code)


# Module management
# -----------------


func add_module(name, output_level = default_output_level, output_strategies = default_output_strategies, logfile = null):
	"""Add a new module with the given parameter or (by default) the
	default ones.
	Returns a reference to the instanced module."""
	if modules.has(name):
		info("The module '%s' already exists; discarding the call to add it anew." % name, PLUGIN_NAME)
	else:
		if logfile == null:
			logfile = get_external_sink(default_logfile_path)
		modules[name] = Module.new(name, output_level, output_strategies, logfile)
	return modules[name]


func get_module(module = default_module_name):
	"""Retrieve the given module if it exists; if not, it will be created."""
	if not modules.has(module):
		info("The requested module '%s' does not exist. It will be created with default values." % module, PLUGIN_NAME)
		add_module(module)
	return modules[module]


func get_modules():
	"""Retrieve the dictionary containing all modules."""
	return modules


# Logfiles management
# -------------------


func set_default_logfile_path(new_logfile_path, keep_old = false):
	"""Sets the new default logfile path. Unless configured otherwise with
	the optional keep_old argument, it will replace the logfile for all
	modules which were configured for the previous logfile path."""
	if new_logfile_path == default_logfile_path:
		return  # Nothing to do

	var old_logfile = get_external_sink(default_logfile_path)
	var new_logfile = null
	if external_sinks.has(new_logfile_path):  # Already exists
		new_logfile = external_sinks[new_logfile_path]
	else:  # Create a new logfile
		new_logfile = add_logfile(new_logfile_path)
		external_sinks[new_logfile_path] = new_logfile

	if not keep_old:  # Replace the old defaut logfile in all modules that used it
		for module in modules.values():
			if module.get_external_sink() == old_logfile:
				module.set_external_sink(new_logfile)
		external_sinks.erase(default_logfile_path)
	default_logfile_path = new_logfile_path


func get_default_logfile_path():
	"""Return the default logfile path."""
	return default_logfile_path


func add_logfile(logfile_path = default_logfile_path):
	"""Add a new logfile that can then be attached to one or more modules.
	Returns a reference to the instanced logfile."""
	if external_sinks.has(logfile_path):
		info("A logfile pointing to '%s' already exists; discarding the call to add it anew." % logfile_path, PLUGIN_NAME)
	else:
		external_sinks[logfile_path] = Logfile.new(logfile_path)
	return external_sinks[logfile_path]


func get_external_sink(_external_sink_name):
	"""Retrieve the first given external sink if it exists, otherwise returns null."""
	if not external_sinks.has(_external_sink_name):
		warn("The requested external sink pointing to '%s' does not exist." % _external_sink_name, PLUGIN_NAME)
		return null
	else:
		return external_sinks[_external_sink_name]


func get_external_sinks():
	"""Retrieve the dictionary containing all external sinks."""
	return external_sinks


func flush_buffers():
	"""Flush non-empty buffers."""
	var processed_external_sinks = []
	var external_sink = null
	for module in modules:
		external_sink = modules[module].get_external_sink()
		if external_sink in processed_external_sinks:
			continue
		external_sink.flush_buffer()
		processed_external_sinks.append(external_sink)


# Default output configuration
# ----------------------------


func set_default_output_strategy(output_strategy_mask, level = -1):
	"""Set the default output strategy mask of the given level or (by
	default) all levels for all modules without a custom strategy."""
	if not output_strategy_mask in range(0, MAX_STRATEGY + 1):
		error("The output strategy mask must be comprised between 0 and %d." % MAX_STRATEGY, PLUGIN_NAME)
		return
	if level == -1:  # Set for all levels
		for i in range(0, LEVELS.size()):
			default_output_strategies[i] = output_strategy_mask
		info("The default output strategy mask was set to '%d' for all levels." % [output_strategy_mask], PLUGIN_NAME)
	else:
		if not level in range(0, LEVELS.size()):
			error("The level must be comprised between 0 and %d." % (LEVELS.size() - 1), PLUGIN_NAME)
			return
		default_output_strategies[level] = output_strategy_mask
		info("The default output strategy mask was set to '%d' for the '%s' level." % [output_strategy_mask, LEVELS[level]], PLUGIN_NAME)


func get_default_output_strategy(level):
	"""Get the default output strategy mask of the given level or (by
	default) all levels for all modules without a custom strategy."""
	return default_output_strategies[level]


func set_default_output_level(level):
	"""Set the default minimal level for the output of all modules without
	a custom output level.
	All levels greater or equal to the given once will be output based on
	their respective strategies, while levels lower than the given one will
	be discarded.
	"""
	if not level in range(0, LEVELS.size()):
		error("The level must be comprised between 0 and %d." % (LEVELS.size() - 1), PLUGIN_NAME)
		return
	default_output_level = level
	info("The default output level was set to '%s'." % LEVELS[level], PLUGIN_NAME)


func get_default_output_level():
	"""Get the default minimal level for the output of all modules without
	a custom output level."""
	return default_output_level


