package main
import (
	"bytes"
	"crypto/sha256"
	"time"
)
/*
1.定義一個(gè)區(qū)塊的結(jié)構(gòu)Block
​a.區(qū)塊頭：6個(gè)字段
​b.區(qū)塊體：字符串表示data
*/
//區(qū)塊
type Block struct {
	Version int64   //版本
	PerBlockHash []byte //前一個(gè)區(qū)塊的hash值
	Hash []byte //當(dāng)前區(qū)塊的hash值，是為了簡(jiǎn)化代碼
	MerKelRoot []byte  //梅克爾根
	TimeStamp int64  //時(shí)間抽
	Bits int64  //難度值
	Nonce int64 //隨機(jī)值
//區(qū)塊體
	Data []byte  //交易信息
}

/*
提供一個(gè)創(chuàng)建區(qū)塊的方法
NewBlock(參數(shù))
*/
func NewBlock(data string ,prevBlockHash []byte) *Block {
	var block Block
	block = Block{
		Version:      1,
		PerBlockHash: prevBlockHash,
		//Hash:         []byte{},   	//區(qū)塊不存儲(chǔ)hash值，節(jié)點(diǎn)接受區(qū)塊后獨(dú)立計(jì)算并存儲(chǔ)在本地。
		MerKelRoot:   []byte{},
		TimeStamp:    time.Now().Unix(),
		Bits:         1,
		Nonce:        1,
		Data:         []byte(data),
	}
	block.SetHash()  //填充Hash
	return &block
}
func (block *Block) SetHash() {
	// 源碼里面是要傳二維切片 func Join(s [][]byte, sep []byte) []byte
	tmp :=[][]byte{
		IntToByte(block.Version),
		block.PerBlockHash,
		block.MerKelRoot,
		IntToByte(block.TimeStamp),
		IntToByte(block.Bits),
		IntToByte(block.Nonce),
	}
	data:=bytes.Join(tmp,[]byte{})    //之后再計(jì)算hash
	hash := sha256.Sum256(data)
	block.Hash = hash[:]  //變切片
}
//創(chuàng)始?jí)K
func NewGensisBlock() *Block{
	return NewBlock("Genesis Block!",[]byte{})
}

package main
/*
1. 定義一個(gè)區(qū)塊鏈結(jié)構(gòu)BlockChain
   Block數(shù)組
*/
type BlockChain struct {
   blocks []*Block
}
/*
2. 提供一個(gè)創(chuàng)建BlockChain()的方法
   NewBlockChain()
*/
func NewBlockChain() *BlockChain {
   block := NewGensisBlock()
   return &BlockChain{blocks:[]*Block{block}}  //創(chuàng)建只有一個(gè)元素的區(qū)塊鏈，初始化
}
/*
3. 提供一個(gè)添加區(qū)塊的方法
   AddBlock(參數(shù))
*/
func (bc *BlockChain)AddBlock(data string)  {
   PerBlockHash := bc.blocks[len(bc.blocks)-1].Hash  //這一個(gè)區(qū)塊的哈希是前一塊的哈希值
   block := NewBlock(data,PerBlockHash)
   bc.blocks = append(bc.blocks,block)
}

package main

import (
   "bytes"
   "encoding/binary"
   "fmt"
   "os"
)

func IntToByte(num int64) []byte {
   //func Write(w io.Writer, order ByteOrder, data interface{}) error {
   var buffer bytes.Buffer
   err := binary.Write(&buffer, binary.BigEndian, num)
   CheckErr("IntToByte",err)
   return buffer.Bytes()
}

func CheckErr(position string,err error) {
   if err != nil {
      fmt.Println("error ,pos:",position,err)
      os.Exit(1)
   }
}

package main
import "fmt"
func main() {
   bc := NewBlockChain()
   bc.AddBlock("A send B 1BTC")
   bc.AddBlock("B send C 1BTC")
   for _,block := range bc.blocks {
      fmt.Printf("Version : %d\n",block.Version)
      fmt.Printf("PerBlockHash : %x\n",block.PerBlockHash)
      fmt.Printf("Hash : %x\n",block.Hash)
      fmt.Printf("MerKelRoot : %x\n",block.MerKelRoot)
      fmt.Printf("TimeStamp : %d\n",block.TimeStamp)
      fmt.Printf("Bits : %d\n",block.Bits)
      fmt.Printf("Nonce : %d\n",block.Nonce)
      fmt.Printf("Data : %s\n",block.Data)
   }
}