package core

import (
	"fmt"

	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/logger"
	"gopkg.in/fatih/set.v0"
)

var txplogger = logger.NewLogger("TXP")

const txPoolQueueSize = 50

type TxPoolHook chan *types.Transaction
type TxMsg struct {
	Tx *types.Transaction
}

const (
	minGasPrice = 1000000
)

type TxProcessor interface {
	ProcessTransaction(tx *types.Transaction)
}

// The tx pool a thread safe transaction pool handler. In order to
// guarantee a non blocking pool we use a queue channel which can be
// independently read without needing access to the actual pool.
type TxPool struct {
	// Queueing channel for reading and writing incoming
	// transactions to
	queueChan chan *types.Transaction
	// Quiting channel
	quit chan bool
	// The actual pool
	//pool *list.List
	pool *set.Set

	SecondaryProcessor TxProcessor

	subscribers []chan TxMsg

	stateQuery StateQuery
	eventMux   *event.TypeMux
}

func NewTxPool(stateQuery StateQuery, eventMux *event.TypeMux) *TxPool {
	return &TxPool{
		pool:       set.New(),
		queueChan:  make(chan *types.Transaction, txPoolQueueSize),
		quit:       make(chan bool),
		stateQuery: stateQuery,
		eventMux:   eventMux,
	}
}

func (pool *TxPool) addTransaction(tx *types.Transaction) {

	pool.pool.Add(tx)

	// Broadcast the transaction to the rest of the peers
	pool.eventMux.Post(TxPreEvent{tx})
}

func (pool *TxPool) ValidateTransaction(tx *types.Transaction) error {
	if len(tx.To()) != 0 && len(tx.To()) != 20 {
		return fmt.Errorf("Invalid recipient. len = %d", len(tx.To()))
	}

	v, _, _ := tx.Curve()
	if v > 28 || v < 27 {
		return fmt.Errorf("tx.v != (28 || 27) => %v", v)
	}

	// Get the sender
	senderAddr := tx.From()
	if senderAddr == nil {
		return fmt.Errorf("invalid sender")
	}
	sender := pool.stateQuery.GetAccount(senderAddr)

	/* XXX this kind of validation needs to happen elsewhere in the gui when sending txs.
	   Other clients should do their own validation. Value transfer could be throw error
	   but doesn't necessarily invalidate the tx. Gas can still be payed for and miner
	   can still be rewarded for their inclusion and processing.
	totAmount := new(big.Int).Set(tx.Value())
	// Make sure there's enough in the sender's account. Having insufficient
	// funds won't invalidate this transaction but simple ignores it.
	if sender.Balance().Cmp(totAmount) < 0 {
		return fmt.Errorf("Insufficient amount in sender's (%x) account", tx.From())
	}
	*/

	return nil
}

func (self *TxPool) Add(tx *types.Transaction) error {
	hash := tx.Hash()
	if self.pool.Has(tx) {
		return fmt.Errorf("Known transaction (%x)", hash[0:4])
	}

	err := self.ValidateTransaction(tx)
	if err != nil {
		return err
	}

	self.addTransaction(tx)

	txplogger.Debugf("(t) %x => %x (%v) %x\n", tx.From()[:4], tx.To()[:4], tx.Value, tx.Hash())

	// Notify the subscribers
	go self.eventMux.Post(TxPreEvent{tx})

	return nil
}

func (self *TxPool) Size() int {
	return self.pool.Size()
}

func (self *TxPool) AddTransactions(txs []*types.Transaction) {
	for _, tx := range txs {
		if err := self.Add(tx); err != nil {
			txplogger.Infoln(err)
		} else {
			txplogger.Infof("tx %x\n", tx.Hash()[0:4])
		}
	}
}

func (pool *TxPool) GetTransactions() []*types.Transaction {
	txList := make([]*types.Transaction, pool.Size())
	i := 0
	pool.pool.Each(func(v interface{}) bool {
		txList[i] = v.(*types.Transaction)
		i++

		return true
	})

	return txList
}

func (pool *TxPool) RemoveInvalid(query StateQuery) {
	var removedTxs types.Transactions
	pool.pool.Each(func(v interface{}) bool {
		tx := v.(*types.Transaction)
		sender := query.GetAccount(tx.From())
		err := pool.ValidateTransaction(tx)
		if err != nil || sender.Nonce >= tx.Nonce() {
			removedTxs = append(removedTxs, tx)
		}

		return true
	})
	pool.RemoveSet(removedTxs)
}

func (self *TxPool) RemoveSet(txs types.Transactions) {
	for _, tx := range txs {
		self.pool.Remove(tx)
	}
}

func (pool *TxPool) Flush() []*types.Transaction {
	txList := pool.GetTransactions()
	pool.pool.Clear()

	return txList
}

func (pool *TxPool) Start() {
}

func (pool *TxPool) Stop() {
	pool.Flush()

	txplogger.Infoln("Stopped")
}