require 'set'

module VagrantPlugins
  module VCloud
    module Action
      # This middleware class will detect and handle collisions with
      # forwarded ports, whether that means raising an error or repairing
      # them automatically.
      #
      # Parameters it takes from the environment hash:
      #
      #   * `:port_collision_repair` - If true, it will attempt to repair
      #     port collisions. If false, it will raise an exception when
      #     there is a collision.
      #
      #   * `:port_collision_extra_in_use` - An array of ports that are
      #     considered in use.
      #
      #   * `:port_collision_remap` - A hash remapping certain host ports
      #     to other host ports.
      #
      class HandleNATPortCollisions
        def initialize(app, env)
          @app    = app
          @logger = Log4r::Logger.new(
            'vagrant_vcloud::action::handle_port_collisions'
          )
        end

        def call(env)
          @logger.info('Detecting any forwarded port collisions...')

          # Determine a list of usable ports for repair
          usable_ports = Set.new(env[:machine].config.vm.usable_port_range)

          # Pass one, remove all defined host ports from usable ports
          with_forwarded_ports(env) do |options|
            usable_ports.delete(options[:host])
          end

          cfg = env[:machine].provider_config
          cnx = cfg.vcloud_cnx.driver
          vapp_id = env[:machine].get_vapp_id

          @logger.debug('Getting VM info...')
          vm_name = env[:machine].name
          vm = cnx.get_vapp(vapp_id)
          vm_info = vm[:vms_hash][vm_name.to_sym]

          vapp_edge_ip = cnx.get_vapp_edge_public_ip(vapp_id)

          @logger.debug('Getting edge gateway port forwarding rules...')
          edge_gateway_rules = cnx.get_edge_gateway_rules(cfg.vdc_edge_gateway,
                                                          cfg.vdc_id)
          edge_dnat_rules = edge_gateway_rules.select {|r| (r[:rule_type] == 'DNAT' && r[:translated_ip] != vapp_edge_ip)}
          edge_ports_in_use = edge_dnat_rules.map{|r| r[:original_port].to_i}.to_set

          @logger.debug('Getting port forwarding rules...')
          vapp_nat_rules = cnx.get_vapp_port_forwarding_rules(vapp_id)
          ports_in_use = vapp_nat_rules.map{|r| r[:nat_external_port].to_i}.to_set

          # merge the vapp ports and the edge gateway ports together, all are in use
          ports_in_use = ports_in_use | edge_ports_in_use

          # Pass two, detect/handle any collisions
          with_forwarded_ports(env) do |options|
            guest_port = options[:guest]
            host_port  = options[:host]

            # Find if there already is a NAT rule to guest_port of this VM
            if r = vapp_nat_rules.find { |rule| (rule[:vapp_scoped_local_id] == vm_info[:vapp_scoped_local_id] &&
                                                 rule[:nat_internal_port] == guest_port.to_s) }
              host_port = r[:nat_external_port].to_i
              @logger.info(
                "Found existing port forwarding rule #{host_port} to #{guest_port}"
              )
              options[:host] = host_port
              options[:already_exists] = true
            else
              # If the port is open (listening for TCP connections)
              if ports_in_use.include?(host_port)
                if !options[:auto_correct]
                  raise Errors::ForwardPortCollision,
                    :guest_port => guest_port.to_s,
                    :host_port  => host_port.to_s
                end

                @logger.info("Attempting to repair FP collision: #{host_port}")

                repaired_port = nil
                while !usable_ports.empty?
                  # Attempt to repair the forwarded port
                  repaired_port = usable_ports.to_a.sort[0]
                  usable_ports.delete(repaired_port)

                  # If the port is in use, then we can't use this either...
                  if ports_in_use.include?(repaired_port)
                    @logger.info(
                      "Repaired port also in use: #{repaired_port}." +
                      'Trying another...'
                    )
                    next
                  end

                  # We have a port so break out
                  break
                end

                # If we have no usable ports then we can't repair
                if !repaired_port && usable_ports.empty?
                  raise Errors::ForwardPortAutolistEmpty,
                        :vm_name    => env[:machine].name,
                        :guest_port => guest_port.to_s,
                        :host_port  => host_port.to_s
                end

                # Modify the args in place
                options[:host] = repaired_port

                @logger.info(
                  "Repaired FP collision: #{host_port} to #{repaired_port}"
                )

                # Notify the user
                env[:ui].info(
                  I18n.t(
                    'vagrant.actions.vm.forward_ports.fixed_collision',
                    :host_port  => host_port.to_s,
                    :guest_port => guest_port.to_s,
                    :new_port   => repaired_port.to_s
                  )
                )
              end
            end
          end

          @app.call(env)
        end

        protected

        def with_forwarded_ports(env)
          env[:machine].config.vm.networks.each do |type, options|
            # Ignore anything but forwarded ports
            next if type != :forwarded_port

            yield options
          end
        end
      end
    end
  end
end