package smartcontract

import (
	"bufio"
	"bytes"
	"context"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"github.com/nspcc-dev/neo-go/cli/flags"
	"github.com/nspcc-dev/neo-go/pkg/compiler"
	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
	"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/rpc/request"
	"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/vm"
	"github.com/nspcc-dev/neo-go/pkg/wallet"
	"github.com/pkg/errors"
	"github.com/urfave/cli"
	"golang.org/x/crypto/ssh/terminal"
	"gopkg.in/yaml.v2"
)

var (
	errNoEndpoint          = errors.New("no RPC endpoint specified, use option '--endpoint' or '-e'")
	errNoInput             = errors.New("no input file was found, specify an input file with the '--in or -i' flag")
	errNoConfFile          = errors.New("no config file was found, specify a config file with the '--config' or '-c' flag")
	errNoMethod            = errors.New("no method specified for function invocation command")
	errNoWallet            = errors.New("no wallet parameter found, specify it with the '--wallet or -w' flag")
	errNoScriptHash        = errors.New("no smart contract hash was provided, specify one as the first argument")
	errNoSmartContractName = errors.New("no name was provided, specify the '--name or -n' flag")
	errFileExist           = errors.New("A file with given smart-contract name already exists")

	endpointFlag = cli.StringFlag{
		Name:  "endpoint, e",
		Usage: "trusted RPC endpoint address (like 'http://localhost:20331')",
	}
	walletFlag = cli.StringFlag{
		Name:  "wallet, w",
		Usage: "wallet to use to get the key for transaction signing",
	}
	addressFlag = flags.AddressFlag{
		Name:  "address, a",
		Usage: "address to use as transaction signee (and gas source)",
	}
	gasFlag = flags.Fixed8Flag{
		Name:  "gas, g",
		Usage: "gas to add to the transaction (network fee)",
	}
	sysGasFlag = flags.Fixed8Flag{
		Name:  "sysgas, s",
		Usage: "system fee to add to invocation transaction",
	}
)

const (
	// smartContractTmpl is written to a file when used with `init` command.
	// %s is parsed to be the smartContractName
	smartContractTmpl = `package %s

import "github.com/nspcc-dev/neo-go/pkg/interop/runtime"

func Main(op string, args []interface{}) {
    runtime.Notify("Hello world!")
}`

	// hashesForVerifyingSeparator delimits `invoke*` parameters from hashes for verifying
	hashesForVerifyingSeparator = "--"
)

