micro/router/route.go

package router

import (
	"fmt"
	"strings"

	"github.com/olekukonko/tablewriter"
)

var (
	// DefaultLocalMetric is default route cost for local network
	DefaultLocalMetric = 1
	// DefaultNetworkMetric is default route cost for micro network
	DefaultNetworkMetric = 10
)

// RoutePolicy defines routing table addition policy
type RoutePolicy int

const (
	// OverrideIfExists overrides route if it already exists
	OverrideIfExists RoutePolicy = iota
	// IgnoreIfExists does not modify existing route
	IgnoreIfExists
)

// String returns human reprensentation of policy
func (p RoutePolicy) String() string {
	switch p {
	case OverrideIfExists:
		return "OVERRIDE"
	case IgnoreIfExists:
		return "IGNORE"
	default:
		return "UNKNOWN"
	}
}

// Route is network route
type Route struct {
	// Destination is destination address
	Destination string
	// Router is the network router
	Router Router
	// Network is micro network address
	Network string
	// Metric is the route cost metric
	Metric int
	// Policy defines route policy
	Policy RoutePolicy
}

// String allows to print the route
func (r *Route) String() string {
	// this will help us build routing table string
	sb := &strings.Builder{}

	// create nice table printing structure
	table := tablewriter.NewWriter(sb)
	table.SetHeader([]string{"Destination", "Router", "Network", "Metric"})

	strRoute := []string{
		r.Destination,
		r.Router.Address(),
		r.Network,
		fmt.Sprintf("%d", r.Metric),
	}
	table.Append(strRoute)

	// render table into sb
	table.Render()

	return sb.String()
}