package BLC

import (
	"bytes"
	"crypto/sha256"
	"time"
)

//实现一个最基本的区块结构
type Block struct {
	TimeStamp int64 //时间戳，区块产生的时间
	Heigth int64//区块高度（索引、号码）代表当前区块的高度
	PreBlockHash []byte//前一个区块（父区块）的哈希
	Hash []byte//当前区块的哈希
	Data []byte//交易数据
}
//创建一个新的区块
func NewBlock(height int64,preBlockHash []byte,Data []byte) *Block {
	var block Block
	block=Block{Heigth: height,PreBlockHash: preBlockHash,Data: Data,TimeStamp: time.Now().Unix()}
	block.SetHash()
	return &block
}
//计算区块哈希
func (b *Block)SetHash() { 
	//int64转换成字节数组
	//高度转换
	heightBytes:=IntToHex(b.Heigth)
	//时间转换
	timeStampBytes:=IntToHex(b.TimeStamp)
//拼接所有属性进行hash
	blockBytes:=bytes.Join([][]byte{heightBytes,timeStampBytes,b.PreBlockHash,b.Data},[]byte{})
	hash:=sha256.Sum256(blockBytes)
	b.Hash=hash[:]
}

package BLC

type BlockChain struct {
	Blocks []*Block //存储有序的区块
}
//初始化区块链
func CreateBlockChainWithGenesisBlock() *BlockChain {
	//添加创世区块
	genesisBlock:=CreateGenesisBlock("the init of blockchain")

	return &BlockChain{[]*Block{genesisBlock}}
}
//添加新的区块到区块链中
func (bc *BlockChain)AddBlock(height int64,data []byte,prevBlockHash []byte){
	newBlock := NewBlock(height,prevBlockHash,data)
	bc.Blocks=append(bc.Blocks,newBlock)
}

package BLC

import (
	"bytes"
	"crypto/sha256"
	"fmt"
	"math/big"
)

//目标难度值，生成的hash前 targetBit 位为0才满足条件
const targetBit =16
//工作量证明
type ProofOfWork struct {
	Block *Block //对指定的区块进行验证
	target *big.Int //大数据存储
}
//创建新的pow对象
func NewProofOfWork(block *Block) *ProofOfWork {
	target:=big.NewInt(1)
	target=target.Lsh(target,256-targetBit)
	return &ProofOfWork{block,target}
}
//开始工作量证明
func (proofOfWork *ProofOfWork)Run() ([]byte,int64) {
	//数据拼接
	var nonce=0 //碰撞次数
	var hash [32]byte //生成的hash
	var hashInt big.Int //存储转换后的hash
	for {
		dataBytes:=proofOfWork.prepareData(nonce)
		hash=sha256.Sum256(dataBytes)
		hashInt.SetBytes(hash[:])
		fmt.Printf("hash:\r%x",hash)
		//难度比较
		if proofOfWork.target.Cmp(&hashInt)==1{
			break
		}
		nonce++
	}
	fmt.Printf("碰撞次数：%d\n",nonce)
	return hash[:],int64(nonce)
}
//准备数据，将区块属性拼接起来，返回字节数组
func (pow *ProofOfWork)prepareData(nonce int) []byte {
	data:=bytes.Join([][]byte{
		pow.Block.PreBlockHash,
		pow.Block.Data,
		IntToHex(pow.Block.TimeStamp),
		IntToHex(pow.Block.Heigth),
		IntToHex(int64(nonce)),
		IntToHex(targetBit),
	},[]byte{})
	return data
}