From bee05d52bfb9f555b7f9c7b625524594bff97826 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Sun, 12 Jan 2014 01:51:52 +0100
Subject: [PATCH] Block verification, TD calculations and overall block
 processing

---
 block_manager.go | 105 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 99 insertions(+), 6 deletions(-)

diff --git a/block_manager.go b/block_manager.go
index 968d9a139..04d45f434 100644
--- a/block_manager.go
+++ b/block_manager.go
@@ -3,40 +3,63 @@ package main
 import (
 	"fmt"
 	"github.com/ethereum/ethutil-go"
+	"errors"
+	"log"
+	"math/big"
 )
 
 type BlockChain struct {
-	lastBlock *ethutil.Block
+	LastBlock *ethutil.Block
 
 	genesisBlock *ethutil.Block
+
+	TD *big.Int
 }
 
 func NewBlockChain() *BlockChain {
 	bc := &BlockChain{}
 	bc.genesisBlock = ethutil.NewBlock(ethutil.Encode(ethutil.Genesis))
 
+	// Set the last know difficulty (might be 0x0 as initial value, Genesis)
+	bc.TD = new(big.Int)
+	bc.TD.SetBytes(ethutil.Config.Db.LastKnownTD())
+
 	return bc
 }
 
-type BlockManager struct {
-	vm *Vm
+func (bc *BlockChain) HasBlock(hash string) bool {
+	return bc.LastBlock.State().Get(hash) != ""
+}
 
-	blockChain *BlockChain
+type BlockManager struct {
+	// Ethereum virtual machine for processing contracts
+	vm *Vm
+	// The block chain :)
+	bc *BlockChain
 }
 
 func NewBlockManager() *BlockManager {
-	bm := &BlockManager{vm: NewVm()}
+	bm := &BlockManager{
+		vm: NewVm(),
+		bc: NewBlockChain(),
+	}
 
 	return bm
 }
 
 // Process a block.
 func (bm *BlockManager) ProcessBlock(block *ethutil.Block) error {
-	// TODO Validation (Or move to other part of the application)
+	// Block validation
 	if err := bm.ValidateBlock(block); err != nil {
 		return err
 	}
 
+	// I'm not sure, but I don't know if there should be thrown
+	// any errors at this time.
+	if err := bm.AccumelateRewards(block); err != nil {
+		return err
+	}
+
 	// Get the tx count. Used to create enough channels to 'join' the go routines
 	txCount := len(block.Transactions())
 	// Locking channel. When it has been fully buffered this method will return
@@ -58,10 +81,80 @@ func (bm *BlockManager) ProcessBlock(block *ethutil.Block) error {
 		<-lockChan
 	}
 
+	if bm.CalculateTD(block) {
+		ethutil.Config.Db.Put(block.Hash(), block.MarshalRlp())
+		bm.bc.LastBlock = block
+	}
+
 	return nil
 }
 
+func (bm *BlockManager) CalculateTD(block *ethutil.Block) bool {
+	uncleDiff := new(big.Int)
+	for _, uncle := range block.Uncles {
+		uncleDiff = uncleDiff.Add(uncleDiff, uncle.Difficulty)
+	}
+
+	// TD(genesis_block) = 0 and TD(B) = TD(B.parent) + sum(u.difficulty for u in B.uncles) + B.difficulty
+	td := new(big.Int)
+	td = td.Add(bm.bc.TD, uncleDiff)
+	td = td.Add(td, block.Difficulty)
+
+	// The new TD will only be accepted if the new difficulty is
+	// is greater than the previous.
+	if td.Cmp(bm.bc.TD) > 0 {
+		bm.bc.LastBlock = block
+		// Set the new total difficulty back to the block chain
+		bm.bc.TD = td
+
+		return true
+	}
+
+	return false
+}
+
+// Validates the current block. Returns an error if the block was invalid,
+// an uncle or anything that isn't on the current block chain
 func (bm *BlockManager) ValidateBlock(block *ethutil.Block) error {
+	// TODO
+	// 1. Check if the nonce of the block is valid
+	// 2. Check if the difficulty is correct
+
+	// Check if we have the parent hash, if it isn't known we discard it
+	// Reasons might be catching up or simply an invalid block
+	if bm.bc.HasBlock(block.PrevHash) {
+		// Check each uncle's previous hash. In order for it to be valid
+		// is if it has the same block hash as the current
+		for _, uncle := range block.Uncles {
+			if uncle.PrevHash != block.PrevHash {
+				if Debug {
+					log.Printf("Uncle prvhash mismatch %x %x\n", block.PrevHash, uncle.PrevHash)
+				}
+
+				return errors.New("Mismatching Prvhash from uncle")
+			}
+		}
+	} else {
+		return errors.New("Block's parent unknown")
+	}
+
+
+	return nil
+}
+
+func (bm *BlockManager) AccumelateRewards(block *ethutil.Block) error {
+	// Get the coinbase rlp data
+	d := block.State().Get(block.Coinbase)
+
+	ether := ethutil.NewEtherFromData([]byte(d))
+
+	// Reward amount of ether to the coinbase address
+	ether.AddFee(ethutil.CalculateBlockReward(block, len(block.Uncles)))
+	block.State().Update(block.Coinbase, string(ether.MarshalRlp()))
+
+	// TODO Reward each uncle
+
+
 	return nil
 }