# Log messages to a file
#
# ~~~
# var log_file = "my_file.log"
# var logger = new FileLogger(warn_level, log_file, append = false)
# logger.error("An error")
# logger.info("Some info")
# logger.close
# assert log_file.to_path.read_all == "An error\n"
#
# logger = new FileLogger(warn_level, log_file, append = true)
# logger.error("Another error")
# logger.close
# assert log_file.to_path.read_all == "An error\nAnother error\n"
#
# log_file.to_path.delete
# ~~~
class FileLogger
	super Logger
	autoinit level, file, append, default_formatter

	redef type OUT: FileWriter

	# File where messages will be written
	var file: String

	# Append messages to `file`
	#
	# If `append` is `false`, the `file` will be overwritten.
	var append: Bool = true is optional

	init do
		var old = null
		if append then
			old = file.to_path.read_all
		end
		out = new FileWriter.open(file)
		out.set_buffering_mode(0, buffer_mode_line)
		if old != null then
			out.write(old)
		end
	end

	# Close the logger and its `file`
	fun close do out.close
end