package ethchain

import (
	"bytes"
	"container/list"
	"fmt"
	"github.com/ethereum/eth-go/ethutil"
	"github.com/ethereum/eth-go/ethwire"
	"math/big"
	"sync"
	"time"
)

type BlockProcessor interface {
	ProcessBlock(block *Block)
}

type Peer interface {
	Inbound() bool
	LastSend() time.Time
	LastPong() int64
	Host() []byte
	Port() uint16
	Version() string
	PingTime() string
	Connected() *int32
}

type EthManager interface {
	StateManager() *StateManager
	BlockChain() *BlockChain
	TxPool() *TxPool
	Broadcast(msgType ethwire.MsgType, data []interface{})
	Reactor() *ethutil.ReactorEngine
	PeerCount() int
	IsMining() bool
	IsListening() bool
	Peers() *list.List
}

type StateManager struct {
	// Mutex for locking the block processor. Blocks can only be handled one at a time
	mutex sync.Mutex
	// Canonical block chain
	bc *BlockChain
	// Stack for processing contracts
	stack *Stack
	// non-persistent key/value memory storage
	mem map[string]*big.Int
	// Proof of work used for validating
	Pow PoW
	// The ethereum manager interface
	Ethereum EthManager
	// The managed states
	// Transiently state. The trans state isn't ever saved, validated and
	// it could be used for setting account nonces without effecting
	// the main states.
	transState *State
	// Mining state. The mining state is used purely and solely by the mining
	// operation.
	miningState *State
}

func NewStateManager(ethereum EthManager) *StateManager {
	sm := &StateManager{
		stack:    NewStack(),
		mem:      make(map[string]*big.Int),
		Pow:      &EasyPow{},
		Ethereum: ethereum,
		bc:       ethereum.BlockChain(),
	}
	sm.transState = ethereum.BlockChain().CurrentBlock.State().Copy()
	sm.miningState = ethereum.BlockChain().CurrentBlock.State().Copy()

	return sm
}

func (sm *StateManager) CurrentState() *State {
	return sm.Ethereum.BlockChain().CurrentBlock.State()
}

func (sm *StateManager) TransState() *State {
	return sm.transState
}

func (sm *StateManager) MiningState() *State {
	return sm.miningState
}

func (sm *StateManager) NewMiningState() *State {
	sm.miningState = sm.Ethereum.BlockChain().CurrentBlock.State().Copy()

	return sm.miningState
}

func (sm *StateManager) BlockChain() *BlockChain {
	return sm.bc
}

func (sm *StateManager) MakeStateObject(state *State, tx *Transaction) *StateObject {
	contract := MakeContract(tx, state)
	if contract != nil {
		state.states[string(tx.CreationAddress())] = contract.state

		return contract
	}

	return nil
}

// Apply transactions uses the transaction passed to it and applies them onto
// the current processing state.
func (sm *StateManager) ApplyTransactions(state *State, block *Block, txs []*Transaction) ([]*Receipt, []*Transaction) {
	// Process each transaction/contract
	var receipts []*Receipt
	var validTxs []*Transaction
	var ignoredTxs []*Transaction // Transactions which go over the gasLimit

	totalUsedGas := big.NewInt(0)
	for _, tx := range txs {
		usedGas, err := sm.ApplyTransaction(state, block, tx)
		if err != nil {
			if IsNonceErr(err) {
				continue
			}
			if IsGasLimitErr(err) {
				ignoredTxs = append(ignoredTxs, tx)
				// We need to figure out if we want to do something with thse txes
				ethutil.Config.Log.Debugln("Gastlimit:", err)
				continue
			}

			ethutil.Config.Log.Infoln(err)
		}

		accumelative := new(big.Int).Set(totalUsedGas.Add(totalUsedGas, usedGas))
		receipt := &Receipt{tx, ethutil.CopyBytes(state.Root().([]byte)), accumelative}

		receipts = append(receipts, receipt)
		validTxs = append(validTxs, tx)
	}

	return receipts, validTxs
}

func (sm *StateManager) ApplyTransaction(state *State, block *Block, tx *Transaction) (totalGasUsed *big.Int, err error) {
	/*
		Applies transactions to the given state and creates new
		state objects where needed.