// NewCommands returns 'contract' command.
func NewCommands() []cli.Command {
	return []cli.Command{{
		Name:  "contract",
		Usage: "compile - debug - deploy smart contracts",
		Subcommands: []cli.Command{
			{
				Name:   "compile",
				Usage:  "compile a smart contract to a .avm file",
				Action: contractCompile,
				Flags: []cli.Flag{
					cli.StringFlag{
						Name:  "in, i",
						Usage: "Input file for the smart contract to be compiled",
					},
					cli.StringFlag{
						Name:  "out, o",
						Usage: "Output of the compiled contract",
					},
					cli.BoolFlag{
						Name:  "verbose, v",
						Usage: "Print out additional information after a compiling",
					},
					cli.StringFlag{
						Name:  "debug, d",
						Usage: "Emit debug info in a separate file",
					},
					cli.StringFlag{
						Name:  "abi, a",
						Usage: "Emit application binary interface (.abi.json) file into separate file using configuration input file (*.yml)",
					},
					cli.StringFlag{
						Name:  "config, c",
						Usage: "Configuration input file (*.yml)",
					},
				},
			},
			{
				Name:  "deploy",
				Usage: "deploy a smart contract (.avm with description)",
				Description: `Deploys given contract into the chain. The gas parameter is for additional
   gas to be added as a network fee to prioritize the transaction. It may also
   be required to add that to satisfy chain's policy regarding transaction size
   and the minimum size fee (so if transaction send fails, try adding 0.001 GAS
   to it).
`,
				Action: contractDeploy,
				Flags: []cli.Flag{
					cli.StringFlag{
						Name:  "in, i",
						Usage: "Input file for the smart contract (*.avm)",
					},
					cli.StringFlag{
						Name:  "config, c",
						Usage: "configuration input file (*.yml)",
					},
					endpointFlag,
					walletFlag,
					addressFlag,
					gasFlag,
				},
			},
			{
				Name:      "invoke",
				Usage:     "invoke deployed contract on the blockchain",
				UsageText: "neo-go contract invoke -e endpoint -w wallet [-a address] [-g gas] [-s sysgas] scripthash [arguments...]",
				Description: `Executes given (as a script hash) deployed script with the given arguments.
   See testinvoke documentation for the details about parameters. It differs
   from testinvoke in that this command sends an invocation transaction to
   the network.
`,
				Action: invoke,
				Flags: []cli.Flag{
					endpointFlag,
					walletFlag,
					addressFlag,
					gasFlag,
					sysGasFlag,
				},
			},
			{
				Name:      "invokefunction",
				Usage:     "invoke deployed contract on the blockchain",
				UsageText: "neo-go contract invokefunction -e endpoint -w wallet [-a address] [-g gas] [-s sysgas] scripthash [method] [arguments...]",
				Description: `Executes given (as a script hash) deployed script with the given method and
   and arguments. See testinvokefunction documentation for the details about
   parameters. It differs from testinvokefunction in that this command sends an
   invocation transaction to the network.
`,
				Action: invokeFunction,
				Flags: []cli.Flag{
					endpointFlag,
					walletFlag,
					addressFlag,
					gasFlag,
					sysGasFlag,
				},
			},
			{
				Name:      "testinvoke",
				Usage:     "invoke deployed contract on the blockchain (test mode)",
				UsageText: "neo-go contract testinvoke -e endpoint scripthash [arguments...] [-- hashesForVerifying...]",
				Description: `Executes given (as a script hash) deployed script with the given arguments
   and hashes to verify using runtime.CheckWitness syscall.
   It's very similar to the tesinvokefunction command, but differs in the way
   arguments are being passed. This invoker does not accept method parameter
   and it passes all given parameters as plain values to the contract, not
   wrapping them them into array like testinvokefunction does. For arguments
   syntax please refer to the testinvokefunction command help.

   Most of the time (if your contract follows the standard convention of
   method with array of values parameters) you want to use testinvokefunction
   command instead of testinvoke.
`,
				Action: testInvoke,
				Flags: []cli.Flag{
					endpointFlag,
				},
			},
			{
				Name:      "testinvokefunction",
				Usage:     "invoke deployed contract on the blockchain (test mode)",
				UsageText: "neo-go contract testinvokefunction -e endpoint scripthash [method] [arguments...] [-- hashesForVerifying...]",
				Description: `Executes given (as a script hash) deployed script with the given method,
   arguments and hashes to verify using System.Runtime.CheckWitness syscall.
   If no method is given "" is passed to the script, if no arguments
   are given, an empty array is passed, if no hashes are given, no array is
   passed. All of the given arguments are encapsulated into array before 
   invoking the script. The script thus should follow the regular convention 
   of smart contract arguments (method string and an array of other arguments).

   Arguments always do have regular Neo smart contract parameter types, either
   specified explicitly or being inferred from the value. To specify the type
   manually use "type:value" syntax where the type is one of the following:
   'signature', 'bool', 'int', 'hash160', 'hash256', 'bytes', 'key' or 'string'.
   Array types are not currently supported.

   Given values are type-checked against given types with the following
   restrictions applied:
    * 'signature' type values should be hex-encoded and have a (decoded)
      length of 64 bytes.
    * 'bool' type values are 'true' and 'false'.
    * 'int' values are decimal integers that can be successfully converted
      from the string.
    * 'hash160' values are Neo addresses and hex-encoded 20-bytes long (after
      decoding) strings.
    * 'hash256' type values should be hex-encoded and have a (decoded)
      length of 32 bytes.
    * 'bytes' type values are any hex-encoded things.
    * 'key' type values are hex-encoded marshalled public keys.
    * 'string' type values are any valid UTF-8 strings. In the value's part of
      the string the colon looses it's special meaning as a separator between
      type and value and is taken literally.

