package api

import (
	"fmt"
	"net"
	"os"
	"path/filepath"
	"regexp"
)

// getExeFilename
func getExeFilename() string {
	_, logfilename := filepath.Split(os.Args[0])
	if logfilename == "" {
		panic("get exe filename failed")
	}
	return logfilename
}

// preferencesMatch
func preferencesMatch(s string, preferences ...string) bool {
	for _, pstr := range preferences {
		reg := regexp.MustCompile(pstr)
		if reg.Match([]byte(s)) {
			return true
		}
	}
	return false
}

// getInstanceIpAddress
func getInstanceIpAddress(preferences ...string) string {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		panic(fmt.Sprintf("getInstanceIpAddress failed: [%s]", err))
	}

	prefer := func() func(string) bool {
		if len(preferences) <= 0 {
			return nil
		}
		return func(ip string) bool {
			return preferencesMatch(ip, preferences...)
		}
	}()

	var ipnets = []*net.IPNet{}
	for _, address := range addrs {
		if ipnet, ok := address.(*net.IPNet); !ok {
			continue
		} else if ipnet.IP.IsLoopback() {
			continue
		} else if ipv4 := ipnet.IP.To4(); ipv4 == nil {
			continue
		} else if prefer == nil {
			var n = *ipnet
			ipnets = append(ipnets, &n)
			continue
		} else if prefer != nil && prefer(ipv4.String()) {
			return ipv4.String()
		}
	}

	// TODO: sort & return first
	if len(ipnets) > 0 {
		return ipnets[0].IP.To4().String()
	}
	panic(fmt.Sprintf("getInstanceIpAddreass failed,"+
		"preferences=[%v], ipnets=[%v]", preferences, ipnets))
}