		If said objects needs to be created
		run the initialization script provided by the transaction and
		assume there's a return value. The return value will be set to
		the script section of the state object.
	*/
	var (
		addTotalGas = func(gas *big.Int) { totalGasUsed.Add(totalGasUsed, gas) }
		gas         = new(big.Int)
		script      []byte
	)
	totalGasUsed = big.NewInt(0)
	snapshot := state.Snapshot()

	// Apply the transaction to the current state
	gas, err = sm.Ethereum.TxPool().ProcessTransaction(tx, state, false)
	addTotalGas(gas)

	if tx.CreatesContract() {
		if err == nil {
			// Create a new state object and the transaction
			// as it's data provider.
			contract := sm.MakeStateObject(state, tx)
			if contract != nil {
				// Evaluate the initialization script
				// and use the return value as the
				// script section for the state object.
				script, gas, err = sm.EvalScript(state, contract.Init(), contract, tx, block)
				addTotalGas(gas)

				if err != nil {
					err = fmt.Errorf("[STATE] Error during init script run %v", err)
					return
				}
				contract.script = script
				state.UpdateStateObject(contract)
			} else {
				err = fmt.Errorf("[STATE] Unable to create contract")
			}
		} else {
			err = fmt.Errorf("[STATE] contract creation tx: %v for sender %x", err, tx.Sender())
		}
	} else {
		// Find the state object at the "recipient" address. If
		// there's an object attempt to run the script.
		stateObject := state.GetStateObject(tx.Recipient)
		if err == nil && stateObject != nil && len(stateObject.Script()) > 0 {
			_, gas, err = sm.EvalScript(state, stateObject.Script(), stateObject, tx, block)
			addTotalGas(gas)
		}
	}

	parent := sm.bc.GetBlock(block.PrevHash)
	total := new(big.Int).Add(block.GasUsed, totalGasUsed)
	limit := block.CalcGasLimit(parent)
	if total.Cmp(limit) > 0 {
		state.Revert(snapshot)
		err = GasLimitError(total, limit)
	}

	return
}

func (sm *StateManager) Process(block *Block, dontReact bool) error {
	if !sm.bc.HasBlock(block.PrevHash) {
		return ParentError(block.PrevHash)
	}

	parent := sm.bc.GetBlock(block.PrevHash)

	return sm.ProcessBlock(parent.State(), parent, block, dontReact)

}

// Block processing and validating with a given (temporarily) state
func (sm *StateManager) ProcessBlock(state *State, parent, block *Block, dontReact bool) error {
	// Processing a blocks may never happen simultaneously
	sm.mutex.Lock()
	defer sm.mutex.Unlock()
	hash := block.Hash()

	if sm.bc.HasBlock(hash) {
		//fmt.Println("[STATE] We already have this block, ignoring")
		return nil
	}

	// Defer the Undo on the Trie. If the block processing happened
	// we don't want to undo but since undo only happens on dirty
	// nodes this won't happen because Commit would have been called
	// before that.
	defer state.Reset()

	// 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 !sm.bc.HasBlock(block.PrevHash) && sm.bc.CurrentBlock != nil {
		return ParentError(block.PrevHash)
	}

	// Process the transactions on to current block
	sm.ApplyTransactions(state, parent, block.Transactions())

	// Block validation
	if err := sm.ValidateBlock(block); err != nil {
		fmt.Println("[SM] Error validating block:", err)
		return err
	}

	// I'm not sure, but I don't know if there should be thrown
	// any errors at this time.
	if err := sm.AccumelateRewards(state, block); err != nil {
		fmt.Println("[SM] Error accumulating reward", err)
		return err
	}

	//if !sm.compState.Cmp(state) {
	if !block.State().Cmp(state) {
		return fmt.Errorf("Invalid merkle root.\nrec: %x\nis:  %x", block.State().trie.Root, state.trie.Root)
	}

	// Calculate the new total difficulty and sync back to the db
	if sm.CalculateTD(block) {
		// Sync the current block's state to the database and cancelling out the deferred Undo
		state.Sync()

		// Add the block to the chain
		sm.bc.Add(block)
		sm.notifyChanges(state)

		ethutil.Config.Log.Infof("[STATE] Added block #%d (%x)\n", block.Number, block.Hash())
		if dontReact == false {
			sm.Ethereum.Reactor().Post("newBlock", block)

			state.manifest.Reset()
		}

		sm.Ethereum.Broadcast(ethwire.MsgBlockTy, []interface{}{block.Value().Val})

		sm.Ethereum.TxPool().RemoveInvalid(state)
	} else {
		fmt.Println("total diff failed")
	}

	return nil
}
func (sm *StateManager) CalculateTD(block *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(sm.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(sm.bc.TD) > 0 {
		// Set the new total difficulty back to the block chain
		sm.bc.SetTotalDifficulty(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.
// Validation validates easy over difficult (dagger takes longer time = difficult)
func (sm *StateManager) ValidateBlock(block *Block) error {
	// TODO
	// 2. Check if the difficulty is correct

