package main

import (
	"errors"
	"fmt"
	"io/ioutil"
	"math/rand"
	"os"
	"path"
	"strings"
	"time"

	homedir "github.com/mitchellh/go-homedir"
	croc "github.com/schollz/croc/src"
	"github.com/urfave/cli"
)

var version string
var codePhrase string

var cr *croc.Croc

func main() {
	app := cli.NewApp()
	app.Name = "croc"
	if version == "" {
		version = "dev"
	}

	app.Version = version
	app.Compiled = time.Now()
	app.Usage = "easily and securely transfer stuff from one computer to another"
	app.UsageText = "croc allows any two computers to directly and securely transfer files"
	// app.ArgsUsage = "[args and such]"
	app.Commands = []cli.Command{
		cli.Command{
			Name:        "send",
			Usage:       "send a file",
			Description: "send a file over the relay",
			ArgsUsage:   "[filename]",
			Flags: []cli.Flag{
				cli.BoolFlag{Name: "no-compress, o"},
				cli.BoolFlag{Name: "no-encrypt, e"},
			},
			HelpName: "croc send",
			Action: func(c *cli.Context) error {
				return send(c)
			},
		},
		cli.Command{
			Name:        "gen",
			Usage:       "generate a permanent key",
			Description: "generates a permanent key that is used each time",
			HelpName:    "croc gen",
			ArgsUsage:   "[key]",
			Flags: []cli.Flag{
				cli.BoolFlag{Name: "new", Usage: "overwrite key if it exists"},
			},
			Action: func(c *cli.Context) error {
				homedir, err := homedir.Dir()
				if err != nil {
					return err
				}
				if codePhrase == "" || c.Bool("new") {
					codePhrase = randStringBytesMaskImprSrc(50)
					if c.Args().First() != "" {
						codePhrase = c.Args().First()
					}
					os.MkdirAll(path.Join(homedir, ".config", "croc"), 0644)
					err = ioutil.WriteFile(path.Join(homedir, ".config", "croc", "key"), []byte(codePhrase), 0644)
				}
				fmt.Printf("your permanent key: %s\n", codePhrase)
				fmt.Println("use -new if you want to regenerate your key")
				return err
			},
		},
		cli.Command{
			Name:        "receive",
			Usage:       "receive a file",
			Description: "receve a file over the relay",
			HelpName:    "croc receive",
			Action: func(c *cli.Context) error {
				return receive(c)
			},
		},
		cli.Command{
			Name:        "relay",
			Usage:       "start a croc relay",
			Description: "the croc relay will handle websocket and TCP connections",
			Flags: []cli.Flag{
				cli.StringFlag{Name: "tcp", Value: "27130,27131,27132,27133", Usage: "ports for the tcp connections"},
				cli.StringFlag{Name: "port", Value: "8130", Usage: "port that the websocket listens on"},
				cli.StringFlag{Name: "curve", Value: "siec", Usage: "specify elliptic curve to use (p224, p256, p384, p521, siec)"},
			},
			HelpName: "croc relay",
			Action: func(c *cli.Context) error {
				return relay(c)
			},
		},
	}
	app.Flags = []cli.Flag{
		cli.StringFlag{Name: "relay", Value: "wss://croc3.schollz.com"},
		cli.StringFlag{Name: "code, c", Usage: "codephrase used to connect to relay"},
		cli.BoolFlag{Name: "no-local", Usage: "disable local mode"},
		cli.BoolFlag{Name: "local", Usage: "use only local mode"},
		cli.BoolFlag{Name: "debug", Usage: "increase verbosity (a lot)"},
		cli.BoolFlag{Name: "yes", Usage: "automatically agree to all prompts"},
		cli.BoolFlag{Name: "stdout", Usage: "redirect file to stdout"},
	}
	app.EnableBashCompletion = true
	app.HideHelp = false
	app.HideVersion = false
	app.BashComplete = func(c *cli.Context) {
		fmt.Fprintf(c.App.Writer, "lipstick\nkiss\nme\nlipstick\nringo\n")
	}
	app.Action = func(c *cli.Context) error {
		return cr.Receive(c.Args().First())
	}
	app.Before = func(c *cli.Context) error {
		cr = croc.Init()
		cr.AllowLocalDiscovery = true
		cr.WebsocketAddress = c.GlobalString("relay")
		cr.SetDebug(c.GlobalBool("debug"))
		cr.Yes = c.GlobalBool("yes")
		cr.Stdout = c.GlobalBool("stdout")
		cr.LocalOnly = c.GlobalBool("local")
		cr.NoLocal = c.GlobalBool("no-local")

		// check if permanent code phrase is here
		homedir, err := homedir.Dir()
		if err != nil {
			return err
		}
		keyFile := path.Join(homedir, ".config", "croc", "key")
		if _, err := os.Stat(keyFile); err == nil {
			codePhraseBytes, err := ioutil.ReadFile(keyFile)
			if err == nil {
				codePhrase = string(codePhraseBytes)
			}
		}

		return nil
	}

	err := app.Run(os.Args)
	if err != nil {
		fmt.Printf("error: %s", err.Error())
	}
}

func send(c *cli.Context) error {
	stat, _ := os.Stdin.Stat()
	var fname string
	if (stat.Mode() & os.ModeCharDevice) == 0 {
		fname = "stdin"
	} else {
		fname = c.Args().First()
	}
	if fname == "" {
		return errors.New("must specify file: croc send [filename]")
	}
	cr.UseCompression = !c.Bool("no-compress")
	cr.UseEncryption = !c.Bool("no-encrypt")
	if c.GlobalString("code") != "" {
		codePhrase = c.GlobalString("code")
	}
	return cr.Send(fname, codePhrase)
}

func receive(c *cli.Context) error {
	if c.GlobalString("code") != "" {
		codePhrase = c.GlobalString("code")
	}
	return cr.Receive(codePhrase)
}

func relay(c *cli.Context) error {
	cr.TcpPorts = strings.Split(c.String("tcp"), ",")
	cr.ServerPort = c.String("port")
	cr.CurveType = c.String("curve")
	return cr.Relay()
}

// needed for croc gen
const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)

var src = rand.NewSource(time.Now().UnixNano())

func randStringBytesMaskImprSrc(n int) string {
	b := make([]byte, n)
	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = src.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return string(b)
}