package BLC

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

//實(shí)現(xiàn)一個(gè)最基本的區(qū)塊結(jié)構(gòu)
type Block struct {
	TimeStamp int64 //時(shí)間戳，區(qū)塊產(chǎn)生的時(shí)間
	Heigth int64//區(qū)塊高度（索引、號(hào)碼）代表當(dāng)前區(qū)塊的高度
	PreBlockHash []byte//前一個(gè)區(qū)塊（父區(qū)塊）的哈希
	Hash []byte//當(dāng)前區(qū)塊的哈希
	Data []byte//交易數(shù)據(jù)
}
//創(chuàng)建一個(gè)新的區(qū)塊
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
}
//計(jì)算區(qū)塊哈希
func (b *Block)SetHash() { 
	//int64轉(zhuǎn)換成字節(jié)數(shù)組
	//高度轉(zhuǎn)換
	heightBytes:=IntToHex(b.Heigth)
	//時(shí)間轉(zhuǎn)換
	timeStampBytes:=IntToHex(b.TimeStamp)
//拼接所有屬性進(jìn)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 //存儲(chǔ)有序的區(qū)塊
}
//初始化區(qū)塊鏈
func CreateBlockChainWithGenesisBlock() *BlockChain {
	//添加創(chuàng)世區(qū)塊
	genesisBlock:=CreateGenesisBlock("the init of blockchain")

	return &BlockChain{[]*Block{genesisBlock}}
}
//添加新的區(qū)塊到區(qū)塊鏈中
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"
)

//目標(biāo)難度值，生成的hash前 targetBit 位為0才滿足條件
const targetBit =16
//工作量證明
type ProofOfWork struct {
	Block *Block //對(duì)指定的區(qū)塊進(jìn)行驗(yàn)證
	target *big.Int //大數(shù)據(jù)存儲(chǔ)
}
//創(chuàng)建新的pow對(duì)象
func NewProofOfWork(block *Block) *ProofOfWork {
	target:=big.NewInt(1)
	target=target.Lsh(target,256-targetBit)
	return &ProofOfWork{block,target}
}
//開始工作量證明
func (proofOfWork *ProofOfWork)Run() ([]byte,int64) {
	//數(shù)據(jù)拼接
	var nonce=0 //碰撞次數(shù)
	var hash [32]byte //生成的hash
	var hashInt big.Int //存儲(chǔ)轉(zhuǎn)換后的hash
	for {
		dataBytes:=proofOfWork.prepareData(nonce)
		hash=sha256.Sum256(dataBytes)
		hashInt.SetBytes(hash[:])
		fmt.Printf("hash:\r%x",hash)
		//難度比較
		if proofOfWork.target.Cmp(&hashInt)==1{
			break
		}
		nonce++
	}
	fmt.Printf("碰撞次數(shù)：%d\n",nonce)
	return hash[:],int64(nonce)
}
//準(zhǔn)備數(shù)據(jù)，將區(qū)塊屬性拼接起來，返回字節(jié)數(shù)組
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
}