	// Check each uncle's previous hash. In order for it to be valid
	// is if it has the same block hash as the current
	previousBlock := sm.bc.GetBlock(block.PrevHash)
	for _, uncle := range block.Uncles {
		if bytes.Compare(uncle.PrevHash, previousBlock.PrevHash) != 0 {
			return ValidationError("Mismatch uncle's previous hash. Expected %x, got %x", previousBlock.PrevHash, uncle.PrevHash)
		}
	}

	diff := block.Time - sm.bc.CurrentBlock.Time
	if diff < 0 {
		return ValidationError("Block timestamp less then prev block %v", diff)
	}

	// New blocks must be within the 15 minute range of the last block.
	if diff > int64(15*time.Minute) {
		return ValidationError("Block is too far in the future of last block (> 15 minutes)")
	}

	// Verify the nonce of the block. Return an error if it's not valid
	if !sm.Pow.Verify(block.HashNoNonce(), block.Difficulty, block.Nonce) {
		return ValidationError("Block's nonce is invalid (= %v)", ethutil.Hex(block.Nonce))
	}

	return nil
}

func CalculateBlockReward(block *Block, uncleLength int) *big.Int {
	base := new(big.Int)
	for i := 0; i < uncleLength; i++ {
		base.Add(base, UncleInclusionReward)
	}

	lastCumulGasUsed := big.NewInt(0)
	for _, r := range block.Receipts() {
		usedGas := new(big.Int).Sub(r.CumulativeGasUsed, lastCumulGasUsed)
		usedGas.Add(usedGas, r.Tx.GasPrice)
		base.Add(base, usedGas)
	}

	return base.Add(base, BlockReward)
}

func CalculateUncleReward(block *Block) *big.Int {
	return UncleReward
}

func (sm *StateManager) AccumelateRewards(state *State, block *Block) error {
	// Get the account associated with the coinbase
	account := state.GetAccount(block.Coinbase)
	// Reward amount of ether to the coinbase address
	account.AddAmount(CalculateBlockReward(block, len(block.Uncles)))

	addr := make([]byte, len(block.Coinbase))
	copy(addr, block.Coinbase)
	state.UpdateStateObject(account)

	for _, uncle := range block.Uncles {
		uncleAccount := state.GetAccount(uncle.Coinbase)
		uncleAccount.AddAmount(CalculateUncleReward(uncle))

		state.UpdateStateObject(uncleAccount)
	}

	return nil
}

func (sm *StateManager) Stop() {
	sm.bc.Stop()
}

func (sm *StateManager) EvalScript(state *State, script []byte, object *StateObject, tx *Transaction, block *Block) (ret []byte, gas *big.Int, err error) {
	account := state.GetAccount(tx.Sender())

	err = account.ConvertGas(tx.Gas, tx.GasPrice)
	if err != nil {
		ethutil.Config.Log.Debugln(err)
		return
	}

	closure := NewClosure(account, object, script, state, tx.Gas, tx.GasPrice)
	vm := NewVm(state, sm, RuntimeVars{
		Origin:      account.Address(),
		BlockNumber: block.BlockInfo().Number,
		PrevHash:    block.PrevHash,
		Coinbase:    block.Coinbase,
		Time:        block.Time,
		Diff:        block.Difficulty,
		Value:       tx.Value,
		//Price:       tx.GasPrice,
	})
	ret, gas, err = closure.Call(vm, tx.Data, nil)

	// Update the account (refunds)
	state.UpdateStateObject(account)
	state.UpdateStateObject(object)

	return
}

func (sm *StateManager) notifyChanges(state *State) {
	for addr, stateObject := range state.manifest.objectChanges {
		sm.Ethereum.Reactor().Post("object:"+addr, stateObject)
	}

	for stateObjectAddr, mappedObjects := range state.manifest.storageChanges {
		for addr, value := range mappedObjects {
			sm.Ethereum.Reactor().Post("storage:"+stateObjectAddr+":"+addr, &StorageState{[]byte(stateObjectAddr), []byte(addr), value})
		}
	}
}