path: root/common/common.go

package common

import (
    "fmt"
    "math/big"
    "os"
    "os/user"
    "path"
    "path/filepath"
    "runtime"
    "time"

    "github.com/kardianos/osext"
)

// MakeName creates a node name that follows the ethereum convention
// for such names. It adds the operation system name and Go runtime version
// the name.
func MakeName(name, version string) string {
    return fmt.Sprintf("%s/v%s/%s/%s", name, version, runtime.GOOS, runtime.Version())
}

func DefaultAssetPath() string {
    var assetPath string
    pwd, _ := os.Getwd()
    srcdir := path.Join(os.Getenv("GOPATH"), "src", "github.com", "ethereum", "go-ethereum", "cmd", "mist")

    // If the current working directory is the go-ethereum dir
    // assume a debug build and use the source directory as
    // asset directory.
    if pwd == srcdir {
        assetPath = path.Join(pwd, "assets")
    } else {
        switch runtime.GOOS {
        case "darwin":
            // Get Binary Directory
            exedir, _ := osext.ExecutableFolder()
            assetPath = filepath.Join(exedir, "../Resources")
        case "linux":
            assetPath = "/usr/share/mist"
        case "windows":
            assetPath = "./assets"
        default:
            assetPath = "."
        }
    }

    // Check if the assetPath exists. If not, try the source directory
    // This happens when binary is run from outside cmd/mist directory
    if _, err := os.Stat(assetPath); os.IsNotExist(err) {
        assetPath = path.Join(srcdir, "assets")
    }

    return assetPath
}

func DefaultDataDir() string {
    usr, _ := user.Current()
    if runtime.GOOS == "darwin" {
        return path.Join(usr.HomeDir, "Library/Ethereum")
    } else if runtime.GOOS == "windows" {
        return path.Join(usr.HomeDir, "AppData/Roaming/Ethereum")
    } else {
        return path.Join(usr.HomeDir, ".ethereum")
    }
}

func ToHex(b []byte) string {
    hex := Bytes2Hex(b)
    // Prefer output of "0x0" instead of "0x"
    if len(hex) == 0 {
        hex = "0"
    }
    return "0x" + hex
}

func FromHex(s string) []byte {
    if len(s) > 1 {
        if s[0:2] == "0x" {
            s = s[2:]
        }
        if len(s)%2 == 1 {
            s = "0" + s
        }
        return Hex2Bytes(s)
    }
    return nil
}
func IsWindows() bool {
    return runtime.GOOS == "windows"
}

func WindonizePath(path string) string {
    if string(path[0]) == "/" && IsWindows() {
        path = path[1:]
    }
    return path
}

// The different number of units
var (
    Douglas  = BigPow(10, 42)
    Einstein = BigPow(10, 21)
    Ether    = BigPow(10, 18)
    Finney   = BigPow(10, 15)
    Szabo    = BigPow(10, 12)
    Shannon  = BigPow(10, 9)
    Babbage  = BigPow(10, 6)
    Ada      = BigPow(10, 3)
    Wei      = big.NewInt(1)
)

//
// Currency to string
// Returns a string representing a human readable format
func CurrencyToString(num *big.Int) string {
    var (
        fin   *big.Int = num
        denom string   = "Wei"
    )

    switch {
    case num.Cmp(Douglas) >= 0:
        fin = new(big.Int).Div(num, Douglas)
        denom = "Douglas"
    case num.Cmp(Einstein) >= 0:
        fin = new(big.Int).Div(num, Einstein)
        denom = "Einstein"
    case num.Cmp(Ether) >= 0:
        fin = new(big.Int).Div(num, Ether)
        denom = "Ether"
    case num.Cmp(Finney) >= 0:
        fin = new(big.Int).Div(num, Finney)
        denom = "Finney"
    case num.Cmp(Szabo) >= 0:
        fin = new(big.Int).Div(num, Szabo)
        denom = "Szabo"
    case num.Cmp(Shannon) >= 0:
        fin = new(big.Int).Div(num, Shannon)
        denom = "Shannon"
    case num.Cmp(Babbage) >= 0:
        fin = new(big.Int).Div(num, Babbage)
        denom = "Babbage"
    case num.Cmp(Ada) >= 0:
        fin = new(big.Int).Div(num, Ada)
        denom = "Ada"
    }

    // TODO add comment clarifying expected behavior
    if len(fin.String()) > 5 {
        return fmt.Sprintf("%sE%d %s", fin.String()[0:5], len(fin.String())-5, denom)
    }

    return fmt.Sprintf("%v %s", fin, denom)
}

// Common big integers often used
var (
    Big1     = big.NewInt(1)
    Big2     = big.NewInt(2)
    Big3     = big.NewInt(3)
    Big0     = big.NewInt(0)
    BigTrue  = Big1
    BigFalse = Big0
    Big32    = big.NewInt(32)
    Big256   = big.NewInt(0xff)
    Big257   = big.NewInt(257)
)

func Bench(pre string, cb func()) {
    start := time.Now()
    cb()
    fmt.Println(pre, ": took:", time.Since(start))
}