// Copyright 2013 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ipv6_test

import (
	"net"
	"testing"
)

func isLinkLocalUnicast(ip net.IP) bool {
	return ip.To4() == nil && ip.To16() != nil && ip.IsLinkLocalUnicast()
}

func loopbackInterface() *net.Interface {
	ift, err := net.Interfaces()
	if err != nil {
		return nil
	}
	for _, ifi := range ift {
		if ifi.Flags&net.FlagLoopback == 0 || ifi.Flags&net.FlagUp == 0 {
			continue
		}
		ifat, err := ifi.Addrs()
		if err != nil {
			continue
		}
		for _, ifa := range ifat {
			switch ifa := ifa.(type) {
			case *net.IPAddr:
				if isLinkLocalUnicast(ifa.IP) {
					return &ifi
				}
			case *net.IPNet:
				if isLinkLocalUnicast(ifa.IP) {
					return &ifi
				}
			}
		}
	}
	return nil
}

func isMulticastAvailable(ifi *net.Interface) (net.IP, bool) {
	if ifi == nil || ifi.Flags&net.FlagUp == 0 || ifi.Flags&net.FlagMulticast == 0 {
		return nil, false
	}
	ifat, err := ifi.Addrs()
	if err != nil {
		return nil, false
	}
	for _, ifa := range ifat {
		switch ifa := ifa.(type) {
		case *net.IPAddr:
			if isLinkLocalUnicast(ifa.IP) {
				return ifa.IP, true
			}
		case *net.IPNet:
			if isLinkLocalUnicast(ifa.IP) {
				return ifa.IP, true
			}
		}
	}
	return nil, false
}

func connector(t *testing.T, network, addr string, done chan<- bool) {
	defer func() { done <- true }()

	c, err := net.Dial(network, addr)
	if err != nil {
		t.Errorf("net.Dial failed: %v", err)
		return
	}
	c.Close()
}

func acceptor(t *testing.T, ln net.Listener, done chan<- bool) {
	defer func() { done <- true }()

	c, err := ln.Accept()
	if err != nil {
		t.Errorf("net.Listener.Accept failed: %v", err)
		return
	}
	c.Close()
}

func transponder(t *testing.T, ln net.Listener, done chan<- bool) {
	defer func() { done <- true }()

	c, err := ln.Accept()
	if err != nil {
		t.Errorf("net.Listener.Accept failed: %v", err)
		return
	}
	defer c.Close()

	b := make([]byte, 128)
	n, err := c.Read(b)
	if err != nil {
		t.Errorf("net.Conn.Read failed: %v", err)
		return
	}
	if _, err := c.Write(b[:n]); err != nil {
		t.Errorf("net.Conn.Write failed: %v", err)
		return
	}
}