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
}