blockchain.go

package main

import (
	"log"

	"github.com/boltdb/bolt"
)

const dbFile = "blockchain.db"
const blocksBucket = "blocks"

type Blockchain struct {
	tip []byte
	db  *bolt.DB
}

func (bc *Blockchain) AddBlock(data string) {
	var lateHash []byte

	err := bc.db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))
		lateHash = b.Get([]byte("l"))
		return nil
	})
	if err != nil {
		log.Panic(err)
	}

	newBlock := NewBlock(data, lateHash)

	err = bc.db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))

		err := b.Put([]byte(newBlock.Hash), newBlock.Serialize())
		if err != nil {
			return err
		}

		err = b.Put([]byte("l"), newBlock.Hash)
		if err != nil {
			return err
		}

		bc.tip = newBlock.Hash
		return nil
	})
	if err != nil {
		log.Panic(err)
	}
}

func NewGenesisBlock() *Block {
	return NewBlock("Genesis Block", []byte{})
}

func NewBlockchain() *Blockchain {
	var tip []byte
	db, err := bolt.Open(dbFile, 0600, nil)
	if err != nil {
		log.Panic(err)
		return nil
	}

	err = db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))

		if b == nil {
			genesis := NewGenesisBlock()

			b, err := tx.CreateBucket([]byte(blocksBucket))
			if err != nil {
				return err
			}

			err = b.Put(genesis.Hash, genesis.Serialize())
			if err != nil {
				return err
			}

			err = b.Put([]byte("l"), genesis.Hash)
			if err != nil {
				return err
			}

			tip = genesis.Hash
		} else {
			tip = b.Get([]byte("l"))
		}
		return nil
	})

	bc := Blockchain{tip, db}

	return &bc
}

type BlockchainIterator struct {
	currentHash []byte
	db          *bolt.DB
}

func (bc *Blockchain) Iterator() *BlockchainIterator {
	return &BlockchainIterator{bc.tip, bc.db}
}

func (i *BlockchainIterator) Next() *Block {
	var block *Block
	err := i.db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(blocksBucket))
		encodedBlock := b.Get(i.currentHash)
		block = DeserializeBlock(encodedBlock)
		return nil
	})
	if err != nil {
		log.Panic(err)
		return nil
	}
	i.currentHash = block.PrevBlockHash
	return block
}