package wallet

import (
	"bufio"
	"context"
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"strings"
	"syscall"

	"github.com/nspcc-dev/neo-go/cli/flags"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
	"github.com/nspcc-dev/neo-go/pkg/rpc/client"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/wallet"
	"github.com/urfave/cli"
	"golang.org/x/crypto/ssh/terminal"
)

var (
	errNoPath         = errors.New("target path where the wallet should be stored is mandatory and should be passed using (--path, -p) flags")
	errPhraseMismatch = errors.New("the entered pass-phrases do not match. Maybe you have misspelled them")
)

var (
	walletPathFlag = cli.StringFlag{
		Name:  "path, p",
		Usage: "Target location of the wallet file.",
	}
	wifFlag = cli.StringFlag{
		Name:  "wif",
		Usage: "WIF to import",
	}
	decryptFlag = cli.BoolFlag{
		Name:  "decrypt, d",
		Usage: "Decrypt encrypted keys.",
	}
	rpcFlag = cli.StringFlag{
		Name:  "rpc, r",
		Usage: "RPC node address",
	}
	timeoutFlag = cli.DurationFlag{
		Name:  "timeout, t",
		Usage: "Timeout for the operation",
	}
	outFlag = cli.StringFlag{
		Name:  "out",
		Usage: "file to put JSON transaction to",
	}
	inFlag = cli.StringFlag{
		Name:  "in",
		Usage: "file with JSON transaction",
	}
	fromAddrFlag = flags.AddressFlag{
		Name:  "from",
		Usage: "Address to send an asset from",
	}
	toAddrFlag = flags.AddressFlag{
		Name:  "to",
		Usage: "Address to send an asset to",
	}
	forceFlag = cli.BoolFlag{
		Name:  "force",
		Usage: "Do not ask for a confirmation",
	}
)

// NewCommands returns 'wallet' command.
func NewCommands() []cli.Command {
	return []cli.Command{{
		Name:  "wallet",
		Usage: "create, open and manage a NEO wallet",
		Subcommands: []cli.Command{
			{
				Name:   "claim",
				Usage:  "claim GAS",
				Action: claimGas,
				Flags: []cli.Flag{
					walletPathFlag,
					rpcFlag,
					timeoutFlag,
					flags.AddressFlag{
						Name:  "address, a",
						Usage: "Address to claim GAS for",
					},
				},
			},
			{
				Name:   "init",
				Usage:  "create a new wallet",
				Action: createWallet,
				Flags: []cli.Flag{
					walletPathFlag,
					cli.BoolFlag{
						Name:  "account, a",
						Usage: "Create a new account",
					},
				},
			},
			{
				Name:   "create",
				Usage:  "add an account to the existing wallet",
				Action: addAccount,
				Flags: []cli.Flag{
					walletPathFlag,
				},
			},
			{
				Name:   "dump",
				Usage:  "check and dump an existing NEO wallet",
				Action: dumpWallet,
				Flags: []cli.Flag{
					walletPathFlag,
					decryptFlag,
				},
			},
			{
				Name:      "export",
				Usage:     "export keys for address",
				UsageText: "export --path <path> [--decrypt] [<address>]",
				Action:    exportKeys,
				Flags: []cli.Flag{
					walletPathFlag,
					decryptFlag,
				},
			},
			{
				Name:   "import",
				Usage:  "import WIF",
				Action: importWallet,
				Flags: []cli.Flag{
					walletPathFlag,
					wifFlag,
					cli.StringFlag{
						Name:  "name, n",
						Usage: "Optional account name",
					},
					cli.StringFlag{
						Name:  "contract",
						Usage: "Verification script for custom contracts",
					},
				},
			},
			{
				Name:  "import-multisig",
				Usage: "import multisig contract",
				UsageText: "import-multisig --path <path> --wif <wif> --min <n>" +
					" [<pubkey1> [<pubkey2> [...]]]",
				Action: importMultisig,
				Flags: []cli.Flag{
					walletPathFlag,
					wifFlag,
					cli.StringFlag{
						Name:  "name, n",
						Usage: "Optional account name",
					},
					cli.IntFlag{
						Name:  "min, m",
						Usage: "Minimal number of signatures",
					},
				},
			},
			{
				Name:      "remove",
				Usage:     "remove an account from the wallet",
				UsageText: "remove --path <path> [--force] <addr>",
				Action:    removeAccount,
				Flags: []cli.Flag{
					walletPathFlag,
					forceFlag,
				},
			},
			{
				Name:        "multisig",
				Usage:       "work with multisig address",
				Subcommands: newMultisigCommands(),
			},
			{
				Name:        "nep5",
				Usage:       "work with NEP5 contracts",
				Subcommands: newNEP5Commands(),
			},
		},
	}}
}

