class Localhost::Authority

def self.fetch(*arguments, **options)
	authority = self.new(*arguments, **options)
	
	unless authority.load
		authority.save
	end
	
	return authority
end

def self.list(root = self.path)
	return to_enum(:list, root) unless block_given?
	
	Dir.glob("*.crt", base: root) do |path|
		name = File.basename(path, ".crt")
		
		authority = self.new(name, root: root)
		
		if authority.load
			yield authority
		end
	end
end

def self.path(env = ENV, old_root: nil)
	path = File.expand_path("localhost.rb", env.fetch("XDG_STATE_HOME", "~/.local/state"))
	
	unless File.directory?(path)
		FileUtils.mkdir_p(path, mode: 0700)
	end
	
	# Migrates the legacy dir ~/.localhost/ to the XDG compliant directory
	old_root ||= File.expand_path("~/.localhost")
	if File.directory?(old_root)
		FileUtils.mv(Dir.glob(File.join(old_root, "*")), path, force: true)
		FileUtils.rmdir(old_root)
	end
	
	return path
end

def certificate
	@certificate ||= OpenSSL::X509::Certificate.new.tap do |certificate|
		certificate.subject = self.name
		# We use the same issuer as the subject, which makes this certificate self-signed:
		certificate.issuer = self.name
		
		certificate.public_key = self.key.public_key
		
		certificate.serial = Time.now.to_i
		certificate.version = 2
		
		certificate.not_before = Time.now
		certificate.not_after = Time.now + (3600 * 24 * 365)
		
		extension_factory = OpenSSL::X509::ExtensionFactory.new
		extension_factory.subject_certificate = certificate
		extension_factory.issuer_certificate = certificate
		
		certificate.extensions = [
			extension_factory.create_extension("basicConstraints", "CA:FALSE", true),
			extension_factory.create_extension("subjectKeyIdentifier", "hash"),
		]
		
		certificate.add_extension extension_factory.create_extension("authorityKeyIdentifier", "keyid:always,issuer:always")
		certificate.add_extension extension_factory.create_extension("subjectAltName", "DNS: #{@hostname}")
		
		certificate.sign self.key, OpenSSL::Digest::SHA256.new
	end
end

def certificate_path
	File.join(@root, "#{@hostname}.crt")
end

def client_context(*args)
	OpenSSL::SSL::SSLContext.new(*args).tap do |context|
		context.cert_store = self.store
		
		context.set_params(
			verify_mode: OpenSSL::SSL::VERIFY_PEER,
		)
	end
end

def dh_key
	@dh_key ||= OpenSSL::PKey::DH.new(BITS)
end

def initialize(hostname = "localhost", root: self.class.path)
	@root = root
	@hostname = hostname
	
	@key = nil
	@name = nil
	@certificate = nil
	@store = nil
end

def key
	@key ||= OpenSSL::PKey::RSA.new(BITS)
end

def key= key
	@key = key
end

def key_path
	File.join(@root, "#{@hostname}.key")
end

def load(path = @root)
	certificate_path = File.join(path, "#{@hostname}.crt")
	key_path = File.join(path, "#{@hostname}.key")
	
	return false unless File.exist?(certificate_path) and File.exist?(key_path)
	
	certificate = OpenSSL::X509::Certificate.new(File.read(certificate_path))
	key = OpenSSL::PKey::RSA.new(File.read(key_path))
	
	# Certificates with old version need to be regenerated.
	return false if certificate.version < 2
	
	@certificate = certificate
	@key = key
	
	return true
end

def name
	@name ||= OpenSSL::X509::Name.parse("/O=Development/CN=#{@hostname}")
end

def name= name
	@name = name
end

def save(path = @root)
	lockfile_path = File.join(path, "#{@hostname}.lock")
	
	File.open(lockfile_path, File::RDWR|File::CREAT, 0644) do |lockfile|
		lockfile.flock(File::LOCK_EX)
		
		File.write(
			File.join(path, "#{@hostname}.crt"),
			self.certificate.to_pem
		)
		
		File.write(
			File.join(path, "#{@hostname}.key"),
			self.key.to_pem
		)
	end
end

def server_context(*arguments)
	OpenSSL::SSL::SSLContext.new(*arguments).tap do |context|
		context.key = self.key
		context.cert = self.certificate
		
		context.session_id_context = "localhost"
		
		if context.respond_to? :tmp_dh_callback=
			context.tmp_dh_callback = proc {self.dh_key}
		end
		
		if context.respond_to? :ecdh_curves=
			context.ecdh_curves = 'P-256:P-384:P-521'
		end
		
		context.set_params(
			ciphers: SERVER_CIPHERS,
			verify_mode: OpenSSL::SSL::VERIFY_NONE,
		)
	end
end

def store
	@store ||= OpenSSL::X509::Store.new.tap do |store|
		store.add_cert(self.certificate)
	end
end