/*
 * Copyright (c) 2013 Conformal Systems LLC <info@conformal.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package main

import (
	"bytes"
	"fmt"
	"github.com/conformal/btcjson"
	"github.com/conformal/btcutil"
	"github.com/conformal/btcwallet/tx"
	"github.com/conformal/btcwallet/wallet"
	"github.com/conformal/btcwire"
	"github.com/conformal/btcws"
	"sync"
)

var accounts = NewAccountStore()

// Account is a structure containing all the components for a
// complete wallet.  It contains the Armory-style wallet (to store
// addresses and keys), and tx and utxo data stores, along with locks
// to prevent against incorrect multiple access.
type Account struct {
	*wallet.Wallet
	mtx               sync.RWMutex
	name              string
	dirty             bool
	fullRescan        bool
	NewBlockTxSeqN    uint64
	SpentOutpointSeqN uint64
	UtxoStore         struct {
		sync.RWMutex
		dirty bool
		s     tx.UtxoStore
	}
	TxStore struct {
		sync.RWMutex
		dirty bool
		s     tx.TxStore
	}
}

// AccountStore stores all wallets currently being handled by
// btcwallet.  Wallet are stored in a map with the account name as the
// key.  A RWMutex is used to protect against incorrect concurrent
// access.
type AccountStore struct {
	sync.Mutex
	m map[string]*Account
}

// NewAccountStore returns an initialized and empty AccountStore.
func NewAccountStore() *AccountStore {
	return &AccountStore{
		m: make(map[string]*Account),
	}
}

// Rollback rolls back each Account saved in the store.
//
// TODO(jrick): This must also roll back the UTXO and TX stores, and notify
// all wallets of new account balances.
func (s *AccountStore) Rollback(height int32, hash *btcwire.ShaHash) {
	for _, w := range s.m {
		w.Rollback(height, hash)
	}
}

// Rollback reverts each stored Account to a state before the block
// with the passed chainheight and block hash was connected to the main
// chain.  This is used to remove transactions and utxos for each wallet
// that occured on a chain no longer considered to be the main chain.
func (a *Account) Rollback(height int32, hash *btcwire.ShaHash) {
	a.UtxoStore.Lock()
	a.UtxoStore.dirty = a.UtxoStore.dirty || a.UtxoStore.s.Rollback(height, hash)
	a.UtxoStore.Unlock()

	a.TxStore.Lock()
	a.TxStore.dirty = a.TxStore.dirty || a.TxStore.s.Rollback(height, hash)
	a.TxStore.Unlock()

	if err := a.writeDirtyToDisk(); err != nil {
		log.Errorf("cannot sync dirty wallet: %v", err)
	}
}

// CalculateBalance sums the amounts of all unspent transaction
// outputs to addresses of a wallet and returns the balance as a
// float64.
//
// If confirmations is 0, all UTXOs, even those not present in a
// block (height -1), will be used to get the balance.  Otherwise,
// a UTXO must be in a block.  If confirmations is 1 or greater,
// the balance will be calculated based on how many how many blocks
// include a UTXO.
func (a *Account) CalculateBalance(confirms int) float64 {
	var bal uint64 // Measured in satoshi

	bs, err := GetCurBlock()
	if bs.Height == int32(btcutil.BlockHeightUnknown) || err != nil {
		return 0.
	}

	a.UtxoStore.RLock()
	for _, u := range a.UtxoStore.s {
		// Utxos not yet in blocks (height -1) should only be
		// added if confirmations is 0.
		if confirms == 0 || (u.Height != -1 && int(bs.Height-u.Height+1) >= confirms) {
			bal += u.Amt
		}
	}
	a.UtxoStore.RUnlock()
	return float64(bal) / float64(btcutil.SatoshiPerBitcoin)
}

