package discover

import (
	"bytes"
	"reflect"
	"testing"
)

var testdata = []struct {
	data   []byte
	packet *packet
	err    error
}{
	{
		[]byte{0x20, 0x12, 0x10, 0x25,
			0x12, 0x34, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x05,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x00, 0x00, 0x00},
		&packet{
			magic: 0x20121025,
			port:  0x1234,
			id:    "hello",
		},
		nil,
	},
	{
		[]byte{0x20, 0x12, 0x10, 0x25,
			0x34, 0x56, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x08,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x21, 0x21},
		&packet{
			magic: 0x20121025,
			port:  0x3456,
			id:    "hello!!!",
		},
		nil,
	},
	{
		[]byte{0x19, 0x76, 0x03, 0x09,
			0x00, 0x00, 0x00, 0x06,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x00, 0x00},
		&packet{
			magic: 0x19760309,
			id:    "hello!",
		},
		nil,
	},
	{
		[]byte{0x20, 0x12, 0x10, 0x25,
			0x12, 0x34, 0x12, 0x34, // reserved bits not set to zero
			0x00, 0x00, 0x00, 0x06,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x00, 0x00},
		nil,
		errFormat,
	},
	{
		[]byte{0x20, 0x12, 0x10, 0x25,
			0x12, 0x34, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x06,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21}, // missing padding
		nil,
		errFormat,
	},
	{
		[]byte{0x19, 0x77, 0x03, 0x09, // incorrect magic
			0x00, 0x00, 0x00, 0x06,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x00, 0x00},
		nil,
		errBadMagic,
	},
	{
		[]byte{0x19, 0x76, 0x03, 0x09,
			0x6c, 0x6c, 0x6c, 0x6c, // length exceeds packet size
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x00, 0x00},
		nil,
		errFormat,
	},
	{
		[]byte{0x19, 0x76, 0x03, 0x09,
			0x00, 0x00, 0x00, 0x06,
			0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21, 0x00, 0x00,
			0x23}, // extra data at the end
		nil,
		errFormat,
	},
}

func TestDecodePacket(t *testing.T) {
	for i, test := range testdata {
		p, err := decodePacket(test.data)
		if err != test.err {
			t.Errorf("%d: unexpected error %v", i, err)
		} else {
			if !reflect.DeepEqual(p, test.packet) {
				t.Errorf("%d: incorrect packet\n%v\n%v", i, test.packet, p)
			}
		}
	}
}

func TestEncodePacket(t *testing.T) {
	for i, test := range testdata {
		if test.err != nil {
			continue
		}
		buf := encodePacket(*test.packet)
		if bytes.Compare(buf, test.data) != 0 {
			t.Errorf("%d: incorrect encoded packet\n% x\n% 0x", i, test.data, buf)
		}
	}
}