package kademlia

import (
  "encoding/hex";
  "rand";
)

const IdLength = 20

type NodeID [IdLength]byte

func NewNodeID(data string) (ret NodeID) {
  decoded, _ := hex.DecodeString(data);
  for i := 0; i < IdLength; i++ {
    ret[i] = decoded[i];
  }
  return;
}

func NewRandomNodeID() (ret NodeID) {
  for i := 0; i < IdLength; i++ {
    ret[i] = uint8(rand.Intn(256));
  }
  return;
}

func (node NodeID) String() string {
  return hex.EncodeToString(node[0:IdLength]);
}

func (node NodeID) Equals(other NodeID) bool {
  for i := 0; i < IdLength; i++ {
    if node[i] != other[i] {
      return false;
    }
  }
  return true;
}

func (node NodeID) Xor(other NodeID) (ret NodeID) {
  for i := 0; i < IdLength; i++ {
    ret[i] = node[i] ^ other[i];
  }
  return;
}

func (node NodeID) PrefixLen() (ret int) {
  for i := 0; i < IdLength; i++ {
    for j := 0; j < 8; j++ {
      if (node[i] >> uint8(7 - j)) & 0x1 != 0 {
        return i * 8 + j;
      }
    }
  }
  return IdLength * 8 - 1;
}

func (node NodeID) Less(other interface{}) bool {
  for i := 0; i < IdLength; i++ {
    if node[i] != other.(NodeID)[i] {
      return node[i] < other.(NodeID)[i];
    }
  }
  return false;
}