// Track requests btcd to send notifications of new transactions for
// each address stored in a wallet and sets up a new reply handler for
// these notifications.
func (a *Account) Track() {
	n := <-NewJSONID
	a.mtx.Lock()
	a.NewBlockTxSeqN = n
	a.mtx.Unlock()

	replyHandlers.Lock()
	replyHandlers.m[n] = a.newBlockTxOutHandler
	replyHandlers.Unlock()
	for _, addr := range a.GetActiveAddresses() {
		a.ReqNewTxsForAddress(addr.Address)
	}

	n = <-NewJSONID
	a.mtx.Lock()
	a.SpentOutpointSeqN = n
	a.mtx.Unlock()

	replyHandlers.Lock()
	replyHandlers.m[n] = a.spentUtxoHandler
	replyHandlers.Unlock()
	a.UtxoStore.RLock()
	for _, utxo := range a.UtxoStore.s {
		a.ReqSpentUtxoNtfn(utxo)
	}
	a.UtxoStore.RUnlock()
}

// RescanToBestBlock requests btcd to rescan the blockchain for new
// transactions to all wallet addresses.  This is needed for making
// btcwallet catch up to a long-running btcd process, as otherwise
// it would have missed notifications as blocks are attached to the
// main chain.
func (a *Account) RescanToBestBlock() {
	beginBlock := int32(0)

	if a.fullRescan {
		// Need to perform a complete rescan since the wallet creation
		// block.
		beginBlock = a.CreatedAt()
		log.Debugf("Rescanning account '%v' for new transactions since block height %v",
			a.name, beginBlock)
	} else {
		// The last synced block height should be used the starting
		// point for block rescanning.  Grab the block stamp here.
		bs := a.SyncedWith()

		log.Debugf("Rescanning account '%v' for new transactions since block height %v hash %v",
			a.name, bs.Height, bs.Hash)

		// If we're synced with block x, must scan the blocks x+1 to best block.
		beginBlock = bs.Height + 1
	}

	n := <-NewJSONID
	cmd, err := btcws.NewRescanCmd(fmt.Sprintf("btcwallet(%v)", n),
		beginBlock, a.ActivePaymentAddresses())
	if err != nil {
		log.Errorf("cannot create rescan request: %v", err)
		return
	}
	mcmd, err := cmd.MarshalJSON()
	if err != nil {
		log.Errorf("cannot create rescan request: %v", err)
		return
	}

	replyHandlers.Lock()
	replyHandlers.m[n] = func(result interface{}, e *btcjson.Error) bool {
		// Rescan is compatible with new txs from connected block
		// notifications, so use that handler.
		_ = a.newBlockTxOutHandler(result, e)

		if result != nil {
			// Notify frontends of new account balance.
			confirmed := a.CalculateBalance(1)
			unconfirmed := a.CalculateBalance(0) - confirmed
			NotifyWalletBalance(frontendNotificationMaster, a.name, confirmed)
			NotifyWalletBalanceUnconfirmed(frontendNotificationMaster, a.name, unconfirmed)

			return false
		}
		if bs, err := GetCurBlock(); err == nil {
			a.SetSyncedWith(&bs)
			a.dirty = true
			if err = a.writeDirtyToDisk(); err != nil {
				log.Errorf("cannot sync dirty wallet: %v",
					err)
			}
		}
		// If result is nil, the rescan has completed.  Returning
		// true removes this handler.
		return true
	}
	replyHandlers.Unlock()

	btcdMsgs <- mcmd
}

// SortedActivePaymentAddresses returns a slice of all active payment
// addresses in an account.
func (a *Account) SortedActivePaymentAddresses() []string {
	a.mtx.RLock()
	defer a.mtx.RUnlock()

	infos := a.GetSortedActiveAddresses()
	addrs := make([]string, len(infos))

	for i, addr := range infos {
		addrs[i] = addr.Address
	}

	return addrs
}

// ActivePaymentAddresses returns a set of all active pubkey hashes
// in an account.
func (a *Account) ActivePaymentAddresses() map[string]struct{} {
	a.mtx.RLock()
	defer a.mtx.RUnlock()

