class Samovar::Options

def self.parse(*arguments, **options, &block)
	options = self.new(*arguments, **options)
	
	options.instance_eval(&block) if block_given?
	
	return options.freeze
end

def << option
	@ordered << option
	option.flags.each do |flag|
		@keyed[flag.prefix] = option
		
		flag.alternatives.each do |alternative|
			@keyed[alternative] = option
		end
	end
	
	if default = option.default
		@defaults[option.key] = option.default
	end
end

def each(&block)
	@ordered.each(&block)
end

def empty?
	@ordered.empty?
end

def freeze
	return self if frozen?
	
	@ordered.freeze
	@keyed.freeze
	@defaults.freeze
	
	@ordered.each(&:freeze)
	
	super
end

def initialize(title = "Options", key: :options)
	@title = title
	@ordered = []
	
	# We use this flag to option cache to improve parsing performance:
	@keyed = {}
	
	@key = key
	
	@defaults = {}
end

def initialize_dup(source)
	super
	
	@ordered = @ordered.dup
	@keyed = @keyed.dup
	@defaults = @defaults.dup
end

def merge!(options)
	options.each do |option|
		self << option
	end
end

def option(*arguments, **options, &block)
	self << Option.new(*arguments, **options, &block)
end

def parse(input, parent = nil, default = nil)
	values = (default || @defaults).dup
	
	while option = @keyed[input.first]
		prefix = input.first
		result = option.parse(input)
		if result != nil
			values[option.key] = result
		end
	end
	
	return values
end

def to_s
	@ordered.collect(&:to_s).join(' ')
end

def usage(rows)
	@ordered.each do |option|
		rows << option
	end
end