package main

import (
	"crypto/ecdsa"
	"crypto/rand"
	"encoding/hex"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"math/big"
	"os"
	"path"
	"strconv"

	"github.com/ethereum/go-ethereum/common"
	crypto2 "github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params"
	clientService "github.com/harmony-one/harmony/api/client/service"
	"github.com/harmony-one/harmony/cmd/client/wallet/lib"
	"github.com/harmony-one/harmony/core/types"
	"github.com/harmony-one/harmony/node"
)

var (
	version string
	builtBy string
	builtAt string
	commit  string
)

func printVersion(me string) {
	fmt.Fprintf(os.Stderr, "Harmony (C) 2018. %v, version %v-%v (%v %v)\n", path.Base(me), version, commit, builtBy, builtAt)
	os.Exit(0)
}

// AccountState includes the balance and nonce of an account
type AccountState struct {
	balance *big.Int
	nonce   uint64
}

var (
	// Account subcommands
	accountImportCommand = flag.NewFlagSet("import", flag.ExitOnError)
	accountImportPtr     = accountImportCommand.String("privateKey", "", "Specify the private key to import")

	// Transfer subcommands
	transferCommand     = flag.NewFlagSet("transfer", flag.ExitOnError)
	transferSenderPtr   = transferCommand.String("from", "0", "Specify the sender account address or index")
	transferReceiverPtr = transferCommand.String("to", "", "Specify the receiver account")
	transferAmountPtr   = transferCommand.Float64("amount", 0, "Specify the amount to transfer")
	transferShardIDPtr  = transferCommand.Int("shardID", -1, "Specify the shard ID for the transfer")

	freeTokenCommand    = flag.NewFlagSet("getFreeToken", flag.ExitOnError)
	freeTokenAddressPtr = freeTokenCommand.String("address", "", "Specify the account address to receive the free token")

	balanceCommand    = flag.NewFlagSet("getFreeToken", flag.ExitOnError)
	balanceAddressPtr = balanceCommand.String("address", "", "Specify the account address to check balance for")
)

// The main wallet program entrance. Note the this wallet program is for demo-purpose only. It does not implement
// the secure storage of keys.
func main() {
	h := log.StreamHandler(os.Stdout, log.TerminalFormat(false))
	log.Root().SetHandler(h)

	// Verify that a subcommand has been provided
	// os.Arg[0] is the main command
	// os.Arg[1] will be the subcommand
	if len(os.Args) < 2 {
		fmt.Println("Usage:")
		fmt.Println("    wallet <action> <params>")
		fmt.Println("Actions:")
		fmt.Println("    1. new           - Generates a new account and store the private key locally")
		fmt.Println("    2. list          - Lists all accounts in local keystore")
		fmt.Println("    3. removeAll     - Removes all accounts in local keystore")
		fmt.Println("    4. import        - Imports a new account by private key")
		fmt.Println("        --privateKey     - the private key to import")
		fmt.Println("    5. balances      - Shows the balances of all addresses or specific address")
		fmt.Println("        --address        - The address to check balance for")
		fmt.Println("    6. getFreeToken  - Gets free token on each shard")
		fmt.Println("        --address        - The free token receiver account's address")
		fmt.Println("    7. transfer")
		fmt.Println("        --from           - The sender account's address or index in the local keystore")
		fmt.Println("        --to             - The receiver account's address")
		fmt.Println("        --amount         - The amount of token to transfer")
		fmt.Println("        --shardID        - The shard Id for the transfer")
		os.Exit(1)
	}

	// Switch on the subcommand
	switch os.Args[1] {
	case "-version":
		printVersion(os.Args[0])
	case "new":
		processNewCommnad()
	case "list":
		processListCommand()
	case "removeAll":
		clearKeystore()
		fmt.Println("All existing accounts deleted...")
	case "import":
		processImportCommnad()
	case "balances":
		processBalancesCommand()
	case "getFreeToken":
		processGetFreeToken()
	case "transfer":
		processTransferCommand()
	default:
		fmt.Printf("Unknown action: %s\n", os.Args[1])
		flag.PrintDefaults()
		os.Exit(1)
	}
}

func processNewCommnad() {
	randomBytes := [32]byte{}
	_, err := io.ReadFull(rand.Reader, randomBytes[:])

