class NetworkConfigurationParser
	def self.parse_file(file_name : String) : InterfaceConfiguration
		content = File.read(file_name)
		content = content.rchop
		ifname = /.([a-zA-Z0-9]+)$/.match(file_name).try &.[1]
		if ifname.nil?
			raise "The interface name is not known from the filename: '#{file_name}'"
		end

		self.parse(ifname.not_nil!, content)
	end

	def self.parse (ifname : String, data : String) : InterfaceConfiguration
		up = false
		description = nil
		mtu = nil
		main_ip_v4 = NotSetup.new
		main_ip_v6 = NotSetup.new

		dns = NetworkCommands::DNS.new

		aliasses = [] of IPAddress

		wireless_networks = {} of String => WirelessAPSetup

		data.split("\n").each do |line|
			case line
			when /^up/
				up = true
			when /^description/
				description = /^description (.+)/.match(line).try &.[1]
			when /^inet6? alias (?<ip>[a-f0-9:.\/]+)/
				ipstr = $~["ip"]
				if ipstr.nil?
					puts "wrong IP address alias, line #{line}"
					next
				end
				aliasses.push IPAddress.parse(ipstr)
			when /^inet6? dhcp/
				# IP address is DHCP
				if /^inet /.match(line)
					main_ip_v4 = DHCP.new
				else
					main_ip_v6 = DHCP.new
				end
			when /^inet6 autoconf/
				# IP address is autoconfigured
				main_ip_v6 = Autoconfiguration.new

			when /^inet6? (?<ip>[a-f0-9:.\/]+)/
				ipstr = $~["ip"]
				if ipstr.nil?
					puts "wrong IP address, line #{line}"
					next
				end
				if /^inet /.match(line)
					main_ip_v4 = IPAddress.parse ipstr
				else
					main_ip_v6 = IPAddress.parse ipstr
				end

			when /^join (?<ssid>[^ \t]+) wpakey (?<wpakey>[^ \t]+)/
				# WPA2-PSK, other security mechanisms are not supported, yet
				ssid = $~["ssid"]
				wpakeystr = $~["wpakey"]

				if ssid.nil?
					puts "wrong SSID in line: #{line}"
					next
				end

				if wpakeystr.nil?
					puts "wrong wpa key in line: #{line}"
					next
				end

				new_ap = WirelessAPSetup.new ifname, ssid, WirelessAPSetup::WPA.new(wpakeystr)
				wireless_networks[ssid] = new_ap

			when /^network (?<ssid>[^ \t]+) inet6 autoconf/
				ssid = $~["ssid"]

				if ssid.nil?
					puts "wrong SSID in line: #{line}"
					next
				end

				access_point = wireless_networks[ssid].not_nil!
				access_point.main_ip_v6 = Autoconfiguration.new

			when /^network (?<ssid>[^ \t]+) inet6? (?<ip>[^ \t]+)/
				ssid = $~["ssid"]
				ipstr = $~["ip"]

				if ssid.nil?
					puts "wrong SSID in line: #{line}"
					next
				end

				if ipstr.nil?
					puts "wrong ip address in line: #{line}"
					next
				end

				ipaddr = IPAddress.parse ipstr
				access_point = wireless_networks[ssid].not_nil!

				if ipaddr.ipv4?
					access_point.main_ip_v4 = ipaddr
				elsif ipaddr.ipv6?
					access_point.main_ip_v6 = ipaddr
				else
					puts "wrong ip address in line: #{line} (neither ipv4 or ipv6)"
				end

			when /^network (?<ssid>[^ \t]+) dhcp6?/
				ssid = $~["ssid"]

				if ssid.nil?
					puts "wrong SSID in line: #{line}"
					next
				end

				access_point = wireless_networks[ssid].not_nil!

				if /dhcp6/.match(line)
					access_point.main_ip_v6 = DHCP.new
				elsif /dhcp/.match(line)
					access_point.main_ip_v4 = DHCP.new
				else
					puts "wrong dhcp instruction in line: #{line}"
				end

			when /^network (?<ssid>[^ \t]+) dns (?<ip>[^ \t]+)/
				ssid = $~["ssid"]
				ipstr = $~["ip"]

				if ssid.nil?
					puts "wrong SSID in line: #{line}"
					next
				end

				if ipstr.nil?
					puts "wrong ip address in line: #{line}"
					next
				end

				access_point = wireless_networks[ssid].not_nil!
				ipaddr = IPAddress.parse ipstr
				access_point.dns.addresses << ipaddr.to_s

			when /^mtu (?<mtu>[0-9]+)/
				mtu = $~["mtu"].to_i

			when /^dns (?<ip>[^ \t]+)/
				ipstr = $~["ip"]

				if ipstr.nil?
					puts "wrong ip address in line: #{line}"
					next
				end

				ipaddr = IPAddress.parse ipstr
				dns.addresses << ipaddr.to_s

			when /^#.*$/
				# simple comment
			when /^[ \t]*$/
				# empty line
			else
				raise "Cannot parse: #{line}"
			end
		end

		InterfaceConfiguration.new(ifname, up,
								   description,
								   mtu,
								   main_ip_v4, main_ip_v6,
								   aliasses,
								   wireless_networks,
								   dns)
	end
end