require 'yaml'

class Settings
	def initialize
		@settings = {}
		@setting_callbacks = {}
	end

	def on_change(key, &proc)
		@setting_callbacks[key] ||= []
		@setting_callbacks[key] << proc
	end

	def load(path)
		File.open(path, 'r') { |file|
			load_settings_from_file(file)
		} rescue nil
		self
	end

	def save(path)
		File.open(path, 'w') { |file|
			save_settings_to_file(file)
		} rescue nil
		self
	end

	def [](key)
		@settings[key]
	end

	def []=(key, value)
		return if (@settings[key] && @settings[key] == value)
		@settings[key] = value
		@setting_callbacks[key].each { |proc| proc.call(value) } if @setting_callbacks[key]
	end

private

	def load_settings_from_file(file)
		settings = YAML.load(file)
		@settings = settings if settings.is_a? Hash
	end

	def save_settings_to_file(file)
		YAML.dump(@settings, file)
	end
end