# Output formatting
# -----------------


# Format the fields:
# * YYYY = Year
# * MM = Month
# * DD = Day
# * hh = Hour
# * mm = Minutes
# * ss = Seconds
# * SSS = Milliseconds
func get_formatted_datetime():
	var unix_time: float = Time.get_unix_time_from_system()
	var time_zone: Dictionary = Time.get_time_zone_from_system()
	unix_time += time_zone.bias * 60
	var datetime: Dictionary = Time.get_datetime_dict_from_unix_time(int(unix_time))
	datetime.millisecond = int(unix_time * 1000) % 1000
	var result = time_format
	result = result.replace("YYYY", "%04d" % [datetime.year])
	result = result.replace("MM", "%02d" % [datetime.month])
	result = result.replace("DD", "%02d" % [datetime.day])
	result = result.replace("hh", "%02d" % [datetime.hour])
	result = result.replace("mm", "%02d" % [datetime.minute])
	result = result.replace("ss", "%02d" % [datetime.second])
	result = result.replace("SSS", "%03d" % [datetime.millisecond])
	return result


func format(template, level, module, message, error_code = -1):
	var output = template
	output = output.replace(FORMAT_IDS.level, LEVELS[level])
	output = output.replace(FORMAT_IDS.module, module)
	output = output.replace(FORMAT_IDS.message, str(message))
	output = output.replace(FORMAT_IDS.time, get_formatted_datetime())

	# Error message substitution
	var error_message = ERROR_MESSAGES.get(error_code)
	if error_message != null:
		output = output.replace(FORMAT_IDS.error_message, " " + error_message)
	else:
		output = output.replace(FORMAT_IDS.error_message, "")

	return output


func set_output_format(new_format):
	"""Set the output string format using the following identifiers:
	{LVL} for the level, {MOD} for the module, {MSG} for the message.
	The three identifiers should be contained in the output format string.
	"""
	for key in FORMAT_IDS:
		if new_format.find(FORMAT_IDS[key]) == -1:
			error("Invalid output string format. It lacks the '%s' identifier." % FORMAT_IDS[key], PLUGIN_NAME)
			return
	output_format = new_format
	info("Successfully changed the output format to '%s'." % output_format, PLUGIN_NAME)


func get_output_format():
	"""Get the output string format."""
	return output_format


# Strategy "memory"
# -----------------


func set_max_memory_size(new_size):
	"""Set the maximum amount of messages to be remembered when
	using the STRATEGY_MEMORY output strategy."""
	if new_size <= 0:
		error("The maximum amount of remembered messages must be a positive non-null integer. Received %d." % new_size, PLUGIN_NAME)
		return

	var new_buffer = []
	var new_idx = 0
	new_buffer.resize(new_size)

	# Better algorithm welcome :D
	if memory_first_loop:
		var offset = 0
		if memory_idx > new_size:
			offset = memory_idx - new_size
			memory_first_loop = false
		else:
			new_idx = memory_idx
		for i in range(0, min(memory_idx, new_size)):
			new_buffer[i] = memory_buffer[i + offset]
	else:
		var delta = 0
		if max_memory_size > new_size:
			delta = max_memory_size - new_size
		else:
			new_idx = max_memory_size
			memory_first_loop = true
		for i in range(0, min(max_memory_size, new_size)):
			new_buffer[i] = memory_buffer[(memory_idx + delta + i) % max_memory_size]

	memory_buffer = new_buffer
	memory_idx = new_idx
	invalid_memory_cache = true
	max_memory_size = new_size
	info("Successfully set the maximum amount of remembered messages to %d." % max_memory_size, PLUGIN_NAME)


func get_max_memory_size():
	"""Get the maximum amount of messages to be remembered when
	using the STRATEGY_MEMORY output strategy."""
	return max_memory_size


func get_memory():
	"""Get an array of the messages remembered following STRATEGY_MEMORY.
	The messages are sorted from the oldest to the newest."""
	if invalid_memory_cache:  # Need to recreate the cached ordered array
		memory_cache = []
		if not memory_first_loop:  # else those would be uninitialized
			for i in range(memory_idx, max_memory_size):
				memory_cache.append(memory_buffer[i])
		for i in range(0, memory_idx):
			memory_cache.append(memory_buffer[i])
		invalid_memory_cache = false
	return memory_cache


func clear_memory():
	"""Clear the buffer or remembered messages."""
	memory_buffer.clear()
	memory_idx = 0
	memory_first_loop = true
	invalid_memory_cache = true