   If no type is explicitly specified, it is inferred from the value using the
   following logic:
    - anything that can be interpreted as a decimal integer gets
      an 'int' type
    - 'true' and 'false' strings get 'bool' type
    - valid Neo addresses and 20 bytes long hex-encoded strings get 'hash160'
      type
    - valid hex-encoded public keys get 'key' type
    - 32 bytes long hex-encoded values get 'hash256' type
    - 64 bytes long hex-encoded values get 'signature' type
    - any other valid hex-encoded values get 'bytes' type
    - anything else is a 'string'

   Backslash character is used as an escape character and allows to use colon in
   an implicitly typed string. For any other characters it has no special
   meaning, to get a literal backslash in the string use the '\\' sequence.

   Examples:
    * 'int:42' is an integer with a value of 42
    * '42' is an integer with a value of 42
    * 'bad' is a string with a value of 'bad'
    * 'dead' is a byte array with a value of 'dead'
    * 'string:dead' is a string with a value of 'dead'
    * 'AK2nJJpJr6o664CWJKi1QRXjqeic2zRp8y' is a hash160 with a value
      of '23ba2703c53263e8d6e522dc32203339dcd8eee9'
    * '\4\2' is an integer with a value of 42
    * '\\4\2' is a string with a value of '\42'
    * 'string:string' is a string with a value of 'string'
    * 'string\:string' is a string with a value of 'string:string'
    * '03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c' is a
      key with a value of '03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c'

   HashesForVerifying represent a set of Uint160 hashes which are used to verify 
   hashes in System.Runtime.CheckWitness syscall. To specify hash use its 
   hex-encoded 160 bit (20 byte) LE representation with optional '0x' prefix. 
   If no hashes were specified, no array is passed.

   Examples:
    * '0000000009070e030d0f0e020d0c06050e030c02'
    * '0x0000000009070e030d0f0e020d0c06050e030c02'
`,
				Action: testInvokeFunction,
				Flags: []cli.Flag{
					endpointFlag,
				},
			},
			{
				Name:      "testinvokescript",
				Usage:     "Invoke compiled AVM code on the blockchain (test mode, not creating a transaction for it)",
				UsageText: "neo-go contract testinvokescript -e endpoint -i testcontract.avm [-- hashesForVerifying...]",
				Action:    testInvokeScript,
				Flags: []cli.Flag{
					endpointFlag,
					cli.StringFlag{
						Name:  "in, i",
						Usage: "Input location of the avm file that needs to be invoked",
					},
				},
			},
			{
				Name:   "init",
				Usage:  "initialize a new smart-contract in a directory with boiler plate code",
				Action: initSmartContract,
				Flags: []cli.Flag{
					cli.StringFlag{
						Name:  "name, n",
						Usage: "name of the smart-contract to be initialized",
					},
					cli.BoolFlag{
						Name:  "skip-details, skip",
						Usage: "skip filling in the projects and contract details",
					},
				},
			},
			{
				Name:   "inspect",
				Usage:  "creates a user readable dump of the program instructions",
				Action: inspect,
				Flags: []cli.Flag{
					cli.BoolFlag{
						Name:  "compile, c",
						Usage: "compile input file (it should be go code then)",
					},
					cli.StringFlag{
						Name:  "in, i",
						Usage: "input file of the program",
					},
				},
			},
		},
	}}
}

// initSmartContract initializes a given directory with some boiler plate code.
func initSmartContract(ctx *cli.Context) error {
	contractName := ctx.String("name")
	if contractName == "" {
		return cli.NewExitError(errNoSmartContractName, 1)
	}

	// Check if the file already exists, if yes, exit
	if _, err := os.Stat(contractName); err == nil {
		return cli.NewExitError(errFileExist, 1)
	}

	basePath := contractName
	fileName := "main.go"

