blockchain.go

package main

import (
  "log"
  "github.com/boltdb/bolt"
)

const dbFile = "blockchain_%s.db"
const blocksBucket = "blocks"

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

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

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

  if err != nil {
    log.Panic(err)
  }

  newBlock := NewBlock(data, lastHash)

  err = bc.db.Update(func(tx *bolt.Tx) error {
    b := tx.Bucket([]byte(blocksBucket))
    err = b.Put(newBlock.Hash, newBlock.Serialize())
    if err != nil {
      log.Panic(err)
    }
    err = b.Put([]byte("l"), newBlock.Hash)
    if err != nil {
      log.Panic(err)
    }
    bc.tip = newBlock.Hash

    return nil
  })
}

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

func NewGenesisBlock(coinbase *Transaction) *Block {
  return NewBlock([]*Transaction{coinbase}, []byte{})
}

// TODO
func NewBlockchain() *Blockchain {
  var tip []byte

  db, err := bolt.Open(dbFile, 0600, nil)
  if err != nil {
    log.Panic(err)
  }

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

    if b == nil {
      genesis := NewGenesisBlock()
      b, err := tx.CreateBucket([]byte(blocksBucket))
      err = b.Put(genesis.Hash, genesis.Serialize())
      if err != nil {
        log.Panic(err)
      }
      err = b.Put([]byte("l"), genesis.Hash)
      if err != nil {
        log.Panic(err)
      }
			tip = genesis.Hash
    } else {
			tip = b.Get([]byte("l"))
		}

    return nil
  })

  if err != nil {
    log.Panic(err)
  }

  bc := Blockchain{tip, db}
  return &bc
}