# Configuration loading/saving
# ----------------------------

const config_fields := {
	default_output_level = "default_output_level",
	default_output_strategies = "default_output_strategies",
	default_logfile_path = "default_logfile_path",
	max_memory_size = "max_memory_size",
	external_sinks = "external_sinks",
	modules = "modules"
}


func save_config(configfile = default_configfile_path):
	"""Save the default configuration as well as the set of modules and
	their respective configurations.
	The ConfigFile API is used to generate the config file passed as argument.
	A unique section is used, so that it can be merged in a project's engine.cfg.
	Returns an error code (OK or some ERR_*)."""
	var config = ConfigFile.new()

	# Store default config
	config.set_value(PLUGIN_NAME, config_fields.default_output_level, default_output_level)
	config.set_value(PLUGIN_NAME, config_fields.default_output_strategies, default_output_strategies)
	config.set_value(PLUGIN_NAME, config_fields.default_logfile_path, default_logfile_path)
	config.set_value(PLUGIN_NAME, config_fields.max_memory_size, max_memory_size)

	# External sink config
	var external_sinks_arr = []
	var sorted_keys = external_sinks.keys()
	sorted_keys.sort()  # Sadly doesn't return the array, so we need to split it
	for external_sink in sorted_keys:
		external_sinks_arr.append(external_sinks[external_sink].get_config())
	config.set_value(PLUGIN_NAME, config_fields.external_sinks, external_sinks_arr)

	# Modules config
	var modules_arr = []
	sorted_keys = modules.keys()
	sorted_keys.sort()
	for module in sorted_keys:
		modules_arr.append(modules[module].get_config())
	config.set_value(PLUGIN_NAME, config_fields.modules, modules_arr)

	# Save and return the corresponding error code
	var err = config.save(configfile)
	if err:
		error("Could not save the config in '%s'; exited with error %d." % [configfile, err], PLUGIN_NAME)
		return err
	info("Successfully saved the config to '%s'." % configfile, PLUGIN_NAME)
	return OK


func load_config(configfile = default_configfile_path):
	"""Load the configuration as well as the set of defined modules and
	their respective configurations. The expect file contents must be those
	produced by the ConfigFile API.
	Returns an error code (OK or some ERR_*)."""
	# Look for the file
	if not FileAccess.file_exists(configfile):
		warn("Could not load the config in '%s', the file does not exist." % configfile, PLUGIN_NAME)
		return ERR_FILE_NOT_FOUND

	# Load its contents
	var config = ConfigFile.new()
	var err = config.load(configfile)
	if err:
		warn("Could not load the config in '%s'; exited with error %d." % [configfile, err], PLUGIN_NAME)
		return err

	# Load default config
	default_output_level = config.get_value(PLUGIN_NAME, config_fields.default_output_level, default_output_level)
	default_output_strategies = config.get_value(PLUGIN_NAME, config_fields.default_output_strategies, default_output_strategies)
	default_logfile_path = config.get_value(PLUGIN_NAME, config_fields.default_logfile_path, default_logfile_path)
	max_memory_size = config.get_value(PLUGIN_NAME, config_fields.max_memory_size, max_memory_size)

	# Load external config and initialize them
	flush_buffers()
	external_sinks = {}
	add_logfile(default_logfile_path)
	for logfile_cfg in config.get_value(PLUGIN_NAME, config_fields.external_sinks, []):
		var logfile = Logfile.new(logfile_cfg["path"], logfile_cfg["queue_mode"])
		external_sinks[logfile_cfg["path"]] = logfile

	# Load modules config and initialize them
	modules = {}
	add_module(PLUGIN_NAME)
	add_module(default_module_name)
	for module_cfg in config.get_value(PLUGIN_NAME, config_fields.modules, []):
		var module = Module.new(
			module_cfg["name"], module_cfg["output_level"], module_cfg["output_strategies"], get_external_sink(module_cfg["external_sink"]["path"])
		)
		modules[module_cfg["name"]] = module

	info("Successfully loaded the config from '%s'." % configfile, PLUGIN_NAME)
	return OK


##=============##
##  Callbacks  ##
##=============##


func _init():
	# Default logfile
	add_logfile(default_logfile_path)
	# Default modules
	add_module(PLUGIN_NAME)  # needs to be instanced first
	add_module(default_module_name)
	memory_buffer.resize(max_memory_size)


func _exit_tree():
	flush_buffers()