	// create base directory
	if err := os.Mkdir(basePath, os.ModePerm); err != nil {
		return cli.NewExitError(err, 1)
	}

	// Ask contract information and write a neo-go.yml file unless the -skip-details flag is set.
	// TODO: Fix the missing neo-go.yml file with the `init` command when the package manager is in place.
	if !ctx.Bool("skip-details") {
		details := parseContractDetails()
		details.ReturnType = smartcontract.ByteArrayType
		details.Parameters = make([]smartcontract.ParamType, 2)
		details.Parameters[0] = smartcontract.StringType
		details.Parameters[1] = smartcontract.ArrayType

		project := &ProjectConfig{Contract: details}
		b, err := yaml.Marshal(project)
		if err != nil {
			return cli.NewExitError(err, 1)
		}
		if err := ioutil.WriteFile(filepath.Join(basePath, "neo-go.yml"), b, 0644); err != nil {
			return cli.NewExitError(err, 1)
		}
	}

	data := []byte(fmt.Sprintf(smartContractTmpl, contractName))
	if err := ioutil.WriteFile(filepath.Join(basePath, fileName), data, 0644); err != nil {
		return cli.NewExitError(err, 1)
	}

	fmt.Printf("Successfully initialized smart contract [%s]\n", contractName)

	return nil
}

func contractCompile(ctx *cli.Context) error {
	src := ctx.String("in")
	if len(src) == 0 {
		return cli.NewExitError(errNoInput, 1)
	}
	abi := ctx.String("abi")
	confFile := ctx.String("config")
	if len(abi) != 0 && len(confFile) == 0 {
		return cli.NewExitError(errNoConfFile, 1)
	}

	o := &compiler.Options{
		Outfile: ctx.String("out"),

		DebugInfo: ctx.String("debug"),
		ABIInfo:   abi,
	}

	if len(confFile) != 0 {
		conf, err := parseContractConfig(confFile)
		if err != nil {
			return err
		}
		o.ContractDetails = &conf.Contract
	}

	result, err := compiler.CompileAndSave(src, o)
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	if ctx.Bool("verbose") {
		fmt.Println(hex.EncodeToString(result))
	}

	return nil
}

func testInvoke(ctx *cli.Context) error {
	return invokeInternal(ctx, false, false)
}

func testInvokeFunction(ctx *cli.Context) error {
	return invokeInternal(ctx, true, false)
}

func invoke(ctx *cli.Context) error {
	return invokeInternal(ctx, false, true)
}

func invokeFunction(ctx *cli.Context) error {
	return invokeInternal(ctx, true, true)
}

func invokeInternal(ctx *cli.Context, withMethod bool, signAndPush bool) error {
	var (
		err                     error
		gas                     util.Fixed8
		sysGas                  util.Fixed8
		operation               string
		params                  = make([]smartcontract.Parameter, 0)
		paramsStart             = 1
		hashesForVerifying      []util.Uint160
		hashesForVerifyingStart = 0
		resp                    *result.Invoke
		acc                     *wallet.Account
	)

	endpoint := ctx.String("endpoint")
	if len(endpoint) == 0 {
		return cli.NewExitError(errNoEndpoint, 1)
	}

	args := ctx.Args()
	if !args.Present() {
		return cli.NewExitError(errNoScriptHash, 1)
	}
	script := args[0]
	if withMethod {
		if len(args) <= 1 {
			return cli.NewExitError(errNoMethod, 1)
		}
		operation = args[1]
		paramsStart++
	}
	if len(args) > paramsStart {
		for k, s := range args[paramsStart:] {
			if s == hashesForVerifyingSeparator {
				if signAndPush {
					return cli.NewExitError("adding hashes for verifying available for test invokes only", 1)
				}
				hashesForVerifyingStart = paramsStart + k + 1
				break
			}
			param, err := smartcontract.NewParameterFromString(s)
			if err != nil {
				return cli.NewExitError(fmt.Errorf("failed to parse argument #%d: %v", k+paramsStart+1, err), 1)
			}
			params = append(params, *param)
		}
	}