	infos := a.GetActiveAddresses()
	addrs := make(map[string]struct{}, len(infos))

	for _, info := range infos {
		addrs[info.Address] = struct{}{}
	}

	return addrs
}

// ReqNewTxsForAddress sends a message to btcd to request tx updates
// for addr for each new block that is added to the blockchain.
func (a *Account) ReqNewTxsForAddress(addr string) {
	log.Debugf("Requesting notifications of TXs sending to address %v", addr)

	a.mtx.RLock()
	n := a.NewBlockTxSeqN
	a.mtx.RUnlock()

	cmd := btcws.NewNotifyNewTXsCmd(fmt.Sprintf("btcwallet(%d)", n),
		[]string{addr})
	mcmd, err := cmd.MarshalJSON()
	if err != nil {
		log.Errorf("cannot request transaction notifications: %v", err)
	}

	btcdMsgs <- mcmd
}

// ReqSpentUtxoNtfn sends a message to btcd to request updates for when
// a stored UTXO has been spent.
func (a *Account) ReqSpentUtxoNtfn(u *tx.Utxo) {
	log.Debugf("Requesting spent UTXO notifications for Outpoint hash %s index %d",
		u.Out.Hash, u.Out.Index)

	a.mtx.RLock()
	n := a.SpentOutpointSeqN
	a.mtx.RUnlock()

	cmd := btcws.NewNotifySpentCmd(fmt.Sprintf("btcwallet(%d)", n),
		(*btcwire.OutPoint)(&u.Out))
	mcmd, err := cmd.MarshalJSON()
	if err != nil {
		log.Errorf("cannot create spent request: %v", err)
		return
	}

	btcdMsgs <- mcmd
}

// spentUtxoHandler is the handler function for btcd spent UTXO notifications
// resulting from transactions in newly-attached blocks.
func (a *Account) spentUtxoHandler(result interface{}, e *btcjson.Error) bool {
	if e != nil {
		log.Errorf("Spent UTXO Handler: Error %d received from btcd: %s",
			e.Code, e.Message)
		return false
	}
	v, ok := result.(map[string]interface{})
	if !ok {
		return false
	}
	txHashBE, ok := v["txhash"].(string)
	if !ok {
		log.Error("Spent UTXO Handler: Unspecified transaction hash.")
		return false
	}
	txHash, err := btcwire.NewShaHashFromStr(txHashBE)
	if err != nil {
		log.Errorf("Spent UTXO Handler: Bad transaction hash: %s", err)
		return false
	}
	index, ok := v["index"].(float64)
	if !ok {
		log.Error("Spent UTXO Handler: Unspecified index.")
	}

	_, _ = txHash, index

	// Never remove this handler.
	return false
}

// newBlockTxOutHandler is the handler function for btcd transaction
// notifications resulting from newly-attached blocks.
func (a *Account) newBlockTxOutHandler(result interface{}, e *btcjson.Error) bool {
	if e != nil {
		log.Errorf("Tx Handler: Error %d received from btcd: %s",
			e.Code, e.Message)
		return false
	}

