package main

import (
	"fmt"
	"encoding/binary"
	"net"
	"github.com/kr/pretty"
	"io/ioutil"
)

type Initializer struct {
	Host string
	Port int
}

func main() {
	fmt.Println("Hello world")

	init := Initializer{"212.114.60.140", 25565}

	data, err := GetData(init)
	if err != nil {
		fmt.Println(err)
	}

	pretty.Println(data)
}

func pack_data(data []byte) []byte {
	length := len(data)
	var bs = make([]byte, 2)
	binary.BigEndian.PutUint16(bs, uint16(length))

	newData := pack_variant(data)

	return append(bs, newData...)
}

func pack_uint32(i int) []byte {
	bs := make([]byte, 4)
	binary.BigEndian.PutUint32(bs, uint32(i))

	return bs
}

func pack_port(port int) []byte {
	var bs = make([]byte, 2)
	binary.BigEndian.PutUint16(bs, uint16(port))

	return bs
}

func pack_variant(d []byte) []byte {
	var bs = make([]byte, 2)
	var o []byte

	for i := range(d){
		b := d[i] & 0x7F
		d[i] >>= 7

		if d[i] > 0 {
			binary.BigEndian.PutUint16(bs, uint16(b) | 0x80)
		} else {
			bs[0] = 0
		}

		o = append(o, bs...)
	}

	return o
}

func GetData(initializer Initializer) (interface{}, error) {
	// Minecraft Server Handshake
	// Two requests should be made
	// first: 0x00 Packet ID + -1 as Protocol Version (VarInt) + ServerAddress as String + ServerPort as Unsigned Short, Next State should be 1 VarInt in this case
	// second: 0x00

	hostport := append([]byte(initializer.Host), pack_port(initializer.Port)...)
	hostport = append(hostport, 0x01)

	hostport = pack_data(hostport)

	first := []byte {0x00, 0x00}
	first = append(first, pack_data(hostport)...)

	second := []byte {0x00}

	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", initializer.Host, initializer.Port))
	if err != nil {
		return nil, err
	}
	defer conn.Close()

	_, err = conn.Write(pack_data(first))
	if err != nil {
		return nil, err
	}

	_, err = conn.Write(pack_data(second))
	if err != nil {
		return nil, err
	}

	//var buf bytes.Buffer
	//io.Copy(&buf, conn)

	buf, err := ioutil.ReadAll(conn)
	pretty.Println(buf)

	//unpack_variant(conn) // Packet length
	//unpack_variant(conn) // Packet ID
	//ret, err := unpack_variant(conn) // String length
	//if err != nil {
	//	return nil, err
	//}
	//
	//var d []byte
	//for len(d) < int(ret) {
	//	data := make([]byte, 1024)
	//	_, err := conn.Read(data)
	//	if err != nil {
	//		return nil, err
	//	}
	//
	//	d = append(d, data...)
	//}

	//returner, err := json.Marshal(&buf)
	return buf, err
}