require "tempfile"

require_relative "../../../../lib/vagrant/util/template_renderer"

module VagrantPlugins
  module GuestDebian
    module Cap
      class ConfigureNetworks
        include Vagrant::Util
        extend Vagrant::Util::GuestInspection::Linux

        NETPLAN_DEFAULT_VERSION = 2
        NETPLAN_DEFAULT_RENDERER = "networkd".freeze
        NETPLAN_DIRECTORY = "/etc/netplan".freeze
        NETWORKD_DIRECTORY = "/etc/systemd/network".freeze


        def self.configure_networks(machine, networks)
          comm = machine.communicate
          interfaces = machine.guest.capability(:network_interfaces)

          if systemd?(comm)
            if netplan?(comm)
              configure_netplan(machine, interfaces, comm, networks)
            elsif systemd_networkd?(comm)
              configure_networkd(machine, interfaces, comm, networks)
            else
              configure_nettools(machine, interfaces, comm, networks)
            end
          else
            configure_nettools(machine, interfaces, comm, networks)
          end
        end

        # Configure networking using netplan
        def self.configure_netplan(machine, interfaces, comm, networks)
          ethernets = {}.tap do |e_nets|
            networks.each do |network|
              e_config = {}.tap do |entry|
                if network[:type].to_s == "dhcp"
                  entry["dhcp4"] = true
                else
                  mask = network[:netmask]
                  if mask && IPAddr.new(network[:ip]).ipv4?
                    begin
                      mask = IPAddr.new(mask).to_i.to_s(2).count("1")
                    rescue IPAddr::Error
                      # ignore and use given value
                    end
                  end
                  entry["addresses"] = [[network[:ip], mask].compact.join("/")]
                end
                if network[:gateway]
                  entry["gateway4"] = network[:gateway]
                end
              end
              e_nets[interfaces[network[:interface]]] = e_config
            end
          end

          # By default, netplan expects the renderer to be systemd-networkd,
          # but if any device is managed by NetworkManager, then we use that renderer
          # ref: https://netplan.io/reference
          renderer = NETPLAN_DEFAULT_RENDERER
          ethernets.keys.each do |k|
            if nm_controlled?(comm, k)
              renderer = "NetworkManager"
              break
            end
          end

          np_config = {"network" => {"version" => NETPLAN_DEFAULT_VERSION,
            "renderer" => renderer, "ethernets" => ethernets}}

          remote_path = upload_tmp_file(comm, np_config.to_yaml)
          dest_path = "#{NETPLAN_DIRECTORY}/50-vagrant.yaml"
          comm.sudo(["mv -f '#{remote_path}' '#{dest_path}'",
            "chown root:root '#{dest_path}'",
            "chmod 0644 '#{dest_path}'",
            "netplan apply"].join("\n"))
        end

        # Configure guest networking using networkd
        def self.configure_networkd(machine, interfaces, comm, networks)
          root_device = interfaces.first
          networks.each do |network|
            dev_name = interfaces[network[:interface]]
            net_conf = []
            net_conf << "[Match]"
            net_conf << "Name=#{dev_name}"
            net_conf << "[Network]"
            if network[:type].to_s == "dhcp"
              net_conf << "DHCP=yes"
            else
              mask = network[:netmask]
              if mask && IPAddr.new(network[:ip]).ipv4?
                begin
                  mask = IPAddr.new(mask).to_i.to_s(2).count("1")
                rescue IPAddr::Error
                  # ignore and use given value
                end
              end
              address = [network[:ip], mask].compact.join("/")
              net_conf << "DHCP=no"
              net_conf << "Address=#{address}"
              net_conf << "Gateway=#{network[:gateway]}" if network[:gateway]
            end

            remote_path = upload_tmp_file(comm, net_conf.join("\n"))
            dest_path = "#{NETWORKD_DIRECTORY}/50-vagrant-#{dev_name}.network"
            comm.sudo(["mkdir -p #{NETWORKD_DIRECTORY}",
              "mv -f '#{remote_path}' '#{dest_path}'",
              "chown root:root '#{dest_path}'",
              "chmod 0644 '#{dest_path}'"].join("\n"))
          end

          comm.sudo(["systemctl restart systemd-networkd.service"].join("\n"))
        end

        # Configure guest networking using net-tools
        def self.configure_nettools(machine, interfaces, comm, networks)
          commands = []
          entries = []
          root_device = interfaces.first
          networks.each do |network|
            network[:device] = interfaces[network[:interface]]

            entry = TemplateRenderer.render("guests/debian/network_#{network[:type]}",
              options: network.merge(:root_device => root_device),
            )
            entries << entry
          end

          content = entries.join("\n")
          remote_path = "/tmp/vagrant-network-entry"
          upload_tmp_file(comm, content, remote_path)

          networks.each do |network|
            # Ubuntu 16.04+ returns an error when downing an interface that
            # does not exist. The `|| true` preserves the behavior that older
            # Ubuntu versions exhibit and Vagrant expects (GH-7155)
            commands << "/sbin/ifdown '#{network[:device]}' || true"
            commands << "/sbin/ip addr flush dev '#{network[:device]}'"
          end

          # Reconfigure /etc/network/interfaces.
          commands << <<-EOH.gsub(/^ {12}/, "")
            # Remove any previous network modifications from the interfaces file
            sed -e '/^#VAGRANT-BEGIN/,$ d' /etc/network/interfaces > /tmp/vagrant-network-interfaces.pre
            sed -ne '/^#VAGRANT-END/,$ p' /etc/network/interfaces | tac | sed -e '/^#VAGRANT-END/,$ d' | tac > /tmp/vagrant-network-interfaces.post
            cat \\
              /tmp/vagrant-network-interfaces.pre \\
              /tmp/vagrant-network-entry \\
              /tmp/vagrant-network-interfaces.post \\
              > /etc/network/interfaces
            rm -f /tmp/vagrant-network-interfaces.pre
            rm -f /tmp/vagrant-network-entry
            rm -f /tmp/vagrant-network-interfaces.post
          EOH

          # Bring back up each network interface, reconfigured.
          networks.each do |network|
            commands << "/sbin/ifup '#{network[:device]}'"
          end
          comm.sudo(commands.join("\n"))
        end

        # Simple helper to upload content to guest temporary file
        #
        # @param [Vagrant::Plugin::Communicator] comm
        # @param [String] content
        # @return [String] remote path
        def self.upload_tmp_file(comm, content, remote_path=nil)
          if remote_path.nil?
            remote_path = "/tmp/vagrant-network-entry-#{Time.now.to_i}"
          end
          Tempfile.open("vagrant-debian-configure-networks") do |f|
            f.binmode
            f.write(content)
            f.fsync
            f.close
            comm.upload(f.path, remote_path)
          end
          remote_path
        end
      end
    end
  end
end