/*
DESCRIPTION
  logger.go provides a "safe" global logger by following the singleton pattern.
  Usage of this should be avoided if possible, but in some instances it might be
  necessary, for example implementations of interfaces where logging is required
  but do not offer parameters where a logger can be passed as an argument.

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>

LICENSE
  Copyright (C) 2022 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
*/

package global

import "bitbucket.org/ausocean/utils/logging"

var logger *globalLogger = nil

type globalLogger struct {
	logging.Logger
}

// SetLogger sets the global logger. This must be set, and only once, before
// the GetLogger function is called. If these requirements are violated panics
// will occur.
func SetLogger(l logging.Logger) {
	if logger != nil {
		logger.Fatal("attempting set of already instantiated global logger")
	}
	logger = &globalLogger{l}
}

// GetLogger returns the global logger. If this has not been set, a panic will
// occur.
func GetLogger() logging.Logger {
	if logger == nil {
		panic("attempted get of uninstantiated global logger")
	}
	// We want to return the underlying logger.
	return logger.Logger
}