	if len(args) >= hashesForVerifyingStart && hashesForVerifyingStart > 0 {
		for i, c := range args[hashesForVerifyingStart:] {
			h, err := parseUint160(c)
			if err != nil {
				return cli.NewExitError(fmt.Errorf("failed to parse hash for verifying #%d: %v", i+1, err), 1)
			}
			hashesForVerifying = append(hashesForVerifying, h)
		}
	}

	if signAndPush {
		gas = flags.Fixed8FromContext(ctx, "gas")
		sysGas = flags.Fixed8FromContext(ctx, "sysgas")
		acc, err = getAccFromContext(ctx)
		if err != nil {
			return err
		}
	}
	c, err := client.New(context.TODO(), endpoint, client.Options{})
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	if withMethod {
		resp, err = c.InvokeFunction(script, operation, params, hashesForVerifying)
	} else {
		resp, err = c.Invoke(script, params, hashesForVerifying)
	}
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	if signAndPush {
		if len(resp.Script) == 0 {
			return cli.NewExitError(errors.New("no script returned from the RPC node"), 1)
		}
		script, err := hex.DecodeString(resp.Script)
		if err != nil {
			return cli.NewExitError(fmt.Errorf("bad script returned from the RPC node: %v", err), 1)
		}
		txHash, err := c.SignAndPushInvocationTx(script, acc, sysGas, gas)
		if err != nil {
			return cli.NewExitError(fmt.Errorf("failed to push invocation tx: %v", err), 1)
		}
		fmt.Printf("Sent invocation transaction %s\n", txHash.StringLE())
	} else {
		b, err := json.MarshalIndent(resp, "", "  ")
		if err != nil {
			return cli.NewExitError(err, 1)
		}

		fmt.Println(string(b))
	}

	return nil
}

func testInvokeScript(ctx *cli.Context) error {
	src := ctx.String("in")
	if len(src) == 0 {
		return cli.NewExitError(errNoInput, 1)
	}
	endpoint := ctx.String("endpoint")
	if len(endpoint) == 0 {
		return cli.NewExitError(errNoEndpoint, 1)
	}

	b, err := ioutil.ReadFile(src)
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	args := ctx.Args()
	var hashesForVerifying []util.Uint160
	if args.Present() {
		for i, c := range args[:] {
			h, err := parseUint160(c)
			if err != nil {
				return cli.NewExitError(fmt.Errorf("failed to parse hash for verifying #%d: %v", i+1, err), 1)
			}
			hashesForVerifying = append(hashesForVerifying, h)
		}
	}

	c, err := client.New(context.TODO(), endpoint, client.Options{})
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	scriptHex := hex.EncodeToString(b)
	resp, err := c.InvokeScript(scriptHex, hashesForVerifying)
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	b, err = json.MarshalIndent(resp, "", "  ")
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	fmt.Println(string(b))

	return nil
}

func parseUint160(s string) (util.Uint160, error) {
	if len(s) == 2*util.Uint160Size+2 && s[0] == '0' && s[1] == 'x' {
		s = s[2:]
	}
	return util.Uint160DecodeStringLE(s)
}

// ProjectConfig contains project metadata.
type ProjectConfig struct {
	Version  uint
	Contract smartcontract.ContractDetails `yaml:"project"`
}

func parseContractDetails() smartcontract.ContractDetails {
	details := smartcontract.ContractDetails{}
	reader := bufio.NewReader(os.Stdin)

	fmt.Print("Author: ")
	details.Author, _ = reader.ReadString('\n')

	fmt.Print("Email: ")
	details.Email, _ = reader.ReadString('\n')

	fmt.Print("Version: ")
	details.Version, _ = reader.ReadString('\n')

	fmt.Print("Project name: ")
	details.ProjectName, _ = reader.ReadString('\n')

	fmt.Print("Description: ")
	details.Description, _ = reader.ReadString('\n')