func claimGas(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	defer wall.Close()

	addrFlag := ctx.Generic("address").(*flags.Address)
	if !addrFlag.IsSet {
		return cli.NewExitError("address was not provided", 1)
	}
	scriptHash := addrFlag.Uint160()
	acc := wall.GetAccount(scriptHash)
	if acc == nil {
		return cli.NewExitError(fmt.Errorf("wallet contains no account for '%s'", addrFlag), 1)
	}

	pass, err := readPassword("Enter password > ")
	if err != nil {
		return cli.NewExitError(err, 1)
	} else if err := acc.Decrypt(pass); err != nil {
		return cli.NewExitError(err, 1)
	}

	gctx, cancel := getGoContext(ctx)
	defer cancel()

	c, err := client.New(gctx, ctx.String("rpc"), client.Options{})
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	// Temporary.
	neoHash, err := util.Uint160DecodeStringLE("3b7d3711c6f0ccf9b1dca903d1bfa1d896f1238c")
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	hash, err := c.TransferNEP5(acc, scriptHash, neoHash, 0, 0)
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	fmt.Println(hash.StringLE())
	return nil
}

func addAccount(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	defer wall.Close()

	if err := createAccount(ctx, wall); err != nil {
		return cli.NewExitError(err, 1)
	}

	return nil
}

func exportKeys(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	var addr string

	decrypt := ctx.Bool("decrypt")
	if ctx.NArg() == 0 && decrypt {
		return cli.NewExitError(errors.New("address must be provided if '--decrypt' flag is used"), 1)
	} else if ctx.NArg() > 0 {
		// check address format just to catch possible typos
		addr = ctx.Args().First()
		_, err := address.StringToUint160(addr)
		if err != nil {
			return cli.NewExitError(fmt.Errorf("can't parse address: %v", err), 1)
		}
	}

	var wifs []string

loop:
	for _, a := range wall.Accounts {
		if addr != "" && a.Address != addr {
			continue
		}

		for i := range wifs {
			if a.EncryptedWIF == wifs[i] {
				continue loop
			}
		}

		wifs = append(wifs, a.EncryptedWIF)
	}

	for _, wif := range wifs {
		if decrypt {
			pass, err := readPassword("Enter password > ")
			if err != nil {
				return cli.NewExitError(err, 1)
			}

			pk, err := keys.NEP2Decrypt(wif, pass)
			if err != nil {
				return cli.NewExitError(err, 1)
			}

			wif = pk.WIF()
		}

		fmt.Println(wif)
	}

	return nil
}

func importMultisig(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	defer wall.Close()

	m := ctx.Int("min")
	if ctx.NArg() < m {
		return cli.NewExitError(errors.New("insufficient number of public keys"), 1)
	}

	args := []string(ctx.Args())
	pubs := make([]*keys.PublicKey, len(args))

	for i := range args {
		pubs[i], err = keys.NewPublicKeyFromString(args[i])
		if err != nil {
			return cli.NewExitError(fmt.Errorf("can't decode public key %d: %v", i, err), 1)
		}
	}

	acc, err := newAccountFromWIF(ctx.String("wif"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	if err := acc.ConvertMultisig(m, pubs); err != nil {
		return cli.NewExitError(err, 1)
	}

	if err := addAccountAndSave(wall, acc); err != nil {
		return cli.NewExitError(err, 1)
	}

	return nil
}

func importWallet(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	defer wall.Close()

	acc, err := newAccountFromWIF(ctx.String("wif"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	if ctrFlag := ctx.String("contract"); ctrFlag != "" {
		ctr, err := hex.DecodeString(ctrFlag)
		if err != nil {
			return cli.NewExitError("invalid contract", 1)
		}
		acc.Contract.Script = ctr
	}

	acc.Label = ctx.String("name")
	if err := addAccountAndSave(wall, acc); err != nil {
		return cli.NewExitError(err, 1)
	}

	return nil
}

func removeAccount(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	defer wall.Close()

	addrArg := ctx.Args().First()
	addr, err := address.StringToUint160(addrArg)
	if err != nil {
		return cli.NewExitError("valid address must be provided", 1)
	}
	acc := wall.GetAccount(addr)
	if acc == nil {
		return cli.NewExitError("account wasn't found", 1)
	}

	if !ctx.Bool("force") {
		fmt.Printf("Account %s will be removed. This action is irreversible.\n", addrArg)
		if ok := askForConsent(); !ok {
			return nil
		}
	}

