rand helper

rand.go

package main

import (
        "crypto/sha256"
        "encoding/hex"
        "flag"
        "fmt"
        "math"
        "math/rand"
        "os"
        "strconv"
        "strings"
        "time"
)

var (
        min = flag.Int64("min", 0, "min length of string, int")
        max = flag.Int64("max", math.MaxInt64, "max length of string, int")
        typ = flag.String("type", "int", "available: string, int, time, date")
)

func nmin(i, j int) int {
        if i < j {
                return i
        }
        return j
}

func die(v interface{}) {
        fmt.Fprintln(os.Stderr, v)
        os.Exit(1)
}

func main() {
        flag.Parse()
        if n, err := strconv.ParseInt(os.Getenv("RAND_MIN"), 10, 64); err == nil {
                *min = n
        }
        if n, err := strconv.ParseInt(os.Getenv("RAND_MAX"), 10, 64); err == nil {
                *max = n
        }
        if s := os.Getenv("RAND_TYPE"); s != "" {
                *typ = s
        }
        rand.Seed(time.Now().UnixNano() + int64(os.Getpid()))
        *typ = strings.ToLower(*typ)
        switch *typ {
        case "date", "time":
                *max = 4102444800
        }
        *max -= *min
        n := *min + rand.Int63n(*max)
        switch *typ {
        case "string":
                hash := sha256.New()
                fmt.Fprint(hash, n)
                fmt.Println(hex.EncodeToString(hash.Sum(nil))[:nmin(int(*max), sha256.Size)])
        case "int":
                fmt.Println(n)
        case "time":
                fmt.Println(time.Unix(n, 0).Format("15:04:05"))
        case "date":
                fmt.Println(time.Unix(n, 0).Format("2006-01-02"))
        }
}