	return details
}

func inspect(ctx *cli.Context) error {
	in := ctx.String("in")
	compile := ctx.Bool("compile")
	if len(in) == 0 {
		return cli.NewExitError(errNoInput, 1)
	}
	b, err := ioutil.ReadFile(in)
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	if compile {
		b, err = compiler.Compile(bytes.NewReader(b))
		if err != nil {
			return cli.NewExitError(errors.Wrap(err, "failed to compile"), 1)
		}
	}
	v := vm.New()
	v.LoadScript(b)
	v.PrintOps()

	return nil
}

func getAccFromContext(ctx *cli.Context) (*wallet.Account, error) {
	var addr util.Uint160

	wPath := ctx.String("wallet")
	if len(wPath) == 0 {
		return nil, cli.NewExitError(errNoWallet, 1)
	}

	wall, err := wallet.NewWalletFromFile(wPath)
	if err != nil {
		return nil, cli.NewExitError(err, 1)
	}
	addrFlag := ctx.Generic("address").(*flags.Address)
	if addrFlag.IsSet {
		addr = addrFlag.Uint160()
	} else {
		addr = wall.GetChangeAddress()
	}
	acc := wall.GetAccount(addr)
	if acc == nil {
		return nil, cli.NewExitError(fmt.Errorf("wallet contains no account for '%s'", address.Uint160ToString(addr)), 1)
	}

	fmt.Printf("Enter account %s password > ", address.Uint160ToString(addr))
	rawPass, err := terminal.ReadPassword(syscall.Stdin)
	fmt.Println()
	if err != nil {
		return nil, cli.NewExitError(err, 1)
	}
	pass := strings.TrimRight(string(rawPass), "\n")
	err = acc.Decrypt(pass)
	if err != nil {
		return nil, cli.NewExitError(err, 1)
	}
	return acc, nil
}

// contractDeploy deploys contract.
func contractDeploy(ctx *cli.Context) error {
	in := ctx.String("in")
	if len(in) == 0 {
		return cli.NewExitError(errNoInput, 1)
	}
	confFile := ctx.String("config")
	if len(confFile) == 0 {
		return cli.NewExitError(errNoConfFile, 1)
	}
	endpoint := ctx.String("endpoint")
	if len(endpoint) == 0 {
		return cli.NewExitError(errNoEndpoint, 1)
	}
	gas := flags.Fixed8FromContext(ctx, "gas")

	acc, err := getAccFromContext(ctx)
	if err != nil {
		return err
	}
	avm, err := ioutil.ReadFile(in)
	if err != nil {
		return cli.NewExitError(err, 1)
	}
	conf, err := parseContractConfig(confFile)
	if err != nil {
		return err
	}

	c, err := client.New(context.TODO(), endpoint, client.Options{})
	if err != nil {
		return cli.NewExitError(err, 1)
	}

	txScript, err := request.CreateDeploymentScript(avm, &conf.Contract)
	if err != nil {
		return cli.NewExitError(fmt.Errorf("failed to create deployment script: %v", err), 1)
	}

	sysfee := smartcontract.GetDeploymentPrice(request.DetailsToSCProperties(&conf.Contract))

	txHash, err := c.SignAndPushInvocationTx(txScript, acc, sysfee, gas)
	if err != nil {
		return cli.NewExitError(fmt.Errorf("failed to push invocation tx: %v", err), 1)
	}
	fmt.Printf("Sent deployment transaction %s for contract %s\n", txHash.StringLE(), hash.Hash160(avm).StringLE())
	return nil
}

func parseContractConfig(confFile string) (ProjectConfig, error) {
	conf := ProjectConfig{}
	confBytes, err := ioutil.ReadFile(confFile)
	if err != nil {
		return conf, cli.NewExitError(err, 1)
	}

	err = yaml.Unmarshal(confBytes, &conf)
	if err != nil {
		return conf, cli.NewExitError(fmt.Errorf("bad config: %v", err), 1)
	}
	return conf, nil
}