	v, ok := result.(map[string]interface{})
	if !ok {
		// The first result sent from btcd is nil.  This could be used to
		// indicate that the request for notifications succeeded.
		if result != nil {
			log.Errorf("Tx Handler: Unexpected result type %T.", result)
		}
		return false
	}
	sender, ok := v["sender"].(string)
	if !ok {
		log.Error("Tx Handler: Unspecified sender.")
		return false
	}
	receiver, ok := v["receiver"].(string)
	if !ok {
		log.Error("Tx Handler: Unspecified receiver.")
		return false
	}
	blockhashBE, ok := v["blockhash"].(string)
	if !ok {
		log.Error("Tx Handler: Unspecified block hash.")
		return false
	}
	height, ok := v["height"].(float64)
	if !ok {
		log.Error("Tx Handler: Unspecified height.")
		return false
	}
	txhashBE, ok := v["txhash"].(string)
	if !ok {
		log.Error("Tx Handler: Unspecified transaction hash.")
		return false
	}
	index, ok := v["index"].(float64)
	if !ok {
		log.Error("Tx Handler: Unspecified transaction index.")
		return false
	}
	amt, ok := v["amount"].(float64)
	if !ok {
		log.Error("Tx Handler: Unspecified amount.")
		return false
	}
	pkscript58, ok := v["pkscript"].(string)
	if !ok {
		log.Error("Tx Handler: Unspecified pubkey script.")
		return false
	}
	pkscript := btcutil.Base58Decode(pkscript58)
	spent := false
	if tspent, ok := v["spent"].(bool); ok {
		spent = tspent
	}

	// btcd sends the block and tx hashes as BE strings.  Convert both
	// to a LE ShaHash.
	blockhash, err := btcwire.NewShaHashFromStr(blockhashBE)
	if err != nil {
		log.Errorf("Tx Handler: Block hash string cannot be parsed: %v", err)
		return false
	}
	txhash, err := btcwire.NewShaHashFromStr(txhashBE)
	if err != nil {
		log.Errorf("Tx Handler: Tx hash string cannot be parsed: %v", err)
		return false
	}
	// TODO(jrick): btcd does not find the sender yet.
	senderHash, _, _ := btcutil.DecodeAddress(sender)
	receiverHash, _, err := btcutil.DecodeAddress(receiver)
	if err != nil {
		log.Errorf("Tx Handler: receiver address can not be decoded: %v", err)
		return false
	}

	// Add to TxStore.
	t := &tx.RecvTx{
		Amt: uint64(amt),
	}
	copy(t.TxHash[:], txhash[:])
	copy(t.BlockHash[:], blockhash[:])
	copy(t.SenderAddr[:], senderHash)
	copy(t.ReceiverAddr[:], receiverHash)

	a.TxStore.Lock()
	txs := a.TxStore.s
	a.TxStore.s = append(txs, t)
	a.TxStore.dirty = true
	a.TxStore.Unlock()

	// Add to UtxoStore if unspent.
	if !spent {
		// First, iterate through all stored utxos.  If an unconfirmed utxo
		// (not present in a block) has the same outpoint as this utxo,
		// update the block height and hash.
		a.UtxoStore.RLock()
		for _, u := range a.UtxoStore.s {
			if bytes.Equal(u.Out.Hash[:], txhash[:]) && u.Out.Index == uint32(index) {
				// Found a either a duplicate, or a change UTXO.  If not change,
				// ignore it.
				a.UtxoStore.RUnlock()
				if u.Height != -1 {
					return false
				}

				a.UtxoStore.Lock()
				copy(u.BlockHash[:], blockhash[:])
				u.Height = int32(height)
				a.UtxoStore.dirty = true
				a.UtxoStore.Unlock()

				return false
			}
		}
		a.UtxoStore.RUnlock()

		// After iterating through all UTXOs, it was not a duplicate or
		// change UTXO appearing in a block.  Append a new Utxo to the end.

		u := &tx.Utxo{
			Amt:       uint64(amt),
			Height:    int32(height),
			Subscript: pkscript,
		}
		copy(u.Out.Hash[:], txhash[:])
		u.Out.Index = uint32(index)
		copy(u.AddrHash[:], receiverHash)
		copy(u.BlockHash[:], blockhash[:])
		a.UtxoStore.Lock()
		a.UtxoStore.s = append(a.UtxoStore.s, u)
		a.UtxoStore.dirty = true
		a.UtxoStore.Unlock()

		// If this notification came from mempool (TODO: currently
		// unimplemented) notify the new unconfirmed balance immediately.
		// Otherwise, wait until the blockconnection notifiation is processed.
	}

	// Never remove this handler.
	return false
}