	if err != nil {
		fmt.Println("Failed to get randomness for the private key...")
		return
	}
	priKey, err := crypto2.GenerateKey()
	if err != nil {
		panic("Failed to generate the private key")
	}
	storePrivateKey(crypto2.FromECDSA(priKey))
	fmt.Printf("New account created with address:{%s}\n", crypto2.PubkeyToAddress(priKey.PublicKey).Hex())
	fmt.Printf("Please keep a copy of the private key:{%s}\n", hex.EncodeToString(crypto2.FromECDSA(priKey)))
}

func processListCommand() {
	for i, key := range readPrivateKeys() {
		fmt.Printf("Account %d:{%s}\n", i, crypto2.PubkeyToAddress(key.PublicKey).Hex())
		fmt.Printf("    PrivateKey:{%s}\n", hex.EncodeToString(key.D.Bytes()))
	}
}

func processImportCommnad() {
	accountImportCommand.Parse(os.Args[2:])
	priKey := *accountImportPtr
	if priKey == "" {
		fmt.Println("Error: --privateKey is required")
		return
	}
	if !accountImportCommand.Parsed() {
		fmt.Println("Failed to parse flags")
	}
	priKeyBytes, err := hex.DecodeString(priKey)
	if err != nil {
		panic("Failed to parse the private key into bytes")
	}
	storePrivateKey(priKeyBytes)
	fmt.Println("Private key imported...")
}

func processBalancesCommand() {
	balanceCommand.Parse(os.Args[2:])
	walletNode := lib.CreateWalletNode()

	if *balanceAddressPtr == "" {
		for i, address := range ReadAddresses() {
			fmt.Printf("Account %d: %s:\n", i, address.Hex())
			for shardID, balanceNonce := range FetchBalance(address, walletNode) {
				fmt.Printf("    Balance in Shard %d:  %s \n", shardID, convertBalanceIntoReadableFormat(balanceNonce.balance))
			}
		}
	} else {
		address := common.HexToAddress(*balanceAddressPtr)
		fmt.Printf("Account: %s:\n", address.Hex())
		for shardID, balanceNonce := range FetchBalance(address, walletNode) {
			fmt.Printf("    Balance in Shard %d:  %s \n", shardID, convertBalanceIntoReadableFormat(balanceNonce.balance))
		}
	}
}

func processGetFreeToken() {
	freeTokenCommand.Parse(os.Args[2:])
	walletNode := lib.CreateWalletNode()

	if *freeTokenAddressPtr == "" {
		fmt.Println("Error: --address is required")
		return
	}
	address := common.HexToAddress(*freeTokenAddressPtr)

	GetFreeToken(address, walletNode)
}

func processTransferCommand() {
	transferCommand.Parse(os.Args[2:])
	if !transferCommand.Parsed() {
		fmt.Println("Failed to parse flags")
	}
	sender := *transferSenderPtr
	receiver := *transferReceiverPtr
	amount := *transferAmountPtr
	shardID := *transferShardIDPtr

	if shardID == -1 {
		fmt.Println("Please specify the shard ID for the transfer (e.g. --shardID=0)")
		return
	}
	if amount <= 0 {
		fmt.Println("Please specify positive amount to transfer")
		return
	}
	priKeys := readPrivateKeys()
	if len(priKeys) == 0 {
		fmt.Println("No imported account to use.")
		return
	}
	senderIndex, err := strconv.Atoi(sender)
	addresses := ReadAddresses()
	if err != nil {
		senderIndex = -1
		for i, address := range addresses {
			if address.Hex() == sender {
				senderIndex = i
				break
			}
		}
		if senderIndex == -1 {
			fmt.Println("The specified sender account does not exist in the wallet.")
			return
		}
	}

	if senderIndex >= len(priKeys) {
		fmt.Println("Sender account index out of bounds.")
		return
	}

	receiverAddress := common.HexToAddress(receiver)
	if len(receiverAddress) != 20 {
		fmt.Println("The receiver address is not valid.")
		return
	}

	// Generate transaction
	senderPriKey := priKeys[senderIndex]
	senderAddress := addresses[senderIndex]
	walletNode := lib.CreateWalletNode()
	shardIDToAccountState := FetchBalance(senderAddress, walletNode)

	state, ok := shardIDToAccountState[uint32(shardID)]
	if !ok {
		fmt.Printf("Failed connecting to the shard %d\n", shardID)
		return
	}
	balance := state.balance
	balance = balance.Div(balance, big.NewInt(params.GWei))
	if amount > float64(balance.Uint64())/params.GWei {
		fmt.Printf("Balance is not enough for the transfer, current balance is %.6f\n", float64(balance.Uint64())/params.GWei)
		return
	}

