package http

import (
	"fmt"
	"net"
	"strconv"
	"strings"

	"github.com/micro/go-micro/registry"
	"github.com/micro/go-micro/server"
)

var (
	privateBlocks []*net.IPNet
)

func init() {
	for _, b := range []string{"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"} {
		if _, block, err := net.ParseCIDR(b); err == nil {
			privateBlocks = append(privateBlocks, block)
		}
	}
}

func extractAddress(addr string) (string, error) {
	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]") {
		return addr, nil
	}

	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return "", fmt.Errorf("Failed to get interface addresses! Err: %v", err)
	}

	var ipAddr []byte

	for _, rawAddr := range addrs {
		var ip net.IP
		switch addr := rawAddr.(type) {
		case *net.IPAddr:
			ip = addr.IP
		case *net.IPNet:
			ip = addr.IP
		default:
			continue
		}

		if ip.To4() == nil {
			continue
		}

		if !isPrivateIP(ip.String()) {
			continue
		}

		ipAddr = ip
		break
	}

	if ipAddr == nil {
		return "", fmt.Errorf("No private IP address found, and explicit IP not provided")
	}

	return net.IP(ipAddr).String(), nil
}

func isPrivateIP(ipAddr string) bool {
	ip := net.ParseIP(ipAddr)
	for _, priv := range privateBlocks {
		if priv.Contains(ip) {
			return true
		}
	}
	return false
}

func serviceDef(opts server.Options) *registry.Service {
	var advt, host string
	var port int

	if len(opts.Advertise) > 0 {
		advt = opts.Advertise
	} else {
		advt = opts.Address
	}

	parts := strings.Split(advt, ":")
	if len(parts) > 1 {
		host = strings.Join(parts[:len(parts)-1], ":")
		port, _ = strconv.Atoi(parts[len(parts)-1])
	} else {
		host = parts[0]
	}

	addr, err := extractAddress(host)
	if err != nil {
		addr = host
	}

	node := &registry.Node{
		Id:       opts.Name + "-" + opts.Id,
		Address:  addr,
		Port:     port,
		Metadata: opts.Metadata,
	}

	node.Metadata["server"] = "http"

	return &registry.Service{
		Name:    opts.Name,
		Version: opts.Version,
		Nodes:   []*registry.Node{node},
	}
}