	if err := wall.RemoveAccount(acc.Address); err != nil {
		return cli.NewExitError(fmt.Errorf("error on remove: %v", err), 1)
	} else if err := wall.Save(); err != nil {
		return cli.NewExitError(fmt.Errorf("error while saving wallet: %v", err), 1)
	}
	return nil
}

func askForConsent() bool {
	fmt.Print("Are you sure? [y/N]: ")
	reader := bufio.NewReader(os.Stdin)
	response, err := reader.ReadString('\n')
	if err == nil {
		response = strings.ToLower(strings.TrimSpace(response))
		if response == "y" || response == "yes" {
			return true
		}
	}
	fmt.Println("Cancelled.")
	return false
}

func getGoContext(ctx *cli.Context) (context.Context, func()) {
	if dur := ctx.Duration("timeout"); dur != 0 {
		return context.WithTimeout(context.Background(), dur)
	}
	return context.Background(), func() {}
}

func dumpWallet(ctx *cli.Context) error {
	wall, err := openWallet(ctx.String("path"))
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	if ctx.Bool("decrypt") {
		pass, err := readPassword("Enter wallet password > ")
		if err != nil {
			return cli.NewExitError(err, 1)
		}
		for i := range wall.Accounts {
			// Just testing the decryption here.
			err := wall.Accounts[i].Decrypt(pass)
			if err != nil {
				return cli.NewExitError(err, 1)
			}
		}
	}
	fmtPrintWallet(wall)
	return nil
}

func createWallet(ctx *cli.Context) error {
	path := ctx.String("path")
	if len(path) == 0 {
		return cli.NewExitError(errNoPath, 1)
	}
	wall, err := wallet.NewWallet(path)
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	if err := wall.Save(); err != nil {
		return cli.NewExitError(err, 1)
	}

	if ctx.Bool("account") {
		if err := createAccount(ctx, wall); err != nil {
			return cli.NewExitError(err, 1)
		}
	}

	fmtPrintWallet(wall)
	fmt.Printf("wallet successfully created, file location is %s\n", wall.Path())
	return nil
}

func readAccountInfo() (string, string, error) {
	buf := bufio.NewReader(os.Stdin)
	fmt.Print("Enter the name of the account > ")
	rawName, _ := buf.ReadBytes('\n')
	phrase, err := readPassword("Enter passphrase > ")
	if err != nil {
		return "", "", err
	}
	phraseCheck, err := readPassword("Confirm passphrase > ")
	if err != nil {
		return "", "", err
	}

	if phrase != phraseCheck {
		return "", "", errPhraseMismatch
	}

	name := strings.TrimRight(string(rawName), "\n")
	return name, phrase, nil
}

func createAccount(ctx *cli.Context, wall *wallet.Wallet) error {
	name, phrase, err := readAccountInfo()
	if err != nil {
		return err
	}
	return wall.CreateAccount(name, phrase)
}

func openWallet(path string) (*wallet.Wallet, error) {
	if len(path) == 0 {
		return nil, errNoPath
	}
	return wallet.NewWalletFromFile(path)
}

func newAccountFromWIF(wif string) (*wallet.Account, error) {
	// note: NEP2 strings always have length of 58 even though
	// base58 strings can have different lengths even if slice lengths are equal
	if len(wif) == 58 {
		pass, err := readPassword("Enter password > ")
		if err != nil {
			return nil, err
		}

		return wallet.NewAccountFromEncryptedWIF(wif, pass)
	}

	acc, err := wallet.NewAccountFromWIF(wif)
	if err != nil {
		return nil, err
	}

	fmt.Println("Provided WIF was unencrypted. Wallet can contain only encrypted keys.")
	name, pass, err := readAccountInfo()
	if err != nil {
		return nil, err
	}

	acc.Label = name
	if err := acc.Encrypt(pass); err != nil {
		return nil, err
	}

	return acc, nil
}

func addAccountAndSave(w *wallet.Wallet, acc *wallet.Account) error {
	for i := range w.Accounts {
		if w.Accounts[i].Address == acc.Address {
			return fmt.Errorf("address '%s' is already in wallet", acc.Address)
		}
	}

	w.AddAccount(acc)
	return w.Save()
}

func readPassword(prompt string) (string, error) {
	fmt.Print(prompt)
	rawPass, err := terminal.ReadPassword(syscall.Stdin)
	fmt.Println()
	if err != nil {
		return "", err
	}
	return strings.TrimRight(string(rawPass), "\n"), nil
}

func fmtPrintWallet(wall *wallet.Wallet) {
	b, _ := wall.JSON()
	fmt.Println("")
	fmt.Println(string(b))
	fmt.Println("")
}