	amountBigInt := big.NewInt(int64(amount * params.GWei))
	amountBigInt = amountBigInt.Mul(amountBigInt, big.NewInt(params.GWei))
	tx, _ := types.SignTx(types.NewTransaction(state.nonce, receiverAddress, uint32(shardID), amountBigInt, params.TxGas, nil, nil), types.HomesteadSigner{}, senderPriKey)
	lib.SubmitTransaction(tx, walletNode, uint32(shardID))
}

func convertBalanceIntoReadableFormat(balance *big.Int) string {
	balance = balance.Div(balance, big.NewInt(params.GWei))
	strBalance := fmt.Sprintf("%d", balance.Uint64())

	bytes := []byte(strBalance)
	hasDecimal := false
	for i := 0; i < 11; i++ {
		if len(bytes)-1-i < 0 {
			bytes = append([]byte{'0'}, bytes...)
		}
		if bytes[len(bytes)-1-i] != '0' && i < 9 {
			hasDecimal = true
		}
		if i == 9 {
			newBytes := append([]byte{'.'}, bytes[len(bytes)-i:]...)
			bytes = append(bytes[:len(bytes)-i], newBytes...)
		}
	}
	zerosToRemove := 0
	for i := 0; i < len(bytes); i++ {
		if hasDecimal {
			if bytes[len(bytes)-1-i] == '0' {
				bytes = bytes[:len(bytes)-1-i]
				i--
			} else {
				break
			}
		} else {
			if zerosToRemove < 5 {
				bytes = bytes[:len(bytes)-1-i]
				i--
				zerosToRemove++
			} else {
				break
			}
		}
	}
	return string(bytes)
}

// FetchBalance fetches account balance of specified address from the Harmony network
func FetchBalance(address common.Address, walletNode *node.Node) map[uint32]AccountState {
	result := make(map[uint32]AccountState)
	for shardID, leader := range walletNode.Client.Leaders {
		port, _ := strconv.Atoi(leader.Port)
		client := clientService.NewClient(leader.IP, strconv.Itoa(port+node.ClientServicePortDiff))
		response := client.GetBalance(address)
		balance := big.NewInt(0)
		balance.SetBytes(response.Balance)
		result[shardID] = AccountState{balance, response.Nonce}
	}
	return result
}

// GetFreeToken requests for token test token on each shard
func GetFreeToken(address common.Address, walletNode *node.Node) {
	for shardID, leader := range walletNode.Client.Leaders {
		port, _ := strconv.Atoi(leader.Port)
		client := clientService.NewClient(leader.IP, strconv.Itoa(port+node.ClientServicePortDiff))
		response := client.GetFreeToken(address)

		txID := common.Hash{}
		txID.SetBytes(response.TxId)
		fmt.Printf("Transaction Id requesting free token in shard %d: %s\n", int(shardID), txID.Hex())
	}
}

// ReadAddresses reads the addresses stored in local keystore
func ReadAddresses() []common.Address {
	priKeys := readPrivateKeys()
	addresses := []common.Address{}
	for _, key := range priKeys {
		addresses = append(addresses, crypto2.PubkeyToAddress(key.PublicKey))
	}
	return addresses
}

// storePrivateKey stores the specified private key in local keystore
func storePrivateKey(priKey []byte) {
	privateKey, err := crypto2.ToECDSA(priKey)
	if err != nil {
		panic("Failed to deserialize private key")
	}
	for _, address := range ReadAddresses() {
		if address == crypto2.PubkeyToAddress(privateKey.PublicKey) {
			fmt.Println("The key already exists in the keystore")
			return
		}
	}
	f, err := os.OpenFile("keystore", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)

	if err != nil {
		panic("Failed to open keystore")
	}
	_, err = f.Write(priKey)

	if err != nil {
		panic("Failed to write to keystore")
	}
	f.Close()
}

// clearKeystore deletes all data in the local keystore
func clearKeystore() {
	ioutil.WriteFile("keystore", []byte{}, 0644)
}

// readPrivateKeys reads all the private key stored in local keystore
func readPrivateKeys() []*ecdsa.PrivateKey {
	keys, err := ioutil.ReadFile("keystore")
	if err != nil {
		return []*ecdsa.PrivateKey{}
	}
	priKeys := []*ecdsa.PrivateKey{}
	for i := 0; i < len(keys); i += 32 {
		priKey, err := crypto2.ToECDSA(keys[i : i+32])
		if err != nil {
			fmt.Println("Failed deserializing key data: ", keys[i:i+32])
			continue
		}
		priKeys = append(priKeys, priKey)
	}
	return priKeys
}