module Protocol::HTTP::URL

def self.assign(keys, value, parent)
	top, *middle = keys
	
	middle.each_with_index do |key, index|
		if key.nil? or key.empty?
			parent = (parent[top] ||= Array.new)
			top = parent.size
			
			if nested = middle[index+1] and last = parent.last
				top -= 1 unless last.include?(nested)
			end
		else
			parent = (parent[top] ||= Hash.new)
			top = key
		end
	end
	
	parent[top] = value
end

def self.decode(string, maximum = 8, symbolize_keys: false)
	parameters = {}
	
	self.scan(string) do |name, value|
		keys = self.split(name)
		
		if keys.count > maximum
			raise ArgumentError, "Key length exceeded limit!"
		end
		
		if symbolize_keys
			keys.collect!{|key| key.empty? ? nil : key.to_sym}
		end
		
		self.assign(keys, value, parameters)
	end
	
	return parameters
end

def self.encode(value, prefix = nil)
	case value
	when Array
		return value.map {|v|
			self.encode(v, "#{prefix}[]")
		}.join("&")
	when Hash
		return value.map {|k, v|
			self.encode(v, prefix ? "#{prefix}[#{escape(k.to_s)}]" : escape(k.to_s))
		}.reject(&:empty?).join('&')
	when nil
		return prefix
	else
		raise ArgumentError, "value must be a Hash" if prefix.nil?
		
		return "#{prefix}=#{escape(value.to_s)}"
	end
end

def self.escape(string, encoding = string.encoding)
	string.b.gsub(/([^a-zA-Z0-9_.\-]+)/) do |m|
		'%' + m.unpack('H2' * m.bytesize).join('%').upcase
	end.force_encoding(encoding)
end

def self.escape_path(path)
	encoding = path.encoding
	path.b.gsub(NON_PCHAR) do |m|
		'%' + m.unpack('H2' * m.bytesize).join('%').upcase
	end.force_encoding(encoding)
end

def self.scan(string)
	# TODO Ruby 2.6 doesn't require `.each`
	string.split('&').each do |assignment|
		key, value = assignment.split('=', 2)
		
		yield unescape(key), unescape(value)
	end
end

def self.split(name)
	name.scan(/([^\[]+)|(?:\[(.*?)\])/).flatten!.compact!
end

def self.unescape(string, encoding = string.encoding)
	string.b.gsub(/%(\h\h)/) do |hex|
		Integer(hex, 16).chr
	end.force_encoding(encoding)
end